Truck and Bus Brake System Performance Requirements (SAE J992) 680175
The new SAE J992 establishes minimum service brake system performance requirements and specifically pertains to vehicle stopping ability, pedal force requirements, and brake stability of new vehicles. Testing for SAE J992 includes procedures that were taken from applicable sections of the truck and brake system road test code, SAE J786 dated 1962.
This paper compares SAE J992 and J786 in the areas of test instrumentation, preburnish check, burnish, water recovery, and efffectiveness requirements. Although SAE J992 is briefer than previous test procedures, it is a valid determination of minimum stopping ability, a check on the initial fade due to heat, and a measurement of the water recovery characteristic. The minimum performance values specified are quite stringent for all types of trucks and buses.