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NOTE: Information in this section is not all inclusive and is subject to change due to law
changes. For the latest information refer to the current CDL Manual for the state you live in.
changes. For the latest information refer to the current CDL Manual for the state you live in.
Pre Trip Inspection Brake Check
Parking Brake Check (Pre Trip Inspection)
Hydraulic Brake Check (Pre Trip Inspection)
Air Brake Check (air brake equipped vehicles only) (Pre Trip Inspection)
Air brake safety devices vary. However, this procedure is designed to see that any safety device
operates correctly as air pressure drops from normal to a low air condition. For safety purposes, in
areas where an incline is present, you will need to use wheel chocks during the air brake check.
The proper procedures for inspecting the air brake system are as follows:
Test Air Leakage Rate (Static check) (Pre Trip Inspection)
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. 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.
Test Air Brake System for Leaks (Pre Trip Inspection)
With parking brake, (all vehicles) and trailer air supply button (for combination vehicles) released
(pushed in), apply firm pressure to the service brake pedal. Watch the air supply gauge and listen
for leaks. 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. If the air loss
rate exceeds these figures, have the air system repaired before operating.
Test Low Pressure Warning Alarm and/or Signal (Pre Trip Inspection)
Turn the key to the on position. Rapidly apply and release the service brake pedal to reduce air
tank pressure. The low air pressure warning signal must come on before the pressure drops to
less than 60 psi in the air tank. If the warning alarm/signal doesn’t work, you could be losing air
pressure without knowing it. This could cause the spring brakes to activate suddenly. Only limited
braking can be done before the spring brakes come on.
Check That the Spring Brakes Come on Automatically.
Continue to rapidly apply and release the service brake pedal to further reduce air tank pressure.
The trailer air supply button (if it is a combination vehicle) and parking brake button should pop out
when the air pressure falls to the manufacturer’s specification (usually between 20 to 40 psi). This
causes the spring brakes to come on.
Check Rate of Air Pressure Buildup (Pre Trip Inspection)
When the engine is operating at 1800 RPM, the pressure should build from 85 to 100 psi within 45
seconds in dual air systems. (If the vehicle has larger than minimum air tanks, the buildup time
can be longer and still be safe. Check the manufacturer’s specifications.) If air pressure does not
build up fast enough, your pressure may drop too low during driving, requiring an emergency stop.
Don’t drive until you get the problem fixed.
Test Service Brakes (Pre Trip Inspection)
Wait for normal air pressure, release the parking brake and trailer air supply button
(for combination vehicles), move the vehicle forward slowly (about 5 mph), and apply the brakes
firmly using the brake pedal. Note any vehicle “pulling” to one side, unusual feel, or delayed
stopping action. This test may show you problems which you otherwise wouldn’t know about until
you needed the brakes on the road.
Parking Brake Check (Pre Trip Inspection)
- Apply parking brake only and make sure it will hold the vehicle by shifting into a lower gear
and gently pulling against the brake.
Hydraulic Brake Check (Pre Trip Inspection)
- With the engine running, apply firm pressure to the service (foot) brake pedal and hold for
five seconds. The brake pedal should not move (depress) during the five seconds. - 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. - Check that the warning buzzer and/or light is off.
- Check the service (foot) brake operation by moving the vehicle forward slowly (about 5 mph)
and apply the brake firmly. Note any vehicle “pulling” to one side, unusual feel or delayed
stopping action.
Air Brake Check (air brake equipped vehicles only) (Pre Trip Inspection)
Air brake safety devices vary. However, this procedure is designed to see that any safety device
operates correctly as air pressure drops from normal to a low air condition. For safety purposes, in
areas where an incline is present, you will need to use wheel chocks during the air brake check.
The proper procedures for inspecting the air brake system are as follows:
Test Air Leakage Rate (Static check) (Pre Trip Inspection)
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. 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.
Test Air Brake System for Leaks (Pre Trip Inspection)
With parking brake, (all vehicles) and trailer air supply button (for combination vehicles) released
(pushed in), apply firm pressure to the service brake pedal. Watch the air supply gauge and listen
for leaks. 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. If the air loss
rate exceeds these figures, have the air system repaired before operating.
Test Low Pressure Warning Alarm and/or Signal (Pre Trip Inspection)
Turn the key to the on position. Rapidly apply and release the service brake pedal to reduce air
tank pressure. The low air pressure warning signal must come on before the pressure drops to
less than 60 psi in the air tank. If the warning alarm/signal doesn’t work, you could be losing air
pressure without knowing it. This could cause the spring brakes to activate suddenly. Only limited
braking can be done before the spring brakes come on.
Check That the Spring Brakes Come on Automatically.
Continue to rapidly apply and release the service brake pedal to further reduce air tank pressure.
The trailer air supply button (if it is a combination vehicle) and parking brake button should pop out
when the air pressure falls to the manufacturer’s specification (usually between 20 to 40 psi). This
causes the spring brakes to come on.
Check Rate of Air Pressure Buildup (Pre Trip Inspection)
When the engine is operating at 1800 RPM, the pressure should build from 85 to 100 psi within 45
seconds in dual air systems. (If the vehicle has larger than minimum air tanks, the buildup time
can be longer and still be safe. Check the manufacturer’s specifications.) If air pressure does not
build up fast enough, your pressure may drop too low during driving, requiring an emergency stop.
Don’t drive until you get the problem fixed.
Test Service Brakes (Pre Trip Inspection)
Wait for normal air pressure, release the parking brake and trailer air supply button
(for combination vehicles), move the vehicle forward slowly (about 5 mph), and apply the brakes
firmly using the brake pedal. Note any vehicle “pulling” to one side, unusual feel, or delayed
stopping action. This test may show you problems which you otherwise wouldn’t know about until
you needed the brakes on the road.
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| Commercial Drivers License (CDL) Pre-Trip Inspection: Brake Check |
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| Pre-Trip Inspection Engine Compartment Cab Check/Engine Start Brake Check External Cab Trailer Double/Triple Trailers Tank Vehicle Coach/Transit Bus |
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