CDL AIR BRAKE PRACTICE TEST FINAL
STUDY GUIDE 2026 SOLVED QUESTIONS
FULLY CORRECT
⫸ The driver must be able to see a low air pressure warning which
comes on before pressure in the service air tanks falls below ____ psi
Answer: 60
⫸ If your vehicle has an alcohol evaporator, every day during cold
weather you should: Answer: Check and fill the alcohol level
⫸ All air brakes equipped vehicles have: Answer: A supply pressure
gauge
⫸ The most common type of foundation brake found on heavy vehicles
is the: Answer: S-cam drum
⫸ Modern air brakes combine three different systems. They are the
service, the parking, and the ___ brakes. Answer: Emergency
⫸ To check the free play of manual slack adjusters of s-cam brakes, you
should park on: Answer: Level ground, chock the wheels and release
parking breaks
, ⫸ Why should you drain water from compressed air tanks? Answer:
Water can freeze in cold weather and cause brake failure
⫸ The spring brakes used on the chambers in a straight truck will bring
you to a stop when air pressure drops below____ psi Answer: 20
⫸ With air brake vehicles, the parking brake should be used: Answer:
Whenever you leave the vehicle unattended
⫸ The safety valve is set automatically when pressure is Answer: 150
⫸ Repeatedly partially increasing and pressing the brake pedal may
result in: Answer: A loss of air brake pressure
⫸ If your truck has dual air brake system, and one of the systems loses
its pressure, what will happen? Answer: Either the front or rear brakes
will not be fully functional
⫸ If you must make an emergency stop, you should brake so you:
Answer: Can steer and so your vehicle stays in a straight line
⫸ The air loss rate for a straight truck or bus with the engine off and the
brakes on should not be more than: Answer: 3 psi in one minute
⫸ You brakes are fading when: Answer: You have to push harder on a
brake pedal to control your speed on a downgrade
STUDY GUIDE 2026 SOLVED QUESTIONS
FULLY CORRECT
⫸ The driver must be able to see a low air pressure warning which
comes on before pressure in the service air tanks falls below ____ psi
Answer: 60
⫸ If your vehicle has an alcohol evaporator, every day during cold
weather you should: Answer: Check and fill the alcohol level
⫸ All air brakes equipped vehicles have: Answer: A supply pressure
gauge
⫸ The most common type of foundation brake found on heavy vehicles
is the: Answer: S-cam drum
⫸ Modern air brakes combine three different systems. They are the
service, the parking, and the ___ brakes. Answer: Emergency
⫸ To check the free play of manual slack adjusters of s-cam brakes, you
should park on: Answer: Level ground, chock the wheels and release
parking breaks
, ⫸ Why should you drain water from compressed air tanks? Answer:
Water can freeze in cold weather and cause brake failure
⫸ The spring brakes used on the chambers in a straight truck will bring
you to a stop when air pressure drops below____ psi Answer: 20
⫸ With air brake vehicles, the parking brake should be used: Answer:
Whenever you leave the vehicle unattended
⫸ The safety valve is set automatically when pressure is Answer: 150
⫸ Repeatedly partially increasing and pressing the brake pedal may
result in: Answer: A loss of air brake pressure
⫸ If your truck has dual air brake system, and one of the systems loses
its pressure, what will happen? Answer: Either the front or rear brakes
will not be fully functional
⫸ If you must make an emergency stop, you should brake so you:
Answer: Can steer and so your vehicle stays in a straight line
⫸ The air loss rate for a straight truck or bus with the engine off and the
brakes on should not be more than: Answer: 3 psi in one minute
⫸ You brakes are fading when: Answer: You have to push harder on a
brake pedal to control your speed on a downgrade
