This SAE Recommended Practice establishes a method of testing the structural integrity of the brake system of all new trucks, buses, and combination vehicles designed for roadway use and falling in the following classifications: aTruck and Bus—Over 4500 kg (10 000 lb) GVWR bCombination vehicle—Towing vehicle over 4500 kg (10 000 lb) GVWR The test consists of two distinct tests: a Structural Endurance Test followed by a Structural Ultimate Strength Test.