Check That the Spring Brakes Come on Automatically.Ĭontinue to rapidly apply and release the service brake pedal to further reduce air tank pressure. Only limited braking can be done before the spring brakes come on. This could cause the spring brakes to activate suddenly. If the warning alarm/signal doesn’t work, you could be losing air pressure without knowing it. The low air pressure warning signal must come on before the pressure drops to less than 60 psi in the air tank.

Rapidly apply and release the service brake pedal to reduce air tank pressure. Test Low Pressure Warning Alarm and/or Signal If the air loss rate exceeds these figures, have the air system repaired before operating. After the initial pressure drop, the loss rate for single vehicles should be no more than 3 psi in one minute and no more than 4 psi in one minute for combination vehicles.

Watch the air supply gauge and listen for leaks.

With parking brake, (all vehicles) and trailer air supply button (for combination vehicles) released (pushed in), apply firm pressure to the service brake pedal. After the initial pressure drop, the loss rate should be no more than 2 psi in one minute for single vehicles and no more than 3 psi in one minute for combination vehicles. With a fully-charged air system (typically 120 psi), turn off the engine, chock the wheels, release (push in) the parking brake button (all vehicles) and trailer air supply button (for combination vehicles) and time the air pressure drop. The proper procedures for inspecting the air brake system are as follows: Test Air Leakage Rate (Static check) For safety purposes, in areas where an incline is present, you will need to use wheel chocks during the air brake check. However, this procedure is designed to see that any safety device operates correctly as air pressure drops from normal to a low air condition. Note any vehicle “pulling” to one side, unusual feel or delayed stopping action.Īir Brake Check (air brake equipped vehicles only)Īir brake safety devices vary.

Check the service (foot) brake operation by moving the vehicle forward slowly (about 5 mph) and apply the brake firmly.

Check that the warning buzzer and/or light is off.

If equipped with a hydraulic brake reserve (backup) system, with the key off, depress the brake pedal and listen for the sound of the reserve system electric motor.

The brake pedal should not move (depress) during the five seconds.

With the engine running, apply firm pressure to the service (foot) brake pedal and hold for five seconds.

Apply parking brake only and make sure it will hold the vehicle by shifting into a lower gear and gently pulling against the brake.

The following is a list of items and components that must be checked by the driver during the CDL pre trip inspection: brake check.

California air brake test