Pennsylvania CDL — Air Brakes Practice Test 7

1.When should you skip setting the parking brakes and use wheel chocks instead?

Any time the vehicle is fully loadedWhenever you park on a downhill gradeOnly while the engine is runningWhen the brakes are very hot, or very wet in freezing weather

2.When the low-air warning first comes on, what should you do?

Stop safely right away, while you still have brake controlKeep driving until the spring brakes apply on their ownPump the brake pedal to rebuild pressureRelease the parking brake and coast

3.Total stopping distance for an air brake vehicle is made up of which four parts?

Perception, reaction, gear-selection and braking distancesReaction, brake lag, coasting and skid distancesPerception, brake lag, downgrade and braking distancesThe perception and reaction distances, plus the brake-lag and braking distances

4.The most common kind of foundation brake on heavy vehicles is which type?

The wedge brakeThe air-over-hydraulic disc brakeThe s-cam drum brakeThe power-screw caliper brake

5.In the snubbing technique, once you have braked to about 5 mph below your safe speed, what do you do next?

Hold steady brake pressure for the rest of the gradeShift into a higher gear and coastSet the parking brake to hold the lower speedLet off the brakes, then reapply once you return to your safe speed

6.A visible low-air-pressure warning must come on before tank pressure drops below what level?

55 psi100 psi20 psi85 psi

7.Why is it a bad idea to repeatedly press and release the brake pedal when it isn't necessary?

It overheats the alcohol evaporatorIt can let air out quicker than the compressor restores it, risking loss of brakingIt forces the governor to stay in cut-outIt makes the safety valve open at 150 psi

8.What is true about front-wheel braking on a commercial vehicle?

Front brakes should be disabled on wet roadsFront-wheel braking helps in all conditions and rarely causes skids, even on iceFront brakes are only useful on dry pavementFront-wheel braking sharply raises the chance of a skid

9.How does an air brake system light up the brake lights for the drivers behind you?

An air-pressure-operated electric switch turns them on as you brakeThe governor sends a signal back to the taillightsA contact at each wheel is closed by the slack adjusterThe wig wag completes the lighting circuit

10.At 55 mph in good conditions, the total stopping distance for an air brake vehicle is greater than about how many feet?

About 100 feetAbout 200 feetAbout 500 feetMore than 300 feet