Maryland CDL — Air Brakes Practice Test 1

11.What happens to the air pressure at the brakes when you press the brake pedal down harder?

The applied air pressure drops offMore air pressure is applied to the brakesThe governor cut-out point is loweredNothing changes until you release the pedal

12.Why should you avoid pushing the brake pedal down while the spring brakes are already applied?

It will drain the tanks in a few secondsIt disables the low air pressure warningThe combined force of the springs and the air pressure can damage the brakesIt automatically releases the parking brakes

13.When going down a long, steep grade, what is the role of the brakes according to the proper braking technique?

To replace engine braking entirelyTo hold the vehicle at a full stop the whole way downTo assist the engine's own braking effectTo keep the wheels locked for maximum drag

14.On newer air brake vehicles, how do you set the parking brakes?

Pull out the yellow, diamond-shaped knobPush in the yellow, diamond-shaped knobHold down the brake pedal for several secondsTurn the ignition key to the accessory position

15.As soon as the low-pressure warning first comes on while you are driving, what should you do?

Speed up to reach your destination before the air runs outPump the brake pedal repeatedly to rebuild pressureIgnore it until the spring brakes apply by themselvesImmediately pull over and stop safely while you still have air to work the brakes

16.What does the emergency brake system rely on to stop the vehicle if a brake failure occurs?

A dedicated backup air compressor mounted on the frameA separate hydraulic reservoir kept in the cabComponents shared with the service and parking brake systemsAn electric brake booster wired to the battery

17.On a vehicle with dual parking control valves and a separate air tank, what limits how you use it to release the spring brakes in an emergency?

It only works when the engine is runningIt can only be used while parked on a downhill gradeIt requires the governor to be at cut-out pressureThe separate tank holds only enough air to release the brakes a few times

18.If an air compressor is built with its own separate oil supply, what should you do before driving?

Drain all of the compressor's oil out firstDisconnect the compressor from the drive beltCheck the compressor's oil levelAdd alcohol to the compressor housing

19.Why does correct brake adjustment matter so much to the emergency and parking brake function?

Adjustment sets the pressure at which the governor cuts outAdjustment decides how fast the storage tanks refill after a stopThe springs can only deliver their full holding force through brakes that are set correctlyAdjustment controls whether the low pressure buzzer will sound

20.Why is repeatedly pressing and releasing the brake pedal when you don't need to a problem?

It overheats the parking brake springsIt raises tank pressure above the safety valve settingIt causes the alcohol evaporator to overfillIt can use up air faster than the compressor rebuilds it, and low pressure means no brakes