This SAE Recommended Practice provides the test procedure and instructions for air braked single unit trucks, buses, and combination vehicles. It also provides recommendations for: a. Instrumentation and equipment b. Vehicle preparation c. Calculating distribution of brake force This procedure provides a method to determine the brake force distribution and threshold pressures for trucks and buses with a GVWR greater than 4536 kg (10 000 lb).
New stopping distance regulations will require a shift in brake force distribution. In addition, new types of brakes such as air disc have different pressure onset and torque output characteristics that can effect low pressure brake force distribution. This procedure therefore will become a more important tool for measuring and comparing brake force distribution on trucks and buses. Experience with the original procedure has shown that test organizations using it would benefit from changes in data recording and safety procedures.