Brake Performance

PURPOSE: This rule describes the procedures and standards for the inspection of brake performance. The inspection of brakes is a requirement of section 307.365, RSMo. (1) A brake performance test shall be performed by an inspector/ mechanic on all single unit motor vehicles equipped with mechanical, hydraulic, or power assisted hydraulic service brakes. The brake performance test may be conducted by using any one (1) of the following procedures: a decelerometer test, a drive and stop test, a brake testing machine, or a dynamometer test. The selected test shall be conducted on the inspection station premises. (A) Decelerometer Test. Mount and level decelerometer on vehicle. At a speed of five to twenty miles per hour (5–20 mph) apply service brake firmly. Observe decelerometer reading. 1. Reject vehicle if— A. The vehicle is unable to develop deceleration equal to or greater than that listed for its classification as prescribed in Table I. (B) Drive and Stop Test. The inspector/mechanic shall operate the vehicle at a speed of five to twenty (5–20) mph and apply the service brakes firmly. In lieu of operating a commercial vehicle presented for inspection, the inspector/mechanic may observe the drive and stop test as it is performed by the presenter. 1. Reject vehicle if— A. The vehicle’s brakes fail to function or if the vehicle pulls significantly to either side. (C) Brake Testing Machine. Drive vehicle onto brake testing machine. Apply brakes firmly at a speed from four to eight (4–8) mph without wheel lock-up. If a computerized brake testing machine is utilized, a copy of the results will be provided to the vehicle owner. 1. Reject vehicle if— A. The vehicle is not capable of developing evaluated braking force equal to or greater than that shown for its classification as prescribed in Table I. At least three (3) tests should be made before a vehicle is rejected; B. Any wheel fails to indicate braking action; C. The reading on any one (1) wheel is less than seventyfive percent (75%) of the reading on the other wheel on the same axle; or D. The braking force of both wheels on one (1) axle is more than seventy-five percent (75%) of the total force of all the wheels. (D) Dynamometer Test. Test in accordance with the manufacturer’s instructions. Table I Braking Force as a Percentage Deceleration Classification of Gross Vehicle in Feet Per of Vehicles or Combination Second Passenger vehicles with a seating capacity of 10 people or less including driver, not having a manufacturer’s Gross Vehicle Weight Rating 52.8% 17 Single unit vehicles with a manufacturer’s Gross Vehicle Weight Rating of 10,000 pounds or less 43.5% 14 Single unit vehicles with a manufacturer’s gross weight rating of more than 10,000 pounds 43.5% 14 AUTHORITY: section 307.360, RSMo 2016.* Original rule filed Nov. 4, 1968, effective Nov. 14, 1968. Amended: Filed Dec. 5, 1969, effective Dec. 15, 1969. Amended: Filed March 9, 1970, effective March 19, 1970. Amended: Filed Nov. 9, 1971, effective Nov. 19, 1971. Amended: Filed May 21, 1974, effective May 31, 1974. Amended: Filed Dec. 1, 1975, effective Dec. 11, 1975. Amended: Filed Aug. 16, 1979, effective Nov. 11, 1979. Amended: Filed March 15, 1999, effective Sept. 30, 1999. Emergency amendment filed Feb. 1, 2000, effective July 1, 2000, expired Dec. 27, 2000. Amended: Filed Feb. 1, 2000, effective July 30, 2000. Amended: Filed Nov. 1, 2001, effective April 30, 2002. Amended: Filed March 16, 2022, effective Oct. 30, 2022. *Original authority: 307.360, RSMo 1967, amended 1971, 1973, 1979, 1999.