Maryland CDL — Air Brakes Practice Test 5

1.How does a wig wag warning device let the driver know the air pressure is getting low?

It sounds a horn outside the cabIt flashes the headlights on and offIt lowers a mechanical arm into the driver's viewIt applies the parking brakes automatically

2.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

3.You are hauling a trailer that has antilock brakes behind a tractor that does not, and the tractor begins to jackknife. What is the right response?

Press the pedal harder to force the tractor back into lineGrab a lower gear and hold steady pressure on the pedalPull the parking brake knob out to straighten the combinationBack off the brake pedal, where it is safe to do so, until you have the rig under control again

4.Why is having air storage tanks important on a vehicle with air brakes?

They keep the engine oil cool during long tripsThey add weight to improve traction on the drive axleThey hold enough air to brake several times even if the compressor stopsThey filter road dust out of the incoming air

5.What describes the controlled braking method during an emergency stop?

Braking as lightly as possible while making large steering correctionsSlamming the brakes fully and holding them lockedBraking as firmly as you can without locking the wheels while steering gentlyUsing only the engine and transmission to slow down

6.An air brake setup is really a combination of which three systems?

A hydraulic, a vacuum, and an electric braking systemA primary, a converter, and a retarder systemA drum, a disc, and a wedge systemA service, a parking, and an emergency braking system

7.If you keep driving after the low air pressure warning comes on and the spring brakes finally apply, why can a heavily loaded vehicle take a long distance to stop?

Because the service brakes apply at double strengthBecause the ABS shuts off all brakingBecause the trailer brakes release automaticallyBecause the spring brakes don't act on every axle

8.What does the governor control on an air brake vehicle?

How fast the vehicle is allowed to travel on the highwayWhen the compressor pumps air into the storage tanksHow much pressure is being sent to the brake chambersWhen the spring brakes release for parking

9.What is true of an air tank fitted with a manual drain valve?

It empties the tank by itself while you driveIt only works when the parking brake is setIt comes standard with an electric heaterYou must open it yourself by turning it or pulling a cable

10.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