Colorado CDL — Air Brakes Practice Test 8

11.For a combination vehicle, what is the maximum acceptable air pressure drop in one minute during the leakage test?

12 psi8 psi6 psi4 psi

12.On an older vehicle, putting the front brake limiting valve control in the "slippery" position does what?

It shuts off the rear brakes entirelyIt cuts the normal air pressure to the front brakes by halfIt doubles the pressure sent to the front brakesIt disables the low air pressure warning

13.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

14.In a vehicle with a dual air system, how much pressure should the compressor build in both systems before you drive?

A minimum of 100 psi in each systemAt least 55 psi in one systemExactly 150 psi in the primary onlyNo minimum is required before driving

15.Air pressure has fallen far enough that the spring brakes apply on their own. What hazard does that create for a lightly loaded truck or one on a slick road?

The air compressor will overheat and shut itself downThe wheels can lock and the vehicle may slide out of controlThe parking brake knob will push itself back inThe foot brakes will keep working at full strength

16.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

17.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

18.About how much distance does brake lag add at 55 mph on dry pavement?

About 5 feetAbout 15 feetAbout 100 feetAbout 32 feet

19.Which sequence describes the stab braking method?

Apply fully, release when the wheels lock, then reapply fully once they rollHold light steady pressure the whole timeSteer hard first, then brake once stoppedRelease the brakes and rely on the spring brakes

20.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