Oklahoma CDL — Air Brakes Practice Test 1

11.In a vehicle without ABS, what happens when the steering-axle wheels lock up during hard braking?

The vehicle stops in a much shorter distanceYou lose steering controlThe parking brakes release automaticallyThe compressor cuts out to protect the tanks

12.Which sequence describes the 'stab braking' method?

Hold the brakes fully down and never release themApply the brakes fully, release when the wheels lock, then reapply fully once they roll againApply light steady pressure and coast to a stopAlternate between the service brake and the parking brake

13.At roughly what pressure is the air system's safety relief valve usually set to open?

55 psi100 psi150 psi200 psi

14.While a vehicle is being driven, what holds the powerful springs of the spring brakes back?

A mechanical latch on each wheelAir pressureThe ABS computerEngine oil pressure

15.During the engine compartment step of the inspection, what extra air brake item should you check on a belt-driven compressor?

The color of the ABS malfunction lampThe setting of the front brake limiting valveThe condition and tightness of the compressor drive beltThe alcohol level in the evaporator reservoir

16.How do you test the low pressure warning signal during the final air brake check?

Rev the engine until the governor cuts outStep on and off the brake with the engine off to lower tank pressure, and watch for the warningDrain both air tanks and listen for the buzzerPull the parking brake knob out and release it over and over

17.What must you always do before leaving your vehicle unattended?

Drain the air tanks completelyRelease the parking brakes to spare the springsApply the parking brakes or chock the wheelsLeave the engine running to keep pressure up

18.How does excessive heat produce brake fade in a drum brake?

It freezes the air lines feeding the chambersIt makes the drums expand so the shoes travel farther and press with less forceIt causes the governor to raise the cut-out pressureIt thickens the brake linings so they grip too hard

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

Push in a round blue knobTurn a red lever a quarter turnPress and hold the foot valvePull out a yellow, diamond-shaped control knob

20.How is the 'controlled braking' method performed during an emergency stop?

Pump the pedal quickly while turning the wheel sharplyPress the brakes fully and hold them until the vehicle stopsUse only the parking brake control to slow downBrake as hard as possible without letting the wheels lock