AZ CDL AIR BRAKES PRACTICE TEST

11. The safety valve is usually set to open at:
100 psi.
150 psi.
200 psi.
12. To check the slack adjusters on S-cam brakes, you should:
release the parking brake valve and begin reducing the air pressure by stepping on and off the brake pedal.
park on level ground, chock the wheels and release the parking brakes, then use gloves and pull hard on each slack adjuster that you can reach.
park on level ground and fan off the air pressure by rapidly applying and releasing the foot brake.
13. Most heavy-duty vehicles use:
dual air brake systems.
triple air brake systems.
single air brake systems.
14. In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
20 to 45 psi
100 to 120 psi
10 to 20 psi
15. Which of the following can cause brakes to fade or fail?
Brakes out of adjustment
Excessive use of the service brakes
All of the above.
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