Alabama CDL — Air Brakes Practice Test 3

1.How does the air brake system warn drivers behind you that you are braking?

By venting air out of a rear valveBy dropping a wig wag arm at the backAn air-operated switch turns on the brake lightsBy sounding the low air buzzer outside

2.At roughly what tank pressure does the governor stop the compressor from pumping more air (the cut-out point)?

About 55 psiAbout 80 psiAbout 150 psiAbout 125 psi

3.What must be true for the spring brakes to deliver their full braking power?

The alcohol evaporator must be fullThe tanks must be at least half drainedThe brakes must be properly adjustedThe front limiting valve must be set to 'slippery'

4.How is the air compressor typically driven?

By exhaust gases passing through a turbineThrough gears or a v-belt tied to the engineBy an independent electric motorBy the rotation of the drive axle only

5.How do antilock brakes (ABS) help you during hard braking?

They always shorten your stopping distance by halfThey apply the parking brakes for you automaticallyThey help prevent wheel lockup so you can keep steeringThey replace the need for the service brakes entirely

6.While holding a steady speed you notice you must keep increasing the application pressure. What does this most likely mean?

The brakes are fading and you should slow down and use a lower gearThe compressor has switched to its backup settingThe air tanks are fully drained of moistureThe spring brakes are about to release on their own

7.The ABS warning lamp lights up while you are driving. What braking ability do you still have?

The ordinary air brakes keep working just as they always haveOnly the parking brakes will function until a repair is madeBraking is cut back to the trailer axles aloneYou lose all service braking and have to coast to a halt

8.In which situation does the manual allow a driver to push the brake pedal all the way down for an emergency stop?

Any time the road surface is wet or covered with iceWhenever the vehicle happens to be running emptyWhen the truck or combination has antilock braking working on all of its axlesOnly when the trailer by itself carries an antilock system

9.For a vehicle with air brakes, total stopping distance is made up of which four parts?

Perception, reaction, cornering, and coasting distanceFollowing, merging, braking, and reaction distancePerception, reaction, brake lag, and braking distanceIdle, cut-in, cut-out, and braking distance

10.On a tractor or straight truck, spring brakes will come fully on when air pressure drops into roughly what range?

About 80 to 100 psiAbout 100 to 125 psiAbout 20 to 45 psiAbout 125 to 150 psi