DMV PA - CDL Air Brakes Endorsement Multiple Choice Test Questions

1. The brake system that applies and releases the brakes when the driver uses the brake pedal is the ________ system.

a. Emergency
b. Service
c. Parking
d. None of the above

2. Air brake systems combine three different systems. They are the service, parking, and the _______ brakes.

a. Drum
b. Emergency
c. Foot
d. S-cam

3. The air compressor governor controls:

a. The speed of the air compressor.
b. When air is pumped into the tanks.
c. Air pressure applied to the brakes.
d. When the brake chambers release pressure.

4. During normal driving, spring brakes are usually held back by:

a. Bolts
b. Air pressure
c. Spring pressure
d. Centrifugal force

5. The application pressure gauge shows how much air pressure you:

a. Are applying to the brakes.
b. Have in the air tanks.
c. Have used on this trip.
d. None of the above.

6. The supply pressure gauge shows how much pressure:

a. You have used in this trip.
b. Is in the air tanks.
c. Is going to the brake chambers.
d. The air can take.

7. All air brake equipped vehicles have:

a. A supply pressure gauge.
b. A hydraulic system, in case the air system fails.
c. At least one brake heater.
d. An air use gauge.

8. The emergency brakes on a tractor trailer rig can only be held in position by something that cannot leak away, like:

a. Spring pressure
b. Fluid pressure
c. Air pressure
d. Any of the above

9. The braking power of spring breaks:

a. Depends on the service brakes being in adjustment.
b. Can only be tested by highly-trained brake service people.
c. Is not affected by the condition of the service brakes.
d. Increases when the service brakes are hot.

10. In air brake vehicles, the parking brakes should be used:

a. Any time the vehicle is parked.
b. As little as possible.
c. To hold your speed when going downhill.
d. Only during pre- and post-trip inspections.

11. The most common type of foundation brake found on heavy vehicles is the:

a. Disc.
b. Wedge drum
c. S-cam drum
d. None of the above

12. Parking or emergency brakes of trucks and buses can be legally held on by _____ pressure.

a. Spring
b. Fluid
c. Air
d. Atmospheric

13. Why should you drain the water from compressed air tanks?

a. The low boiling point of water reduces braking power.
b. Water can freeze in cold weather and cause brake failure.
c. Water cools the compressor too much.
d. To keep from fouling the air compressor oil.

14. If your vehicle has an alcohol evaporator, every day during cold weather you should:

a. Change the alcohol from a new bottle.
b. Clean the air filter with alcohol.
c. Check the oil for alcohol content.
d. Check and fill the alcohol level.

15. If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage air tanks?

a. After every 6 hours of service.
b. At the end of each day of driving.
c. Once a week.
d. Once a month.

16. The brake pedal in an air brake system:

a. Controls the speed of the air compressor.
b. Always needs to be held down 3/4 way during normal driving.
c. Controls the air pressure applied to put on the brakes.
d. Is connected to slack adjusters by a series of rods and linkages.

17. If your vehicle has an alcohol evaporator, it is there to:

a. Rid the wet tank of alcohol that condenses and sits at the bottom.
b. Eliminate the need for daily tank draining.
c. Boost tank pressure the same way that turbochargers boost engines.
d. Reduce the risk of ice in air brake valves in cold weather.

18. Your vehicle has a dual air brake system. If a low air pressure warning comes on for the secondary system, you should:

a. Bring the vehicle to a safe stop and continue only when the system is fixed.
b. Reduce your speed, and test the remaining system while under way.
c. Reduce your speed, and drive to the nearest garage for repairs.
d. Continue at normal speed if only the secondary system fails.

19. If your truck or bus has dual parking control valves, you can use pressure from a separate tank to:

a. Balance the service brake system whenever you are parked.
b. Apply more brake pressure if the main tank is getting low.
c. Stay parked 4 times as long with your service air pressure.
d. Release the spring emergency/parking brakes to move a short distance.

20. Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do?

a. Reduce your speed, and drive to the nearest garage for repairs.
b. Reduce your speed, and test the remaining system while under way.
c. Continue at normal speed. No action is needed when only one system fails.
d. Stop right away and safely park. Continue only after the system is fixed.

21. 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.

a. 20
b. 40
c. 60
d. 80

22. To check the free play in manual slack adjusters on S-cam brakes, you should park on:

a. Level ground with the parking brake, then apply the service brake.
b. Level ground, chock the wheels, and turn off the parking brakes.
c. Level ground and drain off air pressure before adjusting.
d. A slight grade, release the parking brakes, apply the service brakes, and check for vehicle movement.

23. To test the air service brake system, you should brake firmly when moving slowly forward. The brakes are okay if you notice:

a. An unusual feel.
b. The vehicle "pulls" to one side.
c. A delayed stopping action.
d. None of the above.

24. The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:

a. 1 psi in 30 seconds
b. 1 psi in one minute
c. 2 psi in 45 seconds
d. 3 psi in one minute

25. A stright truck or bus air brake system should not leak at a rate of more than ___ psi per minute with the engine off and the brakes released.

a. 1
b. 3
c. 2
d. 4

26. Air brake systems take more time than hydraulic brake systems because:

a. Air brakes use different brake drums.
b. Air takes more time to flow through the lines than hydraulic fluid.
c. Air brakes require heavier return springs.
d. Air is always leaking through air line fittings.

27. Of the choices below, the first thing to do when a low pressure warning comes on is:

a. Adjust the brake pedal for more travel.
b. Open the air supply control valve.
c. Stop and safely park as soon as possible.
d. Shift to the next higher gear.

28. If you must make an emergency stop, brake so you:

a. Can steer hard while braking hard.
b. Use the full power of the brakes and lock them.
c. Can steer and your vehicle stays in a straight line.
d. Use the hand brake first.

29. On long downhill grades, experts recommend using a low gear and light pedal pressure. Why?

a. Air usage is less with light pressure.
b. Brake linings do not heat up as much with light pressure.
c. You can keep vehicle speed constant in a low gear with light pressure.
d. All of the above.

30. Total stopping distance for air brakes is longer than that for hydraulic brakes due to ______ distance.

a. Perception
b. Reaction
c. Brake lag
d. Effective braking

31. You should know that your brakes are fading when:

a. Pressure on the brake pedal is released and speed increases.
b. The brake pedal feels spongy when pressure is applied.
c. You have to push harder on the brake pedal to control your speed on a downgrade.
d. Less pressure is needed on the brake pedal for each stop.

32. With air brake vehicles, the parking brakes should be used:

a. Whenever you leave the vehicle anattended.
b. To hold your speed when going downhill.
c. As little as possible.
d. Only during pre- and post-trip inspections.

33. For emergency stab braking, you should:

a. Pump the brake pedal rapidly and lightly.
b. Press on the brake pedal as hard as you can, release the brakes when the wheels lock, and when the wheels start rolling put the brakes on fully again.
c. Brake hard until the wheels lock, then get off the brakes for as much time as the wheels were locked.
d. Press hard on the brake pedal and apply full hand valve until you stop.

34. The most important thing to do when a low air pressure warning comes on is:

a. Upshift
b. Downshift
c. Adjust the brake pedal for more travel
d. Stop and safely park as soon as possible