Tennessee CDL — Air Brakes Practice Test 6

1.What does the manual say about front wheel braking under slippery conditions?

Front brakes should be turned off on wet roadsFront brakes always skid first on slippery pavementFront wheel braking is good in all conditions and rarely causes a skid, even on iceFront brakes work only above 55 psi

2.At what pressure is the safety relief valve usually set to open?

150 psi100 psi125 psi55 psi

3.Why should you avoid pressing the brake pedal while the spring brakes are already applied?

The combined spring and air forces could damage the brakesIt would drain the tanks below the cut-in pressureIt would release the parking brakes unexpectedlyIt would trigger the safety valve to open

4.According to the manual, what is the most common problem found during roadside inspections?

Worn tiresBrakes that are out of adjustmentCracked windshieldsBurned-out marker lights

5.How large a crack is allowed on a brake drum or disc during inspection?

No crack longer than half the width of the friction areaNo crack longer than the full width of the friction areaAny crack is acceptable if the linings are thickNo crack longer than three inches, regardless of drum size

6.How often must you empty a manually operated air tank drain valve?

Once a week during warm monthsOnly when the low pressure warning comes onAt the close of each driving dayEvery time you refuel

7.What can happen if you press and release the brake pedal more than necessary?

The governor is forced to raise the cut-out pressureThe safety valve is prevented from openingThe air is used up faster than the compressor can rebuild itThe stop lights stop working

8.With the engine off and the foot brake fully applied, what air loss rate is acceptable for a single vehicle over one minute?

No more than six psi in one minuteNo more than ten psi in one minuteAny drop is acceptable if the warning stays offNo more than three psi in one minute

9.On a long, steep downgrade, the braking effect of the service brakes should be treated as what?

The only thing you need to control speedOnly a supplement to the engine's braking effectA replacement for gearing downSomething to avoid using entirely on hills

10.How do you test that the parking brake will hold?

Rev the engine to full throttle in neutralSet it, then in a low gear gently try to ease forward against itRoll downhill and release it suddenlyPump the brake pedal ten times quickly