Arkansas CDL — Air Brakes Practice Test 6

1.Some automatic air tank drains come fitted with electric heating devices. What are the heaters for?

Keeping the automatic drain from freezing in cold weatherWarming the brake linings so they grip betterDrying the air before it reaches the compressorRaising tank pressure faster after start-up

2.A truck with a dual air brake system is pulling an air-braked trailer. Which system feeds air to the trailer?

Only the primary systemOnly the secondary systemBoth the primary and the secondary systemsNeither; the trailer has its own compressor

3.With the controlled braking method, how hard do you press the brakes?

All the way down, releasing only after the wheels lockFirmly, but short of the point where the wheels lockJust hard enough to feel a slowdown, for about three secondsLightly, letting the engine do all the stopping

4.What happens when you press an air brake pedal down harder?

The governor stops the compressor from pumpingMore air pressure is applied to the brakesAir is sent to release the spring brakesThe same pressure is applied; only the timing changes

5.Besides hiding the real fault, why does the manual call it dangerous to hand-adjust an automatic slack adjuster?

It cancels your CDL air brake endorsementIt disconnects the ABSIt can give you a false sense of security about how well the brakes workIt makes the compressor run nonstop

6.Your truck has a dual air system, and its low air warning has quietly stopped working. A slow leak develops. What are you likely to discover when you brake?

Nothing changes, because the second system makes up the difference completelyThe brakes lock instantly on every axleThe ABS takes over and keeps braking normalIt takes longer to stop, and only limited braking is possible before the spring brakes come on

7.Since what year have all vehicles been built with automatic slack adjusters?

1975199720051994

8.On an air-braked vehicle with drum brakes, how are the wheels and brake drums arranged?

The drums are at each end of the axles, and the wheels are bolted to themThe drums sit in the cab and connect to the wheels by cablesEach drum is mounted on the driveshaft, away from the wheelsOnly the front axle has drums; the rear wheels rely on the spring brakes alone

9.On a long downgrade in the right low gear, how firmly should you apply the brakes each time your speed reaches the safe speed?

Just firmly enough to feel a definite slowdownAs hard as possible to stop quicklyBarely touching the pedal so the brakes never warm upHard enough to lock the wheels briefly

10.You are in the proper low gear on a long downgrade and using the brakes to trim your speed. About how long should each brake application last?

About ten secondsAbout one secondAs long as it takes to reach the bottom of the gradeAbout three seconds