J840_200708 Test Procedures for Shear Strength of Automotive Brake Pads and Brake Lining Assemblies

The title for this Recommended Practice has been updated to better reflect the purpose of the test, the characteristic measured (shear strength), and the specific parts where it is applicable (automotive brake pads and brake lining assemblies). The new title also facilitates internet searches, and improves the procedure description when referenced on external documents or technical specifications. Testing a drum brake shoe or a disc brake pad assembly for its shear strength is a valuable parameter during the life-cycle of a brake assembly. All friction brake assemblies have a shear loading equivalent in magnitude to the braking force that depends upon the load input perpendicular to the friction surface, the brake geometry, and the friction coefficient at the transfer layer interface. Regular braking operation also generates heat that migrates through the friction material to the backing plate or shoe rim surface. It is critical for the friction designer, the product engineer, the process manager, application engineer, or purchasing agents, to understand the shear strength and the main influencing factors that will ultimately determine the amount of shear load that the material will withstand without a mechanical failure of the assembly. This revision of the Recommended Practice increases the level of harmonization with other industry standards, allows the testing of mechanical retention systems (MRS), includes the option of testing with the movable ram at constant speed, allows the use of coupons, and improves the repeatability of the test results by introducing the application of a side load for disc brake pads.