This SAE Recommended Practice provides a field test procedure and instructions for air braked single unit trucks, buses, and combination vehicles. Brake force distribution field testing with systems post-reduce stopping distance changes is still appropriate, however, vehicles with electronically controlled braking systems are not covered in this document and may need to be addressed in the future. It also provides recommendations for:

a Instrumentation and equipment.
b Vehicle preparation.
c Test of air-braked single and combination vehicles.
d Calculation of brake force distribution.
e This test procedure is intended to be used as a field procedure. If a more refined method, utilizing laboratory equipment, is required, refer to SAE J1505.