Document VJQxw4XY8aj9Rqvw04a686yEN

*ltten4fate TRAINING SERVICE School ol Diesel, Tractor and Heavy Equipment Courteay of BENDIX WESTINGHOUSE AIR BRAKE CO. UNIT 45 . (REVISED) MISCELLANEOUS CLUTCHES and ' BRAKING SYSTEMS . Portland, Oregon SCF-ALLF-01406 INDEX - UNIT 45 BRAKES Dodge Brakes: Description.................................................. 10 InstaUation of Foot Controller . ............... 20 Adjustment.............................. 31 Instructions for Using Band Gauges .... 16 Bleeding Brake Lines ................................. 35 Instructions for uslngl GO-NO GO Booster Brake Operation.......... .. 36 Gauge................................... 18 Adjustment................................. 39 Magnet & Armature Relation.....................17 Check Valve......................................... 37 Measuring Armature Depression ..... .17 Control Valve...................................... 39 Replacing Magnet Contact Wire Maintenance......................................... 40 Assembly.................................. 19 Operation............................................. 36 Removal & Installing.......................... 39 Testing................................................. 40 Servicing BakelitelCoupling Plug............ 14 Servicing|Coupling Cables....................... .16 Testing Controller................................... .11 Maintenance......................... 36 Testing Load Control................................. 13 Master Cylinder Disassembly...................30 Testing Magnet for Amperage Capacity . 13 Removal & Installation of Brake Shoes . .30 Testing Magnet for Short ................ ^ ... 12 Replacing Brake Lining............................. 31 Trouble Shooting...................................... 27 Wheel Cylinder Disassembly.....................30 Undercutting of Magnet.............................. 18 MACK TRUCK BRAKES Air Brakes................................................. 8 Hand Brake....................................................2 Hydraulic Brakes......................................... 2 Vacuum Booster Operated (External ' Valve Type)............................................ 5 Vacuum Booster Operated (Reactionary Type)..................................................... 3 WARNER ELECTRIC BRAKES Action of Armature on Magnet.................. 16 Amperage Charts........................................12 Brake Installation ............................ 21 Brake Lining Specifications........................16 Checking Amperage at Brakes.................. 12 Checking Amperage at Controller.......... 11 Checking Controller for Short...................11 Checking Drum for Concentricity.......... 20 CLUTCHES Dodge Truck Clutch: Clutch Cover and Pressure Plate Adjusting Release Levers...................... 43 Disassembly and Assembly....................43 Clutch Disc - Refacing............................... 44 Maintenance................................................. 45 Pedal Adjustment........................................ 45 Reinstalling Clutch......................................44 Removal........................................................41 Mack Clutch Clutch Disc Adjustment..............................46 Clutch Finger Adjustment.......................... 46 Clutch Pedal Adjustment............................46 Clutch Spring Tension................................ 46 Lubrication . . .................... 46 '; '-#3 .Wf !>r BRAKES (MACK TRUCK) HAND BRAKE is of the flexible band construc tion mounted on the driveshaft directly behind the transmission. Three adjustments are provided, two for centering the band with respect to the drum and a third for setting the clearance between the drum and lining. The latter should be adjusted so that a .015 feeler gage can be inserted at any point without forcing. HYDRAULIC BRAKES THE SERVICE (FOOT) BRAKES are of in ternal construction and are hydraulically operated. Each wheel is fitted with a hydraulic type of cylinder acting directly on the brake shoes therein and connected by suitable lines to a compensator or, as it is sometimes called, a master cylinder. The latter, in turn, is connected to the brake pedal. Built as part of the master cylinder is a reservoir containing a supply of the special Mack Hydraulic Brake fluid through which the power is trans mitted. The level of this liquid should be checked at 6000 mile intervals and added to if necessary. Do not allow the level, to drop below half full. A plug is located at the top of the reservoir through which the level can be seen. Remove all dirt from around this plug before unscrewing; the presence of sand or grit in the fluid will scratch the cylinder walls and cause leakage. BRAKE SHOE ADJUSTMENT is obtained by means of cams bearing against the shoes in such a way that when they are turned the shoe is moved either away from or toward the drum. The cams are set externally by the two hexagon screw heads located near the top of the anchor plate at the in side of the wheel. An inspection plate in the brake drum will permit measuring the clearance with feeler gage between the drum and lining. This should be a minimum of .010 at the toe (near the hydraulic cylinder) of each shoe and .005 at the heel (near anchor pins). When new lining is installed it may be necessary to recenter the shoes, which can be accomplished by moving the eccentric anchor pins located at the bottom of the anchor plate. Ordinarily, however, the setting of these pins is not altered when simply "taking up" on the brakes. BLEEDING or removing the air from the hy draulic system may be required at infrequent inter vals due sometimes to permitting the fluid level to drop too low in the compensator reservoir, thereby admitting air in the line. A special bleeder valve is fitted in each wheel cylinder and is located just above .the tube connection. When bleeding a systern all four wheels should be bled, the procedure being as follows:-- Remove the small plug from the fitting and screw in a fitting attached to which is a piece of rubber hose. Submerge the end of the hose in fluid spilled into a glass receptacle; then with a suitable wrench turn entire fitting about one-half turn after mak ing certain that there is ample fluid in the reser voir. Have an assistant apply and release the brake several times (until no air bubbles are noticed in the stream of liquid going into the glass). While the pedal is being depressed for the last time tighten the fitting. During the entire time the V pedal is being "pumped," the end of the hose must be submerged in the fluid. A clean receptacle should be used for this purpose and the fluid may be spilled back into the original container after all lines have been bled. Do not spill the fluid imme diately into the reservoir since it may contain small air bubbles which will defeat the purpose of the entire operation. Upon settling for several hours the bubbles will disappear. " Page 3 pheric pressure to the rearward side of the piston u (the piston rod end of the cylinder) without dump ing a charge of raw air into the intake manifold. The vacuum line "V" connects the front of the power cylinder to the manifold (Fig. 3). A check valve is incorporated in the intake line which maintains maximum vacuum in the cylinder during any cycle of operation and also seals the system after the engine is stopped, permitting a power brake application. Special pressure tanks are available for bleeding hydraulic brakes. With their use, one man can do the job. Fluid under pressure is contained in the tank and a special fitting enables tank to be con nected to filler hole of master cylinder reservoir. This eliminates necessity of "pumping" brake pedal to cause fluid circulation. The vacuum power unit is of the reactionary type, that is, it is so connected to the master cylin der and brake pedal that it supplies approximately sixty percent of the power applied to the master cylinder, the other forty percent being supplied by manual effort on the brake pedal pad. This permits the operator to "feel" the brake at all times and to have full control of it. The deceleration of the vehicle increases in direct proportion with pedal pressure. VACUUM BOOSTER OPERATED HYDRAULIC BRAKES The valve operating the power unit is contained within the unit and is operated by a rod extending through the power unit piston rod to the valve operating lever (See Fig. 4 and 5). ) REACTIONARY TYPE If adjustments described later are made cor rectly, a movement of approximately y2" of the brake pedal pad pushes the valve inward, admitting atmospheric pressure to the rearward side of the A reactionary type vacuum power cylinder, per piston. This air, or atmospheric pressure on the mitting greater pressures to be built up in the sys piston moves it toward the front of the cylinder tem with less effort on the part-of the operator, and through the power lever connection applies is explained below. The vacuum power unit "U" pressure to the master cylinder. Figure 1. utilizes the intake manifold vacuum as a From the remote air cleaner (Fig. 3 and Fig. 5), source of power. It is of the "vacuum suspended" air enters the'cylinder through a connection in the type with both sides of the piston submerged in end plate duSticover holes in the hollow piston rod Page 4 and then through the valve to the rear side of the piston. You will .note in examining the construction of the vacuum power unit (Fig.4 and 5) that it is essen tial that about 5/32" travel specified for the valve rod is obtained in order that the valve may open the ports admitting air to the rear of the piston -- travel is required for full opening of the valve when clearance on power lever is all taken up at "A" (Fig. 5). The amount of air admitted to the rear of the cylinder depends upon the brake pedal movement. If the operator stops the forward movement of the brake pedal, the piston will move until the valve closes off the port which admits air to the rear of the piston, the valve remaining in the "neutral" or lap position covering the ports and holding the air in the cylinder on the rearward side of the piston. To accomplish any further movement of the piston or brake application, pedal must be further de pressed. 1 When the operator releases the pressure on the brake pedal the valve is positively moved to the release position by the valve lever attached to the brake pedal. This closes the air passage to the rear side of the piston and opens a passage across the piston, thus restoring the vacuum balance on both sides of the piston (Fig. 4). It is important that adjustments given later be made as outlined, as will be seen from the follow ing description of the construction, and operation of the power brake. The valve operating lever is attached to the brake pedal by two cap screws "C" (Fig. 3) with an over size hole at the bottom cap screw to permit adjust ment. It is absolutely necessary that in the brake release position the clearance (about 1/32"), be tween the shaft hole in the power lever and the pedal shaft must be on the forward side of the shaft (opposite to the master cylinder) as shown at "A", "Release" Fig. 4. Also the power cylinder piston rod clevis pin must be against the rearward wall of the valve lipk Fig. 5 bushing, as shown at "B", Figure 4, Release. From the above it will be observed that any im proper adjustment will affect the application and^ operation of the brakes and brings out the im portance of making adjustments as directed below: In making the adjustments each operation should be made in the_order given:-- 1. Loosen valve lever anchorage screws "C" (Fig ure 3), remove master cylinder and piston rod clevis pins "D" and "E" (Fig. 3). Be sure that leverage system is clean and in correct alignment, with no binding. Then, block brake pedal in release positipn. Be sure that clearance between power lever and pedal shaft is at the front side of the shaft, as shown on "A" (Fig. 4). 2. Adjust master cylinder clevis to permit about 1/32" lost motion in master cylinder piston rod, then insert clevis pin "D" and cotter. 3. Pull power cylinder piston rod all the way out; align piston rod clevis with power cylinder lever by adjusting cylinder position at the mount ing end "F." Never attempt to adjust piston rod clevis as this affects valve positioning, which is correctly set at the time of factory assembly. 4. Be sure that piston rod clevis pin "E" is against sidewall of valve link bushing as shown at "B" (Fig. 4), "Release." Then tighten valve lever adjustment screws "C". Be sure that valve lever fork is central and square on valve rod bushing to avoid binding. 5. If adjustment has been made correctly then the brake pedal when moved by hand should move the valve rod yinward before any movement of the power lever occurs. (Engine not running). 6. Check to be sure cotter pins are in place, lock nuts are tightened and cap screws are tight. If these adjustments are made correctly, brake shoes are properly adjusted, and hydraulic system work ing correctly, the brakes will be satisfactory. TESTING THE CYLINDEU 1. Remove the pipe plug "G" (Fig. 3) at rear of cylinder and connect a vacuum gauge. 2. Start the engine and note the. reading on the gauge. It should show a vacuum of 16 to 20 inches. Stop the engine and note if vacuum is retained for a reasonable length of time. If gauge shows a rapid falling off (more than 10 inches in 10 seconds), it indicates a leak which may be in the cylinder, in the line, or in the check valve in the inlet manifold connection. Leakage in the power cylinder may often be cor rected by a thorough lubrication of the unit. Tests for leaks in cylinder or lines may be made without a vacuum gauge. If the engine idles too fast or unevenly, leakage is indicated. Disconnect manifold connection and plug manifold opening. If engine idles normally with this manifold connec tion plugged, then leakage is in cylinder or lines. If engine continues to idle improperly then there is probably a leak in the inlet manifold or gaskets, or throttle stop screw is improperly adjusted. NOTE: Never attempt to replace the valve with out also installing new piston rod assembly. Piston rods are furnished with undersize bore and must be reamed to "fit" after assembly in piston. Page 5 LUBRICATION Every 6000 miles remove the pipe plug "G" (Fig. 3) in the rear end of the power unit and lubricate with two ounces of Vacuum Cylinder Oil, after which the pipe plug should be replaced. At every chassis lubrication spray the valve and power lever linkage with light oil. cylinder applying pressure to the hydraulic system through the power lever "L". As the power cylinder piston moves rearward the upper end of the power lever, at "C", moves forward, thus causing a "fol low-up" action which tends to close the atmos pheric port of the operating valve (Fig. 9 showing lap position). The remote air cleaner should be examined and cleaned at least twice a year. Remove the hair, wash same thoroughly in kerosene, dry and then saturate with a light machine oil. Replace the hair in the cleaner and reassemble. Clean off all dirt around the rear end of the power unit. It is suggested that for repairs and adjustments the operator secure the services of an authorized Mack Service Station. FROM ROD END OF POWER CYLINDER VACUUM BOOSTER OPERATED HYDRULIC BRAKES REACTIONARY EXTERNAL VALVE TYPE In this type the service or foot brake system is of the vacuum suspended type employing an ex ternal operating valve "A" mounting in the brake pedal linkage and a power cylinder "B" rigidly mounted on the frame side rail to the rear of the hydraulic master cylinder (Fig. 6). With the op erating valve mounted in the rod between the brake pedal and the upper end of the power lever (L) at "C", and the power cylinder attached to the lower end of the power lever at "D", all braking effort from both the brake pedal and the power cylinder is relayed through the power lever, rotating on the idle shaft "S", to the hydraulic master cylinder through its connection at "K". Fig. 7 TO VACUUM TO ROD END OF POWER CYLINDER Fig-. 8 EXTERNAL VALVE is of the reactionary type being incorporated with, and operated through, a special bracket and linkage assembly, whereby the load on the brake pedal rod is carried by the valve support brackets and not by the valve itself. The travel of the valve operating lever (N) is limited to the movement required to fully open and close the TO CHECK VALVE & MANIFOLD-^ The broken lines (Fig. 6) represents the vacuum connections between the engine intake manifold and check valve, the external operating valve and the power cylinder. In the vacuum suspended -type of power brake equipment, vacuum is present on both sides of the power cylinder piston when the brakes are in the released position, because of the open vacuum pass age through the operating valve "A" (Fig. 7). When the brake pedal is depressed the valve rod "R" is pulled outward. Since valve operating lever (N) is . pivoted to the valve linkage, the valve stem is pushed inward, thus closing off the vacuum passage and opening the atmospheric port of the valve, estab lishing a direct connection between the air cleaner on the valve and the piston rod end of the power cylinder (Fig. 8). With this admittance of air at atmospheric pressure to the rod end of the power cylinder, the piston moves rearward in the power VACUUM Fig. 9 END OF POWER CYLINDER valve. Any additional force exerted at the brake pedal after the valve is fully applied is transmitted directly to the brake system through pin (P) which bottoms in an elongated hole in the support bracket. The only applied force acting through the valve itself is that which is required to operate the valve. This valve also incorporates an additional chani- ber fitted with a diaphragm. The cavities of this chamber are connected through passages to the valve proper. A drop in vacuum to the power cylin der also causes a corresponding drop within the diaphragm chamber which unbalances the pressures on the diaphragm. This unbalance of pressures act ing upon the diaphragm creates an opposing force within the valve which reacts against the force ap plied through the pedal tending to open the valve. This opposing force, which tends to keep closing the valve, produces what is termed a "reactionary" effect. The combination of this reactionary effect, along with the follow-up action, which takes place as soon as air is admitted to the power cylinder, is responsible for the finely balanced control obtained with this valve. The reactionary feature combines power with physical effort throughout the range of brake application. The result is gradually increasing pedal feel in direct proportion to the degree of braking effort. This enables the driver to accu rately judge the degree of brake application with the vehicle unloaded or loaded, preventing sudden lock wheel stops. Reactionary control is also a de cided safety factor on wet or icy pavement. The valve requires no greater pedal effort for maximum brake application than does a non-reac tionary valve, but it will require a few hours driving time to become accustomed to the firm reaction and degree of control it provides. VALVE OPERATION RELEASE. In the release position, the return spring (1) holds the valve stem and diaphragm plate against release stops (2) in the valve body. The vacuum valve (3) is held fully open by the stop-washer (4) on the valve stem. This connects the control end of the power cylinder to vacuum. The atmospheric valve (5) is held in the closed po sition by the spring (6). Both valves are free to slide on the valve stem. Reactionary diaphragm (7) is balanced in vacuum. Chamber (8) is connected to vacuum through drilled hole (9) in the valve body. Chamber (10) is open to vacuum through drilled hole (11) in the valve stem. (Fig. 7) LAP. When applying the brakes, the initial movement of the valve stem and stop washer (4) allows the spring (6) to close the vacuum valve (3) before the atmospheric valve (5) starts to open. Later when the brake pedal is held in a partially applied position, the power cylinder will move the brake system and valve linkage in the applied direc tion, to the point where the valve reaches this lap, or holding, position (both valves closed). APPLIED. Further movement of the valve stem in the applied direction forces open the atmos pheric valve (5) by contact with stop washer (12). This admits atmosphere to the control end of the power cylinder, causing the brake application. At the same time, atmosphere is admitted to the reac tionary diaphragm, chamber (10), through drilled hole (11) in the valve stem. Atmospheric pressure in chamber (10) tends to force the diaphragm (7) and valves toward the release position, against the physical effort at the brake pedal, applying the brakes, thus causing the reactionary effect. Upon releasing the brakes, the return spring (1) plus diaphragm reaction, moves the valve assembly' through the lap position and into the release posi-/ tion with the atmospheric valve closed and the,' vacuum valve fully open. ADJUSTMENT If the vacuum power brake equipment is not functioning properly, or if it is found necessary to replace any of the parts, the following adjustment procedure should be followed : 1. Before starting the adjustment, be sure the brake pedal and valve linkage are in the full re lease position. Block the pedal. 2. Adjust the pedal rod and operating valve as sembly to a length (C to F in Fig. 6) of approxi mately that listed in the truck manual. 3. Insert clevis pins at (C) and (F) and cotter. 4. Adjust master Cylinder yoke to permit 1/32" clearance between master cylinder piston rod and piston. 5. Insert clevis pin at (K) and cotter. 6. Pull power cylinder piston rod outward until piston is bottomed against the cylinder end plate; adjust link between piston rod and power lever to align holes in yoke with hole in power lever. 7. Insert clevis pin at (D) and cotter. , 8. Check all lock nuts and vacuum connections to see that they are tight. 9. Remove block from brake pedal. With engine not running, depress pedal and note if valve stem (W) travels 5/16". When the brake pedal is re leased, the valve stem should return immediately to the released position. VALVE ADJUSTMENT 1. Internal adjustments to the valve should not be made in the field. Valves in need of repair should be exchanged for factory-rebuilt units at any Mack Service Station. 2. The only external adjustment of the valve is the valve rod (H)> which is threaded into yoke (G). This adjustment is made with the engine shut off. (Fig. 10) 3. Loosen lock nut (E). Remove rubber guard (T) from the valve housing as shown. Now adjust valve rod (H) to obtain a slight clearance (approx- ' Fig. 10 SW'*.:. :i iW. . ' / imately .002 to .015") between the end of valve rod . (H^ and valve stem (W). . 4. After making the above adjustment, check the total travel of the valve stem (W) as follows: 1Place a scale, graduated in sixteenths of an inch, near the valve rod yoke with the end against the dust cover, as shown in Figure 10. Now carefully apply the brake pedal just enough to take up the ; clearance between the valve rod (H) and valve stem (W). At this point, note the position of the yoke (G) in relation to the scale. . Then fully apply the brake pedal and observe the distance travelled by the yoke. It is very im portant that the valve stem (W) travel 5/16" in order to obtain full opening of the valve in the applied position. Failure of the valve stem to travel 5/16" is usually caused by more than .015" clearance be tween the valve rod and stem in the released posi tion, or by making an adjustment of the valve rod with the brake pedal and valve linkage not in the fully released position. MAINTENANCE Every 6,000 miles, remove the pipe plug from the rod end of the power cylinder and inject 2 ounces of Vacuum Cylinder Oil in the cylinder, after which the pipe plug should be replaced, j Where the PDL type cylinder is used: Every 6,000 miles, remove the pipe plug from center boss of closed end plate, and inject - ounce of Vacuum Cylinder Oil into cylinder | through this opening. Then replace and tighten | pipe plug. I At every chassis lubrication all clevis pins and ' lever bearings should be lubricated with light oil. . The air cleaner on the external operating valve should be removed and cleaned at least twice a year; oftener if operated in dusty sections or on gravel or dirt roads. Remove the hair cleaning . element, wash in kerosene and allow to dry; then dip in light machine oil and allow to drain; after cleaning the other parts of the cleaner, reassemble the air cleaner on the valve. Inspect the rubber dust guard on the power cylinder piston rod and if damaged, replace. It is suggested that repairs or adjustments be made by a Mack Service Station. The following tests will indicate when service is necessary. TESTING THE SYSTEM 1. Remove the )4" pipe plug from the end plate on the piston rod end of the power cylinder and attach a vacuum gauge at this point. 2. Start the engine and note the reading on the vacuum gauge. It should show a reading between - 16" and 20". Now stop the engine and note if the vacuum is retained for a reasonable length of time. If the gauge shows a rapid dropping off (more than 10 inches in 10 seconds) it indicates a leak which may be in the power cylinder operating valve, check valve mounted on the dash, or in the vacuum lines. . 3. Start the engine again and depress the brake . pedal firmly as in making an emergency stop. If Page 7 indicates the operating valve is not functioning properly. 4. In testing the operating brake valve discon nect from the operating valve the vacuum line be tween the valve and the rod end of the power cyl inder, and attach the vacuum gauge to the valve at this point. Start the engine and note the vacuum gauge reading. Then stop the engine and note if the vacuum is retained for a reasonable length of time. If the vacuum gauge shows a rapid drop in vacuum (more than 10 inches in 10 seconds) it in dicates a leak in the operating valve, or in the check valve. 5. Test the check valve by connecting the vacuum gauge to the bottom of the valve. Start the engine and note the vacuum gauge reading. Then stop the engine. If the gauge shows a drop of more than 10 inches in 10 seconds, the check valve should be replaced. 6. Before testing the vacuum lines, inspect all vacuum hose and tubing to see that it is in good condition and check all connections to see that they are tight. If leakage is indicated in the power cylinder, operating valve, or check valve, these units should be taken to a Mack Service Station for repairs or exchange for factory-rebuilt units. ^ -r - ) RESERVOIR AND GAUGE l Where law requires a vacuum reservoir and dash gauge, reservoir is installed in line from manifold check valve to power cylinder. Gauge may be con nected at any point between check valve and res ervoir, and should register from 16 to 20 inches vacuum. If not obtained, vehicle should be stopped immediately and the trouble located before pro ceeding further. TROUBLE SHOOTING CHART (Vacuum Broket) CONDITION CAUSE REMEDY Leak la Opentlaf Vilrt. See Testing Ne, 4, Fag6 7> and Adjustment, Page 6 Vacuum Drop# Rapidly, Broke Action 9low Leak is Check Valve* See Tertlag Ne. S, Page 7 Lack la Lines. Inspect Line* A Fining* lor tightness. *' Leak In Cylinder or Valve. Bachange for Factory Rebuilt UnJl at Mack Service Station. Valve Function* Improperly. See Valve Adjustment, Page 6 Lack of Reac tionary Control, Harsh Braking With Light Load Other Conditions In winter--toe in rystem. Thaw aed dry eut. Valve Function! Improperly* See Valve Adjustment, Page 6 See Adjustment*, Page* Page 6 (Cont. on Fage 8,) TROUBLE SHOOTING CHART (Hydraulic Brakes) CONDITION CAUSE REMEDY Lining Wear. See Pege 2 Braka Shoe* out ol adjustment. See Page 2 Fig. 13 Pedal Goes To Floorboard Leak in System. Pedal Adjustment Improper. Examine all wheel cylinders. Hue and connections. II no leaka, inspect cylinder* lor scored bore*. See Page 5- 7 1. 2. 3. 4. Brake Chambers 8. Pressure Gage 12. Application Valve 5. Air Compressor 9. Reservoir 13. Quick Release Valve 6. Air Filter 10. Drain Cock 14. Relay Valve 7. Governor 11. Safety Valve All Brakes Draff One Wheel Drags Vehicle Swerves To One Side No fluid in aupply tank. Air in ayatam. Improper fluid in eyeienu Pedal Ad|uatment Improper. Weak brake aboo aprlng. Brake ahoe bearing seltcd to anchor' pin. Brake aboo aet too eloaa to dram. Cupa distorted. Loom wheel brga. Creeac-aoaked lining. Shoee Improperly eet. Sea Bleeding. Page 2"3 See Bleeding, Page 2 ~3 Flush clean with alcohol. Re place any swollen eups. Bleed as shown on Pago S. See Page Replace apring. Free op and lubricate. See Page 6~"7 Replace cups, clean and bleed. adjust Rencv* with MACK Lining. See Page Dual shield looeo on axle. Front spring clips loose. Tighten shield and reodjuat brake*. Tighten clip*. Different make# o! lining. Linings vary in irietion. Replace with proper MACA lining. Tires iufleied improperly. Each tire inflated to same pressure. AIR BRAKES When chassis is equipped with an air brake sys tem, the brake shoe cams are actuated by linkage to brake chambers which are operated by air pres sure. An Air Compressor mounted on and driven by t;he engine, replaces the vacuum booster cylinder as the source of power. The service (foot) brakes are of internal, two shoe construction, applying on all four wheels. The shoes are operated by "S" shaped cams giving con stant lift. BRAKE SHOE ADJUSTMENT is made by jacking up the wheel and turning the worm shaft nut of the Slack Adjuster, which rotates the cam shaft with respect to the lever or chamber push rod, until the brake shoes are tight against the drum. See Fig. 11-A Then back off on the worm until the wheel is free. Apply the brakes and note push rod travel. This should be kept to a minimum, as given on page - 9 As the lining wears, the worm should be readjusted to retain the minimum push rod travel. The travel should always be set accurately so as to be the same for both brake chambers on a particular axle. Maintain at least 60 pounds air pressure while mak ing adjustments. . AIR COMPRESSOR furnishes compressed air. to the reservoir. The compressor operates con tinuously while the engine is running, but the governor functions to unload the compressor dis charge Valves when 100,,ta,,J.Q5...pounds reservoir pressure is reached, thereafter allowing the com pressor to operate without any compression until the pressure drops to between 80 and 85 pounds. Every 18,000 miles the compressor head should be detached and the carbon removed. The discharge valves, springs and seats, also the unloader valves, should be cleaned. The passage allowing the pump ing of air from cylinder to cylinder when com pressor operates without compression, must be kept open, otherwise, the Safety Valve will blow off. The discharge line from compressor to reser voir should be checked at this time to insure un restricted flow. The unloader diaphragm should be inspected. The discharge valve lift is .042". The clearance between unloader valve stem and tappet should be set at .010" minimum and .015" maximum. A notice able increase over this clearance indicates carbon accumulation on valve seat. The compressor head is water cooled by connec tions to the engine cooling system. When water is drained from radiator and engine to prevent freez ing, the compressor head should also be drained by removing plug. The compressor is automatically lubricated by pressure from the engine oil circulation system. The oil pressure at compressor should be at least 5 pounds minimum at engine idling speed, and 15 pound minimum at governed speed. AIR CLEANER is fitted to the compressor for removing foreign matter from the air. Every 1500 miles remove the filtering material, wash Page 9 thoroughly in kerosene, dry, and saturate with replaced at this time, as a rule. engine oil. RELAY-EMERGENCY VALVE used on trail GOVERNOR regulates the air pressure in reser voir between minimum and maximum settings, ers, relays the braking action from tractor to trailer. This valve should be tested every 18,000 working in conjunction with unloader valves of the compressor. Every 6,000 miles the governor should be checked for leakage, and tested for correct cut-in and cut out pressure settings. To raise the cut-in.pressure miles for leaks. The diaphragm should be replaced at this time as a rule. Occasionally remove the plug at the bottom of the valve and drain off any moisture which has collected. STOP LIGHT SWITCH working in conjunc increase the tension of the tube on the valve by screwing down the adjusting screw, and to raise tion with the application valve, operates the stop light instantly upon even the slightest brake ap the cut-in and cut-out range, remove one or more plication. If the contact points become pitted, use shims from underneath the upper valve nut. The a fine file to obtain a true contact between points. governor air strainer is packed with lamb's wool. The diaphragm should be replaced at least once a Every 6,000 miles remove the wool, wash in kero year. sene, fluff up, wet with a few drops of light engine oil, and replace. BRAKE CHAMBERS are provided, one for each wheel, to expand the brake shoes. . Air pres RESERVOIR receives the air from the com sure admitted into the brake chamber when the pressor and stores it for use in the brake system. brake pedal is depressed moves the diaphragm, The Drain Cock is located at the bottom of the push rod and slack adjuster applying the brakes. reservoir for draining off moisture which accum As the brake pedal is released the air pressure is ulates due to condensation, All tanks should be exhausted from the chamber and the spring re drained daily. It will be particularly advisable to turns the diaphragm, push rod and slack adjuster drain daily in cold weather. It is good practice to to their normal positions, releasing the brakes. open the drain cock when the truck is laid up at With the brakes applied, the chamber should be night, and close again in the morning before start checked for leakage. The diaphragm should be ing out. This gives the system a chance to properly , replaced at least once a year... In order to reduce drain, and which is not completely accomplished ' air consumption the brakes should be kept in ad with pressure in the units. Attention to proper justment so that the chamber push rod travel is draining will prevent troubles developing with the kept to a minimum of 54" for 4" to 5", 54 fr 5" to various parts of the system. 654". and 54" for 6" or over slack adjusters. Maxi Before starting out in the morning always run engine until air pressure is built up, to at least 60 mum stroke before readjusting is 154" fr 7", 154" for 8" to 10", and 254" fr H" dia. brake chambers. pounds or your first stop may find you without brakes. Consult gauge on instrument panel. This also allows the engine to warm up, and completely lubricate the cylinder walls before placing them under load. SLACK ADJUSTERS are provided between each brake chamber and the brake shoe camshaft. The adjuster is a lever into which a worm and gear is built. Once a year the slack adjusters should be taken apart, thoroughly cleaned, and filled with a SAFETY VALVE it attached to the reservoir. good grade of medium lime base cup grease. Every 18,000 miles this valve should be cleaned and tested to blow off at 150 pounds. TUBINGS AND FITTINGS should be checked under pressure for leakage every 18,000 miles. PRESSURE GAUGE mounted on the dash indi It is suggested that major repairs be done at a cates the air pressure in the reservoir. The gauge Mack Service Station, where expert adjustments mechanism is contained in a sealed case and there may be made, and where units may be exchanged is no method for servicing it other than to return for factory-rebuilt ones, when necessary. To en the gauge on the regular repair-exchange basis. able the operator to obtain the maximum efficiency APPLICATION VALVE operated by foot pres sure, controls brake operation by directing the flow of air from reservoir to Brake Chambers , on the wheels in brake application, and from Brake Cham bers to atmosphere in release. This valve should be from his air brakes at the most economical main tenance cost, the operators, upon payment of a standard flat rate charge, may exchange any serv ice-worn air brake unit for a genuine factory-re conditioned unit. tested for leakage and delivery pressure every 18, 000 miles. The lever travel should also be checked to insure the proper operation of the Valve Mech anism, and the valve diaphragm checked for neces sity of renewal. Add 8 to TO drops of light engine oil to oil cup every 6,000 miles. QUICK-RELEASE VALVE connects two front wheel brakes chambers and assists the application valve in release by exhausting these chambers and thereby producing speedy and simultaneous release on all wheels. This valve should be tested every 18,000 miles for leaks. The diaphragm should be re placed at this time as a rule. RELAY VALVE connects the two rear wheel brake chambers and speeds up the application and release of same. This valve should be tested every 18,000 miles for leaks. The diaphragm should be Page 10 TROUBLE SHOOTING CHART (Air Brakes) CONDITION CAUSE REMEDY Slow Pressure Build Up In Reservoirs Leaking application m brake valve. Leaking compressor dis charge valve. Leaking lines nr connections. No clearance on imloadei valves. Clogged air cleaner. Clean valves or replace with reconditioned unit. Clean valve or replace head with reconditioned unit. Replace tubing and fittings tighten fittings.___________ Adjust valve to .010" clearance. Clean. `a 'm v/"' Worn piston and rings, carbon in discharge line. Replace with reconditioned unit. Quick Loss of Worn and leaking compressor discharge valves. Clean valves or replace head with reconditioned unit. Reservoir Pressure When Engine Is Stopped Tubing or connect ions leaking. Leaking valves. Replace tubing or tighten fittings. Clean or replace unit. Leaking governor. Clean or replace unit. Fig. 12* DESCRIPTION OF THE WARNER Compressor Not Unloading Slow Brake Application Slow Brake Release Inefficient Brakes Broker unloader diaphragm. Too much clearance n un loader valves. Restriction in line from governor to unlnadcr Governor not operating. Low brake line pi ensure (Brake valve to chumbcia). Brake chombei push rod travel excessive. Restriction in line. Leaking brake chamber diaphragm. Brake lining i Drum condition. Leaking brake valve diaphragm. Brake valve lever not re turning fully to stop. Binding cam or rnm shaft*. Brake chamber push rod (ravel excessive. Restriction in tubing or. hose. Improper seating of valve*. Low brake line pressure. Excessive push rod travel on brake chambers. Lining ami drum condition. Brake chamber diaphragm leaking-. Install' new diaphragm. Adjust to .010* clearance. Replace tubing or clean. Replace with reconditioned unit. Adjust pressure valve. Adiust brakes Clean or replace tubing nr hose. Replace diaphragm. ELECTRIC BRAKE AND ITS OPERATION The Warner Electric Brake is a simple me chanical brake, operated by an electro-magnetic clutch. The magnet (item 2) remains stationary on the axle. The armature (item 3) is bolted to the drum, which revolves with the wheel. For maxi mum operation, the brake requires about the same .amount of current used by a tail lighfe^See Figs. 13 and 15). . ` -..... -' / Replace or recondition. The controller (Fig. 12 or 12A) is operated from Replace diaphragm the driver's seat and permits the driver to apply Adjust operating mil. any degree of braking power. As tbe hand.leLyxJ.s moved electric current flows through the .elec.tro - Lobricflig nnj aiien iimperiy. magnet (item 2). The currentenergizes the^mag- Adjust brakes. Cleon or replace. Clean or reploce with conditioned unit. Adjust pressure thru brake valve. Adjust brakes. Replace or repair. Replace diaphragm. het and causes it to cling to the. revolving, armatuxe. disc (item 3). The more' eurrent the diriver allows to reach the magnet, the tighter it clings to the armature disc. This causes the magnet to move. On the larger brakes a lug (Item 7) is attached to the magnet. When magnet moves, the lug -presses the cam (item 4) against the brake band end (item 5). On the 12" and 14"brakes the lug and cam are combined (item 4) and press the brake WARNER ELECTRIC BRAKES In the following pages a description of the War ner Electric Brake is given along with instructions for servicing the equipment. A thorough understanding of the Warner Elec tric Brake will help you to more quickly grasp the reasons for the servicing procedures outlined in this unit. Therefore, we ask that you review the description of Warner Electric Brakes before servicing the system. This is taken from the Warner Company's Serv ice Manual band end (item 5) into the revolving brake drum. Grabbing is eliminated because there is a slight slipping action between the magnet and armature. This type of brake offers several advantages. It permits the use of a flexible band that has approxi mately 50% more lining area than shoe brakes-- thus providing longer life. It has unusual power because the rolling wheel causes the drum to mul tiply the lining pressure provided by the magnet. NO BRAKE ADJUSTMENT IS NECESSARY. The magnet movement is sufficient to wear the brake lining down to the rivet heads. At this point the magnet comes against an automatic stop that prevents scoring of the drum. . Page 11 16" x 2V2" 17V4"x3",4",5 BRAKES Fig. 13 METHOD OF CHECKING AMPERAGE AT CONTROLLER Note: Use a low reading direct current am meter. For a 2 brake system, an ammeter should be used having a maximum scale of 10 to 15 am peres and for a 4 brake system, 15 to 25 amperes. Ammeters having a greater capacity can be used, but the lower the capacity the more accurate the readings. See chart on page 12 for brake magnet values. METHOD OF CHECKING CONTROLLER FOR SHORT 1. Connect ammeter as shown in Fig. 14./ 2. With control-lever in a released pbsition there should be no amperage indicated on ammeter. 3. Hold controller lever in a fully applied posi tion and take ammeter reading. 4. Disconnect both brake wires from controller. 5. Connect ammeter wires to the brake wires and take ammeter reading. 6. Amperage reading in step 5 must not be more than 5% higher than reading in step 3. If controller does not check as indicated iii steps 2 and 5, tighten terminals on controller arid clean controller contactor arm and blades with fine em ery cloth. If this does not correct controller con dition it will be necessary to return controller to factory for reconditioning. TESTING THE CONTROLLER DITACHED FROM VEHICLE Fig. 14 ' 1. Connect controller, battery and TWENTYONE candlepower light bulb as shown in Fig. 16. 2. With the controller shown in illustration, the bulb should light to a glow and increase in bright- Page 12 ness in ten steps as controller lever is moved through its full arc of application. 3. The small controller used with house trailer brakes can be tested in same manner except with this controller the bulb will light to a glow and increase in brightness in seven steps. If controller does not check as indicated, clean contactor arm and blades with fine emery cloth. If contactor blades are bent, straighten them with thin flat nose pliers. If in rechecking the controller the proper results are not obtained the complete controller should be sent to the factory for recon ditioning. METHOD OF CHECKING AMPERAGE AT BRAKES Disconnect either wire from brake and connect*!V.| to ammeter. Connect other lead of ammeter to brake terminal from which wire was disconnected!! (TWO WIRE SYSTEM.) AMPERAGE CHARTS The braking power of the brakes is in-direct:^^'^ proportion to the amount of current used by the'-*"*"*' brakes. A BROKEN WIRE, LOOSE CONNEC TIONS OR POOR CONTACTS reduce the amount of current that passes through the brakes. If tow vehicle is equipped with load control, be sure it is on full capacity when making test. NOTE: Each brake should draw no less nor more than the minimum and maximum amperes as follows: Minimum ^Maximum Brake Size 12 Xl3^ Amperes 2.5 Amperes 3 14 x2 2.8 3.7 16 x2J4 2.8 3.7 17^x3 2.6 3.4 17)4x4 2.6 3.4 17)4x5 3- 4.2 17)4x6 3 4.2 *Maximum amperes represent the magnet capac ity when magnet is connected directly across a 6volt battery. Due to circuit resistance, these values are not obtainable when checking the current at the controller or at the brake. NOTE: The above values are for a two brake system. For systems having more than two brakes, the above values will be slightly less, due to line loss. At controller, the amperage reading must be the sum of the amperages for each brake in the system. For example, a two brake system having 12x2)4 brakes should not read less than 5.6 amperes nor more than 7.4 amperes. If current consumption is less than 5/6 amperes, find the defect in circuit which may include defective controller, defective load control, defective magnet, poor wiring or ground connections. If current consumption is more than 7.4 amperes, it is possible stop light is in . brake circuit, controller, load control, magnet or wiring may have a short. If current consumption is within these limits and brakes are still not effec tive, the trouble will be found in the brake mechan ism. TESTING MAGNET FOR SHORT Fig. 17 Connect magnet as shown in Fig. 18. If any amperage is indicated on ammeter the magnet is shorted.' Connect second magnet wire to ammeter and touch the battery wire to magnet shell. If any am perage is indicated, the magnet is shorted. The short may be in the magnet contact wire assembly or coil maybe shorted in the magnet shell. A short in the magnet wire contact assembly may be cor rected by replacing magnet wire contact assembly as shown on page 19 If with a new magnet wire contact assembly, the magnet is still shorted, the short is in magnet coil and the complete magnet assembly MUST be replaced. Page 13' creased and the amperage reading may be lower than that shown in nameplate. A reverse condition would be found if magnet being tested is cold. EXAMPLE: If. a 3.7 magnet is being tested from a brake that has been exposed to 10 degrees below zero temperature, it would be allowable for magnet to test as high as 4.1. . When magnet does not check within these limits it should be replaced. TESTING LOAD CONTROL Some of the old style magnets in the field have only one wire. These magnets CANNOT be tested as described above. NOTE: When testing, touch battery wire to magnet shell momentarily. If magnet has a dead short it will be harmful to ammeter if connection is made for any period of time. TESTING MAGNET FOR AMPERAGE CAPACITY Fig. 19 Connect magnet as shown in Fig. 19 . and take ammeter reading. Check the amperage reading against the amperage shown on name plate spot welded to the magnet. A variation of 10% from the amperage on name plate is permissible. The amperage on the name plate is the amperage that the magnet should show if tested with exactly 6 volts and the magnet at a temperature of approxi mately 70 degrees F. If the magnet is hot when tested, the resistance in the magnet coil is in- Fig. 20 Connect load control, battery and TWENTYONE candlepower light bulb as shown in Fig. 20. The bulb should light and increase in brightness in 3 steps as load control knob is turned to the right. The bulb MUST stay lit with knob in any position. The load control can be tested on the job by con necting ammeter to the controller as shown on page 11. Hold control lever in a full application position. Move load control from low to full capac ity. The ammeter must show spreading with load control in any position and the amperage indi cated on ammeter should increase in 3 steps as load control knob is turned to the right. Repair or replace load control if it does not check as indicated. Page 14 DOUBLE END SOCKET Socket No. 3337 Tail Light Brake Ground Stop Light Double End Socket lor making cable extensions, avoiding the necessity ol long cables or reels. Fig. 21 12 VOLT RESISTOR WIRING DIAGRAM Electric Brakes are designed to operate from a 6 Volt System. Where a 12 Volt System is used this resistor reduces the current to the required amperage. Hand Coniroller Ho. \ * Hand and Foot Controllers can be supplied with integral stop light switch. 12 VOLT RESISTOR No. 284 3-A for 2 or No. 2843-B for 6 Brakes UT ^ -'-4^ 12 Volt Battery Starter Switch Control or 4 Brakes No. 3363-A lor 6 Brakes No. 3363-C for Axle Loads Less than 2000 Lbs. Fig. 22 SERVICING BAKELITE COUPLING PLUG 3 Wire Cable Assembly (See Fig. 23) Remove outer cover of cable (1) 1)4" back from end exposing rubber covered wires (2). Remove insulation from wires (2) 3/16" back from end. Slide cable (1) through plug handle (10). Place dust shield (12) on cable (1). Assemble cable clamp (3) as close to the end of cable as possible. Slip all wires: (2) through'insulating washer (4). Slide insulating sleeves (5) on wires (2). Solder ter minals (6) on wires (2) and slide insulating sleeves (5) down over soldered ends of terminals (6). Place terminals (6) on bolts (7) in plug end (8) through terminal clip (13). Refer to Figure 2,3 for wire color code and markings on plug end (8). CONNECTIONS MUST BE ACCURATE. Tighten nuts (9) down on terminals (6). Bend terminals (6) up at a 90 angle after tightening nuts (9). If this is not done plug handle (10) will not slide down over wires. Slide plug handle (10) down to plug end (8). Turn plug handle (10) so bolt in cable clamp (3) will not rest on top of either of the two lugs inside of plug handle (10). Be sure the key on plug handle matches with key on plug end. Assemble bolts (11) through plug handle (TO) and plug end (8) to hold them to gether. SERVICING' BAKELITE COUPLING PLUG 4 Wire Cable Assembly(SeeFig. 241 STOP LIGHT WHITE WIRE END VIEW OF PLUG END (?) Page 15 GROUND RED WIRE TAIL LIGHT BROWN WIRE BRAKE NOT USED Fig. 23 PLUG END(?) W 4 WIRE CABLE ASSEMBLY BLACK WIRE wmt Remove outer cover of cable (1) l|" back from end exposing individual rubber covered wires (2). Remove insulation from wires (2) 3/16"backfrom end. Slide cable (1) through plug handle (10). Assemble cable clamp (2) as close to the end of cable as possible. Slip all wires (2) through in sulating washer (4). Slide insulating sleeves (5) on wires (2). Solder terminals (6) on wires (2) and slide insulating sleeves (5) down over soldered ends of terminals (6). Place terminals (6) on bolts (7) in plug end (8) through terminal clip (13). Refer to Fig. 24 for wire color code and markings on plug end (8). CONNECTIONS MUST BE ACCURATE. Tighten nuts (9) down on terminals (6). Bend terminals (6) up at a 90 angle after tightening nuts (9). If this is not done plug handle (10) will not slide down over wires. Slide plug handle (10) down to plug end (8). Turn plug handle (10) so bolt in cable clamp (3) will not rest on top of either of the two lugs inside of plug handle (10). Be sure the key on plug handle matches with key on plug end. Assemble bolts (11) through plug handle (10) and plug end (8) to hold them together. Page 16 SERVICE ON ALL RUBBER TYPE COUPLING CABLES If cable plugs develop short circuits or broken wires, Warner Electric Brake Mfg. Co. will mould new ends for a nominal charge. The cable is shortened about 8" for each new plug. If present cable uses all the slack it may be too short if new ends are made. Cables covered with grease will not bond to new ends and therefore cannot be repaired. BRAKE LINING SPECIFICATIONS 12x194 Standard lining (low friction) 3/16" thick, Kit No. BLN-15. 12x194 High friction lining 3/16" thick, Kit No. BLN-16. 14x2 Standard lining (low friction) )4" thick, Kit No. BLN-19. 14x2 High friction lining )4" thick, Kit No. BLN-20. 16x2)4 Standard lining, )4" thick, Kit No. BLN-7. 16x2)4 Same as standard lining except 1/32" thick er (eliminating 1/32 shim) to be used with worn drums only, Kit No. BLN-H7. 17)4x3 Standard lining, 94" thick, Kit No. BLN-8. 17)4x4 Standard lining, Yb" thick, Kit No. BLN-9. 17)4x5 Standard lining, Yb" thick, Kit No. BLN-10. The above kits include standard lining and rivets for 2 brakes only. INSTRUCTIONS FOR USING BAND GAUGES or block and striking band with a ball peen hammier//, where necessary. Care should be taken to avoid?/^, damaging rivet holes. An out of found band can cause a weak brake"grab". Tf the leading end (toe end) of the band/^l^l/^ is bent away from the band gauge, the brake will be strong or "grabby". When bent in toward the,'/ center the brake will be weak. " The band gauge may be used to check the clear ance between the relined band and the drum. This can be done by placing the band assembly on the band gauge and fitting band (on gauge) into the drum. Where the diameter of the drum is found to be more than 1/16 of an inch larger than overall diameter of band assembly (on band gauge) it is suggested that shim stock be used under lining. CAUTION: When replacing band on backing plate, do not spring bands out farther than neces sary. v ..... dip- "ii.V ;; y At-the factory the bands, are carefully fitted to a gauge before the assembly is made on the backing plate. .//f All shipments of separate bands are carefully packed so when they arrive at their destination they will be round and ready for installation. ,. , ACTION OF ARMATURE ON MAGNET Band Gauge No. 4740--Used with 12x1)4 Brakes. Band Gauge No. 4843--Used with 14x2 Brakes. Band Gauge No. 4698--Used with 16x2)4, 17)4x3, 17)4x4, 17)4x5 Brakes. To get the best performance out of a full wrap brake, it is necessary that the band be round. Check all bands for roundness when service work is done or the band is relined. When band is correct, it should contact the gauge snugly over its entire circumference with a light tension holding it in place, Bands which are out of round or have flat spots when checked on gauge should be corrected. This can be done by placing band on a wood top bench Check armature depression after facing magnet. (See page n .) Old armature will work with an undercut mag net, if pol.e faces on undercut magnet have not been machined. A new armature may be used with an old magnet, but, a new magnet MUST NOT be used with an old armature. MEASUREMENTS TO DETERMINE WHETHER ARMATURE AND MAGNET ARE WORN TOO MUCH TO BE SERVICED. See top left, next page. Warner Electric Brake Mfg. Co. will reface armatures and magnets, if they are not worn under the dimensions shown on illustration. . NOTE: When refaced magnets and armatures are used, spacers will probably be required under the armature mounting ring in order to provide the proper armature depression. See page 17 for arm ature depression. AIR GAP (Brass Strip). Its purpose is to remove excess magnetism from the armature and magnet when current is shut off, thus preventing drag between these parts. A" _L Page 17 1A" Min (12" or 14" 1 A" Min. (16" or 17 V. MAGNET INSERT must not be re faced when the overall height becomes 1%2" or less (for 12" or 14" brakes) or l%a" or less (for 16" or 17V4" brakes). The remain ing thickness of insert after facing would be too thin to provide fur ther satisfactory service. There fore replace with a new magnet. ARMATURES Should not be refaced in field service, unless, the proper equipment is available for holding the armature segments Becurely in place while machining in order to insure true surfaces. . ~ Fig. 27 MAGNET AND ARMATURE RELATION . Armature Magnet Insert Magnet Shell Magnet Poles Undercut (.007" to -010 (See pages 30 and 341 AFTER MANY THOUSAND MILES: Note deeper grooves in armature and worn insert. Arma ture is still in contact, both with magnet poles and insert. NOTE--NO CONTACT: Grease or a glazed surface retards insert wear, also reduces brake ap plying force, resulting in reduced brake efficiency. This condition can be corrected by refacing mag net as shown on page 19 MEASURING ARMATURE DEPRESSION DRUM AND ARMATURE ASSEMBLY ON WHEEL Fig. 28 NEW BRAKES: Armature in contact with mag net poles--not in contact with magnet insert, due to undercut. AFTER FEW MILES: Magnet poles have grooved into armature allowing contact with mag net insert. . NOTE: Armature is in contact, both with mag net poles and insert. Gauge No. 4680--For use with 12"xl54" and 14"x 2" Brakes. Gauge No. 4812--For use with 16"x2}4" and 17J4"x3"-4"-5" Brakes. The armature segments should contact the mag net and be depressed approximately 5/32" when the drum and hub are mounted in running position. This depression can be determined before the drum is placed on axle by the use of armature gauge as shown above. The gauge may be purchased from Service Department. BRAKE ASSEMBLY ON AXLE NOTE: The distance D, from collar to gauge,ps-jj;^ the distance the armature segments will be; de//'';' pressed when the hub and drum is assembled on/.V the axle. This distance should be 5/32" plus orj.,0. minus 1/32".and can be checked with a scale or "go./ii no go" gauge No. 110711. Fig.32 '"/sk4! If the distance at D is less than then space. /// out the armature by using spacers as required un-_, der the armature mounting ring. // If the distance at D is more than 3/16", a HARD- . ' ENED spacer should be used between bearing and 4; bearing shoulder on the axle. Bearing spacers not / furnished by Warner Electric Brake Co. '/ Fig. 33 SPACERS USED UNDER ARMATURE MOUNTING RING Spacer No. 3313, 1/16" Thick Spacer No. 3313A, 1/32" Thick For use with 16"x2-%" and 17%"x3"-4" and 5" brakes. Spacer No. 3516, 1/16" Thick Spacer No. 3516A, 1/32" Thick For use with 12"xlYu" and 14"x2" Brakes. INSTRUCTIONS FOR USING GAUGE 1. Loosen both thumb screws. 2. Place short ends of gauge against magnet facing. 3. Push adjustable rod against bearing shoulder. 4. Tighten thumb screw on the gauge frame. 5. Slide collar against frame. 6. Tighten thumb screw in the collar. 7. At three places wedge the armature segments away from the drum. 8. Place inner bearing in the hub. 9. Place long ends of gauge against armature face. 10. Loosen thumb screw in the gauge frame. 11. Push adjustable rod against the wheel bear ing. (Be sure bearing is snug against bearing race in the hub.) 12. Tighten thumb screw in the gauge frame. 1. If small end of the pin will enter slot at D and large end will not, armature depression is O. K. . 2. If the small end of pin will not enter slot at D, use spacers as required under armature mount ing ring. 3. If large end of pin enters slot D, use hardened spacer between bearing and bearing shoulder on the axle. EXAMPLE: A 14" x 2" brake is being worked on. The armature depression is checked and is found to be 1/16". It would then be advisable to use one layer (three) of No. 3516 spacers, and one layer of No. 3516A spacers under the arma ture mounting ring. This would increase the armature' depression from 1/16" to the required 5/32". In checking the depression, be sure the bearing is snug against the bearing race in the hub and the armature disc is wedged away from the armature mounting ring. In assembling do not allow grease, however slight, to touch any part of the brake. Grease will cause grabbing, locking or loss of power. Bearings must be hand packed with a good wheel bearing grease. Under no circumstances should a grease gun be used and all grease fittings on hubs must be 1 plugged before releasing the unit for service. When drum is placed in running position, the axle nut must be pulled up snug to prevent loose bearings. The brake loses power if the armature is not kept firmly in contact with the magnet. R.H. armature must be mounted on right side of vehicle (facing direction of travel), L.H. armature on op posite side. UNDERCUTTING OF MAGNET When there is a complaint that brakes are weak and nothing is found wrong with the electrical parts of the brake system, it is often necessary to reface the magnet to correct the condition shown in Fig. 31 on page 17. The magnet should be placed in the lathe as illustrated and from .007" to .010" removed from facing only. If when .010" has been removed from the facing there still is evidence of glaze, facing should be undercut until all glaze is removed. Page 19 Fig. 34 Refacing magnet. REPLACING MAGNET CONTACT WIRE ASSEMBLY Shorts or broken wires sometimes make it nec essary to replace the magnet contact wire assem bly. Replace the assembly as follows: (Fig. 35) 1. Use soldering iron to melt solder on terminals. With a screw driver open the copper clips (No. 1) that are pinched against the wires (No. 2) coming from magnet coil. 2. With the screw driver bend the two wires coming from magnet coil so that coil wires (No. 2) point away from magnet shell. 3. Spread the steel clips (No. 3) that hold the assembly on the magnet shell. 4. Release the insulator and wire under the wire clips (No. 4). 5. Remove old contact assembly and replace with new one as shown in Figure 36. 6. Bend the steel clips tight against the fibre block. This may be done by tapping clips lightly with a hammer. 7. Bend the wire clips against the two insulated wires. 8. Fit the wires from coil into the copper clips and pinch the clips together. 9. Solder the coil wires into the copper clips. CAUTION: Be sure no solder is splattered so as to short the coil wires to the magnet shell. 2 \lv\-* & r> f. Fig. 35 Fig. 36 Page 20 . CHECKING THE DRUM FOR CONCENTRICITY MOUNTING 3388AR HAND CONTROLLER, ON AUTOMOBILE Fi*. 37 It is important that the brake drum be concen tric. In the illustration an arbor with cones fitted into hub bearings is used with a dial indicator. The drum may also be checked for concentricity when set up in a drum lathe. It is considered advisable to true up drums when they show more than a .010" total dial indicator reading with the drum mounted on a hub as shown. Out of round drums cause the brakes to be "grabby". Therefore, it is important that the condition of the drums be given considera tion when checking a complaint of "grabby" brakes. It is suggested that not more than 1/16 of an inch of metal be removed from drum. Removal of more than 1/16 of an inch of metal will weaken drum to the extent that with a hard brake applica tion drum may break and cause serious damage to the brake mechanism. NOTE: When drums are rebored it is necessary to use shim stock between lining and brake band to compensate for the larger drum bore. INSTALLATION OF FOOT CONTROLLER A. MOUNTING CONTROLLER AND CON TROLLER ROD ASSEMBLY. 1. Mount the controller on the frame as shown. NOTE: A bracket bolted to the frame is some times used to permit an easier or better installation of the controller. 2. Attach long threaded rod to the center hole on the controller lever. NOTE: Attach long threaded rod to the center hole on the controller lever. NOTE: The threaded rod (approximately 1" long) may be cut to any desired length to make installation easier or better. 3. Have the foot brake pedal and the controller lever in a released position. 4. Attach the "clamp accessory" to the controller rod assembly and tractor brake rod as shown in Fig. 38. Leave clamp accessory nuts loose. 5. Place the controller lever on the serrated shaft as shown in Fig. 38. NOTE: Included angle between controller lever and the controller rod assembly should be from 65 to 70 degrees as shown. j; Page 21 6. Tighten the two clamp accessory nuts. B. TO ADJUST THE CONTROLLER FOR FREE PEDAL TRAVEL. 1. Loosen lock nut No. 2 (Fig. 38) 2. Move the foot brake pedal back and forth through its arc of free travel. 3. Back No. 1 sleeve nut out of controller rod case until about 34 of the free pedal travel does not move controller lever. 4. Tighten lock nut No. 2. 5. By adjusting No. 1 sleeve nut as indicated m step 3, the trailer brakes will be applied slightly ahead of tractor brakes. This is insurance against trailer "jack-knifing". C. CONNECTING CONTROLLER ROD AS SEMBLY TO THE PROPER HOLE IN THE CONTROL LEVER. 1. Remove clevis and pin from controller lever. 2. Hold foot brake pedal in a "maximum brake application position." 3. Hold controller lever in a fully applied posi tion. 4. Replace the clevis and pin in the hole on con troller lever that will hold the controller in a fully applied position. 5. Release foot brake pedal and be sure No. 2 nut and the nuts on the clamp accessory are tight. D. OPERATION, 1. When the free travel of foot brake is changed, it will be necessary to adjust the controller rod free travel by changing position of No. 1 sleeve nut as indicated in adjustment of free travel. DO NOT move clevis and pin to a different hole on controller lever to make an adjustment after the controller has been properly installed. NOTE: As a safety feature, a coil spring is built into the controller rod assembly to allow overall length of controller rod to increase approximately Y%". This spring comes in play ONLY if the con troller rod is in need of adjustment. 14 x2 ....... ....... 3-7/16' 16 x214....... ....... 5-54" 17-54x3 ...... ........ 7-5/16 17-54x4 ...... ........ 8-3/8" 17-54x5 ...... ........ 9-3/16 To accommodate the largest size brake in the minimum space allowed, drums with various over all widths are available. In preparing for the installation remove the hub from the axle. The mounting collar (A) must run at perfect right angles with the flat surface. (B). This is accomplished by placing the hub in a lathe --using its own bearings on the arbor centering. Bore the drum to fit.shoulder (A) holding the lim its to .002 and drill for bolt circle. Mount drum and tighten nuts securely. Peen the studs to insure permanent tightness. BRAKE INSTALLATION The performance of an Electric Brake depends entirely upon an accurate installation. Follow in structions, for accuracy is definitely demanded and a brake properly installed assures long life and de pendable performance. The adapter or mounting collar is to be welded to the axle. As illustrated, mark the inside of the adapter 1/16" larger than actual size of axle. Cut opening with torch. The space (A) allowed between the hub and spring determine the size brake which can be mounted on an axle. Following are minimum clear ance necessary: Brake adapter. (To prevent possible distortion cut through the metal from the hole to shoulder illustrated by arrow). Grind rough edges slightly for in welding these rough edges provide an excel lent bond. Insert welding fixture inside drum and place both in running position on axle. Have wheel bear ing' nut tight. Revolve drum. The fixture must be held to .004 limits as it rotates on axle at location indicated by arrow. Set screws are provided to adjust plate to these limits. Weld broken seams starting on each outer edge --working tov/ard the axle until completed. Bolt adapter to welding fixture. Note in illus tration the clearance between adapter and axle. Approximately 1/16" opening should be allowed to prevent binding. To complete the welding operation start from any corner of the axle and weld to the lug on the adapter as illustrated. Turn axle and repeat. This prevents warping. Remove the bolts, welding fix ture and drum from the axle. Repeat welding opera tion on opposite side of adapter. Mount brake in position. With an electric arc, tack both outer edges of broken adapter as indicated by arrows. Tack the four (4) corners as indicated. Prepare grease guards by cutting hole l/&" larger in diameter than the inner bearing, or grease re tainer. Lay the grease guard in drum and place armature over it--attaching both to drum with cap screws provided. To prevent grease escaping, a gasket sealing compound is used between the grease guard and drum. WARNING: Right and left hand' armatures are furnished and are so marked on arma ture ring. ?' t INSTALLING BRAKES ON COACH TRAILERS NOTE: For installing on axles which do not have brake support plates order brake No. 1210. K OH o S Fig. 51 A space 3-7/16" is required. Brakes can be in stalled at any point indicated above. Qoc -TdaJ> T5 .2 V/ After drums are fitted to hub, fixture No. 4718T-l is then inserted in drum. Hub and drum is placed on axle in normal position. Fixture auto matically indicates exact position of brake support plate No. 4718 and holds it in position while it is being welded to axle. Brake support plate No. 4718 ! must be cut from axle clearance as indicated. CO o CO o CO 8 ZOaa09OS> Page 23 \m Installation of brake No. 1210 completed. Page 24 .% >sa3-,N---i--< 'i. sff ?"xr~3' \\ WIRING DIAGRAM TWO WIRE SYSTEM >v 2 Wheel ^-SV' '*- ., % TRAILER 3529 Socket EMERGENCY BREAK-AWAY ASSEMBLY SAFETY SWITCH HOOK-UP ACCESSORY No. 3392 Coupling Cable, Socket and Safety Switch not included with accessories Fig- 55 TRACTOR 3529 So.cket r?* re- WIRING DIAGRAM TWO WIRE SYSTEM WIRING DIAGRAM SINGLE WIRE SYSTEM The wiring diagram shown above, while followed by some trailer manufacturers, is not recommended by the WARNER ELECTRIC BRAKE MFG. CO. When servicing trailers wired as shown, make sure all ground connections on the frame are welded. Page 25 Page 26 The wiring diagram shown above, while followed by some trailer manufacturers, is not recommended by the WARNER ELECTRIC BRAKE MFG. CO. When servicing trailers wired as shown, make sure all ground connections on the frame are welded. , Page 27 SUGGESTED BRAKE SIZES FOR GIVEN AXLE LOADS AND TIRE SIZES: Brake Size 12x1-34 Max. Axle Load Max. Tire Size (Inch Pay Load) 2,500# 6:50x16 (Single) 6 ply (Standard lining) 12x1-54 3,500# 7 :00xl7 (Single) 8 ply (High friction lining) 14x2 5,500# 8:25x20 (Single) 10 ply (High friction lining) 16x2*4 10,000# 17*4x3 14,000# 17*4x4 18,000# 17^x5 20,000# 7:50x20 (Dual) 10 ply 9:00x20 (Dual) 10ply 11 00x20 (Dual) 12 ply 11:00x20 (Dual) . 12 ply These suggestions are for normal use and condi tions. If you have a specific installation under con sideration, the Engineering Department will be pleased to make brake recommendations upon re quest. When so doing, please state type of vehicle, gross axle loads (including pay load) number of wheels, tire size and weight distribution TROUBLE SHOOTING NO BRAKES OR INTERMITTENT BRAKE PROBABLE CAUSE: Broken wire in circuit. PROBABLE REMEDY: Check entire wiring system for broken wires and install new wire where it is found necessary All splices or joints in the brake circuit MUST BE SOLDERED. PROBABLE CAUSE; Poor connections. PROBABLE REMEDY: Check, clean and tighten all connections of brake, controller, load control and socket. PROBABLE CAUSE: Broken wire on Magnet. PROBABLE REMEDY: If broken wire is on outside of magnet shell, replace the magnet con tact wires, following instructions on page 19 PROBABLE CAUSE: Poor ground connection in circuit. PROBABLE REMEDY: Clean and tighten con nections. All ground connections on frame MUST BE welded. PROBABLE CAUSE: Defective plug or socket. PROBABLE REMEDY : Check plug and socket for loose connections, dirty or corroded blades or broken bakelite insert in socket. When rubber plugs are found defective, repairs can be made as indi cated on page 16 Inspect and repair plastic coupling plugs as per instructions on pages J4_ and 15 - ' PROBABLE CAUSE: Controller defective. PROBABLE REMEDY: 1. With the controller in fully applied position, check the amperage as in dicated on page u - 2. Short out the controller by connecting both ammeter wires to the two brake wire terminals. If ammeter DOES NOT show a reading with the con troller connected as in paragraph 1, but DOES SHOW a reading with controller shorted out, con troller is defective'and should be repaired or re placed. Page 28 PROBABLE CAUSE: Load control burned out or defective. PROBABLE REMEDY: Assuming the wire and other parts in the electrical circuit ARE NOR MAL, the load control can be checked on the job as follows: 1. Connect ammeter in line as shown on page 11 . 2. Hold controller in fully applied position. 3. Turn load control counter-clockwise as far as possible and observe ammeter reading. 4. Slowly turn load control knob clockwise as far as possible. 5. Amperage should increase as load control knob is turned clockwise. . 6. If ammeter fails to indicate a flow of current AT ALL TIMES during the changing of position of knob, load control is defective and must be re placed or repaired. NOTE: The method of checking load control as shown on page 13 - is desirable for a final check or when the condition of other parts in the circuit are questionable. PROBABLE CAUSE: Magnet shorted. PROBABLE REMEDY: With magnet removed from backing plate, check as shown on page 13 . PROBABLE CAUSE: Magnet burned out. PROBABLE REMEDY: Check the magnet as shown on page 13 PROBABLE CAUSE: Resistor burned out. PROBABLE REMEDY: Inspect resistance coil. Replace the coil if it is broken or burned out. WEAK BRAKES PROBABLE CAUSE: Improper lining. PROBABLE REMEDY: Replace with lining recommended by factory. PROBABLE CAUSE: Worn out lining. PROBABLE REMEDY: The brake lining may be worn to the full extent of the magnet travel. Reline brake bands with factory approved lining. PROBABLE CAUSE: Worn brake drums. PROBABLE REMEDY: Reline brake bands, using shim stock, so there will be approximately 1/32".clearance between lining and drum. If the band is made round with a lining grinder that at taches to the axle, as little as ten thousandths of an inch clearance is allowable between lining and drum. NOTE: Above clearances apply to drums that are concentric. If condition of drum is questionable, it should be checked as shown on page 20 or on a drum lathe. DO NOT WELD ON BAND ENDS OR CAMS TO COMPENSATE FOR DRUM WEAR. PROBABLE CAUSE: Glazed magnet facing. PROBABLE REMEDY: Machine magnet as in dicated on page 19 . PROBABLE CAUSE: Greasy magnet facing. PROBABLE REMEDY: If magnet insert is greasy use a new magnet. If there is a small amount of grease on insert, remachine as indicated on page 19 . PROBABLE CAUSE: Greasy brake lining. PROBABLE REMEDY: Replace with lining recommended by the factory. PROBABLE CAUSE: Stop lights connected in brake circuit. PROBABLE REMEDY: Wife a separate cir cuit for stop lights. Stop lights must not be con nected into the brake circuit. This changes the graduation of the circuit as it passes through the controller resulting in weak or grabbing brakes. PROBABLE CAUSE: Tow vehicle equipped with foot control and the foot control is out of adjustment. .. PROBABLE REMEDY: When tractor brakes are adjusted the pedal travel is shortened. This throws the controller out of adjustment. Reset con troller according to new pedal travel to cover full range of the controller as indicated on page 20 PROBABLE CAUSE: Wire broken in insula tion. PROBABLE REMEDY: Check entire wiring system for defective parts. Replace wire that is found defective. All splices MUST BE SOL DERED. PROBABLE CAUSE: Incorrect armature de pression. . PROBABLE REMEDY: The correct armature depression is from J4" to 3/16" inclusive. Instruc tions for checking armature depression will be found on page? is PROBABLE CAUSE: Insufficient current. PROBABLE REMEDY: Insufficient current may be due to poor connections as the brake, sock ets, plugs, controller, load control, starter motor or ground connections. Check, clean and tighten all connections. PROBABLE CAUSE: Poor wiring. PROBABLE REMEDY: Rewire, following dia grams on pages 24- and 26 . NOTE: Brakes not having sufficient capacity for the trailer size, weight, etc., will appear weak although they may be operating correctly. BRAKES GRABBING PROBABLE CAUSE: Loose wheel bearing. PROBABLE REMEDY: A loose wheel bearing is the most common cause of "Grabby" brakes. It is very important that bearings be tightened properly. Common practice is to draw the axle nut tight, enough to make the bearings bind slightly when wheel is rotated. Then back the nut off from onesixth to one-quarter turn and lock it in place. PROBABLE CAUSE: Worn or damaged wheel bearings. PROBABLE REMEDY: Examine the bearings. If they are worn or damaged, it will be necessary to replace the damaged bearing and its matching cup. Check the hub to see if bearing cups fit snugly and that there are no cracks in hub. PROBABLE CAUSE: Sticky or grease coated lining. PROBABLE REMEDY: Replace with new lin ing recommended by factory. Refer to page 16 . Check the concentricity of drums. One method of checking drums is shown on page 20 PROBABLE CAUSE: Drums out of round. PROBABLE REMEDY: Bore out the drum con centric with axle. NOTE: It is necessary to use shim stock under lining when drums are rebored. . PROBABLE CAUSE: Axle flange not mounted square with axle. PROBABLE REMEDY: Reweld flange held in proper welding fixture. Refer to page 21 PROBABLE CAUSE: Axle loose on springs or frame. PROBABLE REMEDY: Make necessary re pairs. . PROBABLE CAUSE: Lining loose on rivets. PROBABLE REMEDY: Tighten rivets or re place with new lining and rivets. PROBABLE CAUSE: Bands distorted. PROBABLE REMEDY: Round up bands to fit the band gauge. Refer to page 17 PROBABLE CAUSE: Only one brake working. PROBABLE REMEDY: Check the amperage at each brake. Inspect the wires leading to brake where no amperage is indicated. If no defect is found in these wires, remove the magnet from backing plate assembly and check it for amperage capacity and shorts as shown on page 13 PROBABLE CAUSE: Stop lights in brake cir cuit. . PROBABLE REMEDY: Rewire the stop light in a separate circuit. PROBABLE CAUSE: Broken or weak band re turn spring. PROBABLE REMEDY: Replace with new springs. PROBABLE CAUSE: Poor electrical connec tions. PROBABLE REMEDY: Check wiring for loose connections and broken wires in insulation. PROBABLE CAUSE: Controller burned out. PROBABLE REMEDY: Check controller as shown on pages 11 and 12 . PROBABLE CAUSE: Contactor arm in control ler pitted. PROBABLE REMEDY: Smooth out contactor arm with fine emery cloth. . PROBABLE CAUSE: Contactor blades in con troller bent. PROBABLE REMEDY: Straighten blades with thin flat-nose pliers. PROBABLE CAUSE: Bushing in magnet worn out. PROBABLE REMEDY: This bushing when new is 1/16" of an inch thick. Check the thickness of bushing and if it is worn to a thickness of less than 1/32 of an inch, it should be replaced. Old bushing can be removed by driving a prick punch between magnet shell and the bushing. Install new bushing by placing magnet (magnet insert facing down) on a clean bench. Place bushing squarely on top of magnet and gradually drive bushing into magnet. Bushing should be seated y4" below level of magnet surface that is away from bench. Rough edges caused by driving bushing into magnet, can be smoothed out by tapping them with a ball peen hammer. BRAKES DRAG PROBABLE CAUSE: Drums out of round. PROBABLE REMEDY: Check drum for con centricity. Refer to page 20 . Page 29 PROBABLE CAUSE: Broken spring in con troller. PROBABLE REMEDY: Replace with new spring. (Serviceable only on small controller used with house trailer brakfes). Other type controllers must be returned to the factory to service broken controller spring. PROBABLE CAUSE: Broken or weak band re turn. PROBABLE REMEDY: Replace springs. Be sure all of broken spring parts are removed from brake assembly. PROBABLE CAUSE: Bands distorted, unequal clearance. PROBABLE REMEDY: Refer to instructions for use of band gauge on page j6 PROBABLE CAUSE: Tow vehicle equipped with foot controller and the foot control is out of adjustment. PROBABLE REMEDY: When tractor brakes are adjusted the pedal travel is shortened. This throws the controller out of adjustment. Reset con troller according to new pedal travel to cover full range of the controller as shown on page 20 . PROBABLE CAUSE: Warped backing plate. PROBABLE REMEDY: If plate is bent beyond repair, replace with new plate. PROBABLE CAUSE: Broken or loose parts. PROBABLE REMEDY: Remove broken parts. Replace with new parts. Check for other injuries. NOISY BRAKES PROBABLE CAUSE: Noisy brakes. PROBABLE REMEDY: Clean or replace lining. PROBABLE CAUSE: Loose or worn wheel bearings. PROBABLE REMEDY: Tighten or replace bearings. PROBABLE CAUSE: Drum out of round. PROBABLE REMEDY: Check drum for con centricity. Refer to page 20 PROBABLE CAUSE: Band distorted. PROBABLE REMEDY: Refer to instructions for use of band gauge on page 16 . PROBABLE CAUSE: Drum scored. PROBABLE REMEDY: Bore out the drum to remove as much scoring as possible without weak ening the drum. Refer to page 20 PROBABLE CAUSE: Lining loose on rivets. PROBABLE REMEDY: Tighten rivets; or re place with new lining and rivets. PROBABLE CAUSE: Improper lining. . PROBABLE REMEDY: Replace with lining recommended by factory. Refer to page 16 . UNEVEN BRAKES PROBABLE CAUSE: May be due to any of previous complaints. . PROBABLE REMEDY: Check the weaker brake first to find the cause. DODGE TRUCK BRAKES The brakes described in this unit are of the Lockheed type and their service procedure is very similar to most other type of hydraulic brakes, such as Bendix, etc., differing only in the manner in which the shoes are adjusted to the brake drum. On the Lockheed brake the brake shoe clearance to the drum is controlled by an eccentric at or near the toe of the shoe, while on the Bendix brake the shoe to drum clearance is adjusted by a star nut located inside the backing plate and is adjusted through a hole in the outside of the backing plate with a special tool for that purpose or, in most cases, this adjustment can be made by using a wide screwdriver. As far as the master cylinder, brake cylinder, bleeding the lines, etc., the servicing, on hydraulic brakes all follows the same general pro cedure. REMOVAL AND INSTALLATION BRAKE SHOES 1. Remove wheels and brake drums. 2. Remove brake shoe return springs with special pliers, to avoid bending spring ends (Fig. 62). 3. Install wheel brake cylinder clamps to prevent forcing pistons out of the wheel cylinder. 4. Remove brake shoe anchor bolt "C" washers, oil washer retainer, oil washer, guide spring re tainer, guide spring and brake shoes. To assemble, reverse operations. Also see "Ad justment." WHEEL CYLINDERS--TO DISASSEMBLE 1. Remove wheel and hub. 2. Block brake pedal at floor board to prevent downward movement of pedal. 3. Disconnect brake line at wheel cylinder. 4. Remove brake shoe return spring. 5. Rock brake shoes so upper ends pull out of brake cylinder boots. 6. Remove cap screws which hold cylinder body to brake support. CAUTION: Do not allow any brake fluid to Fig. 62--Removing Brake Shoe Refurn Spring 1--Tool C-llfi 2--Wheel brake shoe return spring 8--Tool C-812 ` . Fig*<53 --Removing Brake Shoe Wheel cylinder clamp 0416 Anchor bolt lock removing tool 0443 come in contact with brake shoes, either from drip ping or from soiled hands. 7. Roll rubber boot off each end of cylinder. 8. Pistons, cups and internal parts will then come out of cylinder. Assemble in the reverse order. Absolute cleanli ness is necessary while assembling as outlined un der "Master Cylinder." MASTER CYLINDER--TO DISASSEMBLE 1. Disconnect brake line tube at master cylinder. 2. Remove cotter and clevis pin, which connect piston push rod and pedal. (On trucks equipped with booster brakes remove the cotter and clevis pin which connects the piston push rod and operat ing link.) 3. Remove bolts which hold master cylinder to chassis and lift out master cylinder assembly. -4. Remove large boot strap and roll large end of boot off master cylinder body. Piston push rod will then drop out of cylinder. If replacing a boot only, perform operations 2 and 4, also remove small boot strap. . Unless replacing a piston push rod or push rod end, do not change adjustment of the end piece. This is seldom, if ever, required. The factory ad justment, is correct and permits the piston cup to just pass the relief port (1, Fig. 68), and yet avoid covering the supply port (3), when the pedal is in the released position. 5. Clean the outside of the cylinder assembly. 6. Remove reservoir filled plug and drain out all brake fluid. 7. Remove lock rings in open end of .cylinder. 8. Pull out piston stop washer and piston. 9. Tip open end of cylinder downward and piston return spring will come out with the inlet valve assembly. To assemble, reverse the foregoing operations, but care must be taken to clean the entire cylinder body inside and outside thoroughly, and wash all Figs. 64 and 65 --Brake Wheel Cylinder 1-- Boot 2-- Piston (large) rear 3-- Piston cup (large) rear 4-- Bleeder screw cap screw 5-- Piston cup (small) front Q--Piston (small) frfont 7-- Boot 8-- Piston cup expander (service only) large--rear U--Cylinder (body) 10-- Piston cup spring 11-- Piston cup expander (service only) small--front 12-- Bleeder screw (valve) 13-- Bleeder screw cap screw lockwnslicr 14-- Cylinder to brake support screw lockwaslier 15-- Cylinder to brake support screw Absolute cleanliness is essential because the slight est trace of grit or dirt will probably cause scratches in the cylinder and piston cup, which in turn will cause the brake fluid to leak, or cause improper brake operation. The walls of the cyl inder and internal parts should be coated with brake fluid just before assembling. NEVER USE A MINERAL. LUBRICANT FOR THIS PUR POSE. REPLACING BRAKE LINING Do riot install new lining on the brake shoes in one front wheel without relining the brake shoes in the other front wheel, or install new lining on the rear wheel shoes without also relining the shoes on the other rear wheel, with new brake shoe lining of the same material. Factory approved brake lin ing sets are available through the Chrysler Cor poration Part's Division. .When riveting the lining to the shoes, it is im portant that only the proper rivets as supplied by the Chrysler Corporation Parts Division be used. Aluminum rivets should never be used. Hold the lining in the shoe with the brake shoe lining rivet ing template. Fig. 69. `4i. Rivet heads should be countersunk into the lin ing approximately two-thirds of the thickness of the lining. Chamfer the end of the lining back : about yy from the top and bottom, and remove high spots or burrs from around rivet holes. DO NOT USE EMERY CLOTH. Satisfactory brakes depend upon two funda mental factors which should be checked when ad justing the brakes. These factors are: L The drum must be concentric with the wheel hub. - 2. The brake lining must be concentric with the drum. After the lining has been riveted to the shoes snugly and the shoes replaced on the brake sup port, the concentricity of the brake drum should be checked to make sure that the drum is con centric with the wheel hub. If an eccentric condi tion is found, the drum should be finished con centric with a drum reconditiohing tool, or on a drum lathe. ADJUSTMENT Brake shoe adjustments are divided into two classes--minor and major. . A minor brake shoe adjustment is made by mov ing the "toes" of the brakes shoes. The cam for adjustment is made by moving the "toes" of the brake shoes. The cam for adjusting the "toes" of the shoes can be reached from the outside of the brake support plate. A major adjustment is made by moving both the "heel" and "toe" of the brake shoes to centralize the shoes in relation to the drum diameter. To make a major adjustment the wheel and hub assemblies should be removed. The "toe" of the brake shoe is the end which fits into the wheel cylinder. The "heel" is the op posite end, attached to the anchor bolt. Page 32 Figs. 66 and 67j--Brake Master Cylinder 1-- Signal lamp switch 2-- Cover screw 3-- Filler plug 4-- Piston cup 5--Cover ' fl--Cover screw gasket 7-- Cover gasket 8-- Master cylinder and supply tank body 9-- Piston stop lock wire 10-- Boot 11-- Piston push rod end 12-- Outlet connection 18--Hole plug 14-- Valve assembly 15-- Piston return spring 16-- Piston washer 17-- Piston 18-- Piston secondary cup 19-- Piston stop 20-- Piston push rod 21-- Piston push rod end lock nut 22-- Strap--small 28--Strap--large 13 14 15 16 17 18 Fig. 67--Brake Master Cylinder 19 20 21 ) ) Fig. 68--Brake Master Cylinder 1-- Relief port 2-- Fluid chamber 8--Port 4--Piston . 5-- Piston stop lock wire . Fig. 69--Stretching Brake Shoe Facing with Tool C-557 MINOR ADJUSTMENT (except booster) Check total pedal travel. The total travel, of the brake pedal is caused by the following: (See Fig. 70). . A. Travel of the piston rod before touching the piston in the master cylinder. B. Travel of the piston required to cover the re lief port. .. C. Travel of the brake shoes to contact the drums. Pedal travel "A" is termed "Free Play" and should be approximately j4"'to This pedal free play may be felt readily by hand and is the move ment of the pedal before the push rod touches the master cylinder piston. If necessary, this adjust ment can be made by changing the length of the master cylinder push rod. "B" can best be determined by looking into the master cylinder reservoir through the filler cap opening while moving the pedal slowly. After the Fig. 70--Brake Pedal Free Play "Free Play" is taken up, fluid should be forced up through the relief port (Figure 68) until the pedal has moved through an additional 34" to 34" (ap proximately), making an accumulated pedal travel of approximately 34 t0 1 required to close the re lief port with the primary cup. If fluid does not come up through the relief port, or if the flow stops at a pedal travel much less than 344 the free play should be checked. If the free play is not the cause, the master cylinder should be disassembled and inspected for swollen cups, etc. An additional pedal travel, "C", of approximately 1" is required to move the shoes outward against the drums. The total pedal travel required to set the shoes should be approximately 1-34" to 2" with properly adjusted brakes. Brake shoe cam adjust ment will usually rectify excessive pedal travel. To adjust the brake shoe cams the following steps should be taken: 1. Turn the brake shoe cam adjusting nut (Fig. 72) "out" until the front shoe lining is solid against .the drum and the wheel is locked, then back off the nut until the wheel may be spun without inter ference. 2. Turn the cam on the rear shoe "out" at the top until wheel is locked, then back off until free. 3. Follow the same procedure at all four wheels. Page 33 Fig. 71 --Filling Brake Master Cylinder with Automatic Refiller. (ToolC-362) A minor adjustment should be made when the brake drums are at room temperature, otherwise the brakes might drag. MAJOR ADJUSTMENT Before adjusting the brake shoes to their final operating clearance, remove all traces of rough or high spots on the lining. The brake shoe adjusting gauge should be used to check the concentricity of the brake lining with the drum. The procedure for making major brake shoe ad justments is as follows and must be applied after relining brake shoes, when shoes have been re moved for any purpose, or after replacing or re surfacing the brake drums: . Fig. 72--Turning Brake Shoe Cams A--Increasing clearance B--Decreasing clearance 1. Remove wheel and hub. . 2. Remove brake shoe return springs and test the spring tension by comparing with a new spring. 3. Inspect lining for exposed rivet heads, abnor mal wear and glazed braking surface, also for uni form material on opposite wheel. Page 34 4. Inspect brake drums for concentricity, scoring and grease. 5. Install brake shoe return springs and set cams in released position. 6. Check the inside diameter of the brake drums with the brake drum gauge (Fig. 74). Set the brake shoe gauge arbor so that the finger marked "Drum Diameter" is just in contact with the point of the tirake drum gauge pin. Place the proper adapter bushing on the spindle or axle shaft and slide the brake shoe gauge over the adapter bushing. the brake shoes just contact the heel adjusting finger of the brake shoe gauge arbor. The correct .006" heel clearance is built into the arbor of the brake shoe gauge. Fig. 73--Wheel Brake Inspection Hole (except WC. WD15) Fig. 75--Setting Brake Gauge Tool MT-84-B Fig. 74--Checking Brake Drum Tool MT-84-B 7. Place the gauge on the point marked "heel" and loosen the brake shoe anchor bolt nuts. On a few models an arrow is stamped on the anchor bolts as shown in Figure 76, but on all other mod els a center punch mark appears as shown in Fig ure 77. If the arrows or center punch marks on both anchor bolts are not pointing directly toward each other, turn the bolts until they do. These marks must point toward each other before start ing to adjust the shoes. The anchor bolts must be turned, from that position, in the correct direc tions in order to decrease the clearance between the lining and the drum at the "heels" of the brake shoes. The correct procedure is to turnthe righthand anchor bolt, of the pair, anti-clockwise and the left-hand anchor bolt, of the same pair, clock wise as viewed from the side where the wrench is applied (Figures 76 and 77). When turning the anchor bolts, as directed, the heels of the brake shoes will move downward and outward toward the gauge. Turn the anchor bolts until the heels of Fig, 76 -- Checking Brake Shoe Heel Adjustment Tool MT-3+-B 1 and 2--Wheel brake shoe anchor bolts 8. Move the arbor of the gauge to the point marked toe and check the clearance between the lining and drum at the toe of the brake shoe. Turn the toe adjusting cam until the lining at the toe of the brake shoe just contacts the gauge arbor. The toe of the shoe is then properly adjusted, with .012" clearance between the lining and drum. 9. Recheck the clearance first at the heel and then at the toe to make sure no change has occurred in either adjustment and tighten the anchor bolt nuts securely. 10. Install wheel and hub assemblies. 11. Check and refill the master cylinder reser voir with approved fluid. Fig. 77 Brake Shoe Anchor Bolt Adjustment (except WC. WD15) Page 35 BLEEDING BRAKE LINES Air in the braking system seriously impairs brak ing efficiency, resulting in soft, spongy pedal action. It must, therefore, be removed by bleeding the lines if the fluid level has been allowed to get too low or any part of the braking system has been disconnected or replaced. To bleed the brake lines, fill the reservoir with fresh Brake Fluid and replace the bleeder screw in the center of the wheel cylinder where it pro trudes through the brake support with a fitting to which is attached a short length of rubber hose (Figure 80). Allow the free end of the hose to be submerged in a clean glass container of brake fluid and unscrew the bleeder valve l/2 to of a turn. The actual bleeding operation is accomplished by pressing the brake pedal slowly through half the limit of its travel. Allow the pedal to return to its released position, after which it may again be depressed until the fluid runs out of the bleeder hose in a continuous stream, without air bubbles. Fig. 80 Bleeding Brake Lines. 1--Bleeder screw 2--Bleeder hose It is extremely important that the master cyl inder reservoir be full of fluid and that it be re filled before being completely exhausted. If the filler cap of the reservoir is left off during the bleeding operation, it will be possible to watch the fluid to see that it does not get below the half way point. The automatic refiller (Figure 71) for master cylinders will prevent the master cylinder from running dry during the bleeding operation. With the master cylinder reservoir full of fluid, the foot pedal can be given from six to ten half strokes before it is necessary to refill it. It is best to bleed one wheel cylinder at a time in order to make sure that all air is expelled from the system. . CAUTION: Do not allow any brake fluid or grease to come in. contact with the brake lining. When all air bubbles have been forced out of the Page 36 system, the bleeder valve should be closed tightly before taking the bleeder hose out of the fluid. When any part of the braking system is discon nected for any reason, it is necessary to bleed the brake lines at all four wheel cylinders. NOTE: See "Brake Fluid" under Maintenance. ' ' MAINTENANCE ' BRAKE SHOE RETURN SPRINGS Brake shoe return springs should be inspected for tension every time brakes are serviced, and weak or broken springs should be replaced. Only one spring should be used for each pair of shoes, and both front and both rear return springs should be uniform in tension. BRAKE SHOE ALIGNMENT The maximum braking effect can only be pro cured if the entire length and width of the lining contacts the surface of the drum. This alignment can be upset by a sprung brake support, bent shoe or anchor bolt which does not protrude at right angles to the surface of the.support. An examination of the lining will indicate whether or not the shoe is out of alignment and the affected part should be straightened or replaced. BRAKE LINING Grease or oil on brake lining destroys its effec tiveness, resulting in hard pedal pressure, grabbing, unequal braking and excessive noise. Cleaning an oil-impregnated lining, with gasoline or other grease solvent will only give temporary relief at the best. A complete relining is recommended when possible after eliminating the grease leaks and re packing the bearings. Brake lining obtained from the Chrysler Corporation Parts Division is prac tically impervious to the absorption of water. A certain amount, however, might get between the lining and the drum when washing the truck with a pressure spray. Temporary difficulty might be experienced with the brakes until this factor is removed by a few applications of the brakes. It is recommended that a brake pedal depressor be em ployed when washing the vehicle, to keep the water off the lining. . BRAKE FLUID It is recommended that only approved fluid be used in the hydraulic braking system. This is a spe cial fluid compounded for use exclusively in hy draulic brake systems. Iso-Brake Fluid mixes with other brake fluids recommended by automobile manufacturers. How ever, do not mix brake fluid with any fluids con taining glycerine, sugar, glucose, mineral oil or water. SERVICE DIAGNOSIS NO BRAKES 1. Worn lining, improperly adjusted brake shoes, air in system, no fluid in system. 2. Check system for fluid leaks, check master cylinder push rod adjustment. BRAKES DRAG 1. Check master cylinder push rod adjustment to insure that the relief port is open. 2. Piston cups swollen by use of unsuitable fluid. 3. Dirt in master cylinder relief port. 4. Brake shoe clearance insufficient. 5. Check booster valve piston rod adjustment. ONE BRAKE DRAGS 1. Weak brake shoe return spring. 2. Improperly adjusted brake shoes, too close to drum. 3. Brake shoe sticking on anchor bolts. 4. Loose wheel bearings. 5. Wheel cylinder piston or piston cups sticking in wheel cylinder. 6. Obstruction in brake lines. TRUCK PULLS TO ONE SIDE 1. Improperly adjusted brake shoes. 2. Lining on one wheel grease soaked. 3. Brake support loose on the axle. 4. Improperly inflated tires. .5. Linings have different friction qualities on different- shoes. 6. Dent or kink in lines, brake hose plugged. 7. Worn lining or scored drums. 8. Loose front spring U-bolts. SPRINGY OR SPONGY PEDAL 1. Air in system. .2. Brake shoes improperly adjusted. BRAKE PEDAL JAMS 1. Use of unsuitable fluids causing softening of the rubber cups, and the rubber extruding between the piston and cylinder wall or in the holes in mas ter cylinder piston. Use new rubber cups and mas ter cylinder piston washer (16, Figure 66). 2. Install piston cup expanders and spring in wheel cylinders, if not so equipped, for cars oper ating in temperatures below 0 F. BOOSTER BRAKE OPERATION A vacuum suspended type brake booster is sup plied as standard equipment on several models. The booster equipment is not a part of the hy draulic brake system, although it is controlled by the same pedal. which operates the hydraulic brakes. The sole function of the booster is to boost the pressure applied to the hydraulic brake master cylinder by the operator. It is not in tended that the booster will, under all conditions, supply all the effort required to operate the hy draulic brakes. The load applied by the booster depends upon unbalanced pressure in the booster cylinder. With the brakes released and the engine running, air is pumped out of the booster cylinder, creating vac uum in the cylinder. On Diesel trucks a vacuum pump, located on the side of . the engine creates vacuum in the booster cylinder. With no atmo spheric pressure on either side of the booster piston, the .piston, which is connected to the brake pedal, is moved to the front end of the cylinder by the brake pedal pull-back spring and a large coil spring in the booster cylinder. When the brake pedal is depressed by the operator, the booster control valve, which is operated by the movement of the pedal, closes the vacuum line to the front of the booster cylinder and opens a port which allows air to enter the front of the cylinder only. Since there is no air in the rear end of the cylinder, the atmospheric pressure against the front side of the piston causes the piston to move toward the rear of the cylinder and apply pressure to-the master cylinder through the medium of booster brake linkage. The maximum pressure on the master cylinder which can be expected from the booster is limited by the predetermined area of the booster piston, the prevailing atmospheric pressure, and the lever age obtained through the linkage. The degree of efficiency with which the booster operates depends upon maintaining vacuum at the rear end of the booster cylinder while the brakes are being applied. This in turn depends upon the ability of the engine (or vacuum pump on Diesel trucks) to remove air from the system. The engine or pump must remove the air from the front end of the booster cylinder, (or cylinders, if trailer is equipped with vacuum powered brakes), each time the brakes are released, as well as any' air which may leak past the booster piston, control I valve or faulty line connections. The engine will create ample vacuum of 18 to 21 inches at all engine speeds provided the system is closed and free from leaks. The vacuum pump on Diesel models will create 25 to 27 inches of vacuum. When the brakes are repeatedly applied and released in rapid suc cession, air will not be pumped out as fast as it is admitted to the system. Consequently there may not be sufficient vacuum at the rear of the cylinder to provide repeated booster application. This con dition will, of course, be amplified when vacuum i powered trailer brakes are used or by leakage of air i Jn the system but will not. occur if the system is 1 free from leaks and a little time is allowed between brake applications. .: CHECK VALVE (Operation) ' ; , . The check valve is of the normally closed type _ and opens only when the vacuum is higher at the . ehgine (vacuum pump on Diesel trucks) than in ; J?. ^.".the booster system. ... The check valve traps the vacuum in the system 'viy *- making available sufficient reserve vacuum for a application in case of a stalled engine. CONTROL VALVE (Operation) '.... .{All Models Except WK, WL) ; Tlie 'compensating type control valve (Fig. 84>. Page 37 is illustrated in the "off" position. The vacuum line from the engine is . connected through a tee directly to one side of the booster cylinder and through the control valve to the other side of the booster cylinder. When the control valve is in the "off" position, the connection from the booster cyl inder to the engine (pump on Diesel trucks) is made through a passage in the center of the con trol valve diaphragm. In this position, vacuum is maintained on both sides of the diaphragm (B and C, Fig. 84) of the control valve and on both sides of the piston in the booster cylinder. Booster aplication is controlled as follows: The first motion of the brake pedal moves the linkage connected to the piston in the control valve through the length of the elongated hole (18, Fig. 82 and 1, Fig. 83) in the control valve bracket. This causes the control valve piston to move into the valve body, first closing the passage in the center of the control valve diaphragm, so that vacuum is no longer maintained on the front side of the booster cylinder piston. Further movement of the control valve piston opens the air intake valve (1, Fig. 84), allowing air to rush in through the control valve air cleaner to the front of the piston in the booster cylinder. This causes the booster cylinder piston to move toward the rear of the cylinder assisting brake application. If the brake pedal is held in this position, the control valve and linkage assembly moves forward, taking up the travel permitted by the elongated hole in the control valve bracket, due to admitting air to the rear side of the diaphragm, closing the air intake valve. The air intake valve will remain . Fig. 81 Refinishing Brake Cylinder. 1--Brake cylinder 2- Tool C-81 * 8--Electric drill ` y" in this position until either more or less pressure is applied to the brake pedal. The position of the brake pedal, therefore, de termines the amount of travel of the booster piston rod, so that brake application is controlled by the driver. If greater pressure is exerted on the brake pedal, the foregoing operations are repeated until the brakes are fully applied. When the brakes are released, the control valve returns to the "off" posi tion, restoring equal vacuum on both sides of the control valve diaphragm and the booster cylinder piston. The brake pedal pull-back spring and the coil spring in the booster cylinder will return the pedal and linkage to their normal positions. Page 38 1-- Brake pedal --28----CChehcekckvavlavleveasbsreamckbelyt 4 Tube (manifold to check valve) 5-- Cylinder support spring 6--Cylinder assembly . 7-- Cylinder operating lever stop screw 8-- Cylinder bracket 9-- Control valve assembly 10--Control valve piston rod yoke lock nut Fig. 82 Booster Brake. 11-- Control valve piston rod yoke 12-- Brake master cylinder assembly 18--Hose 14-- Cylinder operating lever 15-- Control valve operating lever pin 16-- Control valve operating link 17-- Control valve operating lever 18-- Elongated hole 19-- Tube (check valve to tee) Fir;- S; Boost.-**;- Prnke S;. seen; (Diesel Truck.:;; ; ' clmijrrjii-n luil.i ('I'jarerv'* fi* revir o! pin > Fig. 84 Booster Brake Control Valve. A--Connection opening to check valve B--Front vacuum chamber C--:Rear vacuum chamber D--Connection opening to front of booster cylinder 1--Air intake valve 2-- Diaphragm 8--Valve stop plate 4--Air intake valve spring 5--Air cleaner Fig. 85 Booster Brake Control Valve (WK, WL) A--Clearance at rear of pin CONTROL VALVE (Operation) (WK,WL) On Models WK and WL, booster application is controlled as follows: A piston operating in the cylinder of the control valve opens and closes ports for withdrawing and admitting air to the front end of the booster cylinder. The first movement of the piston in the control valve closes the port through which vacuum is created in the front end of the booster cylinder. Further movement of the control valve piston opens the port which allows air to rush in through the control valve air cleaner to the front of the booster cylinder piston. The booster cylinder piston then moves to the rear of the cylinder assist ing brake application. (See Figure 85)- VACUUM CYLINDER (Operation) The vacuum cylinder provides the booster brak^( .ing effort. The piston is the only working part in :. vthe cylinder assembly and is actuated by unbal- t'anced pressures created through the control valve. The efficiency with which the piston operates de1 pends upon the amount of vacuum maintained at .the rear end of the cylinder. The extended piston rod end of the cylinder is known as the "front end" s(: regardless of how installed on the vehicle. Leakage past the piston sealing cup will rapidly rj.iT,educe the vacuum when the brakes are applied. ^Leakage past the piston rod seal will reduce the vacuum when the brakes are released. REMOVAL AND INSTALLING Vacuum Cylinder Disconnect vacuum hose at front and rear of ^ff^agpum cylinder. Remove 'clevis pin from front end of piston ^:X6d; . . .' Jteinove rear nut from rear end of cylinder support or remove booster cylinder--de- on model of truck. Page 39 . Assemble in reverse order of the foregoing op erations. Vacuum hose connections must be tight to avoid leakage. See "Adjustment--Booster Brake." CONTROL VALVE 1. Disconnect the two vacuum hoses at the con trol valve. 2. Remove clevis pin from front end of valve operating rod. 3. Remove the two bolts and nuts holding valve to operating link. Assemble in reverse order of the foregoing opera tions. Vacuum hose connections must be tight to avoid leakage. See "Adjustment--Booster Brake." CONTROL VALVE AIR CLEANER 1.. Remove snap ring (screws on WK, WL) from the body of control valve and lift off air cleaner. 2. Lift out curled hair and clean in kerosene. On all models except WK, WL, care must be used when installing the air cleaner to make sure that the prongs of the valve stop plate (3, Figure 84) are seated squarely in the recess of the air cleaner screen to prevent bending the valve stop plate prongs. ADJUSTMENT--BOOSTER BRAKE Adjustment will be necessary whenever the hy draulic brake master cylinder, the booster cylinder or the control valve have been disassembled or re moved and replaced. The brake booster should not be adjusted to compensate for a brake shoe adjust ment. Brake shoe adjustment in no way effects brake booster operation. To adjust the booster unit, proceed as follows: ADJUSTMENT 1. Adjust the operating lever stop screw (7, Fig ure 82) so that the brake pedal just clears the underside of the toe board. The purpose of this ad justment is to bring the pin in the brake lever to the rear of elongated slot in the control valve link (18, Figure 82)- 2. Remove the booster brake cylinder pivot and cylinder from the bracket at the rear of the cyl inder. Then adjust the master brake cylinder push rod against its stop so that there is no clearance between the piston of the master cylinder and push rod. 3. Insert the booster cylinder pivot in the bracket and turn the pivot check nut until the booster cyl inder piston is at the forward end of the cylinder, then back off two turns to permit approximately y%" clearance between the piston and cylinder. Make sure that the pin in the control valve linkage remains at the rear of the elongated slot. 4. Tighten the booster cylinder pivot nut and the adjusting screw lock nut. ADJUSTMENT (DIESEL TRUCKS) 1. Adjust brake master cylinder piston push rod so that the piston is against its stop. 2. Remove pin from booster cylinder lever rod. 3. Loosen lock nut and turn adjusting yoke at booster cylinder until pin can be inserted with the Page 40 piston against the forward end of the cylinder. After making the adjustment, the clearance at the sleeve in the pedal should be on the rear side of the pin (1, Figure 83 and A, Figure 85 ). TESTING BOOSTER SYSTEM FOR LEAKAGE . To test the entire system for efficiency, install a vacuum gauge in the line between the check valve and the control valve. Start the engine and note the amount of vacuum shown on the gauge. If approx imately 18 to 21 inches of vacuum* (27 inches on Diesel trucks) shows on the gauge with the engine running, stop the engine. If the vacuum does not drop faster than 2 inches per minute with the brakes released, or more than 8 inches after the engine is stopped and the brakes are applied and held on for 1 minute, the booster system will oper ate efficiently. The amount of drop in vacuum when the brakes are applied will increase with ex cessive brake pedal travel, therefore, the brake shoes must be properly adjusted and the hydrulic brake lines free from air when this test is made. With the engine running and the brakes released, a maximum vacuum reading of less than 18 to 21 inches (27 inches On Diesel trucks) would indicate leaks in the system, insufficient engine vacuum, or a faulty vacuum pump on Diesel models. If the vacuum reading is low, and the vacuum drops faster than 2 inches per minute after releas ing the brakes and stopping the engine, there is a leak somewhere in the system. If the vacuum read ing is low, and the vacuum does not drop faster than 2 inches per minute after releasing the brakes and stopping the engine, insufficient vacuum is be ing created by the engine or vacuum pump or there are air leaks between the check valve and engine (pump on Diesel trucks). In case the maximum vacuum, with the engine running and the brakes released, is not less than 18 to 21 inches (27 inches on Diesel Trucks) and does not drop faster than 2 inches per minute when the engine is stopped, but does drop more than 8 inches when the brakes are applied and held on for 1 minute, there is excessive. leakage past the vac uum cylinder piston or the control valve when the brakes are applied. . CHECK VALVE (Testing) To test the check valve, connect a vacuum gauge to the port leading to the control valve and start the engine. After stopping the engine the gauge reading should remain constant for a reasonable length of time unless the valve leaks. CONTROL VALVE (Testing) To test the control valve, remove both hoses, place finger over the port leading to the check valve and suck on the opposite port. If no air can be drawn through, the valve does not leak. *Diesels are equipped with vacuum pump. VACUUM CYLINDER AND PISTON ' . ASSEMBLY ' . ; (Testing) To test for leakage past the piston sealing cup, disconnect the hose at the front end of the cyl inder. Plug the end of the hose and start the engine, Then install a vacuum gauge in the open port of the cylinder and if the reading builds up rapidly there is excessive leak past the piston and the cyl inder should be serviced. To test for leakage past the piston rod seal, dis connect the hose from the front end of the cylinder and install a vacuum gauge in the end of the hose. Start the engine and take a vacuum reading. Then reconnect the hose with the vacuum gauge installed in the line and take another reading. If there is no leakage past the piston sealing cup, any difference in the two readings would indicate leakage past the piston rod or at the front of the cylinder. 1 *V-` u. )) `V'* VACUUM LINES All connections must be sufficiently tight to pre vent even the slightest leak. Hose connections should be sealed with shellac. VACUUM PUMP (DIESEL TRUCKS) The vacuum pump (Figure 86 ) is of the rotary type and is belt driven. It is lubricated by the en gine oiling system and will require little attention other than maintenance of proper drive belt adjust ment. To adjust belt, loosen the two lower hinge bolt nuts and turn adjustment screw. After adjust ment is made to the vacuum pump drive belt, the generator drive belts must be readjusted. To test the vacuum pump efficiency, disconnect the vacuum line from the pump and install a vac uum gauge in'the port of the pump. A normal pump will create approximately 27 inches of vacuum at idling engine speed, but it is not expected that the pump will maintain 27 inches of vacuum in the sys tem if the brakes are repeatedly applied and re leased in rapid succession. MAINTENANCE ' When installing the booster unit, care should be exercised to make certain that it is in perfect align ment. The connecting link should line up perfectly with the operating lever and it should not have to be sprung in order to assemble the clevis pin. The booster brake unit should be lubricated every 6000 miles with ice machine oil, shock absorber fluid or transformer oil. This is accomplished by removing the hose at the front end pf the cylinder and pouring in about an ounce of the recommended oil. An ounce of oil should also be added through the vacuum line connection at the rear end of the cylinder. Periodic lubrication of the booster unit will keep the piston packing and the piston rod seal in good condition and will insure efficient operation at all times. - -7 .1* -n *7: Page 41 Fig. 86 Vacuum Pump (Diesel Trucks) Dodge Truck Clutch The clutch used in the Dodge truck is a Borg & Beck single plate, dry disc type. As the clutch facings wear, the release levers slowly move proportionally. The outer ends of the release levers move toward the flywheel causing the inner ends to move toward the trans mission. This will result in a decrease of the clutch free travel. To prevent the clutch pedal from riding on the toe board, the clutch free travel should be kept adjusted to about 1" to l|". Clutch Removal Before removing clutch from flywheel, mark with a punch the flywheel, clutch cover and one pressure plate lug, so that these parts may be assembled in their same relative positions, as they were balanced as an assembly. (See fig. 87.) Loosen the holding screws a turn or two at a time in rotation to avoid bending rim of cover. When removing driven plate be sure to mark flywheel side. Clutch Cover and Pressure Plate Proper operation of the clutch is chiefly de pendent upon accurate adjustment of the release levers. They must all be adjusted to exactly the " .Fig. 87 Punch Marks on Clutch Cover and Flywheel. 2. Engine flywheel and ring gear 3. Pressure place 4. Disc facing rivets 5. Pressure plate baffle 6. Disc assembly 7. Engine flywheel bolt 8. Transmission drive pinion 9. Engine crankshaft bushing (transmission drive pinion . pilot bushing) . 10. Engine Crankshaft 11. Release lever -12. Release lever eye bolt . 13. Release lever pin 14. Disc facing Clutch 15. Cover 16. Housing hole plug 17. Pressure spring 18. Release bearing pull-back spring screw 19. Release bearing pull-back spring 20. Release bearing 21. Release bearing sleeve 22. Transmission drive pinion bearing retainer 23. Release fork 24. Release lever spring 25. Release lever eye-bolt nut 26. Release'lever strut 27. Housing pan 28. Clutch release fork flange Page 42 Fig. 89 Removing Clutch Assembly. 1. Clutch release fork ilange 2. Release fork 3. Clutch assembly same predetermined height above the machined surface on the pressure plate, so that it will re main parallel with the flywheel when the clutch is being released and engaged. This adjustment cannot be made by setting the levers parallel to 1. Tool C-360 ' . Fig, 90 Clutch Disc Aligning Arbor. the face of the release bearing after the clutch has been assembled to the flywheel because of variations in thickness of the driven plate. The most accurate method is to adjust the levers by using a special clutch compressing and adjust ing fixture. v t' i: % I; 7i : 3. Pressure plate. 4. Disc facing rivets. 5. Pressure plate baffle. 6. Disc assembly. Fig. 91 Exploded View of Clutch. n. Release lever. 15. Coyer. . 12. Release lever eye bolt. 17. Pressure spring. 13. Release lever pin. 19- Release bearing pull-back spring. . 14, Disc facing. 20. Release bearing. ' 21. 23. 24. 25. 26. Release bearing sleeve. Release'fork. . Release lever spring. Release lever eye bolt nut. Release lever strut. The C-411 clutch compressing and adjusting fixture has been superseded by a new type fix ture known as the C-585. This special fixture is obtainable from the Miller Tool and Manufac turing Company of Detroit, Michigan. Instruc tions in this unit covering the disassembling ad justing and assembling procedure are based on the use of the C-585 fixture. It accurately checks the parallel alignment of the clutch pressure plate while the clutch fingers are under load. The use of the fixture eliminates possibility of error in clutch finger adjustment due to clutch finger leverage ratios and housing strains. Disassembly and Reassembly of Clutch Cover and Pressure Plate (USING C-585 CLUTCH FIXTURE) The clutch cover assembly should be removed from the truck as shown under the heading of "Clutch Disc". Then procede as follows: 1. Mark the cover and pressure plate with a prick punch (4, Figure 92) so that they may be assembled in their original position to maintain balance. 2. Mount the clutch assembly on the clutch compressing and adjusting fixture. 3. Install the three-legged spider over the center screw so that it rests directly against the top of the clutch cover. 4. Install the plain thrust washer and the hex agonal compression nut and compress the springs by turning down the compression nut (Fig. 92). 5. With the springs under compression, re move the clutch release lever eye bolt nuts and slowly relieve the spring pressure by unscrewing the compression nut. 6. The cover may then be lifted off and all parts will be available for inspection (Fig. 87 and 91). To remove the release levers, proceed as follows: . Grasp the lever and eye bolt between the thumb and fingers, as shown in the illustration (Fig. 93), so that the flat side of the lever and upper end of ^||S| the eye bolt are as close together as possible, ' *?4^ keeping the eye bolt pin seated in its socket in |ijthe lever. The strut (1, Fig. 93) can then be ^Ufted over the ridge on the end of the lever, maklling it possible to lift the lever and eye bolt off pressure plate. It is advisable to replace r parts which show wear. .^tAssemble the clutch cover and pressure plate y reversing the foregoing operations, observing ih:following precautions: :'k T. Place the pressure springs in position so ,.^they rest on the small bosses of the pres sure plate and engage the embossed seats on the Fig. 92 Clutch Cover and Pressure Plate Assembly in Fixture. 1. Clutch cover 3. Fixture (Tool C-585) 2. Clutch pressure plate 4. Punch'marks on pressure plate and cover Fig. 93 Assembling Strut. 1. Release lever strut 2. Eye bolt 3- Release lever 2. Matchup the prick punch marks made when disassembling, so that the cover and pressure plate will be assembled in the same position with relation to each other. 3. When installing the cover and pressure plate assembly on the flywheel, make certain that the prick punch marks on the flywheel and clutch cover are matched to keep the assembly ih bal ance. Adjusting the Release Levers (USING C-585 CLUTCH FIXTURE) 1. Mount the clutch cover and pressure plate assembly on the fixture with the release levers over the feeler gauges in the base of the fixture. 2. Place the proper spacer on the center screw of the fixture, selecting it according to the diam eter of the clutch plate: A No. 17 spacer should be used on a 10" clutch while both spacers Nos. Page 44 . 20 and 21 should be used on a 11" clutch. 3. Install the compression plate on the center screw. Make sure that it rests directly against the clutch release fingers. This plate can be re versed for proper clearance depending on the size of the clutch. . 4. Install the self-aligning washer, plain thrust washer and the compression nut. 5. Tighten the compression nut until the clutch is fully compressed. 6. Install the clutch housing clamps over the bolt holes and tighten them securely. 7. Adjust the clutch release levers until each of the three feeler gauges have the same slight "drag" or "feel" while being pushed in and out. Tighten the nuts to decrease "drag" and loosen to increase "drag". 8. Recheck the release lever adjustment to make sure each one is adjusted properly. On 11" clutches having four release levers, two of the levers should be located over two of the three feeler gauges, and adjustment made as outlined in the foregoing instructions. The clutch should then be rotated 180 on the base of the fixture so that the other two release levers can be placed over two of the feeler gauges, and ad justed so that they have the same light drag as the first two release levers. . When removing the clutch cover assembly from the fixture, loosen the housing clamps first, then remove the compression nut. This is important and will avoid throwing unequal strain on the re lease levers. Clutch Re-Facing When installing facings on the clutch disc, only new facings and rivets of the proper thicknesses, size and material should be used. Slight varia tions in thickness of clutch facings will inevit ably result in clutch difficulties. Clutch facings on either side of the disc are in dividually riveted to the plate. That is, each of two facings is fastened to the disc with a sepa rate set of rivets to avoid the possibility of shift ing on the disc or shearing off the rivet heads. When removing the old facing, rivets must be drilled out, to punch out will damage the clutch cushion springs. Care should be taken when in stalling new facing to see that the clutch cushion springs are not bent from their original position. Bending the cushion springs will invariably re sult in clutch difficulties. Do not allow any grease or oil to come in con tact with the friction surfaces of the clutch disc. Even greasy hands touching the friction surfaces will transfer a sufficient amount of grease in many instances, to cause after a short time of Fig. 94 Adjusting Clutch Release Levers. 1. Feeler blades (part ofTool C-585) 2. Compression plate(part 3* Spacers (part of Tool C-585) 4. Clutch release lever eye bolt 5. Clutch release lever eyebolt nut , of Tool C-585) 6. Stake here to lock driving, a glazed surface pnthe clutch disc which in turn results in chattering or grabbing. Reinstalling Clutch 1. Coat the main drive pinion pilot bearing in the end of the crankshaft and the end of the main drive pinion shaft with short fibre wheel bear ing grease, medium. 2. Clean the surfaces of the flywheel andpressure plate thoroughly, making certain that no oil or grease remains on these parts. Fig. 95 Cleaning Clutch Friction Surfaces and Lubricating the Pilot Bushing. 1. Clutch pressure plate 2- Engine flywheel 3. Transmission main drive pinion pilot bushing 3. Hold the clutch cover plate and disc in place and insert the special clutch alignment tool C360 through the hub of the driving disc and into the drive pinion pilot bearing in the crankshaft, (Fig. 90). 4. Bolt the clutch cover plate loosely to the flywheel with the marks on the cover and fly wheel in alignment. 5. The clutch cover bolts should then be tight ened a few turns each in progression until they are all tight. If the aligning tool is not used, the transmission drive pinion (an extra part of one which has been removed from the transmission) may be used for this purpose. The transmission may then be installed by guiding the transmission into place with pilot studs. Adjustment Clutch Pedal Free Movement 1. Loosen pedal adjusting screw lock nuts. 2. Turn clutch pedal adjusting screws until pedal has 1" to l|" free movement. On some installations the adjustment for pedal free movement is made by turning the swivel on the connecting rod between the pedal and opera ting lever. Free movement of the clutch pedal is neces sary to compensate for wear of clutch facing and to avoid slippage. It insures proper clearance between clutch release bearing and clutch re lease lever. Maintenance CHATTER Chatter may be due to: Grease or oil on the disc,flywheel or pres sure plate. 2. Binding of clutch release linkage. 3. Disc facings loose. 4. Broken disc facings or pressure plate. 5. Loose engine mountings. 6. Incorrect adjustment of release fingers. GRABBING Grabbing is usually caused by: Oil or grease on the disc, pressure plate or flywheel. Broken disc facings or pressure plate. Hub of disc not sliding freely on splined shaft, or binding or release mechanism. Slippage ^Slippage may be caused by: ;' - .' Lack of pedal free movement. , . Binding of ciutch release mechanism. Page 45 2. Master cylinder push rod end 9. Clutch pedal adjusting collar nut set screw 3. Master cylinder push rod 10. Clutch pedal adjusting collar assembly clamp screw 4. Brake pedal assembly H. Clutch and brake pedal re- 5. Clutch pedal assembly inforcement bracket 6. Clutch pedaladjusting collar 12. Clutch release fork set screw 13. Clutch pedal pull-back'spring 7. Clutch pedal adjusting collar 14. Clutch pedal adjusting collar set screw nut 15. Brake pedal pull-back spring Fig. 97 Clutch Pedal Free Play. 3. Broken clutch pressure springs. 4. Worn disc facings, pressure plate or fly wheel. 5. Weak pressure plate springs. DRAGGING Dragging or incomplete release maybe caused by:. = 1. Excessive free movement of the pedal. 2. Incorrect adjustment of release fingers. Page 46 3. Loose or broken disc facings. 4. Bent or dished driven disc. SPINNING : Clutch spinning is frequently confused with clutch dragging. A clutch disc which releases perfectly will naturally spin under its own weight and momentum immediately after being released if the transmission gears are in the neutral position. , Gear clash, when shifting from neutral to first speed, or to reverse, is usually caused by the clutch spinning and can be overcome only by re leasing the clutch, allowing the disc to stop spinning and then shifting the gears. Trucks equipped with four and five speed transmissions shouldbe shifted by "double clutch ing". Mack Clutch The MACK clutch is of the single plate, "push er" type; that is, the clutch must be pushed in order to disengage it, Models CL 20 and CL 40 are 14" in diameter and have 18 coil springs while Model CL 28 is 15" in diameter and has 36 coil springs. ', A driven disk with a 3/16" thick facing riveted to each side of it, engages the flywheel, while the other face engages the pressure plate. Disengagement of the clutch is through the ac tion of six ball pivoted fingers on the clutch cover pulling the pressure plate away from the driven disk when the fingers are contacted and pushed toward the flywheel by the forward movement of the clutch release bearing. CLUTCH DISC ADJUSTMENT: The release bearing clearance or gap (3) should be 5/32". As facing wears so this gap is decreased to 1/18", adjust the gap to 5/32" by use of MACK Service Gage which is available at service stations. As these adjustments are made, the clearance (2) will be eventually decreased, and should be re adjusted as follows: CLUTCH PEDAL ADJUSTMENT:' When the release bearing gap of 5/32" (3) is lessened, the clutch release lever on outside of clutch should be adjusted so as to have 3/8" clearance between roller and cam, which is approximately a 2" travel of the clutch pedal at the pad. When all adjustment is used up between roller and cam, remove the clutch release lever from the ser rated shaft and turn it slightly and replace on shaft. This provides more adjustments, and re adjust to 3/8" clearance, as previously described. CAUTION: Never ride the clutch pedal. Do not continue driving with a slipping clutch,, it should be adjusted at once. i? f * Fig. 98 Mack Clutch. CLUTCH FINGER ADJUSTMENT should never be attempted as it is a delicate operation re quiring precision tools. In unusual conditions where finger pivots might wear and repairs are necessary, arrange with MACK Service Station to exchange your assembly for a reconditioned one. CLUTCH SPRING TENSION may decrease when flywheel or the pressure plate are faced. Washers are available to insert in spring cups to compensate for this loss of clutch spring pres sure, and this compensation must never exceed 3/16". The spring tension for the different springs in the different clutches varies greatly and the local MACK Service Station has the data and tools necessary for checking these tensions. LUBRICATION is required at the release bearing at 1500 mile intervals, J[l) in illustration. A high melting point (350" F.) Ball and Roller bearing grease should be used; this is very important. Lubrication is also required at the two throwout yoke shaft bearings every 1500 miles. A good chassis lube will be satisfactory at these points. The pilot bearing in the flywheel is of the pre packed sealed type requiring very little lubrica tion. Every 6,000 miles apply a small amount of high melting point (350 F. or over) semi-fluid Ball and Roller Bearing grease with hand gun, by removing plug (11) in flywheel rim, and in stalling pressure fitting. After lubricating, the fitting must be replaced by the plug. When clutch is disassembled for any reason, clear these passage ways of any hardened grease by inserting a soft iron wire. A