Alabama CDL — Air Brakes Practice Test 2

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

It instantly drains all the air tanksThe combined forces can damage the brakesIt disables the low air warning deviceIt permanently releases the parking brakes

2.How does the air brake system warn drivers behind you that you are braking?

By venting air out of a rear valveBy dropping a wig wag arm at the backAn air-operated switch turns on the brake lightsBy sounding the low air buzzer outside

3.When inspecting brake drums, how large a crack is considered acceptable?

Cracks up to the full width of the friction areaCracks of any length as long as the drum is warmNo longer than one half the width of the friction areaCracks up to twice the width of the friction area

4.You will be stepping away from your truck for only a minute or two. What has to happen first?

Nothing extra is needed for such a brief absenceLeaving the transmission in a low gear is enough by itselfLet the engine idle so the tanks stay chargedSet the parking brakes, or chock the wheels, before you walk away

5.Before driving a vehicle with a dual air system, how much pressure should you let build up in both the primary and secondary systems?

A minimum of 100 psi in both systemsAt least 55 psi in only one systemExactly 150 psi in the primary systemAny pressure above 20 psi is enough

6.How are the powerful springs in spring brakes normally held back while you drive?

By air pressure holding them offBy a locking pin the driver sets by handBy hydraulic fluid in the chambersBy an electric solenoid at each wheel

7.What is the main cause of brake fade?

Too much moisture drained from the tanksExcessive heat from overusing the service brakesSetting the front limiting valve to 'normal'Filling the alcohol evaporator too often

8.Once the spring brakes set themselves because tank pressure has fallen away, why can a heavily loaded truck need so much room to stop?

Spring brakes begin working only below walking speedThey are not fitted to every axle under the vehicleA heavy load stops the brake drums from turning at allSpring brakes release themselves whenever the load is heavy

9.What is the purpose of an alcohol evaporator in an air brake system?

It cools the compressor during hard brakingIt lowers the risk of ice forming in the brake valvesIt replaces the need to drain the tanksIt boosts the pressure the compressor can build

10.Apart from leaning on the service brakes too much, what else makes brake fade more likely?

Tires inflated well above the recommended pressureUsing the engine to help hold your speed downBrakes that have slipped out of proper adjustmentDraining the air tanks more often than required