DISTRICT OF COLUMBIA CDL AIR BRAKES PRACTICE TEST

16. Having ABS on only the trailer:
still gives you more control over your vehicle during braking.
makes the trailer more likely to swing out.
makes the trailer more likely to roll over.
is very dangerous.
17. The Johnson bar is a valve that:
keeps air from going out if the air compressor develops a leak.
reduces the braking pressure to a safe level.
works the trailer brakes.
is installed in the first tank the air compressor pumps air to.
18. When driving in a construction zone, if a construction worker is near the road, you should:
speed up.
maintain a constant speed.
come to a complete stop.
further reduce your speed.
19. Spring brakes are usually held back by:
modulating control valves.
the brake pedal.
the antilock braking system.
air pressure.
20. If air pressure does not build up fast enough:
the pressure may drop too low during driving.
you should turn the electrical power on and step on and off the brake pedal.
you should put the parking brake on and gently pull against it in a low gear.
you may be forced to turn off the engine and release the parking brake.
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