Operation & SafetyQuestion 60 of 60
What is a proper way to test the trailer service brakes while stopped or moving slowly?
a.Slam the tractor foot brake to the floor
b.Move at about 5 mph and apply the trailer hand valve to confirm the trailer brakes engage
c.Set the parking brake and rev the engine
d.Drain the trailer air tank
Explanation
To test the trailer service brakes, move the vehicle slowly (about 5 mph) and apply the trailer hand valve. You should feel the brakes come on, which confirms the trailer brakes and their air connection are working. This should be done as part of your pre-trip checks, not used for normal stopping.
Practice all 60 questions free — no signup required.
Related questions on this topic
- What should you do first if the low air pressure warning comes on while driving?
- When stopping normally with a vehicle equipped with air brakes, how should you apply the brakes?
- Why should you not fan (pump) the brakes on and off on a long downgrade with standard air brakes?
- What is the effect of anti-lock braking systems (ABS) on air brake vehicles?
- To make sure you can stop in time, how should you adjust following distance with air brakes at higher speeds?
- Before starting down a long grade, when should you select the proper gear?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against CDL Air Brakes Knowledge Test · How we review