Connecticut CDL — Air Brakes Practice Test 10

1.As overheated brake drums expand, what happens to braking performance?

The brakes grip harder than normalThe parking brakes releaseThe shoes must travel farther to reach the drum, and contact force dropsThe compressor cut-out pressure rises

2.On many large buses, at what pressure do the low-pressure warning devices commonly activate?

At 55 psiAt 80 to 85 psiAt 20 to 30 psiAt 125 psi

3.You brake hard on a slick road in a truck with no ABS. What happens if the steering axle wheels lock?

The trailer brakes release on their ownYour stopping distance is roughly cut in halfYou can no longer steer the vehicleThe engine shuts down to protect the drivetrain

4.What does an antilock braking system do during hard braking?

It shortens your stopping distance every timeIt keeps the wheels from locking so you can steer and stay in controlIt replaces the need for the service brakesIt automatically applies the parking brakes

5.How is stab braking performed?

Fully apply the brakes, release when the wheels lock, then reapply once they roll againApply light, steady pressure the entire stopHold the brakes fully locked until stoppedUse only the trailer hand brake

6.Your brakes are soaked and the temperature is below freezing. How should you dry them out?

Set the parking brakes and leave them on overnightPour warm water over each brake drumDrive in a low gear while pressing the brakes lightlyRev the engine until the tanks reach cut-out pressure

7.Who needs to study the air brakes section of the manual?

Only drivers of passenger carsOnly mechanicsNobody, since it is optional readingAnyone who will drive or pull a vehicle equipped with air brakes

8.In a dual air brake system, what happens if one of the two systems becomes very low on pressure?

One end of the rig, front or rear, loses full braking power, so stops take longerBoth systems shut down at onceThe parking brakes automatically releaseStopping distance is unaffected

9.What does a 'wig wag' low-pressure warning do?

It sounds a horn outside the cabIt automatically drains the tanksIt drops a mechanical arm into the driver's view when pressure is lowIt flashes the brake lights to the rear

10.Air brakes actually combine three separate braking systems. Which set names them correctly?

Primary, secondary, and reserve circuitsThe service brakes, the parking brakes, and the emergency brakesFoot, hand, and drum brakesHydraulic, mechanical, and electric brakes