CDL AIR BRAKE PRACTICE TEST
COMPREHENSIVE TEST PAPER 2026
COMPLETE ANSWERS ACCURATE
⫸ When should you drain the air tanks? Answer: After every working
day.
⫸ Why drain water from the compressed air tanks? Answer: Water can
freeze in cold weather and cause brake failure.
⫸ Air brake equipped vehicles must have: Answer: A supply pressure
gauge and warning signal when psi drops below 60.
⫸ What can legally hold a parking or emergency brake in position for a
truck, truck tractor or bus? Answer: Spring pressure.
⫸ What makes the total stopping distance for air brakes longer than that
for hydraulic brakes? Answer: Brake lag distance.
⫸ The first thing you should do when the low air pressure warning
comes on? Answer: Stop and safely park ASAP.
⫸ The braking power of the spring brakes: Answer: Depends on the
adjustment of the service brakes.
, ⫸ The air compressor governor controls what? Answer: When air is
pumped into the air tanks.
⫸ The application pressure gauge shows the driver how much pressure:
Answer: Is being applied to the brakes.
⫸ When you apply pressure to the brake pedal, you are... Answer:
Pushing against a spring and against air pressure to the brakes.
⫸ The air compressor is connected to the engine through... Answer:
Gears or a V-belt
⫸ Which type of brake is the most common in commercial vehicles?
Answer: S-cam brake
⫸ An application pressure gauge... Answer: Shows how much air
pressure you are applying to the brakes.
⫸ All vehicles with air brakes are required to have a low pressure
warning signal. This could be... Answer: A red light, wig wag
mechanical arm or a buzzer.
⫸ To test service brakes you should... Answer: Release the parking
brake, move forward slowly and depress brakes.
COMPREHENSIVE TEST PAPER 2026
COMPLETE ANSWERS ACCURATE
⫸ When should you drain the air tanks? Answer: After every working
day.
⫸ Why drain water from the compressed air tanks? Answer: Water can
freeze in cold weather and cause brake failure.
⫸ Air brake equipped vehicles must have: Answer: A supply pressure
gauge and warning signal when psi drops below 60.
⫸ What can legally hold a parking or emergency brake in position for a
truck, truck tractor or bus? Answer: Spring pressure.
⫸ What makes the total stopping distance for air brakes longer than that
for hydraulic brakes? Answer: Brake lag distance.
⫸ The first thing you should do when the low air pressure warning
comes on? Answer: Stop and safely park ASAP.
⫸ The braking power of the spring brakes: Answer: Depends on the
adjustment of the service brakes.
, ⫸ The air compressor governor controls what? Answer: When air is
pumped into the air tanks.
⫸ The application pressure gauge shows the driver how much pressure:
Answer: Is being applied to the brakes.
⫸ When you apply pressure to the brake pedal, you are... Answer:
Pushing against a spring and against air pressure to the brakes.
⫸ The air compressor is connected to the engine through... Answer:
Gears or a V-belt
⫸ Which type of brake is the most common in commercial vehicles?
Answer: S-cam brake
⫸ An application pressure gauge... Answer: Shows how much air
pressure you are applying to the brakes.
⫸ All vehicles with air brakes are required to have a low pressure
warning signal. This could be... Answer: A red light, wig wag
mechanical arm or a buzzer.
⫸ To test service brakes you should... Answer: Release the parking
brake, move forward slowly and depress brakes.
