Document xzV5kGVwJwBZ61aBmBYQ28ZMb

FILE NAME Allied Signal Bendix ASB DATE 1965 May 18 DOC ASB205 DOCUMENT DESCRIPTION US Patent - Brake Drum and Lining United States Patent Office 3,184,001 Patented May 18 1965 2 3,184,001 BRAKE DRUM AND LINING Earl W. Reinsch Dayton and Gene P. Baynes Kettering Obio assiguors to General Motors Corporation Detroit Mich a corporation of Delaware Filled Aug. 16. 1962 Ser No. 217,426 5 Claims Cl 188 71 This invention invention relates to a torque transmitting and energy absorbing device and is specifically directed to brakes clutches and the like More particularly the invertion is directed to the combination of a sintered ferrous brake lining or facing used in conjunction with a brake member including a braking surface formed from steel substantially substantially free from ferrite An object of the invention is to produce a combination of elements for use in a que transmitting and an energy absorbing device and particularly a brake wherein the uniformity of operation improved ^ n carrying out the above object it is a further object of the invention to reduce celd pedal effect normally pics- ent automotive braking system is Further objects and advantages of the present inven- tion will be apparent from the folowing description reference being had to the ccompanying drawings drawings where where in preferred embodiments of the present invention are clearly shown In the drawings drawings drawings TIG 1 phot es uph of SAF 1010 sieci drum showedg the form and is section of a anv the structure 1G as a photo microg aj ho chase section of a SAL Jorf steel drum diew Passes Passes of ferite is the microstructure microstructure Recent trends in automotive design and improved real cinditions have made possibi high ne oo speed travel in automotive vehicles These tients have requited im provement in brak design design construction so that the vehicles may be stopped within fe dist^"^-ezeven from 14 higher speeds In order to make this condition pev sor heavy duty brake to derials derials have been dev oped which are metulit in pacate and which will withh stand the high temperatur conditions which prevan in the brake during a stop or stops froin high speed- These temperature conditions are sufficient ia in many instan instan curse chairing of non Hic type linings including on ganic type material This new brake lining material which is specifically a sintered ferrous material including graphite is disclosed in some detail in US Patents 2.945.291 and 2,945.929 among others which are as- signed to the assignee of this application These metalic friction materials have the ability to provide reasonably constant coefficients of friction over a wide range of temperatures and specifically are capable of maintaining the reasonably high coefficient of friction at high temperatures whereby the vehicle may be brought to a stop with- out excessive pedal pressure and wherein the friction material remains unharmed due to the rise in temperature These same materials however do not provide the ultimate in cold pedal operation under normal conditions Cold pedal may best be defined as a reduction in effective- ness of the brakes after a period of inactivity that is when the automotive vehicle has been standing idle for a period of time for example the rst stop or first few stop made require greater po tal pressure to bring the car to a step than do subsequent operations of the braking system This condition while not scrions from a safety point of view is nevertheless annoying and has acted as a deterrent in some cases toward the application of metal- metalli brake linings in pleasure vehicles We have found that cold pedal conditions may be greatly lessened by utilizing a specific combination of elements in the braking system Thus when using a ferrous metal brake lining such as is disclosed for ex ample in Patent 2,945,291 we have found that the coid pedal effects are greatly lessened if a brake drum surface formed from steel substantially free from ferrite is used in combination therewith Most automotive vehicles made today utilize gray cast iron brake drums The combination of the metallic Ining with the aforementioned steel drum reduces the cold pedal eflect in the order of 25 whereby much better and more uniform operation is obtained from the braking system A typical cold pedal test procedure is as follows the linings and drums are conditioned by making ten stops at mile intervals each from 40 miles per hour at a dece eration rate of 10 ft./sec The vehicle is then parked for a minimum of two bours The cold pedal is then evaluated by making ten stops at 12 mile intervals from 40 mic per hour at a desceration rate of to ft s wherein the initial and final line prestures required to maintain the specific discioration is recorded thro cach stop t Using brake linings as disclosed in the aforementiaoforenmenteione 25 25 patent with a standard cast iron drum condition g 15 tenth stop of the schedule required 270 psi tu praties the desired deceleration After the car was parked for the two hour rest penod from o forward stop the first check stop after the cooling off passed required an int line pros 67 320 p.~ .i. which ma be termed tr cold fete id eftness If the cat pi ba 1 ing off period from a reverse shop then quired initial line pressure of 355 pou termed cold reverse effectiveness effectiveness the car is parked with he ea aes atm This m slup before before ae - the coching period and a controlled reverse stop is made before the first check stop the first check top requires an initial line pressure of 385 pas The tz also call 2 the colflreverse effectiveness effectiveness 40 It will be notes that the 10 pressure increase to effici effect a specific deceleration 10 stop is the sonic sonic to effect LI if the immediate previous stop was a reverse stop whither the reverse stop was before et inter the cooling of penel Thus the difference between wor The effecten at 270 p.s.i. and cold reverse effecteness effecteness at 295 post f. 115 psi This difference will to dcted dcted by the drivi ard is known as harden pude 1 occur porn porn driving when driver backs out of a parking spate an then is requicu to make a fors ud stop | The change i 20 output is noted regardless of the cut spoed Th sme scheduled test were made using drums formed from SAE 1080 steel with all other condi identical In this instance the worm effectiveness dropp - to 215 p.s.i the cold forward effectiveness to 230 pri 55 55 and the cold reverse effectiveness to 250 pisi Thus the steel drum narrowed the difference between the wath stop and the cold reverse stop to 35 p.s.i. over the 115 p.s.i. required when using a gray cast iron drum In addition to the improved brake characteristics staci 60 has greatly improved tensile strength over the usu grap cast iron as is well known Further when substantially free from ferrite the steel has reduced scoring tendencie This is a very important consideration since free for such as is formed in SAF 1010 steel produces marked 05 05 scoring 1 'ndenciesand is not us ful in braking applications Steel offers another benefit that is commercially im portant namely due to the increased strength over gray cast iron the drums may be made conside lighter with decreased wall thickness without sacrificing rega de 77195 77195 It should be understood that similar resik can be obtained using cast iron druny lined with the desire steel surface Thus when th term drum is used herein 8,184,001 4 the term is sufficiently broad to include any combination providing the braking surface is substantially free from ferrite In place of SAE 1080 or 1085 steel any other steel which has a structure substantially free from fertile is useful for example SAE 8660 9260 Alloy steels or energy absorption over a wide range of operating temperatures 2. A torque transmitting device comprising a sintered ferrous facing and a mating surface consisting of steck substantially free from ferrite 3. A brake for use in an automotive vehicle and the of this character may also be used where specific physical like comprising in combination a sintered ferrous brake characteristics are desired which may be obtained from lining and a braking surface cooperating with said lining the alloy said braking surface consisting of steel substantially free In general sintered ferrous linings and facings hav 10 from ferrite whereby the combination of the sintered fer- ing a sintered ferrous base and including graphite in quan- tities above 10 with or without known friction fortifying and modifying materials may be used effec- rous lining and the said steel braking surface effect uniform braking conditions over a wide range of operating temperatu tively in the combination 4. A brake for use in an automotive vehicle and the Any steel drum having a metallographic structure sub- 15 like comprising in combination a sintered ferrous brake stantially free from ferrite when used in combination with a sintered ferrous brake lining material will offer im- lining and a brake drum for use as a rubbing surface against said lining said drum having a contacting surface proved operational characteristics particulmily in the cold pedal range Such improvements are easily noticeable consisting of steel substantially free from ferrite whereby the combination of the sintered ferrous lining and the said by the operator of the vehicle and lessen the difference in steel braking surface effect uniform braking conditions pedal pressures required to bring a car to a stop under any over a wide range of operating temperatures given set of conditions 5. A brake for use in an automotive vehicle and the It to be understood that the principles involved are like comprising in combination 4 sintered ferrous brake equally applicable to disc brakes drum brakes clutches and or other torque transmitting and or energy absorb absorb Jining and a braking surface cooperating with said lining said braking surface consisting of SAE 1080 steel sub- ing devices wherein sliding or rubbing engagenient engagenient occurs stantially free from ferrite whereby the combination of between between the several element of the structure While the embodiments of the present invention as heroin disclosed constitute preferred forms it is to be said sintered brake lining and said SAE 1080 steel braking surface effect uniform braking conditions over a wide range of operating conditions understood that other forms might be adopted What chumed is as follows References Cited by the Examiner 1. A torque transmitting and energy absorbing device UNITED STATES PATENTS ( prising in combination a driving and a driven miniber wherein one of sad members comprises a sintered for- rous surface and wherein the other of said members con- sist of a steel surface substantially free from ferrite whereby the combination of the sintered ferrous surface and the 900.804 2,097.125 2,097.125 2.945.291 3/33 10/37 7/60 Crowe _-_ 22-2. 188-218 Le Jeune ee 22-2 188-218 Ankeny et al -----2.- 29-1823 29-1823 ARTHUR L. LA POINT Primary Examiner said stool surface effect uniform torque transmission and / EUGENE G. BOTZ Examiner May 18 1965 E. W. REINSCH ETAL BRAKE DRUM AND LINING Filed Aug. 16 1962 3,184,001 INVENTORS Earl W Reinsch BY Gene P Boynes -- Their Attorney