ORGANIC-TYPE BRAKE LININGS FREE OF ASBESTOS

Abstract: An organic-type brake lining (20) is provided com­ posed of carbonaceous material and metallic powders. The use of asbestos in the organic-type brake lining is eliminated without significant alteration of properties. The physical and chemical characteristics and properties of asbestos have been replaced by similar percentages of carbonaceous material, such that the comparative test­ ing demonstrates improved properties for the organic-type brake lining (20), from which asbestos has been elimi­ nated.

Description: BACKGROUND OF THE INVENTION This invention relates to the composition of organic-type brake linings and the improved properties resulting from the elimination of asbestos as a component thereof. Heretofore, for the past several decades, the organic-type brake lining has included asbestos for its heat resistant and fibrous properties. Organic-type brake linings as distinguished from carbon or metallic brake disks or linings traditionally included asbestos, metallic powders and various resins, fillers, and abrasive particles to provide satisfactory wear resistance while also providing adequate frictional characteristics for the intended use of the lining in brake surfaces, clutch surfaces, and other analogous requirements known to those skilled in the art. Within-the last-decade, it has become increasingly clear that the use of asbestos in manufacturing and production, as well as for its intended use, has been increasingly recognized as a detriment to the health of human beings. Asbestos has been characterized as a carcinogenic material, and the type and size of fibers are a major source of concern to industry and consumers. Increasingly, the use of asbestos has been restricted, and significant precautionary steps must be taken to prevent-its carcinogenic properties from affecting the personnel of manufacturers and the consumers like. Governmental regulations have limited the use of asbestos in a wide variety of applications. By definition, asbestos is characterized as the fibrous form of actinolite, composed of fibrous magnesium or calcium silicate-. Because the art of organic-type brake surface linings has traditionally relied upon asbestos as a necessary component, and because asbestos is recognized as a dangerous compound to the health of human beings, it is necessary to find a composition for the organic-type brake linings which maintains or improves the properties of the linings while eliminating the asbestos material therefrom. 0 OBJECTS OF THE INVENTION Consequently, it is an object of the invention to provide an organic-type brake lining having eliminated asbestos, a previously significant component now recognized as a carcinogen. :#It is another object of the invention to provide an organic-type brake lining as above, where the substituted materials for asbestos provide comparable or improved wear resistant and frictional properties. Yet another object of the invention is to provide an organic brake type lining, as above, wherein the composition may replace traditional organic-type brake disk linings in frictional lining applications. These and other objects of the invention, which will become more apparent as the detailed description of the preferred embodiment proceeds, are achieved by a brake lining of the organic type, comprising: a composite wear resistant pad, said pad having a composition of carbonaceous material and metallic powders integrally admixed therein. DESCRIPTION OF THE DRAWINGS For an appreciation of the use of the organic-type brake disk lining of this invention, reference is had to the following drawing, wherein: The figure is a cross-sectional view of braking surface module showing the brake lining of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For an understanding of the preferred application the organic-type brak lining of the present invention, reference is had to the figure. A braking surface module, generally shown as 10, is mounted on stationary member 30 by methods such as rivets, adhesives, welding and the like, known to those skilled in the art. Module 10 is designed as a stationary unit to contact an opposing rotating frictional brake disk 40. The braking surface module 10 and disk 40 may exist in pairs, or in a brake disk stack known to those skilled in the art. Braking surface module 10 is composed of housing 12 and organic type brake lining 20 'of the present invention, in the form of a wear-resistant pad used to contact the opposing frictional brake disks. The application of the composition of the organic-type brake linings is not limited to brake disk art, but may be used for clutch surfaces, or any other application known to those skilled in the art deptanding significant wear resistance and frictional properties. The composition of the organic-type brake disk lining 20 of the present invention is a radical departure from the traditional organic type brake lining. As described above the organic type brake lining has traditionaliv been formed from a combination of asbestos with other materials typically metallic powders, resins, filler and abrasive particles. Brake lining 20 of the present invention eliminates asbestos as a material component,for the health and safety reasons described above without a loss of performance properties. The traditional organic-type brake lining composition was typically about 40 percent of asbestos, about 25 percent of metallic powders, and about 35 percent of conventional resins, conventional fillers, and conventional abrasive particles. The organic-type brake lining 20 of the present invention has carbonaceous material integrally admixed therein from about 10 percent to about 80 percent of the entire lining composi-tion. Preferably, the carbonaceous material comprises about 40 percent of the lining composition. Furthermore, the organic-type brake lining of the present invention has metallic powders comprising from about 10 percent to about 70 percent of the lining composition. Preferably, the metallic powders comprise about 25 percent of the composition of lining 20. Finally, the conven tional materials of lining 20 are resins, fillers, and abrasive particles comprising from about 10 to about 50 percent of the lining composition. Conventional resins typically include furan resins and phenolic resins. Typical fillers known to those in the art include calcium carbonate and clay. Conventional abrasive particles are silicon carbide and aluminum oxide. These conventional materials are well known to those skilled in the art, and the area of the invention does not relate to preferences of composition and concentration therewithin. The carbonaceous material of the present invention may include, graphite, carbon fiber, coat tar pitch chars, oil pitch chars, resin chars, or any bulk carbon or particulate carbon along or in combination with other carbonaceous material, capable of being combined pyrolized and into a wear resistant material having frictional properties. The metallic powders of the present invention may be elemental metals or alloys and may include bronze, iron, copper, zinc, and tin. It is apparent from the figure that lining 20 is composed of materials integrally admixed therein. The carbonaceous material, metallic powders, resins, fillers, and abrasive particles are mixed and sintered according to procedures well known to those skilled in the art. The entire thickness of lining 20 is bereft of incongruities. To determine whether the composition of the present invention has successfully replaced the traditional composition of organic-type brake lining having asbestos, "50 stop" brake disk tests were conducted, with the only deviation being the substitution of asbestos in the composition of the traditional brake lining with carbonaceous material in the preferred composition of the brake lining of the present invention. Table I summarizes the results of this brake test comparison. TABLE I BRAKE TEST SUMMARY 50 STOP TEST TRADITIONAL ORGANIC ORGANIC BPAKE BRAKE LINING CON- LINING WITHOUT TAINING ASBESTOS ASBESTOS KINETIC ENERGY 827,805 ft.lbs. 827,805 ft.lbs'. TEMPERATURE RISE 7860 F. 8650 F. BRAKE PRESSURE 467 lbs./in.2 494 lbs./in.2 STOP TIME 12.75 secs. 12.7 secs. COEFFICIENT ,291 .287 TORQUE 752 722 PEAK TORQUE 1160 1210 TOTAL LINING WT. LOSS .10 lbs. .07938 Ibs. TOTAL LINING WEAR .3995 in. .2667 in. WEAR/FACE/STOP .00133 in. .00088# in. DISK WT. LOSS .07 libs. .0227 Ibis. DISK THICKNESS LOSS ' .0060 in. .00025 in. It is apparent from the comparison of the traditional organic brake lining and the brake lining of the present invention that the elimination of asbestos does not impair the physical and chemical properties of the lining While the stop time remained virtually identical, and the coefficient was very similar, the organic brake lining of the present invention unexpectedly improved the wear characteristics, reducing wear as seen by comparison of total lining wear, total lining weight loss, wear/face/stop, disk weight loss and disk thickness loss. Therefore, it is apparent that the organic brake disk lining of the present invention is synonymous with, or superior to, the traditional organic brake linings containing asbestos. The elimination of asbestos does not materially affect the performance of the organic brake linings, but removes a component serious to the health and safety of human beings. The fibrous nature of asbestos is difficult to control both during manufacture and lining wear during use. The elimination of asbestos eliminates the detrimental health conditions of production or use of the traditional organic linings in closed environments. While the "50 stop" test compares lining compositions, it was also determined that, against lining 20 of the present invention, the opposing frictional brake disk 40 had improved wear life with no degradation in other performance characteristics. Therefore improved overall braking performance is achieved bv linings 20 having the comp#si- tion of the present invention. while in accordance with the patent statutes, the best mode of the invention has been disclosed. It is understood that the invention is not to be limited thereto or thereby. Consequently, for--#comp1ete understanding of the scope of the invention, reference is had to the following claims. WHAT IS CLAIMED IS:

Claims: 1. A brake disc lining of the organic type, comprising: a composite wear-resistant pad, said pad having a composition of carbonaceous material and metallic powders integrally admixed therein 2. A brake disc lining of the organic type, according to Claim 1, wnerein said carbon ceous material is selected from the group consisting of graphite, carbon fiber, coal tar pitch char, oil pitch char, bulk carbon, particulate carbon, resin char, and combinations thereof. 3. A brake disc lining of the organic type, according to Claim 1, wherein said metallic powders are elemental metals or alloys selected fromXthe group consisting of iron, copper, tin, zinc, bronze, and combinations thereof. 4. A brake disc lining of the organic type, according to Claim 1, wherein said carbonaceous material comprises from about 10 percent to about 80 percent by weight of said pad composition. 5. A brake disc lining of the organic type, according to Claim 4, wherein said carbonaceous material comprises about 40 percent by weight of said pad composition. 6. A brake disk lining of the organic type, according to Claim 1, wherein said metallic powders comprises from about 10 to about 70 percent by weight of said pad composition. 7. A brake disc lining of the organic type, according to Claim 6, wherein said metallic powders comprise about 25 percent by weight of said pad composition. 8. An improvement to frictional linings of the organic type hereinbefore typically comprising asbestos, wherein the improvement comprises a lining having carbonaceous material in substitution for the asbestos. 9. An improvment to frictional linings of the organic type, according to Claim 8, wherein said carbonaceous material is selected from the group consisting of graphite, carbon fiber, coal tar pitch char, oil pitch char, bulk carbon, particulate carbon, resin char, and combinations thereof: and wherein said carbonaceous material comprises from about 10 percent to about 80 percent by weight of the lining composition. 10. An improvement to frictional linings of the organic type, according to Claim 9, wherein said carbonaceous material comprises about 40 percent by weight of the lining composition.

Inventors: MIANOWSKI, HENRY STANLEY, NELSON, JOHN PAUL
Applicants: GOODYEAR AEROSPACE CORPORATION
Application year: 1981
Main classification: F16D69
IPC codes: C09K3, F16D69