California CDL — Air Brakes Practice Test 4

11.If you double your speed from 25 mph to 50 mph, what happens to the distance your vehicle needs to brake to a stop?

It roughly doublesIt roughly quadruplesIt stays about the same if the brakes are well adjustedIt increases by about 10 percent

12.Which type of foundation brake is found at the wheels of most heavy vehicles that use air brakes?

S-cam drum brakesAir-over-hydraulic disc brakesWedge brakesElectric drum brakes

13.In which situation should you NOT use the parking brakes when parking?

When parked on any downhill gradeWhen the brakes are very hot or very wet in freezing temperaturesWhen the trailer is loaded above half its rated capacityWhen the outside temperature is above 90 degrees

14.Your spring brakes are applied. Why should you avoid pushing down on the brake pedal?

It releases the spring brakes and lets the vehicle rollIt empties the air tanks within a few secondsSpring force and air pressure together could damage the brakesIt makes the low air pressure warning come on

15.You must make a quick emergency stop in a vehicle without anti-lock brakes. Which describes the stab braking method?

Apply light, steady pressure and steer sharply around the hazardApply the parking brake in short bursts while steering straightApply the brakes fully, release when the wheels lock, and reapply when they start rolling againPump the pedal rapidly several times per second until stopped

16.Some buses have a second control valve, fed by its own air tank, that releases the spring brakes after main air pressure is lost. Why must you plan carefully before using it to move the bus?

Using it permanently disables the spring brakesIt works only while the engine is shut offIt releases the brakes on the front axle onlyIts tank holds only enough air to release the brakes a few times

17.How are the brake lights turned on in an air brake system?

A cable connected to the brake pedal pulls a mechanical switchAn electric stop light switch that works by air pressure turns them onThe driver must turn them on with a dashboard toggleThe governor activates them at cut-out pressure

18.Some vehicles have an application pressure gauge, which shows the air pressure you are putting on the brakes. If you need more and more pressure just to hold the same speed, what does that tell you?

The governor cut-out pressure is set too highThe compressor is pumping too much air into the systemThe brakes are fading, so slow down and shift to a lower gearThe stop light switch has failed

19.You are going down a long, steep downgrade and your safe speed is 40 mph. Using the proper braking technique, when and how should you use the service brakes?

Hold light, steady brake pressure the whole way down the gradeBrake firmly to about 35 mph, release, and reapply when speed returns to 40 mphStay off the brakes entirely and rely on the parking brake if neededBrake hard to about 20 mph once, then coast the rest of the grade

20.Total stopping distance for a vehicle with air brakes is made up of which four factors?

Perception, reaction, brake lag, and effective braking distancePerception, reaction, coasting, and skidding distanceReaction, brake lag, downshift, and coasting distancePerception, signaling, braking, and following distance