Nevada CDL — Air Brakes Practice Test 5

1.Your pre-trip check shows air pressure building more slowly than it should. Besides being a repair item, why does the manual say this matters on the road?

The safety valve will open and vent all the airThe ABS will shut off until the tanks are fullThe spring brakes will refuse to apply when you parkPressure could drop too low while you drive, forcing an emergency stop

2.How does the manual have you fit the extra air brake items into a pre-trip inspection?

Skip the seven-step inspection and do only the air brake checksFinish the seven steps, then do every air brake item as a separate eighth stepDo the regular seven-step inspection and add each air brake check in the step where it belongsDo the air brake checks only when the low air warning has come on

3.You've just come down a long, steep grade and are pulling in to park. The brakes are very hot. When does the manual say you can set the parking brakes?

Right away, so the heat is spread across the spring brakesOnly after the hot brakes have had a chance to coolOnly after you drain the air tanksNever again on this trip

4.An air brake system is really three braking systems in one. Which pairing of a system with the thing that puts it to work is correct?

Service brake system: the parking brake control in the cabEmergency brake system: a separate set of brakes held in reserve for emergenciesParking brake system: the brake pedal during normal drivingParking brake system: the parking brake control in the cab

5.In a typical dual air brake truck, you notice the secondary system's pressure sinking while the primary holds steady. Which brakes are probably not working fully, and what should you expect?

The front-axle brakes; it will take you longer to stopThe rear-axle brakes; your stopping distance will not changeEvery brake on the truck; it will stop instantlyOnly the trailer brakes; the tractor will stop as usual

6.You're in the proper low gear at the top of a long, steep downgrade. How does the manual describe the role of your service brakes on the way down?

They should hold the truck at a steady speed with light, constant pressureThey back up the engine's braking, which does the main workThey do most of the work, with the engine as a backupThey are needed only if the ABS lamp comes on

7.During your pre-trip leakage test, the air pressure falls faster than the allowed rate. What does the manual say to do, and why?

Drive gently to the next shop, since leaks only matter under hard brakingFind and fix the leaks before driving, or you could lose your brakes on the roadDrain the air tanks and run the test again until it passesRaise the governor cut-out pressure to make up for the leak

8.The safety relief valve on the first air tank protects the system from too much pressure. At about what pressure is it usually set to open?

About 55 psiAbout 100 psiAbout 150 psiAbout 250 psi

9.On your walk-around, a brake's lining looks fine and its drum has no cracks, but one of its mechanical parts is missing. How should you treat this?

As acceptable, because the lining and drum passedAs acceptable if the slack adjuster moves less than an inchAs a defect, because the mechanical parts must be in place and not broken or missingAs a concern only if the low air warning comes on

10.Over one week you drive three tractor-trailers: one with ABS only on the tractor, one with ABS only on the trailer, and one with ABS on both. How should your braking technique change from rig to rig?

It shouldn't; brake the same way, using only enough force to stop safely and keep controlBrake harder on the rig with ABS on both units, since it cannot skidPump the brakes on the rig with ABS on the tractor onlyUse the trailer hand valve alone on the rig with ABS on the trailer only