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Chapter 28
End of Chapter Review Questions Answer Key
1. Which of the following air brake system components functions as a lever?
2. Which of the following components sets the system cut-in and cut-out pressures?
3. What is the function of a system safety pop-off valve?
4. The function of the foot valve or dual-circuit application valve is to:
5. The potential energy of an air brake system is:
6. Which of the following components is a requirement on every air tank?
7. What is the minimum total storage volume of air dedicated to brake system
requirements of an air brake-equipped trailer?
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8. The function of an air brake chamber is to:
9. An air brake equipped truck is traveling on a highway at 60 mph (100 kph) and the
driver makes a service brake application. Which of the following should be true in all
of the spring brake chambers on the vehicle?
10. Technician A says that automatic slack adjusters can improve brake balance and
reduce downtime and maintenance costs. Technician B says that automatic slack
adjusters should not be adjusted after installation. Who is correct?
11. When an inversion valve becomes functional during a brake failure, what force is
used to brake the vehicle?
12. Which of the following determines the amount of leverage gained by a slack adjuster?
13. Which of the following is an advantage of an open anchor brake shoe?
14. The brake shoes, retraction, and fastening hardware are mounted to:
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15. In order for a service signal to pass through a TP valve, which of the following must
be true?
16. What actuates the relay piston in a foot valve on an air brake system when the valve is
operating normally?
17. Which of the following does the most to ensure that the driver has brake feel at the
foot valve in a truck air brake system?
18. Which of the following best describes the term coefficient of friction?
19. Technician A says that in a tractor/trailer B-train combination, the crack pressures of
the relay valves over the pup axles would be the highest on the rig. Technician B says
that quick-release valves on the service gladhands can speed up service brake release
times on multitrailer combinations. Who is correct?
20. A trailer air brake system compliant with a spring brake priority system has no air in
its on-board air tanks. When coupled to a tractor air supply, where is the air directed
to first?
21. What is the usual color of the tractor-to-trailer service hose?
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22. What is the usual color of the tractor-to-trailer supply hose?
23. When polarized gladhands are used, which of the following should be impossible?
24. Technician A says that air disc brakes usually produce higher mechanical braking
efficiencies than equivalent S-cam brakes. Technician B says that the reason wedge
brakes produce higher mechanical braking efficiencies than equivalent S–cam brakes
is that they are usually double actuated. Who is correct?
25. In the event of a total failure of the primary circuit in an FMVSS 121 compliant
vehicle, how is the relay/secondary circuit actuated in the foot valve?