Louisiana CDL — Air Brakes Practice Test 10

1.On vehicles with dual parking control valves and a separate air tank to release the spring brakes, why must you plan your moves carefully?

The separate tank refills only when the vehicle is parkedThe spring brakes will release just once each dayThe separate tank holds only enough air to release the spring brakes a few timesThe valve locks out the service brakes while moving

2.Why does a heavily loaded vehicle need a long distance to stop once the spring brakes come on?

The service brakes lock all the wheels at onceThe compressor keeps adding air the whole timeThe ABS shuts down completelyThe spring brakes do not act on all of the axles

3.While you are driving, what keeps the spring brakes from applying?

The alcohol evaporatorThe slack adjustersThe safety relief valveAir pressure holding back the powerful springs

4.Why is it important to drain the air tanks?

Water and oil collect inside and can lead to frozen, failing brakesTo lower the pressure so the governor can resetTo let the alcohol evaporator refill itselfTo keep the safety valve from opening at 150 psi

5.At about what pressure does the governor tell the compressor to stop pumping air?

About 60 psiAbout 125 psi, the cut-out levelAbout 100 psiAbout 150 psi

6.Which statement about ABS is accurate?

ABS increases your normal braking powerABS works even during gentle, everyday brakingABS removes the need for regular brakesABS does not necessarily shorten stopping distance but helps you keep control during hard braking

7.What is the purpose of a modulating control valve?

To pump extra air into the tanksTo let the driver apply the spring brakes gradually if the service brakes failTo drain the tanks automaticallyTo limit air pressure to the front brakes

8.Why should you avoid pressing and releasing the brake pedal more than necessary?

It overheats the safety valveIt forces the governor to cut in earlyIt fills the tanks with waterIt can release air faster than the compressor can replace it, dropping pressure until the brakes fail

9.What does the stop light switch do in an air brake system?

It turns on the brake lights to warn drivers behind youIt shuts off the compressor at cut-outIt drops the wig wag arm into viewIt releases the spring brakes for parking

10.If your ABS stops working, what happens to your braking?

You still have your normal brakes, so drive normally but get it serviced soonYou lose all braking abilityOnly the parking brakes will workThe spring brakes apply automatically