Colorado CDL — Air Brakes Practice Test 1

11.How do you test that the parking brake will hold?

Rev the engine while the brake is releasedPump the brake pedal ten times quicklySet the parking brake and gently tug against it in a low gearCoast downhill without touching the pedal

12.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

13.What causes brakes to fade from excessive heat?

Overheating that reduces lining friction and expands the drumsToo much moisture drained from the tanksUsing the engine to help slow the vehicleRunning the compressor above cut-out pressure

14.During the engine-compartment inspection of a belt-driven air compressor, what should you check?

That the drive belt is in good condition and properly tightThat the belt is coated with oil for lubricationThat the belt is completely loose so it can slipThat the belt color matches the hoses

15.On newer air brake vehicles, how do you apply the parking brakes?

Push in a round green buttonHold down the brake pedal and set a latchPull out the yellow, diamond-shaped knobFlip a red toggle switch on the dash

16.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

17.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

18.If your air tanks have manually operated drain valves, how often should you drain them?

Only when the low air warning comes onAt the end of each day of drivingAbout once a monthOnly during freezing weather

19.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

20.You always drive a straight truck whose anti-lock brakes work on every axle. What does the manual allow during an emergency stop?

Pump the pedal lightly so the system has time to reactPress the brake pedal all the way down and hold itUse stab braking, letting go each time a wheel locksPull the parking brake knob out to help slow the load