Tuesday, August 1, 2017

CDL Air Brakes Endorsement - Exam 7 - 36 Questions

By Gary Boutin

1. To determine if slack adjusters need adjustment.

a. Apply the service brakes and release the parking brakes.
b. Apply both the service and parking brakes.
c. Pull out the automatic slack adjustment control knob.
d. Release both the service and parking brakes.

2. The governor stops pumping air when it reaches the "cut out" level, is or around ___ psi.

a. 125-psi.
b. 200-psi.
c. 225-psi.
d. 175-psi.

3. Foundation brakes are used:

a. Only in emergencies.
b. When parking.
c. At each wheel.
d. During freeway travel.

4. Your truck has a properly functioning dual air brake system and minimum size air tanks. The air pressure should build from 85 to 100-psi within:

a. 30-seconds.
b. 45-seconds.
c. 60-seconds.
d. 240-seconds.

5. When you apply your brakes, the air brake system works with an electric switch, by air pressure, to turn on the brake lights.

a. True.
b. False.

6. What do air brakes use to make the brakes work?

a. Compressed gas.
b. Compressed oil.
c. Compressed air.

7. Air brakes are really three different braking systems: service brake, parking brake and emergency brake.

a. True.
b. False.

8. The S-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. It is called the S-cam because:

a. It is shaped like the letter Z.
b. It is shaped like the letter N.
c. It is shaped like the letter S.

9. What is a dual air brake system?

a. A dual air brake system has two separate air brake systems, the first system is called the primary system and the second is called the secondary system.
b. A dual air brake system has two separate air brake systems, each system has its own air tanks, hoses, lines, etc.
c. A dual air brake system has two separate air brake systems, both systems supply air to the trailer if there is one.
d. None of the above.

10. How should you check the free play of manual slack adjusters on S-cam brakes?

a. Park on a level ground, secure the wheels and then free parking brakes.
b. Stop on a level ground and apply parking brakes.
c. Park on level ground and drain off air pressure before making adjustments.
d. Park on a slight grade and release the parking brake, then apply the service brakes and check for any vehicle movement.

11. Excessive use of the service brakes result in overheating which can lead to:

a. Improper adjustment of the S-cam.
b. Increased contact between the brake drum and brake linings.
c. Expansion of the brake drums.

12. The air brake system for a straight truck or bus 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.

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

a. Use the hand brake before the brake pedal.
b. Use the full power of the brake pedal.
c. Can steer and your vehicle stays in a straight line.

14. The proper method of braking when going down long/or steep grades, after selecting the proper gear, is to brake you speed about ___ miles per hour below your safe speed, then release your brakes.

a. 5.
b. 10.
c. 5.

15. 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 your driving.
c. Stop and safely park. Continue only after the system is fixed.

16. The driver must be able to see a warning before air pressure in the service brakes air tanks falls below ___ psi.

a. 50-psi.
b. 60-psi.
c. 80-psi.

17. The brakes pedal in air brake system.

a. Controls the speed of the air compressor.
b. Controls the air pressure applied to put on the brakes.
c. Connects the slack adjusters by a series of rods and linkages.

18. Before driving a truck or bus with a dual air brake system the pressure in each system should be at least ___ psi.

a. 80-psi.
b. 100-psi
c. 120-psi.

19. To check the free play of manual slack adjuster on S-cam brakes.

a. Chock the wheel and turn off the parking brakes.
b. With the parking brakes on and then apply the service brakes.
c. And Drain off air pressure before adjusting vehicle movement.

20. Under normal condition to engage the parking brakes the driver must first:

a. Turn off the engine only.
b. Let the air out of the air brake system.
c. Be sure that the air brake system is fully pressurized.

21. 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 one minute.
b. 2-psi in 45-seconds.
c. 3- psi in one minute.

22. The air brake lag distance at 55-mph on dry pavement adds about ___ feet to your stopping distance.

a. 12-feet.
b. 32-feet.
c. 52-feet.

23. How should you check that the trailer brakes come on when air pressure in the system drops below a certain level?

a. Park on a slight incline, drain off air pressure, set the parking brakes and check for movement.
b. Chock the wheels, apply the parking brake, shut off the engine, and pump the brake pedal to reduce air tank pressure.
c. Wait for normal pressure, release the parking brake, move the truck forward slowly, and apply the brake firmly.

24. To test your service brakes you should:

a. Stop the vehicle and put the parking brake on.
b. Release the parking brake, move forward slowly and depress brakes.
c. Put parking brake on and release air pressure.
d. Depress brakes when traveling at highway speeds.

25. Stab braking occurs when you:

a. Press on the brake pedal as hard as you can.
b. Release the brakes when the wheels lock up.
c. Apply the brakes when the wheels start rolling.
d. All of the above.

26. Air brakes take longer to stop than hydraulic brakes because:

a. The reaction time is longer for the driver.
b.  It takes longer for the air to flow through the lines.
c. The linings get hotter more quickly.
d. None of the above.

27. The proper way to go down long grades is to:

a. Use a low gear and push hard on the brakes.
b. Let up on the brakes from time to time to cool them.
c. Use a low gear and apply light pressure on the brakes.
d. Brake on and off down the hill.

28. You should avoid using the parking brake:

a. On steep hills.
b. If the air pressure is low.
c. When the brakes are hot.
d. Any time you park.

29. Air tanks should be drained:

a. At the end of each day or shift.
b. To keep sludge from clogging brake system valves.
c. Manually when automatic devices fail.
d. All of the above.

30. Fanning air brakes:

a. Cools them off.
b. Increases the air pressure.
c. Increases the braking power.
d. Decreases the air pressure.

31. If your air compressor stops working:

a. You will lose your brakes immediately.
b. The brakes will immediately lock up.
c. You'll still have air pressure left in the air tanks.
d. Your brakes won't be affected.

32. The governor allows the air to start pumping again when it reaches the cut in level, or around:

a. 200-psi.
b. 100-psi.
c. 150-psi.
d. 125-psi.

33. You should not use the parking brakes:

a. On a steep hill.
b. If the air pressure is low.
c. When the brakes are hot.
d. In hot weather.

34. The brake drums or discs:

a. Must have linings that fit loosely on the brake shoes.
b. Must not have any cracks.
c. Must not have cracks longer than half the width of the friction area.
d. Should be kept well-greased.

35. Slack adjusters:

a. Never need to be adjusted.
b. Should only be adjusted by a qualified mechanic.
c. Can be adjusted manually or automatically.
d. Should travel at least two inches from where the push rod is attached.

36. To determine if slack adjusters need adjustment:

a. Apply the service brakes and release the parking brakes.
b. Apply both the service and parking brakes.
c. Pull out the automatic slack adjustment control knob.
d. Release both the service and parking brakes.


1. d.
2. a.
3. c.
4. b.
5. a.
6. c.
7. a.
8. c.
9. a.
10. a
11. c
12. b
13. c
14. a
15. c
16. b
17. b
18. b
19. a
20. b
21. c
22. b
23. b
24. c
25. b
26. b
27. c
28. c
29. a
30. d
31. c
32. b
33. b
34. b
35. c
36. d

Note: All the test have duplication questions sometimes with different wording. Some tests more than other, because the DMV want to make sure you understand these area of the commercial driving exams.

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