Free CDL Air Brakes Endorsement II Practice Test Questions

1. What is a dual air brake system?
  1. A two brake system, one operates the front brakes and one operates the back brakes. 
  2. A two braking system, one for each side of the vehicle. 
  3. A two braking system, one for daytime and one for nighttime driving.
2. What are the slack adjusters?
  1. It is the space between the back wheels. 
  2. It is an adjusting nut on the backside of the brake drum used for adjusting the brakes. 
  3. It is an adjusting nut under the cab to adjust the springs.
3. How can you check the slack adjuster?
  1. Park on level ground, turn off parking brakes, pull hard on each slack adjuster. It shouldn’t move more than one inch. 
  2. Park on level ground, turn off parking brake and press brake pedal. 
  3. Park on an incline and see if the vehicle rolls.
4. How can you test the low pressure warning signal?
  1. While the engine is running, step on and off the brake pedal. 
  2. Shut off the engine and see if the air pressure leaks down. 
  3. Shut off the engine with enough air pressure, turn on the electrical power and step on and off the brake pedal until the low air pressure warning signal comes on.
5. What can you check to see if the spring brakes come on automatically?
  1. Step on and off the brake, with the engine off, the parking brake knob should pop out when air pressure falls between 20-40 psi. 
  2. Get under the vehicle and pull on the spring brakes. 
  3. Turn on the engine and pump the brake pedal down to the floor.
6. What are the maximum leakage rates?
  1. Less than four psi in one minute for single vehicles and less than eight psi in one minute for combination vehicles. 
  2. Less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles. 
  3. Less than six psi for all vehicles.
7. Should you ever leave your vehicle unattended without applying parking brakes or chocking the wheels?
  1. Yes 
  2. No
8. If you are away from your vehicle only a short time, you don’t need to use the parking brake.
  1. True 
  2. False
9. How often should you drain air tanks?
  1. Daily 
  2. Weekly 
  3. Monthly
10. The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine.
  1. True 
  2. False
11. What factors can cause brakes to fade or fail?
  1. Not pressing the brake pedal hard enough. 
  2. Over heating, low air pressure, and not relying on the engine braking effect.
  3. Not taking your foot off the accelerator pedal.
12. Why should you be in the proper gear before starting down a hill?
  1. So you only have to apply the brake just hard enough to feel a definite slowdown. 
  2. So you don’t have to shift gears going downhill. 
  3. So you can go through the gears on the way down.
13. If oil and water collect in the air tanks what can happen to the brakes?
  1. The brakes could heat up. 
  2. The brakes could fail. 
  3. The brakes could lock up.
14. What is the purpose of an alcohol evaporator?
  1. So you don’t have to drain the air tanks as often. 
  2. To have a drink available if you get thirsty. 
  3. To reduce the risk of ice in the brake valves and other parts in cold weather.
15. What is another name for controlled braking?
  1. Steady braking 
  2. Squeeze braking 
  3. Hard braking


Answer Key

1. A 
2. B 
3. A 
4. C 
5. A 
6. B 
7. B 
8. B 
9. A 
10. A 
11. B 
12. A 
13. B 
14. C 
15. B