California CDL — Air Brakes Practice Test 8

11.During the walk-around inspection, when is a crack in a brake drum too long to be acceptable?

Only when it runs the full width of the friction areaWhen it is longer than one-half the width of the friction areaWhen it is longer than one-quarter the width of the friction areaAny crack is acceptable as long as the drum is not leaking air

12.Which type of foundation brake is found at the wheels of most heavy vehicles that use air brakes?

S-cam drum brakesAir-over-hydraulic disc brakesWedge brakesElectric drum brakes

13.During the air brake check, how do you test the low pressure warning signal?

Drive at low speed and apply the parking brake to see if the light flickersRev the engine to operating rpm and watch for the warning at cut-out pressureOpen a drain valve slightly and listen for the buzzer at 100 psiFan down air pressure with the brake pedal, key on and engine off, until the warning comes on before 55 psi

14.Some air compressors carry their own oil supply instead of being lubricated by engine oil. What should you do on a vehicle with that kind of compressor?

Drain the compressor oil at the end of every shiftCheck the compressor's oil level before you driveAdd alcohol to the compressor oil in cold weatherNothing — a self-lubricated compressor never needs checking

15.It is freezing outside and your brakes are very wet. Before you park, what does the handbook suggest doing about the wet brakes?

Drag the brakes gently in a low gear so the heat dries them outSet the parking brakes right away so the linings cannot freezeFan the brake pedal with the engine off to blow the water outDrain the air tanks to remove the water from the brake drums

16.You are driving a vehicle with a dual air brake system and one of the two systems loses pressure. What should you expect, and what should you do?

Braking is unaffected; finish your trip and report it laterStopping distance increases; stop safely and get the system fixed before driving onThe vehicle cannot be stopped at all; use the escape rampOnly the trailer brakes are lost; drive slowly to the destination

17.You are going down a long, steep downgrade and your safe speed is 40 mph. Using the proper braking technique, when and how should you use the service brakes?

Hold light, steady brake pressure the whole way down the gradeBrake firmly to about 35 mph, release, and reapply when speed returns to 40 mphStay off the brakes entirely and rely on the parking brake if neededBrake hard to about 20 mph once, then coast the rest of the grade

18.The air compressor governor controls when the compressor pumps air into the storage tanks. At about what pressure does the governor stop the compressor from pumping (the "cut-out" pressure)?

About 60 psiAbout 100 psiAbout 125 psiAbout 150 psi

19.What is the correct way to confirm that the parking brake holds the vehicle?

Release it on a downgrade and see whether the vehicle rollsSet it, then pull gently against it in a low gearDrive forward at about 5 mph and pull the control knob outHold the brake pedal down for one minute and watch the air gauge

20.Total stopping distance for a vehicle with air brakes is made up of which four factors?

Perception, reaction, brake lag, and effective braking distancePerception, reaction, coasting, and skidding distanceReaction, brake lag, downshift, and coasting distancePerception, signaling, braking, and following distance