Alabama CDL — Air Brakes Practice Test 7

1.Which type of foundation brake is the most common on vehicles with air brakes?

The wedge brakeThe disc brakeThe s-cam drum brakeThe band brake

2.Besides slowing the vehicle, what else is produced when the brake shoes press against the drum?

Heat, which in excess can stop the brakes from workingExtra compressed air for the tanksAlcohol vapor that protects the valvesA charge that powers the brake lights

3.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

4.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'

5.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

6.What do air brakes rely on to make the braking mechanism work?

A vacuum drawn from the engine intakeCompressed air stored in the systemHydraulic fluid pressurized by a master cylinderElectric current sent to each wheel motor

7.Your brakes have gotten soaked. How does the manual suggest you dry them out?

Roll along in a low gear and apply light brake pressure to warm themPark the truck and wait for the water to evaporate on its ownHold the parking brakes on hard for several minutesPump the pedal rapidly while the vehicle sits still

8.Apart from leaning on the service brakes too much, what else makes brake fade more likely?

Tires inflated well above the recommended pressureUsing the engine to help hold your speed downBrakes that have slipped out of proper adjustmentDraining the air tanks more often than required

9.If the safety relief valve lets air escape, what does that indicate?

The tanks have finished draining normallyThe system is working exactly as intendedSomething is wrong and a mechanic should fix itThe alcohol evaporator needs refilling

10.You are pulling a trailer fitted with ABS behind a tractor that has none, and the tractor starts to jackknife. What does the manual advise?

Push the pedal harder to force the tractor back into lineHold the trailer hand valve down on its own until it straightensGrab a lower gear and let go of the steering wheelEase off the brake pedal, where it is safe, until control returns