Document DGe0Lked4wym2ojVvXbVD1DnQ

SUPREME COURT OF THE STATE OF NEW YORK SEVENTH JUDICIAL DISTRICT In Re: Seventh Judicial District Asbestos Litigation SEVENTH JUDICIAL DISTRICT ASBESTOS LITIGATION This Document Applies to: SUPREME COURT OF THE STATE OF NEW YORK COUNTY OF ONTARIO ANNE M. TINKER, Executrix of the Estate of TIMOTHY W. TrNKER, Deceased, and Individually as the Surviving Spouse of TIMOTHY W. TINKER, Plaintiff, CASE NO. 83778 vs. A.E. CLEVITE, INC.,; et al.. Defendants DEFENDANT MACK TRUCKS, INC.'S SUPPLEMENTAL RESPONSES TO PLAINTIFF'S SUPPLEMENTAL REQUEST FOR INSPECTION AND PRODUCTION OF DOCUMENTS Defendant, MACK TRUCKS, INC. ("Mack Trucks"), serves this Supplemental Response to Plaintiff's Supplemental Request for Inspection and Production of Documents dated June 3, 1997. INTRODUCTION AND GENERAL RESPONSE Responses provided herein have been prepared pursuant to a reasonable and duly diligent investigation and search for the information requested. In conducting its business, Mack Trucks has each year created thousands of documents that have been kept in numerous locations and have been moved as the organization changed and as employees changed jobs. Accordingly, Mack Trucks cannot represent that these re sponses contained herein provide all information requested; rather, these responses reflect information obtained before this date by Mack Trucks pursuant to a reasonable and duly diligent search and investigation in those areas where responsive information was expected to be found. To the extent that the request purports to require more, Mack Trucks objects on grounds that include that compliance with the request would impose an undue burden and expense. These responses are intended to be accurate to the best of Mack Truck's knowledge and belief as of the time of the service of this response. To the extent that the responses are not consistent with any previous responses made in other cases, these responses are intended to supersede such earlier responses. Mack Trucks reserves the right to supplement these responses should it discover new information. Some of the discovery requests ask for "all" documents that may pertain to a subject. Mack Trucks objects to requests for any and all of something on grounds that the requests are overly broad and unduly burdensome. You have served Mack Trucks with discovery and yet you already may have some pertinent information or documents, perhaps even some information or documents not received from Mack Trucks. Mack Trucks objects on the grounds that it would be less burdensome, more convenient and less expensive for you to identify what documents you already have that fall within the scope of these requests. This would accomplish several purposes: (a) it would obviate Mack Trucks having to search 2 for and copy documents already in your possession; (b) it would enable Mack Trucks to use the documents provided by you as guides in looking for related material; and it would, if your purposes were to obtain authentication of particular documents, enable Mack Trucks to authenticate the copies provided by you without having to conduct an uninformed search for those documents in Mack Trucks' files. Mack Trucks further objects to requests where the matter sought is neither relevant to the subject matter involved in the pending action nor reasonably calculated to lead to the discovery of admissible evidence. DEFINITIONS As used in Mack Trucks' objections to these requests: (I) "Lack of Relevance" means that a request calls for information which is not relevant to the subject matter of this action and is not reasonably calculated to lead to the discovery of admissible evidence; (ii) "Unduly Burdensome" means that it would be oppressive, time consuming or expensive to require Mack to compile and furnish the information in light of the degree of its relevance and materiality, if any; (iii) "Overly broad" means that such request is overly broad as to scope, time or location; (iv) "Lack of Particularity" means that a request does not state with reasonable particularity the information to be furnished, is vague and ambiguous or incomprehensible; 3 (v) "Improper Assumption" means that a request assumes facts which are not true or accurate; (vi) "Improper Opinion" means that a request improperly calls for an opinion, conclusion, contention or inference; (vii) "Privileged" means a request calls for information protected by the attorney/client privilege or the work-product doctrine or the rule protecting materials prepared in anticipation of or in connection with litigation; and (viii) "Premature" means that a request calls for opinion or contention that relates to fact or the application of law to fact and should not properly be required to be responded to at this time. These comments and objections are incorporated into each Mack response set forth below as if they were set forth in their entirety as they apply to each response. Responses made after objections are not waivers of objections. RESPONSES 1. All asbestos-containing brake and brake products (including but not limited to brake shoes and brake linings, brake pads and brake assemblies), and clutches, clutch facings, and any other clutch products manufactured, distributed, sold or relabeled by Mack Trucks or placed in their vehicles (except automobiles) between 1970 and 1980. RESPONSE: Objections: unduly burdensome, overly broad, lack of particularity. Subject to and without waiving these objections, Mack Trucks states that, after a reasonably diligent search, exemplar brake components containing asbestos sold during 1970-1980 have not been located. 4 Date 23,./?9? i, Florida TO: Michael A. Ponterio, Esq. Lipsitz & Ponterio, LLC 135 Delaware Avenue Suite 506 Buffalo, NY 14202-2410 David M. Lipman, Esq. 5901 S.W. 74 Street Suite 304 Miami, FL 33143-5186 cc: All Counsel of Record CHRIS N. KOLOS, ESQUIRE Florida Bar No.: 438235 MAGUIRE, VOORHIS & WELLS, P.A. Two South Orange Plaza 2 South Orange Avenue Post Office Box 633 Orlando, Florida 32802-0633 Phone: (407) 244-1100 Fax: (407) 423-8796 Attorneys for Defendant, MACK TRUCKS, INC. 5 DIRECT DIAL (407) 244-1185 DIRECT FACSIMILE (407)640-4664 INTERNET E-MAIL CKOU3SQMVW.COM Maguire, Voorhis & Wells, P.A. oMifomeyi atJaa> TWO SOUTH ORANGE PLAZA 2 SOUTH ORANGE AVENUE ORLANDO, FLORIDA 32801 TELEPHONE (407) 244-1100 FACSIMILE (407) 423-8796 P.O. BOX633 ORLANDO, FLORIOA 32802 May 29, 1997 Chris N. Kolos David M. Lipman, Esquire 5901 S.W. 74th Street Suite 304 Miami, Florida 33143 Re: Tinker v. Mack Trucks, Inc., et ai. Ontario County Index No.: 83778 Dear David: Enclosed please find additional documentation responsive to paragraphs 7 and 11 of Plaintiff's First Request to Produce to Mack. These documents consist of relevant portions of Mack's Highway Vehicle Service Manual concerning the maintenance of brakes and clutches and that part of certain engine work involving gaskets. Also enclosed are service bulletins from the 1970 to 1980 time period. Thank you for your attention to this matter. Sincer CNK:jo Enclosures ChVt DIRECT OUL (407)244-1165 OIRECT FAC3RMLE (407)648-4064 INTERNET E-MAIL CKOLOSQMVMr.COM Maguire, Voorhis & Wells, P.A. Cdtfomeytat TWO SOUTH ORANGE PLAZA 2 SOUTH ORANGE AVENUE ORLANDO, FLORIDA 32801 TELEPHONE (407) 244-1100 FACSIMILE (407) 423-8796 PO. 90X633 ORLANOO, FLORIDA 32802 May 29, 1997 Chris N. Kolos David M. Lipman, Esquire 5901 S.W. 74th Street Suite 304 Miami, Florida 33143 Re: Tinker v. Mack Trucks, Inc., et at. Ontario County Index No.: 83778 Dear David: Enclosed please find additional documentation responsive to paragraphs 7 and 11 of Plaintiff's First Request to Produce to Mack. These documents consist of relevant portions of Mack's Highway Vehicle Service Manual concerning the maintenance of brakes and clutches and that part of certain engine work involving gaskets. Also enclosed are service bulletins from the 1970 to 1980 time period. Thank you for your attention to this matter. CNK:jo Enclosures T 1U1 cccc SeMc&vty&tiUf/iotue ELYRIA INSTRUCTION & SERVICE DM OHIO SD-38 DD3 SAFETY ACTUATOR DESCRIPTION Tms Safety Actuator; CD describes the double dia phragm and the suffix 3 denotes the triple action for service, parking and emergency braking. The actuator functions normally as a service brake chamber but in addition has a means of mecr.anicaily locking a brake application so it can safely be used for parking. '.Vith various system arrangements the actuator may be installed to be auto matically or manually applied under emer gency braking conditions. The DD3 Safety Actuator is stud mounted and a selection of actuators are available to fit either vertical or hori zontal standard mounting scud centers. Three (3) connecting lines are used for the actuator installations; to the parking, service and locking ports. In late 1968, desien improvements were incorporated into all ED3 Actuators. Changes incorporated are as follows: 1. The non-pressure plate was redesigned to provide better protection against entrance of water into the roller cavity and non-pressure area. Details of this redesign are: a. A new design cap incorporating an "O" ring and shaft seal. b. A heavier splash plate and gasket. c. Scuds installed ir. "blind holes" replace the T-bolcs used on the old design nonpressure plate. d. .An exhaust check valve in the non-pressure plate to purge the non-pressure cavity area each time the actuator is applied. DD3 SAFETY ACTUATOR RELEASE OF PARKING APPLICATION To -elease a canting appi.iciti.on of the LD3 Actuator, it is necessary to re-appiv air pressure to equal a shaft force approximately cr.e same as '-as usee :n making the parking apoiicarion. This is necessary to release the locking rollers so they car. he moved a**av :rom cr.e snare when air is re-applied to the locking piston. This ci* he accomplished bv making a heaw service application after the control valve is operated :: release the parking application. To release a oarking irpiicaticr., air enters cr.e locking piston and the air on the auxiliary diaphragm is exhauscea. A heavy service brake application will be necessary to force the shaft forward sufficiently to allow tne locking rollers to dis-engage and unlock the shaft. Upon release of the service application, tne return spring will return the shaft to the release position, releasing tne parking application. EMERGENCY OPERATION Throug-. differed system arrangements, the ED3 Safety Actuator in con- ^ junction with otr.er automatic or manual air applied valves will oper ate for emergency situations in the same sequence as described under "Parking". PREVENTIVE MAINTENANCE General - Depending on experience and type of operation, the drain ' slot in the actuator non-pressure plate should be checked and cleared of any restricting road grime, mud, ice, snow, etc. Brakes should be adjusted as is customary with any brake chambers. Push rod travel should be as short as possible -ithout brakes dragging. Excessive travel not only shortens the normal service life of diapr.ragms but gives slow braking response, wastes air, and could possibly result in decreasing crake torque output. Push rod to slack ad:-ster alignment should bt checked in both the applied and released positions, the rod should move out and return properly without binding. .Also, check the angle formed by the slack adjuster arm and push rod. It snould be 90 or greater when the actuator is in the applied cr released positions when brakes are adjusted. EVERY YEAR OR 3600 OPERATING HOURS OR AFTER 100,000 MILES DEPENDING ON TYPE OF OPERATIC Disassemble ED3 Actuator, clean all parts and lubricate locking mechanism. Install new diaphragms and other rubber parts/or parts if they are worn or deterio rated. When diaphragms or return spring or both are replaced, like parts in the correspond ing actuator on the same axle s.-.ould also be replaced. OPERATING AND LEAKAGE CHECKS OPERATING With the actuator m the released position, make several service brake applica tions and note teat actuators apply and release properly. Operate parking cr-.crol valve and observe that actuators apply. While actuators are in a parking position, dram air supply to auxiliary diaphragm and noce that actuators remain applied. Replenish air supply to auxiliary diaphragm. Operate control valve to release parking application, then make a full service application to complete release of actuators. The magnitude of the service brake application to release the brakes may vary on different vehicles due co compressor governor secti.ngs. Normally a service application of approximately *0 psi should release the brakes. LEAKAGE With system pressure up and ED3 actuators in the released position, check drain slot and around the tush rod boot ", ith a soapy solution to detect possible leakage by the locking piston grommet. Make and hold a sen :: brake application and again check the actuator drain slot or exhaust check valve if so et-.pped for servi.ee diaphragm leakage. Continue co hold the service application and coat a-tur.d the servi.ee and auxiliary diaphragm clamping rings with the soapy solution to detect sell leakage. Operate the actuate- control valve co a parking position and check the exhaust port of a service brake application to uetect auxiliary diaphragm leakage. This auxiliary diaphragm leakage detection coi't could be the exhaust pone of the foot brake valve, quick release valve or relay valve c-.nereing svster., While still in a parking position, the aux iliary diaphragm clamping ring ,-ould be roared a11h the soap solution to detect seal leakage. Should leakage be directed at tne clamping rings in either of the above tests, the clamping ring nut * -ould b: tightered even.lv but only enough to stop leakage. If the CD3 Safecv actuator ace? not function as described or leakage is excessive, it is recommended that oe ret-rn.eu c: tne nearest Benci x-W'e s t mg nouse authorized uiscrib- ucor for a factory recc-o i c: one; actuator ur.uer tne repair exc.nar.ge plan. !f this is not possible, tne actuacor can oe -rcaireu .tn gerwine Benoix-W'escingnouse parts in which case DD3 SAFETY ACTUATOR CLEANING AND INSPECTION Wash ill metal parts in a 20od cleaning solvent and dry thoroughly. It is generally recommended that all rubber parts be replaced; however, any rubber parts tr.ac are to be reused should be wiped dry. - Discard felt breather. Inspect all parts for excessive wear or deterioration. Particular attention should be given to the piston and collar bores in the non-pressure plate. The air passage from the 1 ock port to piston bore should be checked for restriction and cleaned; if necessary, remove the inspection plug to thoroughly clean this passage. 4. Rollers should be carefully checked, and all rollers replaced if one or more need replacing. j. Check springs for cracks, distortion, or corrosion. 6. Replace all parts not considered serviceable during these inspections. If servicing older design actuators, it may be necessary to replace existing parts with parts of che newer design which obsolete and supersede parts of the older design actuator. For further information, refer to section titled "Description". ASSEMBLY SOTE: This procedure covers both the old and new design actuators; for further information, refer to "Description" section. 1. Line up parts as they were marked prior to assembly. 2. If che bearing in the non-pressure plate was removed, it should be reinstalled or re placed if necessary. 3. Lubricate piston and collar bores, shaft, piston "O" ring, piston and roller cavity liberally with "Never Seez" lubricant (BW 404--M). 4. Position piston "O" ring in piston bore, then piston with smooth end down against "O" ring. 5. Place collar in its bore (chamfer side down). 6. Coat rollers thoroughly and liberally with "Never Seez" lubricant (BW 404-M) and place eight (8) rollers in groove formed by top of piston and collar ramp. Pack roller cavity liberally with "Never Seez" lubricant (BW 404-M). 3. Place roller spring seat washer on top of rollers. 9. Position cone-shaped roller spring on washer with smaller end to washer. 10. - iNew Design Chlv) Install "0" rings in cap, small "0" ring in inner bore, large "O" ring on outside of cap, making certain "O" rings are properly seated in grooves. 11. (New Design Only) Place seal in bore of cap. Lip of seal should face front of cap. Place retainer spring on seal, position retainer on spring, compress spring, line up cabs on retainer to slots on cap, and lock retainer in cap by turning 1/4 turn counter clockwise. 12. Position cap on roller spring. (SOTE: On new design cap, drain hole in cap should be positioned so that ic lines up with drain area of non-pressure plate.) Press cap down and hold while installing four (4) machine screws evenly and securely. Install new felt breather. 13. (New Design Chly) Turn over non-pressure plate assembly, and install rear seal. Lip of seal faces non-pressure cavity. Install spring retainer, making certain ic is retained in groove of non-pressure plate. 14. install push place return spring (larger end down). iJ. Position push plate and shaft over return spring and press down so shaft moves chrougn lock. The lock should hold shaft position against return spring. If not, check previous assembly procedure. 16. Install separator on service diaphragm, making certain bead on diaphragm engages and retains separator. (SOTE: It Is recommended that a new service diaphragm with separator and a new auxiliary diaphragm be used as a sec and noc mixed with the old style diaphragm fwitnouc separator) in any combination. The new style diaphragm with separator can ana should be used with both the old and new style actuators. CAL'TION: DO NOT ATTEMPT TO INSTALL SEPARATOR IN COMBINATION WITH THE OLD STYLE SERVICE DIAPHRAGM IWITHOUT RETAINING BEAD). BULLETIN NOV. 20, 1970 IMo. Q67 under brakes FOR BRANCHES, DISTRIBUTORS ANO CUSTOMERS. BRAKE DRUM WEAR LIMITS (All Models) PURPOSE To advise field of maximum brake drum wear limits. INFORMATION Maximum allowable wear limits have been estab lished for all size brake drums to aid inspections and provide pro tection in field against over-boring of used drums. These limits are based on nominal drum diameter plus an allowable wear factor. A wear factor of 0.090 inch is assigned to drums up to and including 14 inches and 0.120 inch to drums over 14 inches. To determine _ the actual maximum allowable wear diameter for brake drums up to and including 14 inches, add 0.090 inch (wear factor) to nominal diameter, brake drums over 14 inches add 0.120 inch (wear factor) to nominal brake drum diameter. Present production brake drums have the maximum wear diameter plainly and permanently marked on outside face. RECOMMENDATION Inform and advise personnel of established allowable brake drum limitations. Replace drums if wear limit is exceeded. rtlN H D IN U S A. Service Operations, Allentown. Pa. U. S. A. Mm BULLETIN MAR. 17. 1972 \0. Q68 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. SPRING LOADED BRAKE CHAMBER SERVICING IMPORTANT BULLETIN CAUTION PURPOSE To caution all field personnel to be most careful when working on spring loaded brake chambers. INFORMATION More and more spring loaded brake chambers are being used on trucks of all makes. Spring loaded auxiliary brakes are STANDARD equipment on Mack chassis with either cam or wedge type brakes. Because of this, it is important to remind ail Customer, Distribu tor or Branch service personnel that spring loaded brake chambers contain heavy coil springs which, in many cases, must be retained either in an arbor press, special fixture, safety cage or by com pressing the spring with a stud or capscrew arrangement. Inform mechanics not to just disassemble brake chambers. Units of various styles differ in construction. If in doubt, place units under controlled compression, such as in an arbor press or special fixture. Literature is available on spring loaded brakes as used on Mack trucks. Distribution of various items has been made in the past, however, any of the following literature can be obtained through Mack Service outlets. Requests from these locations will be for warded to the Technical Service Department at Allentown, Pa. for handling. CAUTION It is extremely important to use a retaining method on all spring brake chambers. The spring is under heavy compression and, if improperly handled, can expand rapidly with great force and cause injury. As a guide, the following methods of retention are used by the spring brake manufacturers: ANCHORLOK Remove release stud assembly from carrying pocket built into chamber body. Remove dust cap and insert stud into pressure plate. Turn one quarter turn to capture pressure plate. Tighten nut on stud until spring is fully caged. HINTED IN USA (Continued Over) U. BULLETIN MAY 5, 1972 No. Q69 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. ROCKWELL-STANDARD COMPANY (Technic Aid (Brakes) Bulletins) PURPOSE To advise the field of current service information affecting Rockwell-Standard brake components supplied to Mack Trucks, Inc. INFORMATION Service information covering Rock well-Standard brakes will be issued periodically and will be mailed individually without an accompanying bulletin or other publication. Rockwell-Standard brake bulletins received are to be filed in Brakes section of your bulletin binder, immediately follow ing this bulletin. File by Aid number sequence, not date of receipt, to facilitate location of desired information. RECOMMENDATION File attached Rockwell-Standard Technic Aid #54 as described herein. Advise all personnel dealing with Rockwell Standard brake components of this information. MINTED IN U SA Sprvirp OnpraHnn. ATIpntnwn Pa TT C A AUG. 29, 1972 FOR BRANCHES. DISTRIBUTORS ANO CUSTOMERS. BULLETIN No. Q7o under brakes fllN llD IN U SA TRAILER HAND BRAKE CONTROL VALVE (All Chassis So-equipped) PURPOSE To caution field subject control valve is not to be used as a parking brake control. INFORMATION Reports received indicate attempts have been made to utilize the trailer hand brake control valve as a unit parking brake control. This control valve is designed to activate the trailer brakes independently of the chassis brakes. The control valve provides a finely graduated means of applying and releasing the brakes and, therefore, does not contain detents or lock positions to hold brakes in "ON" position; however, when control valve is new, there is a possibility the control will remain in the "ON" position due to the friction drag on the new parts. This is a false setting and will dis appear as the control valve wears in. To stress the fact this con trol valve is not to be used as a parking brake control, "NOT FOR PARKING" is embossed on top of control handle. RECOMMENDATION Advise all concerned of this bulletin on proper operation of trailer hand brake control valve. CIRCULAT] 01 Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadm an Inspector Leadman Inspector Leadm an Unit Over haul Room Shop Office r*__ SERVICE BULLETIN DEC. 22, 1972 No. Q7i under brakes cOH BRANCHES. DISTRIBUTORS AND CUSTOMERS. fltN U O IN U $ A BENDIX-WESTINGHOUSE SERVICE BULLETINS (All Vehicles with Bendlx-Westinghoilse Equipment) PURPOSE To advise field of current service bulletins supplied by Bendix-Westinghouse to Mack Trucks, Inc. INFORMATION Service bulletins covering Bendix-Westinghouse equipment will be issued periodically and will be mailed individually without an accompanying bulletin or other publication. BendixWestinghouse service bulletins received are to be filed in Brakes section of your bulletin binder, immediately following this bulletin. File by service bulletin number sequence, not date of receipt, to facilitate location of a desired bulletin. Bendix-Westinghouse parts are to be ordered through Mack parts outlet in the usual manner. In lieu of a Mack number, the BendixWestinghouse part number with the numeral 745 prefixed (e.g. 745282633) is to be used when ordering Bendix-Westinghouse parts. RECOMMENDATION File the attached Bendix-Westinghouse service bulletin 242 following this bulletin. Inform all personnel dealing with Bendix-rWestinghouse of this procedure and emphasize importance of using the code prefix when ordering parts. CIRCULATI Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room Service ODerations. Allentown, Pa. U. S.A. Shop Office Mack. r r BULLETIN JUNE 8, 1973 No. Q72 under brakes FOR BRANCHES. DISTRIBUTORS ANO CUSTOMERS. BRAKE LINING FASTENERS (All Models with Roctcweli "P" Series Brakes) PURPOSE To inform field of a brake lining rivet change and the availability of brake lining bolts. INFORMATION Effective March 1, 1973 all brake lining will be secured with 1/4 inch rivets in place of 3/16 inch rivets used pre viously. When replacing brake lining, drill the brake shoes to ac cept the new 1/4 inch rivets. Where service facilities are not equipped with a rivet machine, a brake shoe lining bolt is available for securing the lining to the brake shoe. Parts required: Part No. 8235-15X882 20AX1 36AX1 Description Brake Shoe Lining Bolt Nut, 1/4-28 Lockwasher, 1/4 inch Rivet Replaces 341SZ110-P2 or 341SZ113 Installation Instructions 1. Position the lining on the brake shoe so the holes in the lining and shoe are in perfect alignment. 2. Clamp the lining to the shoe with "C" clamps. Locate the clamps as close to the holes as possible. 3. Line drill the lining and brake shoe holes 0.261 inch diameter using a "G'' drill or 0.257 inch with an "F" drill. 4. Secure the lining to the brake shoes with the bolts, nuts and lockwashers in the sequence shown in the illustration. Torque the nuts to 84 lb. in. and remove the "C" clamps. RECOMMENDATION When replacing brake lining, secure the lining to the brake shoes as instructed herein. Parts are available now. 44 CmCULAT Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Roorr rilN ItO IN U S * Shop Office Mnrb BULLETIN JULY 5, 1973 No. Q73 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. BRAKE CHAMBER (Anchorlok) PURPOSE To advise of improved diaphragm and boot available for service re placement. INFORMATION Short service life of diaphragm and boot used in brake chambers 19QE430-P1, P2, P3andP4 may occur under some conditions, such as construction service or use of hand control valve in conjunction with service brakes. To insure longer life of these components, an improved diaphragm and boot have been made available. They will be supplied in kit form under part number 6152-11M26934. When replacing diaphragm, it is recommended that chamber be re moved from vehicle and cleaned thoroughly. Install both diaphragm and boot contained in kit. WARNING When working with spring brake ar rangements DO NOT remove spring brake clamp (at end of assembly away from actuating clevis) from assembly without compressing heavy spring with special release tool contained in car rying pocket built into chamber body. RECOMMENDATION Use new kit listed in bulletin for all future service require ments. Do not use previous service diaphragm 64SM28A in Anchorlok brake cham bers. Present stock of 64SM28A can be used in other vendor chambers. This is a product improvement. CIRCULAT Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room niN T ID IN USA Service Operations, Allentown, Pa. U.S.A. Shop Office Mack SERVICE BULLETIN JULY 5, 1973 IMo. Q74 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. BRAKE ACTUATING WEDGE (All with Rockwell-Standard i5x7" Wedge Brakes) PURPOSE To point out that two different wedge angles have been used on these brake assemblies and to caution against intermixing wedges with different angles on an Individual chassis. INFORMATION At various times, wedges with an angle of either 12 or 14 degrees have been used in production on these brake as semblies. Intermixingwedges withdifferent angles, as might occur during brake repairs, willresult In unbalanced braking action. Be cause of this possibility, wedges should be Inspected when brakes are serviced and any having wrong angle, replaced. Also, check plunger angle which must be same as wedge. The angle is marked on both parts for easy identification. See Illustration for arrange ment. NINTH) IN Ul-A. RECOMMENDATION During routine servicing or when investigating brake com plaints, check wedge and plunger angle and replace any that are of incorrect angle. Be sure tlat all brake assemblies on a particular chassis have wedges and plungers with same angle. CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room Shop Office BULLETIN OCT. 25, 1973 l\lo. Q75 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. INITIAL BRAKE ADJUSTMENT WITH AUTOMATIC SLACK ADJUSTERS (All Models with Eaton Automatic Slack Adjusters) PURPOSE To inform field of correct method of brake adjustmert after a brake overhaul (new lining) on subject models. INFORMATION Whenever new brake lining has been installed on a chassis with Eaton automatic slack adjusters, the brakes must be adjusted as follows: 1. Remove the 1/4 in. pipe plug on the slack adjuster to expose the worm shaft. See illustration. 2. With a 1/4 in. male hex wrench (Allen), turn the worm shaft clockwise until the brake shoes are tight against the drum. NOTE Backing off the slack adjuster requires much more force than taking up the slack adjuster. 3. Back off the worm shaft counterclockwise, approximately 3/4 of a turn until wheel drag is eliminated. NOTE The Eaton automatic slack adjuster is lubri cated for life; no further lubrication is necessary. 4. Reinstall the 1/4 in. pipe plug in the slack adjuster. RECOMMENDATION When new brake lining has been installed on subject vehi cles, adjust the brakes as described herein. rtlNTfO IN USA (Continued Over) Service Operations, Allentown, Pa. U.S.A. Mack SERVICE BULLETIN NOV. 27, 1973 No. Q76 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. AUTOMATIC SLACK ADJUSTER OVER ADJUSTMENT (All Models with Eaton Automatic Slack Adjusters) PURPOSE To inform the field howto correct over adjustment of automatic slack adjusters. INFORMATION Under certain conditions, Eaton automatic slack adjusters may over adjust and cause the brakes to drag. If not cor rected, this will result in shortened brake lining and drum life. To correct over adjustment, replace the 1/4 in. link pin securing the connecting drive link to the clevis with an undersize link pin, part no. 2719-1000657. NOTE The link pins are specially hardened and ground pins and no substitution must be made. After the undersize link pin is installed the brake must be adjusted as follows: 1. Remove the 1/4 in. pipe plug on the slack adjuster to expose the worm shaft. 2. With a 1/4 in. male hex wrench (Allen), turn the worm shaft clockwise until the brake shoes are tight against the drum. NOTE Backing off on the slack adjuster re quires much more force than taking up on the slack adjuster. 3. Back off the worm shaft counterclockwise, approximately 3/4 of a turn, until wheel drag is eliminated. 4. r Reinstall the 1/4 in. pipe plug in the slack adjuster. RECOMMENDATION To correct over adjustment of Eaton automatic slack ad justers, install the undersize link pins and adjust brakes as outlined herein. PUNTED N USA. Marhr _ A llaviTnwn Pa . TT. S. A SERVICE BULLETIN JAN. 15, 1974 No. Q78 FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. under brakes PRESSURE REDUCING VALVE (All with Hand Control Valve for Rear Service Brakes) PURPOSE To recommend installation of a pressure reducing valve in the hand control valve circuit if operating conditions require considerable use of the hand control valve. INFORMATION When the rear wheel brakes are applied by the hand control valve a surge of pressure, equal to full reservoir pressure, is admitted to the brake chambers. This is more pres sure than required for parking and creates unnecessary wear on the brake diaphragm. The pressure reducing valve limits pressure at hand control valve to 60 psi, thereby prolonging diaphragm life. The pressure reducing valve is Bendix-Westinghouse part number 282811. This valve is not stocked by Mack and must be obtained locally. It is installed in the hand control valve supply line. The supply port is at the end opposite the adjusting cap and the delivery port is on side of valve body. The mounting arrangement will have to be determined locally. RECOMMENDATION Install the pressure reducing valve if use of hand control valve causes reduced diaphragm life. This is a product improvement to be installed only when unusual operating conditions require it. CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room rtlN U O IN U SA. Shop Office Service Operations, Aiientown, Pa. U.S.A. Mac BULLETIN MARCH 19, 1974 No. Q79 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNQ-'HAYWARDH'OAKVILLEQ'' BRAKE CAMSHAFT (SW5711C and 5731C with Eaton 16-1/2 x 7 Cam Brake) PURPOSE To inform service personnel that the camshaft on these brake assemblies does not require periodic lubrication and to advise against installing a grease fitting. INFORMATION The camshaft on Eaton brake assembly 1QDA4220 is "lubed for life" at time of manufacture and normally does not require additional lubrication. To insure against the entrance of contaminants, the lubrication passage is sealed with a plug. This plug should be left in place while chassis is in operation. Do not replace it with a grease fitting. If the camshaft is removed or replaced during brake repairs, it must be lubricated at assembly. Remove the plug, install a grease fitting and apply MG-A grease in the normal manner. Remove fitting when lubrication is completed and reinstall plug. RECOMMENDATION Advise everyone concerned with lubrication that Eaton brake camshafts do not require periodic lubrication and that the plug used to seal the grease passage should not be replaced with a grease fitting. CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room rtlN H O IN U SA. r>n TT G A Shop Office Mnrh RVIC BULLETIN MAY 27. 1375 No. Q8i under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. . / CHASSIS AFFECTED ALLENTOWN0 HAYWARDS! OAKVILLESf BRAKE SHOE SUPPORTS (SW56. 57, 571. 573, 76, 59, 592 ana 68 Series Bogies with Rockwell-Standard Cam Brakes) PURPOSE To inform service personnel of an improvement that can be added at time of braxe overhaul. CIRCULATION Service Manaeer Shop Foreman Night Foreman Night Foreman Inspector Leadman 'nspectov .eadman Inspector Leadman Unit Over haul Room INFORMATION Current brake assemblies incorporate brake shoe supports. These items stabilize the shoes and extend life of shoe and spider anchor pin bores, camshaft splines and bushings and slack adjuster splines. The parts required are contained in kit form and installation is shown in sam ple instruction sheets. Parts required: Bogie Brake Shoe Support Kit SW56C,57C,571C,573C and76C Series 8235 - MPS2008 SW59C, 592C Series 124QE220 SW68C Series 124QE219 * Each kit services one axle (Two wheels) Before installing brake shoe supports, check lateral movement of brake shoes at cam head. If it is 3/8 inch or less, add the shoe supports to existing spiders (if not already installed), do not replace spiders. Shop Office If shoe movement exceeds 3/8 inch, replace spiders. Replace only spi ders that are unusable: it is not necessary to replace in pairs or sets. New service spider assemblies will have provision for shoe supports. Consult with your Mack branch or distributor for part number of latest spiders and related parts. RECOMMENDATION Install brake shoe supports when rebuilding subject brake assemblies if lateral movement of shoes is within limit specified in bulletin. This is a product im provement to be made at customers option and expense. Attachment to Service Bulletin ________ BRAKE SHOE SUPPORT KIT ________ Q81 BRAKES (1-3/4" and 2-1/2" Spider Offset Cast Shoes) Mack SW59C, 592C and 68C Bogies INSTALLATION INSTRUCTIONS: 1. With 1/2 inch thick brake spider flange: a. Remove four (4) mounting bolts shown. b. Select and position 1/4 inch spac ing washer under hole locations marked "X'.' For 1.75 Spider Offset (4) 3280-M-6123 Shoe Support Pads For 2.50 Spider Offset (2) 3280-N-6124 Shoe Support Pads (2) 3280-P-6126 Shoe Support Pads c. Use feeler and measure clearance between shoe web and shoe support bracket (See View A). d. Select proper thin shim washer as measured. Install shim washer under sup port pad at the mounting bolt to nearest .032. VIEW A e. Retorque mounting bolts to 210 270 ft. lbs. for .625 diameter bolt, 365 470 ft. lbs. for .750 diameter bolt. f. Drill one .312 diameter hole in shoe web located by scribing a radius off of the anchor pin center of 9-3/4 and a radius off of the roller pin center of 5-15/16. (See View B.) g. Bolt shoe spring clip to underside of shoe for both forward and reverse shoes with 1/4 inch diameter capscrew, lockwasher and nut provided. (See View C.) Torque capscrew to 14 - 18 ft. lbs. h. Position shoe support between spring clip and shoe web in proper working position. Clip should provide approximately 65 lbs. lateral support force against the shoe support bracket. Check for free return at brake shoe against camhead by normal shoe return spring action. Lubricate if necessary. 2. With 3/4 inch thick brake spider flange: SAMPLE INSTRUCTION SHEET a. Remove cast spider material shown in View D flush with mounting face both sides shown shaded. b. Follow steps a through h above, but do not-use 1/4 spacer washer. SERVICE BULLETIN FEBRUARY 6, 1976 No. Q82 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWND HAYWARDEf OAKVILLE ANTI-WHEEL LOCK WIRING (Mack Western RL, RS, WL and WS Models with MVSS121 Brake System) PURPOSE To advise of a change in the anti-wheel lock warning unit wiring. RECOMMENDATION Inform all service personnel of the revised wiring and stress importance of determining which system is in use before attempting to diagnose a malfunction. INFORMATION Starting October 19, 1975, connections at the antiwheel lock warning unit "W" terminals were changed. Connections for current and non-current chassis are as follows. Chassis built on and after October 19, 1975 Two-axle vehicles - W1 terminal monitors steering axle W2 terminal monitors rear axle Three-axle vehicles - W1 terminal monitors steering axle W2 terminal monitors bogie forward axle (no change) W3 terminal monitors bogie rear axle Chassis built prior to October 19, 1975 Two-axle vehicles - W1 terminal monitors rear axle W2 terminal monitors steering axle Three-axle vehicles - W1 terminal monitors bogie rear axle W2 terminal monitors bogie forward axle W3 terminal monitors steering axle When trouble shooting the anti-wheel lock system determine, either by build date or physically tracing the wiring, which system is used. This practice will insure that time is not lost checking the wrong axle related components. CIRCULATION Service Manager Shop Foreman Might Foreman Might Foreman inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room i !i fllN ltO IN U SA. Service Operations, AUentewn, Pa. U.S.A. Shop Office Mack BULLETIN FEBRUARY 9. 1976 Mo. 083 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWN^HAYWARD^OAKVILLE!Ef SPRING BRAKE VALVE (All with MVSS121 Brake Systems) PURPOSE To recommend that operation of subject valve be checked periodically. RECOMMENDATION Check performance of the spring brake valve regularly, following the procedure and schedule given in bulletin. INFORMATION The spring brake (SR-1) valve supplies a specific limited hold-off pressure to the spring brakes and. in the event air is lost in the primary brake system, it modulates the spring brakes through the treadle valve. In normal operation, internal parts of the valve undergo little or no movement and as a result could corrode and become inoperative over a period of time. To insure that the SF-1 valve will function in an emergency, it's operation should be checked every 24.000 miles or at 3 months maximum. In addition to verifying correct valve operation, the checking procedure 'exercises" the valve and helps to maintain it in good operating condition. The SR-1 valve (20QE3110R) is located as follows: F and MB - under cab on right hand frame rail. R, RD. FM, DM. DMM and U - on crossmember just behind cab. RL and RS - front of cowl, ahead of air vent WL and WS - under left hand splash shield, back of head light. CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman inspector Leadman Unit Over haul Room F tlN ltO IN USA. (Continued Over) Service Operations. Allentown. Pa. U.S.A. Shop Office Mack BULLETIN FEBRUARY 26, 1976 No. Q84 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWN0 HAYWARDGjf OAKVILLEEf AIR RESERVOIR CHECK VALVE (All Vehicles with MVSS121 Brake System) PURPOSE To inform service personnel of a repair kit for subject valve. RECOMMENDATION Repair a malfunctioning check valve by installing the kit an nounced in this bulletin. INFORMATION Repair kit 5396-RN10FB has been made available to service inline check valve 20QE1237R. This is the check valve (two required) that is mounted on the primary and secondary res ervoirs (see illustration). The repair kit contains improved parts, consisting of a cap, cap O-ring, spring and rubber valve. The kit parts can be installed without removing valve from system. Be sure all air is drained from affected tank, then remove and discard cap, cap O-ring, spring and valve. Check for and remove broken parts in valve body. Install the new parts as shown in illus tration. Parts available March 15, 1976 BODY' CHECK VALVE 20QE 1237R AIR COMPRESSOR GOVERNOR. AIR COMPRESSOR CIRCULAT Service Manager Shop Foreman Night Foreman iftght Foreman Inspector Leadman Inspector Leadm an Inspector Lea dm an Unit Over haul Room rtiN ito in u s a Shop Office RVIC BULLETIN APRIL 30. 1976 No. Q85 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNtZf HAYWARDD OAKVILLE RELAY VALVE RELOCATION (Models R, RD. RM. DM and DMM with SW6&1 Series Bogies) PURPOSE To eliminate an interference condition. RECOMMENDATION Follow instructions contained herein when interference exists between the relay valve and the forward axle carrier. INFORMATION During extreme articulation an interference con dition may exist between the spring brake relay valve and the bogie forward axle carrier housing cover. To correct interference, the spring brake relay valve must be moved forward on the frame sidemember. 1. Drain air tanks and disconnect all air connections to the spring brake relay valve except the "Balance" line connection. 2. Move relay valve six inches forward on the frame sidemember. Use relay valve as template and drill two 0. 406 inch diameter mounting holes. Secure the relay valve in new location. 3. Shorten the "Reservoir Double Check Valve to Relay Valve Supply Line" six inches. Use a new 1/2 inch diameter compression sleeve (ferrule), 52AX50017. and secure the line to the relay valve. 4. Shorten the "Spring Brake Control Valve Delivery to Relay Valve Line" six inches. Use a new 3/8 inch diameter compression sleeve (ferrule). 52AX5001S, and secure the line to the relay valve. 5. Remove the "Relay Valve Delivery to Pear Axle Line" and replace with new air line tubing, 101AX126RF50. six inches longer. Do not splice old tubing. Salvage connectors from replaced line and use two new 1/2 inch diameter compression sleeves (ferrules). 52AX50017. and install new line. 6. Test for air leaks and valve operation and return to service. CIRCULATIC Service Manager Shop Foreman Night Foreman Might Foreman inspector Leadman Inspector Leadman inspector Leadman Unit Over haul Room M iN ItO IN U S A /-\_ 11 TT C Shop Office Mnnh SERVICE BULLETIN OCTOBER 25, 1976 No. Q88 under brakes FOR BRANCHES. DISTRIBUTORS ANO CUSTOMERS. / S/ CHASSIS AFFECTED ALLENTOWN0 HAYWARD OAKVILLE RADIO FREQUENCY INTERFERENCE (All Vehicles Equipped with Anti-Wheel Lock Brake System) PURPOSE To inform owners and operators of the possibility that field installed electrical equipment may affect operation of the anti-wheel lock system. RECOMMENDATION Perform the test outlined in this bulletin if additional electrical equipment is Installed on subject vehicles. INFORMATION It is possible for some electrically powered or controlled equipment to cause interference with the operation of other vehicle components. This interference may be conducted or radiated and is dependent on frequency and power level of the added equipment. If additional electrical equipment is installed in the field, the operator or installer must be certain any signals generated by this equipment will not adversely affect existing components. This precaution is particularly important on vehicles equipped with an anti-wheel lock brake system. To insure that added electrical equipment is compatible with the anti-wheel lock components, the following test should be made. 1. Perform check procedure with vehicle stationary, engine running, and brake air system at normal operating pressure. 2. Depress and hold brake pedal at full application pressure. 3. Operate the added equipment in all its starting, running, and shut-down modes. Listen for air exhausting from the anti wheel lock controllers and also observe the anti-lock warning light to see if it is illuminated. 4. If air is exhausted from the controllers and/or the anti-lock warning light is illuminated momentarily or constantly, an interference condition exists which must be eliminated before the chassis is released for service. CIRCULATION Service Manager Shop Foreman Night Foreman blight Foreman inspector Leadm an Inspector Leadmaa Inspector Leadman Unit Over haul Room HINTED IN U SA. Service Ooerations. AlleJIttJWn. Pa. U.S.A. Shop Office Mack. SERVICE BULLETIN NOVEMBER 24, 1976 |\|0* Q89 Under BRAKES FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNQ^HAYWARDS^OAKVILLE BRAKE IMPROVEMENTS (All with Stopmaster II 15 x 7 Wedge Brakes) PURPOSE To advise of improved parts for the self-adjusting mechanism. RECOMMENDATION Install the new parts listed in bulletin when overhauling the brakes or if existing adjusters bottom out with a useable amount of lining left. INFORMATION Early production cf Stopmaster II brake assemblies had a limited travel adjusting bolt. These brakes reach their maximum adjustment before the lining is worn to the rivet heads. A new adjusting bolt is used in current production brake assemblies that permits additional lining wear. This bolt does not have the retainer ring to serve as a stop, thereby allowing full length of the bolt for adjustment. A new actuator is required with this bolt. See Figure 1 for details of this change. rtIN H D IN U SA. FULL LENGTH THREADS IN ACTUATOR RETAINER RING NOT USED SEAL ACTUATOR ADJUSTING BOLT -- CURRENT NON<URRENT FIGURE 1 ADJUSTING BOLT AND ACTUATOR ACTUATOR COUNTER BORED FOR RETAINER RING CLEARANCE RETAINER RING TO LIMIT BOLT TRAVEL Stopmaster II assemblies can be identified by the slotted adjusting pawl guide hole and keyed adjusting pawl as shown in Figure 2. Late production assemblies also have the designation 'STOPMASTER II" stamped on dust shield. SERVICE NOTE A special, longer adjusting bolt is available for service use to permit full lining wear with reflnished drums. This bolt is 0.100 inch longer than the standard bolt and is ..^signed for use with drums having a diameter greater than 15.060 inches but less than 15.120 Inches. It is intended for use with regular service thickness linings and can be identified by a large letter 'S" on bolt shaft. (Continued Over) Service Operations, AllefltOwn, Pa. U.S.A. CIRCULATI Service Manager ; Shop ! Foreman TTIgEE--------I Foreman ! Night ^ Foreman ! Inspector Leadman ; Inspector i Leadman : Inspector Leadman | Unit OverI haul Room Shop Office Mark. SERVICE BULLETIN DECEMBER 7, 1976 No. Q9o under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNS''HAYWARD S'oAKVILLES'' ANTI-WHEEL LOCK WARNING UNIT (All Vehicles with Asti-Wheel Lock Brake Systems) PURPOSE To advise that the warning unit can be damaged by short circuiting or grounding-either the warning unit or anti-lock warning light circuit. RECOMMENDATION Avoid grounding or short circuiting the warning unit or warning light circuit when trouble shooting this equipment. Always use a voltmeter to determine if voltage exists at any point in the system. INFORMATION Permanent damage to the warning unit can occur if the terminals are grounded or "shorted" while the unit is powered. Damage can also occur if a test light or screwdriver is used to check for voltage at the warning light by shorting to the side cf the bulb socket. "Shorts" or grounds of this nature will cause failure aLthe warning units Internal components (transistors, diodes, etc.) and render it Incapable of indicating a failure in the anti-wheel lock system. v.;-- . v1.;-, "S.-`if. - -- 'X. >- 'v -'* -iv.- CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room - - FtlNTlD IN U-S>- Service Operations, Allentown, Pa. U.S.A. Shop Office Mark SERVICE BULLETIN FEBRUARY 11, 1977 ____________ No. Q9i under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. a f CHASSIS AFFECTED ALLENTOWN HAYWARD0 OAKVILLE0 TROUBLE SHOOTING THE ANTI-WHEEL LOCK SYSTEM (All Vehicles Equipped with Rockwell International Front Drive Axle) PURPOSE To provide procedure for trouble shooting the combination anti-wheel lock system used on subject vehicles. RECOMMENDATION Advise all service personnel of the special trouble shooting procedures contained in this bulletin. INFORMATION These front driving axles are equipped with the Rockwell International 'Skid-Trol" anti-wheel lock system; whereas, the rear axle or bogie has the standard production Eaton or B. F.' Goodrich system. It is important that the mechanic determine which system is at fault so that the appropriate trouble shooting procedure can be applied. Trouble shooting instructions for the basic systems are not given here as they have already been issued to the field. In addition to the normal anti-lock components, the Rockwell system incorporates a computer power relay (CPR). To ascertain that a malfunction exists, turn key switch on and observe the anti-wheel lock warning light. It should glow for approximately three to five seconds and then go out; however, if a malfunction exists, the warning light will stay on. In this case, proceed as follows: 1. Determine if the basic anti-wheel lock system (bogie or rear axle) is Eaton or Goodrich. 2. Using instructions applicable to the basic system, check at warning unit to determine which axle is affected. If both front axle (W1 or Pi terminal) and one or both of the rear axles (W2, P2 and W3, P3) indicate a malfunction, check out the basic system first. Refer to service literature covering system involved. 3. If the basic system checks out satisfactorily, proceed to the front axle system. Refer to trouble shooting charts A, B and C and Figures 1 through 5. CTRCULATIC Service Manaeer Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room (Continued Over) Shop Office W N IIO IN USA Service Operations. Allentown, Pa. U.S.A. Mark. No. Q91 under BRAKES (Sheet *2) CHART C Road Test I" ' ' 1.............. I 1. Self test failure indicator light. If it will not self test, correctbefore proceeding. ! 2. Drive vehicle at 40 mph for a minimum of 15 seconds, maintain above 20 mpn for a j minimum of 100 seconds. i | 3. Observe failure indicator light ! If light off -- system OK proceed to 4 i * If light ot\ rework of wheel end assembly is required in I the following areas: Sensor to rotor gap adjustment Rotor runout is excessive One sensor not plugged In 4. Make a "panic" brake stop from 20 mph. Cycling of front and rear wheels or a 'light on" condition indicates that a system test and rework is required. NOTE: Panic stops should not be made with a light on" condition since the skid-trol is not functioning on one or more axles. CHECKING COMPUTER POWER RELAY VEHICLE GROUNO sgNsOR CABLE RESISTANCE CHECK SENSOR RECTANGULAR PENCIL (ALL) OUTBOARD f* OHMS B 1 soo-1 ooo a 1 450-700 A 1 600-1000 A. 300-300 a 225-350 A 300-300 A FIGURE 2 CHECKING SENSOR RESISTANCE POWER CA8LE VOLTAGE CHECK PrV'ER CABLE RESISTANCE CHECK FIGURE 3 FIGURE 4 CHECKING POWER CABLE RESISTANCE CHECKING POWER CABLE VOLTAGE (Continued Over) SERVICE BULLETIN SEPTEMBER 1, 1977 Mo. Q88a under BRAKES FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNQ' HAYWARD BT OAKVILLE B' RADIO NOISE SUPPRESSION (All Models Equipped With Anti-Wheel Lock Brake System) PURPOSE To instruct owners and operators how to suppress radio noise on subject vehicles. RECOMMENDATION When radio noise is encountered, follow instructions in this bulletin. INFORMATION Operator complaints of undue noise from radio speakers (AM-FM, tape players etc.) have been received. This could be the result of poor grounding of the radio chassis to the vehicle chassis. A poor ground can aggravate conditons whereby brake controller hum and vehicle borne noise can be carried through the power line to the radio and then through the speaker system. If after Insuring that the grounding is satisfactory, and radio noise is still excessive, proceed as follows: CAUTION Electrolytic capacitors are polarity sensitive, having both apositiveand negative end. Use caution when in stalling. Connect a 100 MFD capacitor having a 50 volt WVDC (working voltage, direct current) from the radio power lead to the vehicle chassis as illustrated in Fig ure 1 for positive ground or Figure 2 for negative ground, depending on the vehicle electrical system. NOTE The 100 MFD capacitors with a 50 volt WVDC are available from radio/TV repair shops or stores such as Lafayette Electronics, Radio Shack, etc. CIRCULAT Service Manager shop Foreman TTIgnt-----Foreman Nipt Foreman Inspector" Leadman Inspector" Leadman Inspector" Leadman ifnit Overhaui Room 4. 100 MFD CAPACITOR - SO WVDC FIGURE 1 POSITIVE GROUNO 3. VEHICLE CHASSIS 4. 100 MFD CAPACITOR - SO WVDC FIGURE 2 negative ground Service Operations, Allentowm^a. U.S.A. Skop Office Mackz BULLETIN DECEMBER 2, 1977 T \0. Q92 under brakes = 0H BRANCHES. DISTRIBUTORS AND CUSTOMERS. . / CHASSIS AFFECTED ALLENTOWNEj HAYWARDtZf OAKVILLEiZl BRAKE shoe return spring (RAS512C, RAD529C, RAD530C, Rl70C, Ll55c Rear Axles and SW56C, SW57C,S V/571C, S W573C, SW76C Bogies with Rockwell International 16 1/2 x 7 Cam Brakes) PURPOSE To inform the field of an improved spring. RECOMMENDATION Install the new spring when replacement is required. INFORMATION The improved brake shoe return spring is made of high tensile steel for increased service life. Part number is 8235-2258-U-619 and it replaces spring 364SM27. The new spring is painted blue for identi fication. f f lN I IL> IN U Ai CTRCULATIO Service Manager Saop Foreman Nignt j Foreman I Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room 1 Shop Office - SERVICE BULLETIN DECEMBER 22, 1977________ T IMo. Q93 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. / CHASSIS AFFECTED ALLENTOWN0 HAYWARD0 OAKVILLE S'" CAM BRAKE ASSEMBLIES (All Highway Models WlthSW56C, 57C Series Bogies and FAW5361C, 5371C Series Front Axles) PURPOSE To inform the field of changes in cam brake usage and to describe means of identifying the various brake assemblies involved. RECOMMENDATION Advise service personnel of these changes in brake application to eliminate possible-errors with respect to service procedure and replacement parts. INFORMATION Bogie Brakes - The SW56C (34,000 lb.) and SW57C (38,000 lb.) bogies will be built with either of two cam brake assemblies. The brake used will depend on vehicle model and application, not bogie model. This is in contrast to past prac tice whereby a particular bogie model would be equipped with one standard brake assembly. Brake assemblies that will be installed are Rockwell "P" series 16 1/2 x 7 and Eaton 16 1/2 x 7 cam brakes. The Rockwell brake is shown in Figure 1, the Eaton brake in Figure 2. Note from the illustrations that these assemblies can be identified by the number of anchor pins; two are used on the Rockwell brake and one is used on the Eaton brake. MINTED IN U S A 1. ANCHOR PINS (TWO) FIGURE 1 ROCKWELL BOGIE BRAKE ASSEMBLY 1. ANCHOR PIN (ONE) FIGURE 2 EATON BOGIE BRAKE ASSEMBLY A 11____ T f C* A CIRCULA' Service Manager Shop Foreman Night Foreman Night Foreman inspector" Leadman Inspector Leadman Inspector*- Leadman Unit Over haul Room Shop Office AM BULLETIN FEBRUARY 22, 1978 \o. Q94 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNEf HAYWARD OAKVILLE Ef" ANTI-WHEEL LOCK SYSTEM Trouble Shooting Procedure" (Bendix MC-1 and MC-2 Systems) PURPOSE To provide service personnel with trouble shooting procedures for this new anti-wheel lock system. RE COMMENDATION Make the information contained in this bulletin available to all who are responsible for brake system service. INFORMATION The Bendix anti -wheel lock system is similar to others in use on Mack vehicles. It consists of an electronic controller with integral warning unit, that modulates a control valve and a wheel speed sensor sys tem. Two systems are available, MC-1 and MC-2. The MC-1 system utilizes one controller for each axle, whereas the MC-2 system hais a single controller to monitor two axles. The following trouble shooting guide is offered to facilitate diagnosis and correction of any problems that may develop. See Figure 1 and 2. n iN ltO IN USA. 1. 'VEHICLE POWER 2. SOLENOID 3. SOLENOID 4. 'VEHICLE GROUND 5. SENSOR COMMON 9. RIGHT WHEEL SENSOR 7. LEFT WHEEL SENSOR 6. ELECTRONIC SPEEDO (OPT.) 9. INOICATOR LAMP REVERSED IN A POSITIVE GROUND SYSTEM FIGURE 1 EC-1 CONTROLLER TERMINAL CONNECTIONS 2. SOLENOID 3. SOLENOIO 4. 'VEHICLE GROUND 5. INOICATOR LAMP S. LEFT & RIGHT WHEEL SENSOR 7. LEFT WHEEL SENSOR 8. RIGHT WHEEL SENSOR 9. RIGHT WHEEL SENSOR 10. LEFT WHEEL SENSOR 11. LEFT AND RIGHT WHEEL SENSOR 12. ELECTRONIC SPEEDO (OPT.) 'REVERSED IN A POSITIVE GROUND SYSTEM FIGURE 2 EC-2 CONTROLLER TERMINAL CONNECTIONS circular Service Manager Shoo Foreman Nignt Foreman Night Fore-nan Inspector Le adman Inspector Lfladrnan inspector Leariman Unit uver haul nocn Shop Office Service ODerations, Allentown, Pa. U.S.A. Mack FEBRUARY 22, 1978 No. Q94 under BRAKES -- (Sheet 2) (Continued) C. If ohm reading is between 250 and 10,000 ohms, sensor wiring is o.k. If ohm reading is less than 250, sensor or sensor wiring is shorted. If ohm read ing is more than 10.000. sensor or sensor wiring is open. Sensor wiring and/or sensor must be re placed. Repeat for each sensor. D. Attach leads of volt/ohmeter to one sensor lead and chassis. Re sistance should be 100,000 ohms or greater. If not sensor or sen sor wire is shorted to chassis. Repair/replace as necessary. E. If all sensors and wires check o.k., reconnect all wires. Re peat self-check and proceed to probable cause #2. 2. Faulty lamp relay (Optional on some negative ground vehicles and all posi tive ground. If there is no relay proceed to the next probable cause #3). * 1. Check voltage across relay coil. Volt age must be within two (2) volts of battery voltage. If voltage is not satis factory wire from relay to the -PWR terminal of controller or the relay ground is defective. Repair or re place as necessary. If the voltage is satisfactory proceed to probable cause #3. 3. Fail wire shorted to chassis. * 1. Remove fail wire from FAIL terminal If the light does not go out, the relay is defective and should be replaced. If the light goes out, the controller is probably defective. Replace wires am repeat self-check. If the light does nc go out, replace the controller. 4. Defective solenoid 1. Visually inspect solenoid wires for po sible open or shorts; repair or replac as necessary. If solenoid wires appei to be o.k. proceed to next step. 2. Remove solenoid wires from solenoid terminals, check solenoid with volt/ ohmeter as follows: A. Solenoid resistance should be 3-5 ohms. (If not, replace solenoid). (Continued Over) B. Attach one lead of volt/ohmeter to one solenoid wire and one lead of volt/ohmeter to controller case; resistance should be greater than 100,000 ohms. (If not, replace solenoid). If correct, go to proba ble cause #5. __________________________ !______________-- BULLETIN MARCH 15, 1978 \Q. 087 under brakes =or branches, distributcrs amd customers. (Supersedes Bulletin dated JULY 16. 1976) CHASSIS AFFECTED ALLENTOWNE HAYWARDE OAKVILLEE filN ltU IN U iA ANTI-WHEEL LOCK PICKUP AND VALVE/CONTROLLER ASSEMBLY Service Subassemblies and Components (Eaton. Goodrich and Bendix; PURPOSE To provide service personnel with part numbers of the component parts used in subject assemblies. RECOMMENDATION Whenever possible, replace failed components instead of the complete assembly when servicing anti-wheel lock valve/controller assemblies and wheel speed pickups. This practice will lower cost of replacement parts and gen erally reduce labor time. INFORMATION Anti-wheel lock controller assemblies consist of three major components or subassemblies which can easily be re placed in the field. They are the valve, controller and solenoid(s). The following parts list shows part number of the valve/controller assemblies currently in use and their components. Valve/'Controller Assembly Component Parts - See Figures 1, 2, 4 and 5. Vendor Assembly No. 1 Controller Eaton Model 5MN41R-P1 (1)2719-630oB3(Pos. Grd.) 21 5MN41R-P2 (1)2719-630069(Neg. Grd.) Model 5MN48R 2719-630383(Neg. Grd.) 1201 5MN401R 2719-630380(Neer. Grd.) B.F. Goodrich 5MN35R 7MN31R 5MN4ft 745-289670(Neg. Grd.1 Bendix 5MN400R 745-289367(Neg. Grd.) 5MN402R 745-289367(Pos. Grd.) 5MN403R 745-289670(Pos. Grd.) Valve Solenoid Kit 2719-600084 2719-640023 2719-600084 2719-640023 2719-600084 2719-640023 3355-1700-6 (3)3355-1670-1 745-289614 745-289278 745-289614 745-289278 745-289614 745-289278 745-289614 745-289278 Includes gasket, harness pigtail and clip Includes O-rings (*y Includes O-rings and cover gasket CIRCULATI Service Mimgif Shop Fonmin Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room (Continued Over) Service Operations. Allentown. Pa. U.S.A. i l Shop Office Mack MARCH 15, 1978 No. i<Joi uncier ..,:. vrvr.:s (Sheet 2) 2. GROUND STRAP NUT POSITIVE GROUND UNIT FIGURE 3 2. GASKET AND O-RINGS INCLUDED IN SOLENOID KIT 3. CONTROLLER 4. VALVE 5. 1/4 IN. SPADE TERMINALS (SOLENOIO NO. 21 (. 3/16 IN. SPAOE TERMINAL (SOLENOID NO. 1) FIGURE 4 .F. GOODRICH VALVE/CONTROLLER ASSEMBLY 5MN 35R 1. CONTROLLER 2. SOLENOIO 3. O-RINGS 4. VALVE FIGURE 5 BENDIX VALVE/CONTROLLER ASSEMBLY Wheel speed pickup assemblies consist of the pickup, pickup gage blocks and mounting bracket. Gage blocks experience some wear during the initial operating period following a clearance adjustment. They must be re placed when the wear indicator grooves are no longer visible. The fol lowing parts list shows part numbers for the gage block service kit and the pickup. Bracket part numbers are not shown because they vary de pending on the axle used. Consult chassis record for correct bracket part number. (Continued Over) MARCH 20, 1978 T \o. 095 under brakes FOR BRANCHES, DISTRIBUTORS ANO CUSTOMERS. / / / CHASSIS AFFECTED ALLENTOWN HAYWARD OAKVILLE BRAKE IMPROVEMENTS (All With Air Over Hydraulic Disc Brakes) Service Manager aaop Foreman ingot Foreman Nignt Foreman Inspector" Leadman Inspector- Leadman Inspector"" Leadman Unit Over haul Room PURPOSE To advise of improvements to increase disc brake service life and to provide part numbers for disc brake service kits and replacement parts. Shop Office RECOMMENDATION The improvements described in this bulletin will increase service life of disc brakes. Due to a recent change in motor vehicle safety standard 121, older MVSS121 equipped vehicles can incorporate these improvements if the operator desires. These changes are nek mandatory however, and are to be made at the operators request and expense. INFORMATION One of the original stopping requirements for vehicles subject to MVSS121 requirements was 243 feet from 60 mph on dry roads. A revised standard, now in effect, increased the allowable stopping distance to 293 feet under the same conditions. Some Mack vehicles built to comply with the origi nal standard, utilized disc brakes at the front wheels to achieve the high brak ing force required. It has been found that short life of these disc brakes can result from failure to keep the rear brakes in adjustment. Disc brakes are self-adjusting and oper ate at minimum lining to-rotor clearance at all times. As a result, they pro vide the major portion of the braking force under light braking conditions if the rear wheel brakes are out of adjustment. If a particular operation entails considerable light braking, disc brake life can be increased by installing a metering valve in the hydraulic system. The meter ing valve reduces pressure to the disc brakes under low application pressure, causing the rear brakes to assume a larger proportion of the braking effort. At higher application pressure, normal pressure is restored to the disc brakes. Installation of 17 to 1 ratio intensifier in place of a 23 to 1 ratio unit will increase disc brake life. This modification is permissible on highway vehicles equipped with a bogie rated at 55,000 pounds or less. The intensifier uses brake system air pressure to develop hydraulic pressure for the disc brakes. With a 17 to 1 intensifier, 100 psi of air pressure will generate 1700 psi hydraulic pressure. With a 23 to 1 intensifier, 100 psi air pressure will generate 2300 psi hydraulic pressure. Longer lining life can also be achieved by installing current service linings. The less stringent stopping requirements now in effect make it possible to use a dif ferent lining material which has better wear characteristics than the material originally required. Correct adjustment of rear axle manual slack adjusters is essential for achieving correct balance between front and rear brakes. If the operator prefers, auto matic slack adjusters can be installed on the SW56, 57, 571, 573 and 76 series bogies to aid in maintaining correct adjustment. niN U O in u j a (Continued Over) Service Operations. Allentown, Pa. U.S.A. Mack: MARCH 20, 1978 Mo. q95 under BRAKES (Sheet 2) 2. Installing low ratio intensifier'- (a) The 17 to 1 intensifier is directly interchangeable with the 23 to 1 intensifier. Parts required: Qtv. Mew Part | Description 1 Replaces 1 8QE429R(17 to 1) Intensifier 8QE430R(23 to 1) 3. Installing automatic slack adjusters on SW56, 57,571, 573 and 76 series bogies. , a. Remove existing slack adjusters. b. Install new slack adjuster on brake camshaft. Be sure arrow on ad juster points in direction unit rotates for a brake application. See Figure 3. 2. PUSH roo J. DIRECTION OF BRAKE APPLICATION FIGURE 3 c. Install slack adjuster retainer bracket on brake assembly using existing spider mounting bolts as shown in Figure 4. Do not tighten the bolts. Align clevis pin hole in slack adjuster with push rod clevis by turning worm adjusting nut as shown in Figure 5 and install clevis pin. 1. EXISTING SPIOER MOUNTING BOLTS 2. BRACKET 72RU 28S1-PS. PS 3. SETSCREW TAX 2S2Z, WASHER 3TAX 473, NUT 21 AX 317 4. SLACK ADJUSTER FIGURE 4 (Continued Over) MARCH 20, 1978 No. Q95 under BRAKES (Sheet 3) 3. Servicing the disc brake caliper. Various components and service kits are available to expedite overhaul of these units. These items are shown in accompanying parts list. General repair procedures are given in Highway Vehicle Service Manual TS442. Follow these procedures, taking particular care to observe the following points: a. Minor corrosion and stains in the piston bores can be polished with crocus cloth. Do not use emery cloth or other abrasives. Also check seal groove f6r scoring, nicks or corrosion. If any de fects are noted, replace caliper. b. The piston's outer diameter is plated and sized to a very close toler ance and must not be refinished by any means. If the O.D is scored, knicked, corroded or the plating is worn or damaged, the piston must be replaced.** *** Parts required: Qtv. * ** *** Part Number 4891-09726602 4891-09906101 , 4891-09829401 4891-0929501 Description Kit, Boot and Seal Kit, Shoe and Lining Piston - Lining Holdown Kit * Services one caliper ** Service two calipers *** As required Eft VICE BULLETIN APRIL 13, 1978 T \o. Q97 under brake; FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWN&Zf HAYWARDEf OAKVILLE Ef DISC BRAKE ROTOR Refinishing Braking Surface (All Highway Models With Disc Brakes) PURPOSE To inform the field that rotors can be refinished and to advise maximum amount of material that can be removed. RECOMMENDATION Follow the recommendations in this bulletin when performing subject operation. INFORMATION As in the case of brake drums, it is permissible to machine the braking surfaces of a disc brake rotor to correct scoring, heat checks etc. When performing this operation, it is very important not to remove anexcessive amount of material, otherwise the rotor will be weakened to the point where it is no longer serviceable. The rotor can be machined to a minimum thickness of 1.63 inches (nominal thick ness when new is 1. 75 in. ). As a guide to the machinist, this dimension is cast into the inner face of rotor hub as shown in Figure 1. Figure 2 is a cross-sec tion through the rotor and brake assembly showing where this demension applies. rtlN H D IN U S.A 1. DISC BRAKE ROTOR 2. "MIN. ROTOR THICKNESS I.S3" CAST INTO ROTOR FIGURE 1 (Continued Over) Service Operations. Allentown. Pa. U.S.A. CIRCU LA Service MannerSiicp Foreman TTTm Forcm nr. Nil"-.: ; Fc rein on Inspector Leaciznnn inspector Lesa'm.tn inspector Lenin", an c: ! otucH Mack SERVICE BULLETIN AUGUST 18. 1978 iMo> Q95a Under BRAKES FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. . CHASSIS AFFECTED ALLENTOWN0 HAYWARDEf 0AKVILLE2f BRAKE INTENSIFIER (All With Air Over Hydraulic Disc Front Brakes) PURPOSE To provide the field with procedure for changing intensifier pressure ratio from 23. 5 to 1 to 17 to 1. RECOMMENDATION Follow procedure outlined herein when changing intensifier ratio. This modification is permissible on highway vehicles with a bogie rated at 55,000 pounds or less. INFORMATION Improved service life of disc front brakes has been achieved in many cases by changing the intensifier ratio from 23. 5 to 1 to 17 to 1. This change lowers the hydraulic system pressure and reduces amount of braking force developed by the disc brakes. As pointed out in Bulletin Q95 under BRAKES, 23. 5 to 1 and 17 to 1 intensifiers are directly interchangeable as assemblies, making it possible to install a complete 17 to 1 intensifier to effect a ratio change. It is possible to convert a 23. 5 to 1 intensifier to the 17 to 1 ratio by installing the smaller Rotochamber used on the low ratio unit. This latter method is less expen sive and is recommended if the master cylinder is in good condition. A switch is mounted on the chamber which actuates a warning light if there is a failure in the hydraulic system. This switch is the same for both intensifier ratios and can be transferred from old to new assembly. Part number of the switch is listed in case ex isting switch is not useable. Parts required: Qty. Part No. 745-^8^757 * 1 1MR2321 DescriDtion Rotochamber, Type 36 Warning Switch * Required only if existing switch is not serviceable CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inapector Leadman Inapector Leadman Inapector Leadman Unit Over haul Room (Continued Over) Service Operations, Allentown, Pa. U.S.A. Shop Office Mack: SERVICE BULLETIN OCTOBER 16, 1978 OH |\o. Q98 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNGZf HAYWARDQ OAKVILLEEf DISC BRAKE SUPPORT BRACKET (M3SAX and MP404X Off-Highway Models) PURPOSE To provide field personnel with a method for reinforcing the brake support bracket. This modification applies to the rear wheel brakes on the M35AX and both front and rear wheel brakes of the MP404X. RECOMMENDATION Install the brake support bracket reinforcements as a product improvement when performing normal brake service. INFORMATION It has been found desirable to strengthen the brake support bracket on M$5AX rear brakes and both front and rear brakes of theMP404X. This is done by welding a reinforcement plate to each side of the support bracket in the caliper mounting area. Parts Required: J-Q*Vty.1 - Part Number (1RU13U75 DescriDtion Reinforcement Plate * 4 required per axle. Can be made locally from 1 x 1-3/4 x 8 in. carbon steel. The following illustration shows details for installing the reinforcement plates. Note that the brake caliper must be mounted on the bracket during the welding operation to prevent warpage of brake mounting surfaces. 1. REINFORCEMENT 71 HU 1307S. (1.0" X 1.7S X 8.0 CARBON STEEL) LOCATE INBOARD FROM OUTER FACE OF SUPPORT BRACKET. USING DIMENSION SHOWN. CIRCULATIt Same. Manaqaf Shop Foreman Night Foreman Night Foreman Inopoctor taadman Inspector (admin Inspector Laadman Unit Ovarhaul Room ftlN U O IN USA END Service Operations. Allentown. Pa. U.S.A. Shop Otflca Mack SERVICE BULLETIN DECEMBER 8, 1978 T \0. Q99 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENT0WN2T HAYWARDL OAKVILLE0 BRAKE DUST SHIELDS (All With FA(W)616C, 617c Front Axles) PURPOSE To provide part numbers of dust shields available for the cam brake assemblies used on these axles. RECOMMENDATION Dust shields should be installed as a product improvement on operations where the brakes are exposed to large quantities of dust, water and other contaminants. INFORMATION Dust shields were originally offered as optional equipment for the 16 1/2 by 5 cam brake assemblies 1QDA4239 and 1QDA4240 installed on these axles. In some cases it has been found desirable to retrofit shields on vehicles not originally equipped with them, due to adverse operating conditions. Dust shields can be installed without modification on current production vehicles. To install shields on non-current vehicles it is necessary to modify existing brake drums or replace them with current production drums. Current production drums have a re lief on inboard side that provides clearance for the shields. A similar relief can be added to non-current drums if desired. See illustration for dimensions. fU N IfO IN U J.A. IN THIS AREA TO PROVIDE CLEARANCE WITH SHIELD. 2. NON-CURRENT PRODUCTION BRAKE DRUMS DO NOT HAVE A RELIEF. Parts required per axle. Qty. New Part Description "T4" 17QJ3239-PI------- * Brake Drum 2 17QJ3239A-P2 * Brake Drum 2 17QJ3240A 2 8235-A3236Z1794 * Brake Drum Dust Shield Service Assembly 12 4AX17 12 36AX3 Screw, Dust Shield Mntg. Lockwasher, Dust Shield Mntg. Screw Replaces 17QJ3239-P1 17QJ3239-P2 17QJ3240 CIRCULA' Service Menaqar Shop Foreman Night Foreman Night Foreman Inspector Laadman Inspector Laadman Inspector Leadman Unit Over haul Room * Check chassis record to determine brake drum originally installed on vehicles. Chassis built after mid-1976 will be equipped with cur rent production brake drums. END Page 1 Q99 Service Operations, Allentown. Pa. U.S.A. Shop Office Mack BULLETIN FEBRUARY 12, 1979 OH \0. qioo under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNSZf HAYWARDG OAKVILLEBT BRAKE ACTUATOR BREATHER (M35AX, M65BX and MP404X Off-Highway Models With Disc Brakes) PURPOSE To announce availability of a breather for brake actuators currently in service. RECOMMENDATION The breather is a product improvement that should be added to actuators not so equipped, to insure best operation. INFORMATION A breather is now installed as standard equipment on the actuator air chamber to prevent the possibility of contaminants entering and fouling the master cyl inder. Parts required to add a breather to actuators in service are available in kit form under part number 3355-304-231. The kit contains a special mounting stud, elbow fitting and the breather. Procedure - See Illustration rtIN U O IN USA. CIRCULA 1. AIR CHAMBER 2. APPLY SEALER 3. SPECIAL STUD BREATHER 5. ELBOW Servlet Manager Shop Foreman 1. Disconnect air line from air chamber. .2 Remove the two mounting stud nuts and separate air chamber from master cylinder. Remove chamber from chassis. 3. Without disassembling the chamber, remove one of the existing studs and re place it with the special stud contained in service kit. Ntyit Foreman Night Foreman inspector Leadman inspector Leadman Inspector 4. Apply a non-hardening sealer to the area of chamber that seats against mas- Leadman ter cylinder, then reinstall chamber. Be sure breather stud is opposite mountinglugs. The sealer isnecessary to insure correct operation of breather. Unit Over haul Room Torque nuts (dry) 130 to 140 lbs. ft. 5. Install elbow and breather on special stud and reconnect air line. END Service Operations, Allentown, Pa. U.S.A. Shop Office Mack SERVICE BULLETIN FEBRUARY 28, 1979 T l\o. qioi under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. / * CHASSIS AFFECTED ALLENTOWN^ HAYWARDD OAKVILLEE^ BRAKE CHAMBER MODIFICATION (All Models With FA(W) 616C or 617C Front Axle) PURPOSE To inform the field of a procedure for preventing entry of moisture and dust into the brake chamber on vehicles engaged in off-highway operations. RECOMMENDATION Modify brake chambers as outlined herein if operating conditions require improved sealing. INFORMATION Brake chambers in these axles are mounted with the push rod pointing upward at approximately 60 degrees from the vertical. In this position it is possiole for moisture and dust to enter the non-pressure side of chamber through the breather openings. Chamber venting is accomplished by a controlled gap between end cover and chamber body. To prevent entry of water and dust, the entire circumference of the chamber to cover joint must be sealed with Silastic sealer, or equivalent, and a new vent hole added. The new vent is located on underside of chamber, in line with mounting studs as shown in Figure 1. Use a magnetic drill to keep metal particles out of chamber. n iN Ifl) IN u s * . 1. OUST COVER 2. BOOT FIGURE 2 DUST COVER ANO BOOT Future production of these brake chambers(part no. 19QE452R) will incorporate a new boot and dust cover to exclude moisture and dirt. When these parts are available they can be used on existing chambers, if desired, eliminating need for the pre ceding modification. See Figure 2. Part numbers are: Part Number i Description 2SQBZ73---- Dust Cover 745-231609 Boot CIRCULATE Same* j Manager i Shop Foreman | Night Foreman | Night Foreman Inapoctor Laadman Inapoctor Laadman Inapoctor Laadman Unit Over haul Room END Service Operations, Allentown. Pa. U.S.A. Shop Olflca Mack SERVICE BULLETIN MARCH 16, 1979 OH No. Q102 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWN5Z HAYWARDD OAKVILLEsZf BRAKE CALIPER INSTALLATION (M35AX, M65BX and MP404X Off-Highway Models With Disc Brakes) PURPOSE To inform the field of a modification required to permit installation of latest caliper assembly or torque plate. RECOMMENDATION Be sure all service personnel are familiar with the procedure described her INFORMATION An improved torque plate is used in current production caliper assemblies. This torque plate is similar to the replaced torque plate and utilizes the same internal components, however a change in the mounting lug configuration causes an interference with the existing caliper mounting bracket. To insure proper assembly of this torque plate, or a new caliper assembly, it is necessary to grind a chamfer on inboard edge of the bracket mounting lugs as shown in Figures 1 and 2. Chamfer brackets on both front and rear axles. Longer bolts, as shown in parts list, are required to mount the new torque plate/ caliper assembly due to use of thicker mounting lugs. Reuse hardened flat washer 35AX1438 under the boltheads. Torque the bolts 1000 lb. ft. (dry). MINTED INus> 1. CHAMFER INBOARD EDGE AT SHADED AREAS FIGURE 1 CALIPER MOUNTING BRACKET - FRONT AXLE Page 1 (Continued Page 2) Service Operations, Allentown, Pa. U.S.A. CIRCULATION Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Laadman Unit Over haul Room Shop Office Mack MARCH 16, 1979 1. TOROUE PLATE 2. BLEEDER VALVE 3. BOOT 4. PACKING ASSEMBLY S. PISTON 8. PACKING 7. PACKING RETAINER 1. CAP S. FLAT WASHER 10. BOLT 11. PIN 12. CARRIER ANO LINING ASS'Y 13. SETSCREW 14. SETSCREW FIGURE 3 CALIPER ASSEMBLY END Page 3 Q102 BULLETIN JUNE 8. 1979 _________________No. Q87 under brakes for branches, distributors and customers. (Supersedes Bulletin dated MARCH 15, 1978) CHASSIS AFFECTED ALLENTOWN0 HAYWARD0 OAKVILLE0 ANTI-WHEEL LOCK PICKUP AND VALVE/CONTROLLER ASSEMBLY Service Subassemblies and Components (Eaton, Goodrich and Bendix) PURPOSE To provide service personnel with part numbers of the component parts used in subject assemblies. RECOMMENDATION Whenever possible, replace failed components instead of the complete assembly when servicing anti-wheel lock valve/controller assemblies and wheel speed pickups. This practice will lower cost of replacement parts and gen erally reduce labor time. INFORMATION Anti-wheel lock controller assemblies consist of three major components or subassemblies which can easily be re placed in the field. They are the valve, controller and solenoid(s). The following parts list shows part number of the valve/controller assemblies currently in use and their components. Valve/Controller Assembly Component Parts - See Figures 1, 2, 4 and 5. Vendor Assemblv No. Controller Eaton Model DMN41R-P1 (i)i4Ti!J-S736M(Pos. Gref) 21 5MN41R-P2 O)2719-630069(Neg. Grd.) Model 5MN48R 2719-630383(Neg. Grd.) 1201 5MN401R 2719-630380mee. Grd.i B.F. Goodrich 5MN35R 7MN31R 5MN49R 745-289670(Neg. Grd.) Bendix 5MN400R 745-289359(Neg. Grd.) 5MN402R 745-289359(Pos. Grd.) 5MN403R 745-289670(Pos. Grd.) Valve Solenoid Kit 2719-600084 (2)2719-640023 2719-600084 2719-640023 2719-600084 2719-640023 3355-1700-6 (3)3355-1670-1 745-289614 745-289278 745-289614 745-289278 745-289614 745-289278 745-289614 745-289278 (I) Includes gasket, harness pigtail and clip Includes O-rings Includes O-rings and cover gasket Manaqar Shop Foreman Night Foreman Night Foreman Inapactor Laadman Inapacior Laadman Inapactor Laadman Unit Ovarhaul Room ftlN U D IN USA _______________ Page 1 (Continued Page 2) Service Operations, Allentown, Pa. U.S.A. Shop Ofllca Mack JUNE 8, 1979 1. GROUND STRAP NUT NEGATIVE GROUND UNIT 2. GROUND STRAP NUT POSITIVE GROUND UNIT FIGURE 3 2. GASKET ANO O-RINGS INCLUDED IN SOLENOIO KIT 3. CONTROLLER 4. VALVE 5. 1/4 IN. SPADE TERMINALS (SOLENOID NO. 2) S. 3/16 IN. SPADE TERMINAL (SOLENOID NO. 1) FIGURE 4 B.F. GOODRICH VALVE/CONTROLLER ASSEMBLY 5MN 35R 1. CONTROLLER 2. SOLENOIO 3. O-RINGS 4. VALVE FIGURE 5 BENDIX VALVE/CONTROLLER ASSEMBLY Wheel speed pickup assemblies consist of the pickup, pickup gage blocks and mounting bracket. Gage blocks experience some wear duringthe initial operating period following a clearance adjustment. They must be re placed when the wear indicator grooves are no longer visible. The fol lowing parts list shows part numbers for the gage block service kit and the pickup. Bracket part numbers are not shown because they vary de pending on the axle used. Consult chassis record for correct bracket part number. PSEge 3 Q87 (Continued Page 4) BULLETIN JUNE 20, 1979 No. qio3 under brakes FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. CHASSIS AFFECTED ALLENTOWNEf HAYWARDS'OAKVILLEs/ DISCONNECTING ANTI-WHEEL LOCK SYSTEM (All Vehicles So Equipped) PURPOSE To inform the field regarding legality of disconnecting or by-passing anti wheel lock function on vehicles in service. RECOMMENDATION If the anti-wheel lock system is in good operating condition it is recom mended that it be left in operation unless otherwise instructed (e. g. by a mandatory safety cam paign). If an anti-wheel lock system is disconnected, be sure to follow the instructions given here INFORMATION In October, 1978 a Federal Court rendered a decision that invalidated thenecessity for anti-wheel lock equipment. This decision means that a manufacturer, distributor, repair shop or owner may legally remove or make inoperative the antiwheel lock equipment on any vehicle so equipped, regardless of date of manufacture. Anti-wheel lock function is no longer required to meet the brake standards which the Federal Court modified. This decision does not mean that anti-wheel lock systems cannot be installed or used. Mack Trucks, Inc. does not recommend that anti-wheel lock systems be disabled unless a condition exists that may increase stopping distances. However, some owners may want to disconnect their system. As a convenience to these owners we are providing the following instructions. NOTE We suggest that the disconnected wires be left intact and protected from damage so the system can be reconnected if desired. A. Disconnecting the Anti-Wheel Lock Electrical System NOTE To insure complete deactivation of the anti-lock electrical system, it must be disconnected at two locations as described in following Steps 1 and 2. The procedure is the same for front and rear axle or bogie systems. 1. Disconnect the system power lead(s) at the cab circuit breaker. Lo cation of the circuit breaker and wire identification is shown in the ac companying chart. After disconnecting, tape end of wire(s) so it can not make electrical contact. CIRCULAT Service Manager Shop Foreman Night Foreman Night Foreman Inspector Laadman Inspoctor Laadman Inapactor Laadman Unit Over haul Room rtlN ftO IN USA. Page 1 (Continued Page 2) Service Operations, Allentown, Pa., U.S.A. Shop Office JUNE 20, 1979 1. ANTI-WHEEL LOCK CONTROLLER 2- POWER/WARNING LEAO CONNECTOR 3. CONTINUITY CA8LE (IF USED) NOTE The anti-wheel lock warning light will remain lit whenever the key switch is in the run pos ition. This feature is an additional warning to the driver that the anti-lock system is inoperable. IMPORTANT WARNING BE SURE THE NOTICE LABEL 4MR1452 (RE PRODUCED BELOW) IS AFFIXED TO THE IN STRUMENT PANEL IN FULL VIEW OF THE VEHICLE DRIVER. NOTICE The Wheel Anti-Lock System on this Vehicle has been made Inoperative by Disconnecting the Power Supply. The Brakes are Fully Driver Controlled. 4 MR 1452 B. Front (Steering) Axle Brakes If the anti-wheei lock capability is removed from front wheel brakes, it is essential that the brakes do not have excessive braking ability, otherwise they may lock up and cause loss of steering control. This condition can exist on FA536 and 537 series front axles built between March 1, 1975 and June 1, 1976 and FA616D, 617D and 618D disc brake equipped front axles. These axles must be checked and if not equipped as follows, they must be modified. Consult your Mack service center. Cam Brakes . Type 20 brake chambers . 5 1/2 in. slack adjusters . Medium friction (EE) brake lining Disc Brakes . 17:llntensifier (Type 36 Rotochamber - Refer to Service Bulletin Q95a under BRAKES) or as an alternative. . Install drum brakes - Consult your Mack service center. Rockwell Front Driving Axle No change required JUNE 11, 1970 No. Q63 under brakes FOR BRANCHES, DISTRIBUTORS AND CUSTOMERS. BRAKE SPIDER MOUNTING FLANGE (DM600 and DM800 Chassis with SWD68 Bogie and ll.OOx 22 Tires) PURPOSE To inform field of possible modification to spider mounting flange when replacing axle housing. INFORMATION The original SWD68 bogie series design featured aflat on top of brake spider mounting flange parallel with the hori zontal center line of cast housing. This was necessary to avoid a potential interference between flange and air cylinder when bogies are fitted with 11.00 x 22 tires and 7.00 inch long slack adjusters. To standardize components and introduce a product improvement 7.7 5 inch long slack adjusters have replaced the 7.00 inch long slack adjusters on current production units. This change increased the clearance gap sufficiently to discontinue the operation required for the flats. However, when installing new type axle housing without flats on the brake spider mounting flange to replace one with flats and T. 00 inch slack adjusters, be sure to hand grind sufficient clear ance between brake spider mounting flange and air cylinder. See illustration. RECOMMENDATION The modification to brake spider mounting flange is required only to eliminate possible interference that may develop when replacing housing. M IN H O IN U H . BRAKE SPIDER MOUNTING FLANGE MODIFICATION Service Operations, Allentown, Pa. U.S.A. Mack fc. 7.. USZXET 39 iacs irjcrs- ise60r--"C3UT3 ALLENTOTN JULY 17, 1970 IMo. Q65 FOR BRANCHES. DISTRIBUTORS AND CUSTOMERS. under brakes INSTRUCTIONS AND SERVICE DATA (All Mack Chassis Equipped with Bendix-Westinghouse DD-3 Brake Actuators) PURPOSE To inform field of Instructions and service data applicable to DD-3 brake actuators. INFORMATION Bendix-Westinghouse Instruction and Service Data Bulletin SD-38 provides detailed information on maintaining, servi cing and replacing DD-3 actuators. Inaddition to established general preventive maintenance procedures it is recommended that yearly or after 50,000 miles, depending on type of operation, the DD-3 actua tors be completely disassembled to inspect condition of internal parts and replace diaphragms and other rubber parts/or parts if worn or deteriorated. RECOMMENDATION File the attached Bendix-Westinghouse Instruction and Ser vice Data SD-38, following this bulletin. Inform all affected personnel of its con tent. O ZE Service Operations, Allentown, Pa, U.S.A. Mack BULLETIN No. Q104 under BRAKES :OR BRANCHES. DISTRIBUTORS AND CUSTOMERS. . CHASSIS AFFECTED ALLENTOWN0 HAYWARDS OAKVILLE^ BRAKE LINING SERVICE KITS (All With 16-1/2 x 7 Cam Type Rear Axle Brakes) PURPOSE material. To inform the field of new service linings made of non-asbestos RECOMMENDATION Install non-asbestos lining kits if improved lining and drum life and/or quieter operation is desired. INFORMATION The non-asbestos linings provide longer drum and lining life along with reduced noise levels. They are directly interchangeable with standard and combination service kits on axles rated at 20,000 pounds (40,000 per bogie) or less. They can also be used on axles rated up to and including 23,000 pounds (44,000 per bogie) if type 30 brake chambers and six inch slack adjusters are installed. Lining kits currently available are: Standard Combination Service Kits Service Kits 202SMII204 202SMH204-P2 not available 202SMH210 202SMH220 202SMH220 Non-Asbestos Service Kits 202SMM204N 202SMM210N 202SMM220N - Aoniication Rockwell Pand Q Rockwell P-44,000 lb. Eaton bogle nuN fto in u s a END Service Operations. Allentown, Pa., U.S.A. CIRCULATIO Service Manager Shop Foreman Night Foreman Night Foreman Inspector Leadman Inspector Leadman Inspector Leadman Unit Over haul Room Shop Oftlcs 9 CLUTCH REMOVAL _ NOTE Always mark clutch cover and fly wheel with a center-punch before removing clutch to facilitate rein stalling clutch in same position. 1. Use three spring retention tools (17-T1123 for CL-28, 40 and 50 series, 17-T1766 for CL-47 series) or retaining cups as shown in Figure 4-1, when removing a clutch assembly from the flywheel. Figure 4-1. Retaining Cups To use spring retention tools, bottom screws in tapped holes in pressure plate. Set tool nuts up snugly against tool bracket. Tighten tool nuts evenly to relieve spring tension on pressure plate. Not used on CL-58 Series. 2. Remove two clutch-to-flywheel cap screws with lockwashers at the ten o'clock and two o'clock positions of the flywheel and install two long headless guide studs to support the clutch assembly during removaLof the remaining attaching capscrews. 3. After removal of all capscrew fasten ers, carefully remove heavy clutch and disc assembly from flywheel counterbore and place on bench. Be careful not to drop driven disc assembly which is now free. Also remove the temporary guide studs from flywheel. CLUTCH INSTALLATION 1. Using spring retention tools, bottom screws in tapped holes in pressure plate. Set tool nuts up snugly against tool brack et. Not used on CL-58 Series. NOTE Three retaining cups and screws are used to hold a new clutch as sembly together until it is in stalled on the flywheel. Spring cups are pressed into the clutch cover hence the retaining cups are necessary to prevent spring cups loosening and slipping out of the cover during handling. Re taining cups and screws must be removed after the clutch is as sembled to the flywheel. A tag is attached to new clutches (CL-28, 40 and 50 Series) calling attention to this fact and cups and screws are painted red for ready identi fication. 2. Engage splined end of clutch disc align ing mandrel or a spare main driving pinion with hub splines of driven disc from rear of long hub side. Then position driven disc assembly in flywheel so that spigot end of shaft engages inner race of clutch pilot bearing mounted in flywheel. This arrangement positions the disc assembly in proper alignment until clutch is com pletely assembled and secured in flywheel. 3. Install two long guide studs in the ten and two o'clock positions in flywheel rim. Mount clutch assembly on guide studs and push unit into flywheel bore until clutch cover flange enters counterbored pilot pro vided. Be careful not to disturb disc aligning mandrel. 4. Lubricate and installcover-to-flywheel capscrews with their lockwashers. Tighten capscrews a few turns at a time so that cover will not be misaligned and forced into flywheel pilot by the tightening of the cap screws. Remove the two guide studs and re place with capscrews and their lock wash ers. Remove aligning mandrel. CL-28 and 40 SERIES Description CL-28, -40 Series assemblies are single plate, dry disc pusher type clutches. They consist of a pressure plate, a cover, and a driven disc which is splined to the trans mission main driving pinion shaft. When 4-3 engaged, the driven disc is clamped between the pressure plate and the flywheel by the pressure of coil springs which are mounted in cups on the cover. Drive is transmitted to the pressure plate by pressure plate lugs which fit in the cover openings. Six re lease levers have ball pivots and are linked to the pressure plate by eyebolts. The in ner ends of the levers are held by the notched release thrust washer. See Figure 4-2. 1. Clutch Spring 12. Washer (outer) 13. Fulcrum Adjust 2. Clutch Spring (in ment Nut ner, where used) 14. Lock Nut 3. Release Bearing 15. Eyebolt 4. Release Collar 16. Eyebolt Pin 5. Thrust Washer 17. Cover Plate 6. Release Lever 18. Pressure Plate 7. Lever Spring 19. Flywheel 8. Spring Washer 20. Pilot Bearing 9. Lever Pivot 21. Driven Disc 10. Lever Bushing Assembly 11. Eyebolt Ful 22. Driven Disc crum Facings Figure 4-2. Sectional View of CL-28. 40 Series Clutch 4-4 Disassembly NOTE Before disassembly of the various parts, it is good practice to mark these parts with a center-punch, so that at reassembly, they can be re assembled in their original posi tions. This is necessary in order not to disturb the dynamic balance of the clutch. 1. Before removing the three spring re tention tools, compress clutch release lever springs, remove washer pins, then remove washers and release lever springs. Pry off snap ring from thrust washer. Remove eyebolt nuts, fulcrums, and clutch release levers. CAUTION : If retaining cups are used instead of tool (17-T-1123), clamp the cover in a press before removing the cups. This is necessary be cause the screw used does not have sufficient thread length to com pletely release the spring load before coming out of the pressure plate. 2. While holding spring retention tool screws, back off tool nuts alternately mak ing one turn at a time. When spring is entirely relieved, back out the three tool screws. 3. Remove clutch cover and springs. If heat-insulating washers are removed from pressure plate spring pockets, retain them for reassembly. The eyebolts need not be removed unless inspection reveals distor tion or loose fit on pins. Inspection and Repair Remove all traces of dirt and oil with a suitable safe solvent. Inspect parts care fully for cracks, distortion or excessive wear. 1. If cover is cracked or distorted, re place. Tack-weld loose spring cups (on covers having this construction) replace worn or loose ball-fulcrums. Replace loose or bent py^_rivets. 2. Replace springs if cracked or defec tive. Check all springs on a spring tester. Replace all that do not meet specifications. 3. Replace thrust washer if worn, bent or defective. 4. Replace-worn release levers, springs and ball seats. Check levers with a straight edge and 11/16 inch ball (17-T-1126), see Figure 4-3, and if bent so that dimension (1) is more than 11/32 inch when measured at a point where distance (2) is 2-1/2 inch, replace the lever. Figure 4-3. Checking Release Lever for Bend 5. If pressure plate is scored, heat check ed, or warped more than 0.020 inch, it must be replaced or refaced. Remove only enough metal to obtain a smooth flat sur face. Finish with a light cut and polish with emery cloth. When thickness (1) be comes less than the worn limit given in specifications, the plate must be replaced. Measure at outer spring pocket, see Fig ure 4-4. Measuring at inner pocket is not accurate, if pressure plate is dished. If cleft lugs are worn, cracked or distorted, replace the plate. Replace eyebolts if they are distorted, have worn threads or keyways. Figure 4-'4. Pressure Plate Thickness Dimension 6. If flywheel is warped or heat checked and surface is refinished, maintain the 1.594 inch dimension between disc sur face and bolting face for proper release lever adjustment. See Figure 4-5. No more than .070 inch maximum may be removed by grinding. Figure 4-5. Flywheel Rubbing Surface-toClutch Cover Bolting Surface Dimension 7. Inspect driven disc assembly for cracks, loose rivets, worn splines, warped or dished condition. If cracked, or hub splines are worn excessively, replace disc assembly. If facings are worn down nearly even with countersunk facing-retaining rivet heads and provided assembly is in other wise good condition, it may be rebuilt. 8. Pilot bearing should be removed, clean ed and checked each time clutch or engine is removed. Discard bearing if balls or races are chipped or scored. After inspec tion, hand-pack bearing with recommended clutch pilot bearing grease and install bear ing in flywheel. Tap into place with shielded side toward clutch and snap ring seated in counterbore. NOTE Old bearings without a snap ring cannot be used in new throughbored flywheels. After bearing is properly installed, pack the cavity in back of the bearing with re commended clutch pilot grease. NOTE To prevent damage to the bearing seal when the transmission is as sembled to the engine, the space occupied by the main driving pinion pilot must not be filled with grease. See Figure 4-6. All current Mack-made engine flywheels have been manufactured by boring the clutch pilot bearing hole straight-through and counterboring a recess to provide proper positioning for the snap ring type pilot bear ings now in use. FLYWHEEL PRESS FIRMLY CLUTCH PILOT BALL 8EARIA (SNAP-RING TYPE) WITH BUILT-IN GREASE SEAL HANO-PACK CAVITY EXACTLY AS SHOWN AFTER BALL BEARING INSTALLATION. CENTRAL AREA MUST BE CLEAR OF GREASE BEARING SNAP-RING COUNTERBORE Figure 4-6. Cut-away View of Clutch Pilot Bearing Grease Reservoir Correctly Packed ~N*rWP-~W-'~^ : CAUTION Do not install a new snap ring bearing in an old flywheel without removing the snap ring and dis carding. In old flywheels without the counterbore, the snap ring would position the bearing too far rearward, which would result in early bearing failure and consid erable damage to costly compon ents. Use only the recommended snap ring type bearings specified. These bearings will function with out premature failure where slight misalignment exists between en gine and transmission. Before assembling the clutch, a positive wear check should be made to insure that it will provide maximum disc wear. This check will uncover any wear conditions that might prevent full release lever travel and allow corrections to be made before the clutch is assembled. Place the pressure plate assembly and cov er (without springs) into position as shown in Figure 4-7, making sure that shims of the correct thickness (.200) are inserted between cover and spacer (17-T-1763). In stall each release lever and while pressing firmly on the fulcrum, measure distance (1) inboard end of lever is above cover. 4-6 SURFACE PLATE ITM7H- Figure 4-7. Wear Check' Correct height for theCL-28 Series, 3-9/32 inches, for the CL-40 Series, 3 inches. Reassembly 1. Remove the shims used for the wear check. Lightly lubricate pivot ball bush ing, fulcrum groove, eyebolt pin and in board end of release lever with clutch lever grease. 2. Place the pressure plate on a face plate with the spring pockets of the pres sure plate up. Place heat-insulating wash ers and the springs in the pressure plate spring pockets. NOTE K pressure plate wras refaced, in sert washers into the spring cups of a thickness equal to the metal removed from the pressure plate. Shellac the washers in place to facilitate retention. 3. Place the cover in position, align the springs in the pockets. Bottom the screws of the three spring retention tools into the threaded holes of the pressure plate and bring the tool nuts down snugly against the tool bracket. Tighten the tool nuts alter nately, one turn at a time, guiding the pres sure plate lugs into the clutch cover holes until the inside face of the cover is 1.125 inch from the face of the pressure plate. Special tool (17-T-1763), is used to facilit ate obtaining this dimensions, see Figure 4-8. 4. Place the clutch release levers on the ball fulcrums and eyebolt shanks. Place the lever springs on the spring pins with the small diameter against the release levers. ( < i assembled in their original posi tions. This is necessary in order not to disturb the dynamic balance of the clutch. 1. Equally space three steel blocks 3/8 inch thick, on bed of arbor or drill press. 2. Place clutch with pressure plate side down, on blocks. (This is done in order to raise clutch to permit disassembly). 3. Place a block of wood, such as a two by four, across cover plate in a position that does not interfere with tips of release levers, as shown in Figure 4-10. Compress clutch assembly slightly, removing lever adjusting screw locknuts. Figure 4-10. Compressing Clutch 4. Turn each lever adjusting screw down (clockwise), a few turns with a screw driver, releasing spring tension a small amount. Repeat operation until all lever adjusting screws are entirely free of cover plate. Release remaining spring tension, and lift cover plate off pressure springs. 5. Pressure springs may now be removed. After extracting cotter pins and lever pins, remove release levers. Inspection and Repair Clean all parts thoroughly with a suitable safe solvent, then inspect carefully for ex cessive wear, distortion, or cracks as out lined below: 1. Check cover plate for distortion, ex cessive wear at indentations which register between drive bosses on pressure plate, and for stripped threads in holes accommodating release lever adjusting screws. If the above mentioned conditions are apparent, replacement of cover plate is required. 2. Replace springs if cracked or defective. Check all springs on a spring tester. Re place all that do not meet specifications. 3. Replace release levers that are badly worn on tips (this is an indication of a stick ing release bearing), worn threads on lever adjusting screws and nuts, or where bind ing appears to be present, which retards free back and forth movement. NOTE Release levers are serviced as a subassembly only, and consist of lever, adjusting screw, roller, rol ler block, lever spring and spring retaining pin. 4. If pressure plate shows signs of scor ing, excessive wear at lever pin holes, inside of drive bosses, heat checking, or if warped more than .020 inch, plate must be refaced or replaced. (When refacing pressure plate, remove only sufficient metal to obtain a smooth flat surface.) NOTE When pressure plate thickness be comes less than 1.141 inch, re placement is necessary. 5. If flywheel is warped or heat checked and surface is refinished, maintain the 1.188 inch dimension between disc surface and bolting face for proper release lever adjustment. No more than .070 inch maxi mum may be removed by grinding. 6. Inspect driven disc assembly for cracks, loose rivets, worn splines, warped or dished condition. If cracked, or hub splines are worn excessively, replace disc assembly. If facings are worn down nearly even with countersunk, facing-retaining rivet heads and provided assembly is in otherwise good condition, it may be rebuilt. ( 7. Pilot bearing should be removed, clean ed and checked each time^jclutch or engine is removed. Discard bearing if balls or races are chipped or scored. .After in spection, hand-pack bearing with clutch pilot bearing grease and install bearing in flywheel. Tap into place with shielded side toward clutch. After bearing is properly installed, pack the entire cavity in back of the bearing with the same specified clutch pilot grease. NOTE To prevent damage to the bearing seal when the transmission is as sembled to the engine, the space occupied by the main driving pinion pilot must not be filled with grease. See Figure 4-11. 2. Place pressure springs in position on pressure plate, as shown in Figure 4-12. Figure 4-12. Assembling Clutch 3. Lay cover plate over springs, being sure that all springs are seated on bosses of pressure plate, and around indentations on inside of cover. 4. If pressure plate was refaced, it will be necessary at assembly, to add shims under each pressure spring equal to total metal removed. 5. Compress assembly slowly, aligning lever adjusting screws with threaded holes in cover plate. (The indentations inside cover, should enter the spaces between Figure 4-11. Cut-away View of Clutch drive bosses on pressure plate freely.) Pilot Bearing Grease Reservoir Correctly With screwdriver, thread ends of adjust Packed ing screws into cover evenly, until screws protrude about 1/2 inch. Hold assembly compressed, while placing locknuts in posi Use only the recommended pilot bearings tion, but do not tighten. specified. These bearings will function without premature failure where slight 6. To facilitate installation on flywheel, misalignment exists between engine and place wood blocks approximately 3/8 inch transmission. thick, between the tops of release levers and inner rim of cover plate. (Be sure Reassembly these stay in position as all tension is released). I 1. Mount release lever assemblies on pressure plate. Set pressure plate as sembly on three equally spaced steel blocks 7. Insert the three spring retention tools (17-T-1766), through cover and bottom in 3/8 inch thick, on bed of arbor or drill tapped holes in pressure plate (center hole press, plate side down. of each five series in cover). With pres- 4-9 sure plate face down on smooth surface, insert three clutch cover spacer gages (17-T-1767) (3/4 inch) at three equidistant points around edge of cover. These gages may be held with bolts, but do not allow bolts to extend beyond lower face of gages. 8. Holding bolt head of spring retention tool, draw up nuts evenly until blocks can be removed from between release levers and cover. After removing blocks, re lease tension by backing off nuts until pres sure plate and cover spacers rest evenly ,~on smooth surface. Using lever setting gage (17-T-1768), check distance from release lever tips to smooth surface. Ad just screws until desired setting is obtained. See specifications. Then lock screws in position with locknuts. CL-50 SERIES Description CL-50 Series assemblies are two-plate, dry disc pusher type clutches. In engage ment, the two driven discs and the inter mediate plate are clamped between the pressure plate and the flywheel by the force of multiple-helical springs backed up by the cover which is bolted to the flywheel. Six lugs in the flywheel, drive the inter mediate plate, but permit free longitudinal movement. Pressure plate drive is trans mitted by six cleft lugs which fit openings in the cover. The release levers have ball pivots and are linked to the pressure plate by eyebolts. The inner ends of the levers are held by the notched release thrust washer. See Figure 4-13. Disassembly NOTE Before disassembly of the various parts, it is good practice to mark these parts with a centerpunch, so that at reassembly, they can be reassembled in their original posi tions. This is necessary in order not to disturb the dynamic balance of the clutch. 1. Before removing the three spring re tention tools, compress clutch release lever springs, remove washer pins, then remove washers and release lever springs. Pry off snap ring from thrust washer. Remove eyebolt nuts, fulcrums. and clutch release lev ers. 4-10 1. Flywheel 13. Lever Bushing 2. Intermediate 14. Eyebolt Fulcrum Plate Drive Pin 15. Adjusting Nut 3. Adjusting Spacer Washer 4. Clutch Spring 16. Eyebolt Adjust- 5. Spring Cup ing Nut 6. Insulating Washer 17. Eyebolt Lock 7. Driven Disc Nut 8. Thrust Washer 18. Eyebolt 9. Release Bearing 19. Clutch Cover 10. Release Lever 20. Pressure Plate 11. Lever Spring 21. Intermediate 12. Lever Pivot Plate 22. Pilot Bearing Figure 4-13. Sectional View of CL-50 Series Clutch CAUTION ; If retaining cups are used instead of tool (17-T-1123), clampthecov er in a press before removing the cups. This is necessary because the screw used does not have suf ficient thread length to completely release the spring load before coming out of the pressure plate. 2. While holding spring retention tool screws, back off tool nuts alternately, mak ing one turn, at a time. When spring is entirely relieved, back out the three tool screws. 3. Remove clutch cover and springs. If heat-insulating washers are removed from pressure plate spring pockets, retain them for reassembly. The eyebolts need not be removed, unless inspection reveals distor tion or loose fit on pins. be replaced. Measure at outer spring pock et as shown in Figure 4-13. Measuring at inner pocket is not accurate if pressure plate is dished. If cleft lugs are worn, cracked or distorted, replace the plate. The intermediate plate features a double set of drive slots for increased service life. At clutch installations after rebuild, it is re commended that the set with less wear be used. Replace eyebolts if they are dis torted, have worn threads or keyways. Inspection and Repair Remove all traces of dirt and oil with a suitable safe solvent. Inspect parts care fully for cracks, distortion or excessive wear as follows: 1. If cover is cracked or distorted, re place. Tack-weld loose spring cups (on covers having this construction) replace worn or loose ball-fulcrums. Replace loose or bent release lever spring pins. 2. Replace springs if cracked or defec tive. Check all springs on a spring tester. Replace all that do not meet specifications. 3. Replace thrust washer if worn, bent or defective. Figure 4-15. Pressure Plate Thickness Dimension 6. If flywheel is warped or heat checked and surface is refinished, maintain the 2.797 inch dimension between disc sur face and bolting face for proper release lever adjustment. See Figure 4-16. Nomore than .070 inch maximum may be removed by grinding. 4. Replace worn release levers, springs and ball seats. Check levers with a straight edge and 11/16 inch ball (17-T-1126) as il lustrated, in Figure 4-14 and if bent so that dimension (1) is more 11/32 inch when measured at a point where distance (2) is 2-1/2 inch, replace the lever. Figure 4-16. Flywheel Rubbing Surfaceto-Clutch Cover Bolting Surface Dimension Intermediate plate drive pins should be inspected for abnormal wear. Figure 4-14. Checking Release Lever for Bend When pins have been removed to permit flywheel machining, or require replace ment, squareness between flywheel friction and pin drive faces must be maintained at installation. A positioning tool will assist in establishing necessary alignment. Suitable for this purpose, will be a slotted 5. If pressure and intermediate plates are steel block 4 inches long, 2-1/2 inches scored, heat checked, or warped more than wide and 1-1/2 inches thick. One 2-1/2 0.020 inch, they must be replaced or re inches x 4 inches face should be ground faced. Remove only enough metal to ob for maximum flatness, as it will constitute ) tain a smooth flat surface. Finish with a the major working surface. A 3/16 inch x light cut and polish with emery cloth. When 45s chamfer along all edges of this face will thickness (1) becomes less than the worn tend to prevent burrs that would affect limit given in specifications, the plate muse accuracy. See Figure 4-17. 4_11 !! I 1S` CHAMBER. WFAOCREKING Figure 4-17. Drive Pin Positioning Tool Midway between ends of the 4 inch length, a .628/.627 inch wide, slot 1-1/4 inch deep should be machined through the 1-1/2 inch thickness. The slot must be exactly square with the ground face for it will determine flywheel to drive pin head alignment. A half -inch drift pin clearance hole, drilled from the side opposite, and intersecting with, the slot will complete the tool. Hole centerline should be 7/8 inch from the ground face, so that driving force will be centered over the head. Magnetizing the block will minimize movement during driv ing and lessen possibility of marring fly wheel face. In use, the threaded portion of the pin is inserted in the flywheel hole. The position ing tool slot is placed over the drive head, with the ground surface held flat against the flywheel friction face. The pin is then driven until fully seated. 7. Inspect driven disc assembly for cracks, loose rivets, worn splines, warped or dished condition. If cracked, or hub splines are worn excessively, replace disc assembly. If facings are worn down nearly even with countersunk facing-retaining rivet heads and assembly is in otherwise good condition, it may be rebuilt. 8. Pilot bearing should be removed, clean ed and checked each time clutch or engine is removed. Discard bearing if balls or races are chipped or scored. .Afterinspec tion, hand-pack bearing with clutch pilot bearing grease and install bearing in fly 4-1 9 wheel. Tap into place with shielded side toward clutch and snap ring seated in coun terbore. Old bearings without a snap ring cannot be used in new through-bored fly wheels. After bearing is properly installed, pack the entire cavity in back of the bearing with the same specified clutch pilot grease. NOTE To prevent damage to the bearing seal when the transmission is as sembled to the engine, the space occupied by the main driving pinion pilot must not be filled with grease. See Figure 4-18. CRANKSHAFT FLYWHEEL CLUTCH PILOT BALL BEARING (SNAP-RING TYPE) WITH BUILT-IN GREASE SEAL HAND-PACK CAVITY EXACTLY AS SHOWN AFTER BALL BEARING INSTALLATION. CENTRAL AREA MUST BE CLEAR OF GREASE 9EARING SNAP-RING CCUNTERBORE Figure 4-18. Cut-away View of Clutch Pilot Bearing Grease Reservoir Correctly Packed All current Mack-made engine flywheels have been manufactured by boring the clutch pilot bearing hole straight-through and counterboring a recess to provide proper positioning for the snap ring type pilot bearings now in use. CAUTION ; Do not install a new snap ring bear ing in an old flywheel without re moving the snap ring and dis carding. In old flywheels without the counterbore, the snap ring would position the bearing too far rearward, which would result in i i early bearing failure arfd consider able damage to costly components. Use only the recommended snap ring type bearings specified. These bearings will function with out premature failure where slight misalignment exists between en gine and transmission. Before assembling the clutch, a positive wear check should be made to insure that it will provide maximum disc wear. This check will uncover any interference that might prevent full release lever travel and allow corrections to be made before the clutch is assembled. Place the pressure plate assembly and cov er (without springs) into position as shown in Figure 4-19, making sure that shims of the correct thickness (.250) are inserted between cover and spacer (17-T-1763). In stall each release lever and while pressing firmly on the fulcrum, measure distance (1) inboard end of lever is raised above cover. Correct height is 3-11/32 inches. Remove any interference that prevents ob taining this dimension. Figure 4-19. Wear Check Reassembly 1. Remove the shims used for the wear check. Lightly lubricate pivot ball bush ing, fulcrum groove, eyebolt pin and in board end of release lever with clutch lever grease. 2. Place the pressure plate on a surface plate with the spring pockets of the pres sure plate up. Place heat-insulating wash ers and the springs in the pressure plate spring pockets. NOTE If pressure plate and intermediate plate were refaced, insert wash ers into the spring cups of a thick ness equal to the metal removed from the pressure plate and inter mediate plate. Shellac the wash ers in place to facilitate retention. 3. Place the cover in position, align the springs in the pockets. Bottom the screws of the three spring retention tools into the threaded holes of the pressure plate and bring the tool nuts down snugly against the tool bracket. Tighten the tool nuts alter nately, one turn at a time, guiding the pres sure plate lugs into the clutch cover holes until the inside face of the cover is 1.1875 inch from the face of the pressure plate. Special tool (17-T-1763) and a 1/16 inch spacer (17-T-11337), is used to facilitate obtaining this dimension. See Figure 4-20. NOTE If the intermediate driving plate is worn or has been machined, the consequent reduction in thickness will produce the same effect as worn clutch discs when the clutch assembly is installed in a vehicle. In an extreme case, one-half the available release collar wear travel may be used up before the vehicle is put back into service. To compensate for this condition, shims of appropriate thickness must be inserted be tween cover and spacers (17-T-1763) while the clutch is adjusted. Measure thickness of the intermediate driving plate which will be used with clutch being adjusted and com pare with new thickness as shown in speci fications. If plate is .010 inch or more below new thickness, secure shims equal in thickness to amount of metal removed and insert them between clutch cover and spacers (17-T-1763) at equally spaced in tervals. See Figure 4-20. 4. Place the clutch release levers on the ball fulcrums and eyebolt shanks. Place the lever springs on the spring pins with the small diameter against the release levers. Place the spring washers in position, com- 4-13 when SETTING THESE CLUTCHES, PLACE A 1 16 SPACER UNDER BOTH GAGE AND TOOL T7-T-1763 17-T.11337 MAY BE USED AS 1 16 SPACER. SHIM TO COMPENSATE FOR INTERMEDIATE PLATE WEAR MACHINING ONLY. THICKNESS TO EQUAL amount machined FROM PLATE. USE 6 EQUALLY PLACED. -7 AA // A // A A?________X Figure 4-20. Method of Setting Clutch press, and insert the washer lock pins. In stall the fulcrums and adjust the nuts until the distance between the convex surface of each lever to the pressure plate (dimen sion (1), Figure 4-20) agrees with specifi cations. Special tools (17-T-11307) and a 1/16 inch spacer (17-T-11337) are used to facilitate obtaining this dimension. See Figure 4-20 showing use of these tools. Torque eyebolt locknut 40 to 45 lbs. ft. Install the thrust washer on the release levers and lock it in place with the snap ring. CL-58 SERIES Description The CL-58 Series clutches are of the con ventional single-plate, dry-disc pushertype. They consist of a cast iron pressure plate, a cast iron cover and a rigid-type driven disc which is splined to the trans mission main driving pinion shaft. When engaged, the driven disc is clamped be tween the pressure plate and flywheel web by the pressure of thirty-six compressed helical main springs reacting on the rigid cast iron cover. The springs are arranged symmetrically in groups of six between each pair of levers. Drive from cover-topressure plate is by engagement of six pairs of integral lugs on the pressure plate which are straddled by six pairs of mating lugs integral with the cover. The six forged and hardened steel release lev ers have anti-friction needle roller bearing mounting to the plate at the drive lugs and pivot in similar anti-friction needle roller bearings supported by yokes bolted to the cover. All six release levers are pro vided with individual anti-rattle springs. The notched release lever thrust washer ring is held in engagement with the lever tips by wire clamp extensions of three alternate lever anti-rattle springs. See Figure 4-21. Disassembly NOTE Before disassembly of the various parts, it is good practice to mark these parts with a centerpunch. so that at reassembly, they can be reassembled in their original posi tions. This is necessary in order not to disturb the dynamic balance of the clutch. 1. With a screwdriver, unhook the wire clamps that retain slotted thrust washer ring to the lever tips and remove ring. 2. With pressure plate side down, position clutch assembly on rebuild machine table. With a suitable clamping device, compress the spring-loaded cover assembly. Remove nut lock plate retaining screws, lockwashers, nut lock plates and lever adjusting nuts from cover and put aside for use at reas sembly. See Figure 4-22. Clamping pres sure on the clutch cover may now be re lieved. 3. Remove inverted leaf springs from lev er yoke stems, -helical main springs, and 1. Clutch Cover 11. Double Torsion 2. Release Cover Anti-Rattle Spring 3. Release Lever 12. Thrust Washer Pin Clamp 4. Needle Bearings 13. Lever Thrust 5. Release Lever Washer Ring Yoke 14. Pressure Plate 6. Yoke Leaf 15. Helical, Main Spring Spring 7. Lever Adjust- 16. Heat Insulator ing Nut Ring 8. Adjusting Nut 17. Driven Disc Lock Plate Assembly 9. Lock Plate Lock 18. Facing Rivet Screw 19. Driven Disc 10. Yoke Clevis Pin Facings Figure 4-21. Sectional View of CL-58 Series Clutch main spring insulator washers from pres sure plate bosses. NOTE Do not remove the six lever anti rattle springs from the cover un less replacement is necessary. 4. Lay pressure plate on bench and with a soft metal drift, drive hardened lever pins out of pressure plate drive lugs to free re lease levers. With a pair of pliers, remove cotter pin from each lever yoke clevis pin and then press out each yoke clevis pin by hand. NOTE When removing levers from pres sure plate drive, lugs and lever yoke, be very careful not to lose any of the small uncaged needle rollers. Inspection and Repair Remove all traces of dirt and oil with a suitable safe solvent. Inspect parts care fully for cracks, distortion or excessive wear as follows: 1. Replace springs if cracked or defective. Check all springs on a spring tester. Re place all that do not meet specifications. 2. If pressure plate is scored, heat check ed, or warped more than .025 inch, it must be replaced or refaced. Remove only enough metal to obtain a smooth flat surface. No more than .070 inch maximum may be re moved by grinding. 4-15 3. Inspect clutch release lever tips and clevis pin holes.for excessive wear. Make sure levers are not bent. Replace where necessary. 4. Inspect release lever yokes for con dition of threads. Slight thread damage may be cleaned up with a three-cornered Swiss file. Replace lever yokes if clevis pin holes are elongated. 5. Check clevis pins and lever pins for wear. Replace if wear is excessive. Check lever slotted thrust washer ring for exces sive wear. Replace if slots are excessive ly worn. 6. Check lever needle roller bearings for wear. If flats are such that rollers slide rather than roll, replace rollers. 7. Inspect driven disc assembly for cracks, loose rivets, worn splines, warped or dished condition. If cracked, or hub splines are worn excessively, replace disc assembly. If facings are worn down nearly even with countersunk facing-retaining rivet heads and provided assembly is in otherwise good condition, it may be rebuilt. 8. If flywheel is warped or heat checked and surface is refinished, maintain dimen sions shown in Figure 4-23 between disc surface and bolting face for proper release lever adjustment. No more than .070 inch maximum may be removed by grinding. Figure 4-23. Flywheel Rubbing Surfaceto-Clutch Cover Bolting Surface Dimension 9. Pilot bearing should be removed, clean ed and checked each time clutch or engine is removed. Discard bearing if balls or races are chipped or scored. After inspec tion, hand-pack bearing with clutch pilot bearing grease specified and install bear ing in flywheel. Tap into place with shield ed side toward clutch and snap ring seated in counterbore. After bearing is properly installed, pack the entire cavity in back of the bearing with the same specified clutch pilotgrease. NOTE To prevent damage to the bearing seal when the transmission is as sembled to the engine, the space occupied by the main driving pinion pilot must notbe filled with grease. See Figure 4-24. CRANKSHAFT flywheel CLUTCH PILOT BALL BEARING ISNAP-RING TYPE! WITH BUILT-IN GREASE SEAL MANO-PACK CAVITY EXACTLY AS SHOWN AFTER BALL BEARING INSTALLATION. CENTRAL AREA MUST BE CLEAR OF GREASE 9EARING SNAP-RING CCUNTERBORE Figure 4-24. Cut-away View of Clutch Pilot Bearing Grease Reservoir Correctly Packed Use only the recommended snap ring type bearings. These bearings will function with out premature failure where slight mis alignment exists between engine and trans mission. Reassembly 1. Apply a light coat of clutch lever grease on the loose needle bearings and install rollers in each pin hole of levers. When bearings are installed, apply additional grease to each assembled bearing group. 2. Spread a thin coat of lever grease on the two rubbing flats of each lever and on all yoke rubbing surfaces. Center lever yoke clevis pin holes over lever inner bear NOTE ing-lined pin holes and carefully insert clevis pin through the aligned holes. Lock Make sure leaf springs are in pin in position with cotter pin. verted on yoke stems and parallel to levers so that their upturned 3. Apply a thin even coat of lever grease ends will bear against under side on all pressure plate drive lug rubbing sur of cover when assembled, thus faces. Carefully position lever assembly spring-loading each yoke. between drive lugs. Align pinholes in drive lugs with assembled needle rollers and push 5. Position yokes vertically. Position pin through lugs and bearing opening. clutch cover over assembly. After center ing all main springs in their counterbored NOTE seats in cover, set up clamping arrange Remove all excess grease. ment and compress springs slowly. Make sure ALL yoke stems are in alignment, 4. Position clutch pressure plate and lev then continue to compress springs until all six stems are sticking out of their cover er assembly in clutch overhaul machine, arbor press, drill press or whatever clamp holes. ing arrangement being used. After center 6. Apply a very thin coat of clutch lever ing thereon, install heat insulator washers on the spring heat grids, then main springs in their correct specified positions. grease to adjusting nut spherical seats in cover. Then install adjusting nuts. Clamp ing pressure on clutch cover may now be NOTE relieved. 7. Lay engine flywheel on bench. Make Except as specified below, install up four spacers exactly .402 inch thick BLACK or COLORLESS main each and arrange them on flywheel rubbing springs on all locating bosses re maining without springs. surface. The spacer thickness of .402 inch corresponds to the mean driven disc as CL-58, install an all RED spring on each sembly thickness under load. See Figure 4-26. Then without disturbing the .402 No. 1 and No. 3 spring boss. CL-581, in inch spacer arrangement, position clutch s i stall an all WHITE spring on each No. 4 and 5 spring boss. in flywheel counterbore. Install clutch in flywheel counterbore. Install clutch cover- to-flywheel capscrews with their lock wash CL-582, install an all WHITE spring on ers. Tighten capscrews a turn or two at a each No. 6 spring locating boss. See Fig time, in rotation, so cover will not be cock ure 4-25. Install inverted yoke springs ed and forced into flywheel pilot by the on yoke stems. tightening of the screws. Figure 4-25. Main Spring Arrangement In One of the Six Identical Pressure Plate Segments Figure 4-26. Clutch Lever Adjustment Spacer Arrangement in Flywheel 4-17 1 J* l i f * i \ \ i 4 f ; I 1. Pressure Plate 2. Return Spring 3. Pivot Pin 4. Spring Clip 5. Adjusting Ring 6. Lever 7. Snap Ring 8. Release Sleeve Ring 9. Release Sleeve Retainer 10. Spring Pivot 11. Pressure Spring 12. Flywheel Ring 13. Adjusting Ring Lock 14. Bolt & Lock Washer Assy 15. Release Bearing & Bearing Assy 16. Driven Rear Disc 17. Intermediate Plate 18. Driven Front Disc Figure 4-33. Exploded View AS-1550 Series Clutch Assembly .Removal and Disassembly A suitable "sling" or transmission jack should be used to properly support andmaintain the engine/transmission alignment when removing or installing a transmission on an engine. DO NOT let the rear end of the transmission drop down and hang unsupported in the splined hubs of the clutch discs to avoid bending or distorting the friction discs. Disconnect the external linkage from the clutch release arm to permit the release yoke to turn up and pull free of the release bearing thrust pads. 1. Prior to actual clutch removal, assemble a clutch disc aligning tool to the driven disc and release bearing assembly. It is important that two 3/4 inch blocks of wood as shown in Figures 4-34 and 4-35 be inserted between the clutch release bearing housing and clutch flywheel ringas the clutch mounting bolts are loosened around the fly wheel. These blocks will relieve the heavjL. internal spring load, preventing cocking and bending within the clutch and insure easy re moval of remaining mounting bolts. 2. When all bolts have been removed, slide clutch assembly back and off using caution to keep aligning tool in place to retain discs and intermediate plate. 3. Carefully remove aligning tool, rear disc, intermediate plate and front disc. 4-29 Figure 4-36. Removing Adjusting Ring Lock Figure 4-34. Location of Support Block AS-1400 Series Figure 4-37. Removing Return Spring 6. Turn the adjusting ring and lever assem bly counter-clockwise until free of flywheel ring. Then lift and remove assembly. See Figure 4-38. Figure 4-35. Location of Support Block AS-1550 Series 4. Remove bolt and lockwasher assembly and adjusting ring lock. Use screwdriver or similar wedge to remove adjusting ring lock. See Figure 4-36. 5. Set clutchassembly (without driven discs and intermediate plate) upside down on a flat table or workbench. Unhook four return springs from flywheel ring and lift pressure plate off. See Figure 4-37. NOTE Mark pressure plate in relation to flywheel ring for reassembly pur poses. Figure 4-38. Turning Adjusting Ring 7. Remove snap ring from release sleeve retainer. See Figure 4-39. 4-30 Remaining Clutch Life Chart - % Figure 4-43. Removing Retainer Clip Inspection and Repair Clean all parts thoroughly with a suitable safe solvent. Many clutches are replaced as a preventative maintenance item at low mileage during re pairs of the transmission or engine. Before the Clutch Assembly is replaced, the unit should be inspected for the following items: REMAINING CLUTCH LIFE 163.76 Driven Discs Inspect disc assembly for cracks, loose ri vets, worn splines, warped or dished condi tion. Re-straighten if dished or warped 0.015 inch maximum runout. Replace if hub is cracked, or splines are worn excessively. 1. Heat cracks in the pressure plate. 2. Excessive wear in all drive slots. 3. Broken springs. 4. Dry or damaged release bearing. 5. Broken intermediate plate. 6. Excessive driven disc hub spline wear. 7. Burned facings. 8. Excessive wear on drive pins or inter mediate plate slots. If the preceding list has been inspected and looks to be in good condition, use the chart to determine the approximate remaining clutch life by measuring the thickness of the rear driven disc assembly. Find thickness of rear disc on column to left then follow curve on right then drop this point down to'read % of clutch life remaining. Replace facings if they are glazed, scored, worn down to rivet heads, burned, or if grease or oil are on them. The riveted asbestos facing driven discs, use high-quality facings riveted to the steel disc. They may be furnished with rigid disc or damper type. Used discs can be reworked in the field by drilling out the rivets to re move old facings. Use the correct size drill when removing old rivets to avoid enlarging holes in disc. Use proper facings andastar set anvil to reline used discs. Ceramic friction material, a combination of metal and ceramic, is relatively new to the clutch facing industry. It is used in pro ducing round or trapezoidal buttons which are riveted to steel discs. These clutch discs, available with either rigid or damper hubs, offer many advantages for heavy-duty_ applications. Reworking these discs in the field is not recommended because the ceram ic buttons must be assembled and ground to hold thickness as well as squareness with splines. pressure plate. Smooth and flat pressure plate surfaces must be used for satisfactory clutch life. Check drive lugs for wear per Specification Chart. Super-duty discs have six trapezoidal cer amic buttons and are available with rigid or damper hubs. These S-D discs are thinner than standard discs while the intermediate plate is thicker. This combination of more ceramic buttons and thicker intermediate plate provides longer life and increased torque capacity. A super-duty kit consisting of two driven discs and an intermediate plate is available for converting astandard Angle-Spring clutch into a super-duty A-S clutch. It is very im portant that the kit be installed as a unit and its components should never be intermixed with standard components. Intermediate Plate Inspect friction surfaces of intermediate plate for heat checks, scoring or distortion. If friction surface is badly scored, heat checked, warped or dished in excess of 0.020 inch, resurface or replace with new intermediate plate. Smooth and flat inter mediate plate surfaces must be used for sat isfactory clutch life. Inspect driving slots of intermediate plate for wear per Specifi cation Chart. Release Levers Flywheel_Ring Inspect the flywheel ring for cracks. Re place if cracks are visible. Check slots for indentation caused by wear of pressure plate driving lugs. See Specification Chart for slot limits. Inspect bolt circle face and pilot for nicks and burrs due to removal or handling. Re move burrs with file to insure proper seat ing and squareness when clutch is mounted to flywheel. Inspect levers for excessive wear at points of contact with pressure plate, release sleeve retainer, and pivot pin. If levers are bent or worn, replace with new levers. It is good preventive maintenance to replace levers during clutch rebuild. Release Sleeve Retainer Inspect for wear in lever groove and internal splines. Refer to specifications for driving slot clearance between flywheel ring drive slots and release sleeve retainer drive lugs. Adjusting Ring Check pivot pin holes for wear. Clearance may not exceed 0.010 inch between pin and hole. Inspect for cracks; replace if cracks are visible. Pressure Plate Inspect fulcrum for wear. If wear exceeds 0.015 inch, remachine. See Specification Chart for maximum rework. Inspect friction surface of pressure plate for scoring, burning, heat checking or distor tion. If friction surface is badly scored, heat checked, warped or dished in excess of 0.010 inch, resurface or replace with new Spring Pivots Inspect for cracks; if visible, replace. Release Sleeve Sub-Assembly Check bushing for excessive wear. Check bearing diameter for tight fit. Refer to Specifications Chart and replace if nece ssary. Release Bearing and Sleeve Assembly It is recommended that the release bearing and sleeve assembly be replaced as a unit at the time of clutch rebuild. Assemblies are available as service replacement items. ENGINE HOUSING Figure 4-82. Checking Flywheel Face Runout Figure 4-83. Checking Flywheel Bore Runout 2. Check recessed type flywheel for cor rect depth. See specifications. 3. Replace release bearing and carrier, if worn, and flywheel pilot bearing. Pilot bearing should be a hand press fit in the fly wheel recess and on the transmission drive gear. The release yoke or fork should con tact the release bearing carrier pads evenly to prevent a bind on the front bearing cap extension. 4. The friction face of the flywheelmust be free from heat cracks, score marks and taper. The presence of any of these condi tions will have an adverse effect on clutch function and life. Installing Clutch Assembly It is a good idea to try the cover assembly on the flywheel without the disc assembly to check fit where cover is piloted at O.D. Install driven disc, making sure that it is properly positioned and insert an aligning shaft. Normally the long end of the driven disc hub extends toward the transmission, but in a few instances the long end may face toward the engine. Make sure that the driven disc hub does not come within 5/32 inch of the pilot bearing. Bolt the cover assembly to the flywheel, tightening each capscrew gradually until the cover is drawn up tight. Extreme care must be exercised to make sure flywheel ring or cover is seated in piloting rim on recessed type flywheels. Some cover assemblies are piloted to the flywheel by capscrews with a ground shank which fits the reamed holes in the cover. The machined shank extends through the cover into a recessed or counterbored hole in the flywheel. If a flywheel has been reground there is a chance that the counterbores could be too shallow and may require deepening. If the flywheel has been remachined several times to remove heat cracks or scores, the counterbored holes may not be deep enough to allow complete tightening of the capscrews. This will nece ssitate replacing the flywheel. Dimension 'A' Dimension 'A' is the distance from the top of the clutch flywheel ring (cover) to ends of release levers. See Figure 4-84. Figure 4-84. Checking 'A' Dimension Check specification chart for correct 'A' Di mension. Satisfactory operation of the clutch depends greatly upon the accuracy of the lever setting, as this controls the parallel movement of the pressure plate. 3/8 inch capscrews. 7/16 inch capscrews are used for 15-1/2 inch - 2 applications. The pressure plate is driven by means of driving lugs extending into mating slots of the flywheel ring (cover). The intermediate plate is driven by drivepins located in the engine flywheel. Depressing the clutch pedal pulls the release bearing toward the transmission. The re lease bearing being connected to the release levers thus retracts the pressure plate from contact with the driven disc assembly, therebyrelieving the pressure on the intermediate plate and the forward driven disc assembly which disengages the clutch. heads are perfectly square to the friction surface. Drive pins must be square to pro vide proper clearance for the drive slots in the intermediate plate. A machinist's square and feeler gage may be used to check for squareness. After the pins are installed and properly squared, try the intermediate plate for fit over the pins. With new pins and a new in termediate plate, there should be from 0.006 inch to 0.014 inch clearance. Try the plate in different positions and select the position which provides the greatest freedom of move ment. Mark the plate for location to the fly wheel. Lock the drive pins in place with the socket head or Allen set screws. Releasing the clutch pedal allows the release bearing assembly to move toward the engine permitting the pressure plate to move to ward the flywheel gripping the discs, causing engagement. Clutch Installation Before installing the clutch on the flywheel, check for free fit of cover assembly to fly wheel and flywheelalignment before proceed ing with installation. See Figures 4-80, 481, 4-82 and 4-83. Driven discs are marked, "Pressure Plate Side" and "Flywheel Side", to indicate their proper positions. Install as indicated. The cover assembly may now be installed on the flywheel but, before tightening cap screws, install an aligning shaft through the two hubs and into pilot bearing. Cover capscrews may now be tightened pro gressively around the flywheel using 35 to 40 ft. lbs. of torque. Be sure that intermediate drive pins are a press fit in holes inflywheel rim and that the Remove the three hold down bolts from cover before removing splined aligning shaft or disc assemblies may fall out of position. 4-51 frame cooling front axle steering springs and suspension wheels brakes electrical cabs HIGHWAY VEHICLE SERVICE MANUAL ' * *. TRUCKS T)w Cmtnt Mama M Truan MACK TRUCKS, INC. -- one oi T.oe Signal Comcanies _J TS442 TS442 TS442 TS442 TS442 TS442 REV. REV. REP. REV. REV. 10/67 8/69 5/71 12/72 8/75 9/77 10M 10M 10M 10M 10M 18M Printed in U. S. A. The system for actuating the wedge brake has an air chamber power unit threaded into the wedge bore of the plunger housing. Air applied to the diaphragm pushrod pushes the wedge rod against the plungers. See Figure 8-13. V- OUTER SHOE ' 1. Plunger Housing 2. Adjusting Bolt Assembly 3. Adjusting Sleeve (Actuator) 4. Adjusting Plunger 5. Guide Screw 6. Anchor Plunger (solid) 7. Plunger Seal and Retainer 8. Wedge Assembly 9. Brake Air Cham ber Assembly Figure 3-13. Wedge Actuation Air Chamber Disc Brakes Front axles that incorporate disc brakes are of the sliding caliper, dual piston design. The dual pistons are actuated by hydraulic pressure which is multiplied through the use of an air over hydraulic fluid intensifier. Hy draulic pressure is increased over air pres sure by a ratio of 17 to 1 or 23. 5 to 1, de pending on the model intensifier. The master cylinder includes both air and hydraulic systems. They should be con sidered as separate systems, although op erating together. Air pressure actuates a diaphragm in the master air chamber which actuates a plunger in the hydraulic master cylinder, creating pressure to the disc brake units. See Figures 8-14 and 8-15. Figure 8-15. Air Hydraulic Intensifier Adjustment Cam Brakes Initial adjustment on cam brakes is done by adjusting the slack adjusters, which can be either the manual or automatic type. Main taining correct drum to lining clearance requires periodic readjustment of the manual slack adjusters, usually monthly or at approx imately 8, 000 miles. Under severe braking conditions, adjustments may be needed at more frequent intervals. Accuracy of the wheel bearing adjustment cannot be overemphasized as it has a direct effect on brake performance. You cannot properly adjust a brake if the wheel bearing has not been correctly adjusted. It is there fore important that a torque wrench be used in the adjusting and that you adhere to the manufacturer's specification. NOTE Do not adjust brakes when drums are hot because the brakes will 8-12 drag when the drums cool - al ways adjust brakes when the drums are cool or a: room temperature. The routine of adjusting brakes to a drag and then relieving the drag should be supple mented with a feeler gauge check. This is the only true means of establishing what the actual clearances are at the three vital pos itions of cam, center and anchor on both shoes. When self-centering of the shoes in the drum is possible we should utilize this feature by applying the brakes a few times and rechecking the clearances. Be certain that the initial adjustment at time of reline affords extra lining to drum clearance be cause of lining swell. A clearance of . 020 between lining and drum, should be adhered to on a newly relined vehicle. After the breakin period . 010 clearance would be the rule. Actual brake to drum adjustment procedure is covered under Slack Adjuster section. Automatic Adjustment Type The automatic type maintains the correct lining-to-drum clearance. This is accom plished by the action of an adjusting bolt and sleeve fitted into a hollowed plunger, body working with an adjusting pawl, a spring, and a retainer cap screw. The end of the pawl has saw-tooth teeth which engage sim ilar teeth on the outside of the adjusting sleeve. See Figure 8-16. HOUOW CAP SCHW Wedge Brakes Twotypesof adjustable plungers are in use manual and automatic. The manually ad justed plunger has an adjusting bolt threaded into the plunger proper. The bolt head is scalloped to facilitate adjustment and carries a detent arrangement which engages the brake shoe web and prevents accidental rotation of the bolt. Manual Adjustment Type To adjust manual adjusters. 1. Jack or hoist wheels free of ground. 2. Remove dust cover from adjusting slot two places on each brake. The adjusting slots are below the forward and above the rear power unit. If star-wheel adjusting bolts are not found at these positions, the brake had been assembled on the wrong side of the vehicle. 3. Adjusting bolts have right hand threads. With an adjusting spoon, turn the star-wheel until a heavy drum drag is developed. Then back off the bolt to a very light drag on the drum. Repeat for other shoe on the brake. Replace dust covers in adjusting slots. Re peat for other brakes. NOTE Recommended adjusting spoons, are Snap-On-Blue-Point S-9523, Wizard 4-H-2530 and Proto 2006. Figure 8-16. Automatic Adjustment Components When the brake is actuated, the plunger, sleeve, and bolt are forced outward applying the brakes. The sloping teeth on the adjust ing sleeve push the pawl back against the spring. At this point, the pawl teeth disen gage from the sleeve teeth. If the brake shoes have traveled sixty thousandths of an inch (. 060 ) or less to apply the brakes, all adjusting parts will return to their original position when the brake is released. As the lining wears and shoe to drum clear ance exceeds sixty thousandths of an inch (. 060 ), the pawl climbs over and drops into the next tooth space on the sleeve. When the brake is released, the new tooth position causes the sleeve to rotate, advancing the adjuster bolt. Current production models of the wedge brake incorporate a limited travel adjusting bolt to prevent over adjustment and possible sleeve damage. This is accomplished by using a snap ring retainer located around the bottom of the adjusting bolt. The snap ring acts as a stop against a shoulder in the ad justing sleeve. 8-13 Disc Brakes No manual adjustment required. Brakes adjust automatically during braking oper ation. The square-cut piston seal is dis torted when pressure is applied to piston. When braking pressure is released, the seal returns to its normal condition and pulls the piston away from the lining. This action, plus some slight rotor lateral runout ("wob ble"), considehednormal, provides adequate running clearance. \ Disassembly and Assembly When brakes are relined or disassembled for other repairs, all parts should be in spected for wear and worn parts should be replaced as required. Cam Brakes - (See Figure 8-10) Disassembly 1. Remove shoe return spring. 2. Remove lock rings, retainers, and felts from brake shoe anchor pins. 3. Cut lock wire and remove anchor pin lock screws. 4. Remove anchor pins and shoe assemblies. 5. Remove brake shoe roller retaining clip (or screw) and remove roller. 6. Remove slack adjuster lock ring and spacing washers. 7. Remove camshaft, washer, and felt seal (if used ). 8. Remove nylon bushings if replacement is necessary. Use suitable tool for both re moval and installation of bushing. See Figure 8-17. NOTE On brakes where lip type seals are used, these will have to be removed and replaced if nylon bushings are replaced. *2-1/2"* ""-- Suitable length ---- ------ \-------1.492" ! 1 i 1.863" ! Figure 8-17. Bushing Removal and Installation Tool 8-14 Assembly 1. Install new nylon bushings, if required, using suitable tool. (Install new lip type seal if used.) 2. Install brake shoe rollers and retainers. Make certain rollers are of proper size. See instructions relative to brake shoe "Cam Roll-Over. " 3. Install camshaft, washer, and felt seals, (if used.) 4. Position brake shoe assembly over spi der and tap anchor pin into position with brass punch, "flat" in line with lock screw hole. 5. Install lock screws, tighten securely and thread with lockwire. 6. Position felts, retainers, and lock rings on anchor pins. 7. Install shoe return spring. New springs should be used with each brake reline. Ten sion loss occurs from normal use and heat build up. New springs will ensure that shoes are returned to fully relaxed position, and not in contact with drum, which would cause premature wear. 8. Assemble slack adjuster on splined end of camshaft; using spacers and washers on each side of adjuster to obtain .030-. 060 end play. Wedge Brakes - ('See Figure 8-12) Disassembly 1. Remove shoe return springs. Use brake spring pliers. (Do Not use screwdriver.) 2. Remove brake shoe assembly. 3. Remove plunger guide screws and gaskets from plunger housing. If brake is automatic adjusting, remove hollow capscrew, gaskets, spring and adjusting pawl. It may be neces sary to use a magnet to remove the adjusting pawl. 4. Using a suitable screwdriver, pry the seals loose and remove anchor (solid) plungers, adjusting plungers, adjusting sleeves (actuators) and adjusting bolts. 5. Thoroughly inspect and clean all parts including the housing plunger and seal bores and shoe rest pads. DO NOT solvent clean any rubber parts (plunger seals or gaskets). Wire brush plunger parts and adjusting bolt threads to remove caked on dirt and cor rosion. Carefully inspect plunger seals and gaskets for tears, cuts or deterioration, and replace if necessary. Also check the angled plunger roller faces for pits, grooves or nicks and replace if necessary. NOTE Brakes have one adjusting plunger and one anchor (solid) plunger per plunger housing. The anchor plungers are marked on the shoe slot end, "R" for right hand brakes and "L" for left hand brakes. DO NOT mix at reas sembly. Assembly - Anchor (Solid) Plunger 1. To assemble seals into plungers, apply a film of grease to inside surfaces of seals. See Figure-8-13. 2. Inspect nose for burrs. Mask brake shoe web slot in the plunger nose with mask ing tape to protect seal. Carefully push the double lip seal onto the plunger, stretching the outer seal lip over the plunger nose end, until the inner seal lip is completely in the second plunger groove and the outer seal lip is in the first plunger groove. Remove masking tape. (Brakes employing single grooved plungers and single lip seals should be assembled in the same manner except masking tape is not used.) IMPORTANT: DO NOT ASSEMBLE SEALS INTO PLUNGER HOUSING FIRST. THIS WILL RESULT IN COMPLETE LACK OF SEALING OF INTERNAL PLUNGER HOUSING COMPONENTS. 3. Coat all plunger bores with grease. 4. Make sure anchor plungers marked "L" are installed in left hand brake and anchor plungers marked "R" are installed in the right hand'brake. 5. Coat entire anchor plunger with grease, packing cavity behind seal, and insert plunger and seal into housing with plunger keyway slot aligned with guide screw hole. Make certain the plunger goes all the way into the plunger bore and seats on bosses at the bottom. 6. Seat plunger seal in plunger housing with correct seai driver tool. Driver must be centered over seal retainer to prevent dam age to seal assembly. NOTE If seal driver is not available, a 1-3/4'' wrench socket can be used for spider mounted brakes and 1-3/8" wrench socket can be used for backing plate mounted brakes. 7. Assemble gasket and guide screw into plunger housing. Make certain guide screw endenters the plunger key-way slot so plunger can slide freely in housing bore. Tighten guide screws to 15-20 ft. lbs. torque. CAUTION Wedge and plunger assemblies are 12 or 14 angles. Also "Right" and "Left" plung ers. Any inter-mixing of these parts will cause erratic and uneven braking. Assembly (Manual Adjusting Plungers) 1. Apply film of grease to inside surfaces of seals. 2. Push the inner seal lip over the threaded hole end of the plunger until the lip com pletely enters the plunger seal groove. 3. Apply grease to outside of plunger and in stall plunger and seal into plunger housing in the same manner. Refer to AssemblyAnchor (solid) Plunger steps 5, 6 and 7. 4. Coat adjusting bolt threads with grease and turn bolt into the adjusting plunger by working it through the hole in the outer seal flap, being careful not to pinch the seal on the threads. Turn adjusting bolt in just short of the seal. DO NOT bottom bolt on the seal. Assembly (Automatic Adjusting Plungers) Two types of automatic adjusting plungers are being used. The Latest designed parts are readily identified since the new plunger seal has only a single sealing Lip instead of a double lip. The adjusting bolt of the latest design also has a retaining ring. 8-15 leading to the bottom of the container. The air then rises through the alcohol and passes into the line to the compressor, carrying alcohol in the form of vapor with it. The alcohol, thus introduced into the air system acts as an anti-freeze. iff tilt. I f Figure 8-55. Alcohol Evaporator Preventive Maintenance Every 1, 000 Miles or as Determined by Act ual Usage Check alcohol level andif necessary replenish with 188 proof methanol alcohol. In cold weather, alcohol level should be at least 2/3 full. NOTE If alcohol is not being consumed, it indicates the evaporator is in operative and should be inspected. Every 1, 800 Operating Hours or 50.000 Miles Remove strainer if present in bottom of evap orator body and clean thoroughly in solvent. Every Year, 3,600 Operating Hours or 100, 000 Miles Disassembly evaporator unit and clean thoroughly. Inspect all parts for cracks and be sure evaporator tube is not clogged with dirt. Replace all gaskets and rubber parts. Inspection When the compressor is compressing air. air bubbles should be passing through the alcohol. If air bubbles are not present when the compressor is compressing air. then the alcohol evaporator is not functioning properly. 8-34 Check to be sure ail connections are tight. Check condition of filler cap gasket and cover gasket. RELINING & RECONDITIONING Drum-Type Brakes After supporting the axle on stands, cage the springs in the spring brake chambers. Re move the tires, wheels, and drums as an assembly, and inspection drums for heat checks, cracks, distortion or other damage. Close inspection of all worn brake parts may leadto clues for corrective action to improve lining life and future drum damage. Scored Drum Only the tops of the ridges will contact brake lining. Since a small percentage of the brake lining is required to do all the work, hard pedal and fade will result. A scored drum must be reconditioned in a lathe. See Figure 8-56. Hard Spots Hard spots are "islands" of steel in the cast iron surface. They result from a change in metallurgy caused by the heat of braking Hard spots must be ground out or brake perform ance will be poor and erratic. See Figure 8-57. Bell-Mouthed Drum If a drum is bell-mouthed or flared, full lin ing to drum contact cannot be achieved. Hard pedal, fade and noise can be expected. A bell-mouthed drum must be trued in a lathe in order to procure full lining to drum contact. See Figure 8-58. Figure 8-53. Bell Mouthed Drum. Heat checking and discoloration, if only superficial, can be corrected by resurfacing the drum, otherwise replace drum. Drums having more than . 010" out of round, or any of the conditions described above should be resurfaced. Use only those drums which produce a satisfactory surface finish. CAUTION Drum manufacturer and state vehicle inspection laws (where applicable) govern the amount of drum diameter increase allowed when resurfacing. Most drums are stamped by manufacturers as to maximum oversize allowable. Excessive removal of drum mat erial could result in drum failure or unsatisfactory brake perform ance and is illegal in some states. NOTE When reconditioning brakes, it is important that the brake assem blies on each side of the same axie be serviced in exactly the same manner. This will avoid unequal braking performance. (Drums on the same axie should be resurfacedwithin . 010 of each other. Cam Roll-Over Increasing the drum diameter will permit the cam to rotate beyond its maximum lift when the lining becomes worn. To prevent cam "Roll-Over, " oversize roller cam fol lowers are available. Standard (1.250" O. D. ) Standard rollers are used when installing standard linings with standard drums. "X" lining (1/16 oversize) with 1/16 oversize drums, and "XX" lining (1/8 oversize) with 1/8 overside drums. 1/8" Oversize (1.375") 1/8" oversize rollers are to be used with the installation of standard linings with worn or trued drums which are 1/32" oversize. 1/8" oversize rollers should be installed and the liners circle ground a few thousandths less than drum diameter. 1/4" Oversize (1. 500") Where "X" linings have been installed with 1/16" oversize drums and standard rollers, these rollers should be removed and 1/4" oversize installed before the lining becomes worn to a point where the brake cam is no longer effective with the standard rollers. 1/2" Oversize (1.750") Where "XX"linings and 1/8" oversize drums have been used, the standard rollers should be removed when the linings become approx imately 50ao worn and 1/2" oversize rollers installed. Brake Linings Linings must be the correct material for a specific application, and the same type lining should be used for each wheel on the same axle. Handle lining carefully to prevent grease, oil, or any other type of contamination to come m contact with lining surface. 8-35