Louisiana CDL — Air Brakes Practice Test 8

1.Which describes the 'stab braking' method?

Gently feathering the pedal to keep the wheels turningFully applying the brakes, releasing when the wheels lock, then reapplying fully once they roll againPressing the pedal halfway and holding it steadyUsing only the trailer brakes to slow down

2.When should you NOT use the parking brakes?

When the brakes are very hot from a steep grade, or very wet in freezing temperaturesWhenever you leave the vehicle unattendedAny time you park on level groundAt the end of each working day

3.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

4.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

5.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

6.Before driving a vehicle with a dual air system, the compressor should build a minimum of what pressure in both systems?

60 psi45 psi125 psi100 psi

7.If the ABS malfunction lamp stays on after the bulb check or comes on while driving, what does it likely mean?

The tanks need drainingThe parking brakes are engagedABS may no longer be working at one or more of the wheelsThe compressor has reached cut-out

8.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

9.A visible low air pressure warning must come on before tank pressure falls below what level?

100 psi45 psi60 psi20 psi

10.Air brakes are actually made up of which three separate braking systems?

Hydraulic, mechanical, and vacuum systemsThe service, parking, and emergency braking systemsPrimary, secondary, and reserve systemsFront, rear, and trailer systems