Colorado CDL — Air Brakes Practice Test 5

1.Which statement about ABS and stopping distance is accurate?

ABS may not reduce stopping distance but helps you stay in controlABS always cuts stopping distance roughly in halfABS replaces your normal service brakesABS works only when the vehicle is fully loaded

2.How do you test the service brakes after building normal air pressure?

Apply the brakes while parked with the engine offDrive at highway speed before touching the brakesHold the pedal down for a full minute while stoppedMove forward slowly, apply the brakes firmly, and note any pulling or delay

3.During a walk-around, how much movement in a manual slack adjuster suggests it needs adjustment?

Any movement at allMore than a quarter inchMore than about one inchMore than three inches

4.How do spring brakes stay released while you are driving?

A dashboard switch keeps them locked openThe compressor physically pulls them backEngine vacuum holds the springs in placeAir pressure holds the springs back until the pressure is removed

5.If one system in a dual air brake vehicle drops very low on pressure while driving, what is the effect?

Both systems shut down instantlyPart of the brakes stop working, so it takes longer to stopThe parking brakes release automaticallyThe compressor doubles its output to compensate

6.The yellow ABS lamp stays lit after the start-up bulb check. What does that tell you about your braking for the rest of the trip?

Anti-lock control may be missing at one or more wheels, but the normal brakes still workYou have lost the service brakes entirely and must coast to a haltThe spring brakes will set themselves once you pass five mphYour stopping distance has automatically been cut roughly in half

7.Total stopping distance for an air-braked vehicle is made up of how many factors?

TwoThreeFourFive

8.Testing a single vehicle, the air pressure may not leak down by more than how much in one minute with the brakes fully applied?

10 psi7 psi3 psi1 psi

9.Why is it important to drain the air tanks completely?

Collected water and oil can foul the system, and water may freeze and cause brake failureEmpty tanks let the compressor build pressure more quicklyDraining raises the governor cut-out pressureIt keeps the alcohol evaporator from overfilling

10.Why can brakes that are out of adjustment leave you without enough braking power to control the vehicle?

They let moisture collect in the tanks and freeze the linesThey stop the spring brakes from ever releasingThey quit carrying their share, so the rest overheat and fadeThey make the governor cut out at a much lower pressure