Nebraska CDL — Air Brakes Practice Test 3

11.A driver says his new ABS-equipped truck lets him follow more closely because ABS shortens stopping distance. How does the manual answer that?

ABS does not necessarily shorten a stop; what it does is help the driver stay in control when braking hardHe is right; ABS always cuts stopping distance by about a thirdABS lengthens every stop, so he must double his following distanceABS shortens stops only when the trailer is empty

12.Some vehicles, buses among them, carry a separate air tank tied to the parking brake controls. What is it there for?

To give the service brakes extra stopping power on downgradesTo release the spring brakes so the vehicle can be moved in an emergency after main air pressure is lostTo keep the low air warning from sounding in trafficTo hold the spring brakes off for good once air is lost

13.During the in-vehicle part of Nebraska's vehicle inspection test, you check the ABS indicator on the dashboard of a combination vehicle. What should the trailer's ABS light do?

The ABS light at the rear of the trailer on the driver's side should come on and then go offThe light on the passenger side should stay lit the whole timeIt should flash until the vehicle is moving faster than five mphNothing; the trailer's ABS light is checked only on the road test

14.Nebraska's vehicle inspection test section gives a reason for inspecting brake lines and hoses on an air-braked vehicle. What does it say losing air pressure may cause?

Wheel lockupA spongy pedal that sinks to the floorLoss of power steeringBoiling brake fluid

15.A driver skips the slack adjuster check because the truck has automatic slack adjusters. What does the manual say?

That is fine; automatic adjusters never need checkingThey need checking only after the brakes have been relinedThey still have to be checked, even though they adjust themselvesOnly a mechanic is allowed to check automatic adjusters

16.During the Step 7 air leakage test your pressure falls faster than the manual allows. What does the manual tell you to do?

Drive, but stop to rebuild pressure every hourDrain the tanks and repeat the test until it passesRaise the governor cut-out pressure to make up the lossFind the air leaks and get them fixed before you drive

17.Using controlled braking, you had to release the brakes because the wheels locked. When does the manual say to put them back on?

As soon as you canAfter a full three secondsOnly after the vehicle has stopped rollingNot until you have shifted to a lower gear

18.A converter dolly in your fleet was made in 2001. What does the manual say it is required to have for its ABS?

A lamp on the tractor's instrument panel onlyNothing; dollies are exempt from the ABS rulesA red lamp on its right rear cornerA malfunction lamp on its left side

19.In the first part of Nebraska's Air Brake Check you build air pressure up to governor cutoff. What else does the Nebraska Specifics page expect you to do at that point?

Shut the engine off and drain every air tankIdentify the cutoff pressure for the vehicle you are testing inPump the pedal until the low air warning comes onSet the parking brake and pull against it in a low gear

20.What does the manual mean by 'brake lag' on a vehicle with air brakes?

The time a driver takes to notice a hazardThe distance covered while the driver's foot moves to the pedalThe time the compressor needs to refill the tanksThe time the brakes take to work once the pedal has been pushed