Kansas CDL — Air Brakes Practice Test 8

1.During the final air brake check, how does the manual have you confirm that the parking brake will actually hold the vehicle?

Set it, then rev the engine in neutral while watching the air gaugeSet it, then press the service brake pedal to see whether it feels firmPull gently against it in a low gear with the vehicle stopped and the parking brake onDrain the air tanks and watch whether the parking brake knob pops out

2.How long can it take locked wheels to begin rolling again after you let off the brakes during stab braking?

About a tenth of a secondUp to about one secondThree to five secondsNot until the vehicle has fully stopped

3.In an emergency, you hand-adjust an automatic slack adjuster so you can get the truck to a repair shop. What should you expect afterward?

The adjuster is now repaired for goodThe adjuster will stay in manual mode from now onThe brake will probably slip out of adjustment again soon, because the cause hasn't been fixedThat brake will now apply harder than the others

4.A tour bus has lost main air, and you need to reposition it using the separate air tank that serves its dual parking control valves. What limitation should shape how you plan the move?

Each push of the release button wears out the spring brakes permanentlyThe separate tank holds only enough air to release the brakes a few timesThe release button only works while the engine runs at a fast idleThe low air warning shuts the engine off after about one minute

5.Your trailer has ABS but your tractor does not. What does the trailer's ABS make less likely when you brake?

The trailer swinging outThe tractor jackknifingLosing steering control at the frontBrake lag

6.On an older single air brake system (pre-1975), the typical buildup check is 50 to 90 psi within 3 minutes. At what engine speed is that measured?

Full governed engine speedOperating rpm with the vehicle under loadAny speed, as long as the parking brake is releasedAn idle of about 600 to 900 rpm

7.On a long downgrade, a couple of your truck's brakes are out of adjustment while the rest are properly adjusted. How does this lead to trouble?

The adjusted brakes lock up, which sets off the spring brakes on the drive axlesThe poorly adjusted brakes overheat first and turn on the ABS malfunction lampThe air compressor falls behind, so the tanks empty before the bottom of the gradeThe badly adjusted brakes stop pulling their weight, so the others overheat and fade

8.A bus is fitted with dual parking control valves. Which of the two do you use to set the spring brakes when you park?

The valve that is spring-loaded in the 'out' positionWhichever valve draws air from the separate tankThe push-pull valveNeither; you hold the brake pedal down instead

9.On an air-braked vehicle, during which step of the seven-step inspection do you check the slack adjusters, brake drums, linings, and brake chamber hoses?

Step 2, the engine compartment checksStep 5, the walk-around inspectionStep 7, the final air brake checkStep 1, the vehicle overview

10.Each time you let up on the air brake pedal, what happens to the air that was applying the brakes?

It flows back into the compressor to be reusedPart of it is vented, so tank pressure drops and the compressor must replace itIt is stored in the spring brake chambers for parkingNothing; tank pressure stays exactly the same