Washington CDL — Air Brakes Practice Test 9

1.What can happen to drum brakes if they take on more heat than they can handle?

They grip harder and shorten the stopping distance.They switch the vehicle onto the emergency circuit.They cause the governor to cut in early.They can stop working.

2.Why can the brakes still be applied several times even after the compressor quits pumping?

Because the wheels store braking energy mechanically.Because the governor keeps generating pressure on its own.Because the storage tanks hold a reserve of compressed air.Because the spring brakes recharge the system automatically.

3.During a walk-around, a manual s-cam slack adjuster likely needs adjustment if it moves more than about how far where the push rod attaches?

About four inches.About one half inch.About three inches.About one inch.

4.Why is it important to remove the water and oil that gather in the air tanks?

Because moisture can freeze in cold weather and knock the brakes out.Because oil raises the governor's cut-out pressure over time.Because water improves stopping power and must be rationed.Because the compressor cannot run while any liquid remains.

5.In a vehicle without ABS, what happens if you brake hard enough on a slick road to lock the steering wheels?

You lose the ability to steer the vehicle.The spring brakes release to free the wheels.The trailer brakes take over the whole stop.Steering becomes easier because the tires slide.

6.Pushing the air brake foot pedal down harder has what effect?

It routes air away from the front brakes.It recharges the storage tanks more quickly.It locks the parking brake into place.It applies more air pressure to the brakes.

7.If one half of a dual air brake system loses most of its pressure while driving, what results?

Both systems shut down at once.The parking brake releases automatically.Either the front or rear brakes lose full operation, so stopping takes longer.The compressor doubles its output to compensate.

8.Air pressure has dropped far enough for the spring brakes to set on an empty rig or on a slippery road. What is the particular danger?

The air tanks can rupture from the sudden load.The warning buzzer stops working permanently.The vehicle may skid and get away from you.The compressor will overheat and seize.

9.What does the 'controlled braking' method involve during an emergency stop?

Slamming the pedal to the floor and holding it there.Pumping the pedal rapidly regardless of the wheels.Braking as hard as possible without locking the wheels, keeping steering movements small.Releasing the brakes fully and coasting to a stop.

10.Why is needlessly pumping the brake pedal on and off a dangerous habit in an air brake vehicle?

It overheats the alcohol evaporator.It can drain air faster than the compressor can replace it, leaving too little to brake.It permanently raises the governor cut-in pressure.It causes the safety valve to seal shut.