Iowa CDL — Air Brakes Practice Test 7

11.The manual says to set the parking brakes whenever you park, with two exceptions. Which pair of conditions are they?

Parking on a grade, and parking for only a few minutesParking a loaded trailer, and parking after darkBrakes that were just adjusted, and tanks that were just drainedBrakes that are very hot, and brakes that are very wet in freezing weather

12.During the air leakage part of Iowa's air brake check, you press the foot brake all the way down. When does the one-minute timing start?

The moment your foot first touches the pedalAfter the gauge settles from the first drop caused by applying the brakesOnce the low air warning buzzer soundsAs soon as you restart the engine

13.Several parts of the final air brake check are done with the engine shut off. Which of these checks is done with the engine running?

Timing the air leakage rate with the foot brake held downFanning the pressure down to see when the low air warning comes onFanning the pressure down until the parking brake valve pops outWatching for the governor to cut the compressor out and back in

14.You usually drive a medium truck with hydraulic brakes, but today you're in an air-braked truck at the same speed. Even if you react just as quickly, how should this change the room you leave ahead?

Leave the same room, because air brakes work the instant you touch the pedalLeave less room, because air brakes stop a truck faster than hydraulic brakesLeave more room, because air brakes need half a second or more to start working after you press the pedalLeave more room only on wet roads, because brake lag disappears on dry pavement

15.While checking the engine area on Iowa's inspection test, you hear air hissing. Why does the manual treat an air leak there as important?

It shows the safety relief valve is working normallyIt matters only if a puddle forms under the engineIt means the alcohol evaporator needs refillingIt can point to a failing part, such as the air compressor, that is hard to inspect directly

16.A brake line on the primary side of your dual air brake system bursts, and that side loses its air. Why does the secondary side keep its pressure?

The governor stops feeding the leaking side and sends all of its air to the otherThe safety relief valve seals off the side that is leakingEach side has its own air tanks, hoses, and linesThe secondary side refills itself from the trailer's air tanks

17.During the final air brake check, you idle the engine and fan the brake pedal. The gauge falls through 100 psi, then 90, then 80, and never starts climbing again. What has the check revealed?

A normal result, since the compressor waits until about 55 psi to restartA leak in one of the hoses feeding the brake chambersA low air warning light that has burned outA governor that is not cutting the compressor back in and needs repair

18.Your straight truck has ABS on all axles, but its yellow ABS lamp has stayed lit all day. A car stops suddenly ahead and you must brake hard. Which approach fits the manual?

Stand on the pedal and hold it, since full application is allowed on a truck with ABS on all axlesStop with the parking brake control alone, since the service brakes are tied to the failed ABSUse controlled or stab braking, since the regular brakes still work but the wheels can now lockPump the pedal lightly until the lamp goes out, and only then brake hard

19.On Iowa's inspection test, you check that the power unit's parking brake holds a combination vehicle. How should the trailer brakes be set during that check?

Released, so only the power unit's parking brake is holdingApplied, so the trailer helps hold the rigReleased, with your foot holding the service brake downIt does not matter, as long as the vehicle does not move

20.You're building air in a truck with a dual air brake system. The low air light and buzzer shut off while both gauges read about 70 psi. Are you ready to drive?

Yes, the warning shutting off means both systems are fully chargedYes, as long as the primary gauge reads higher than the secondaryNo, wait until both the primary and secondary systems reach at least 100 psiNo, wait until the safety relief valve opens to show the tanks are full