DISTRICT OF COLUMBIA CDL COMBINATION PRACTICE TEST
11.
You have uncoupled a trailer and want to inspect the landing gear. The tractor should be positioned:
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with the tractor frame under the trailer.
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with the tractor frame above the trailer.
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completely clear of the trailer.
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None of the above.
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12.
On
a tractor-trailer equipped with a trailer brake hand
valve, the hand valve can be used to:
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hold compressed air.
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keep from rolling back.
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prevent movement of cargo.
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reduce the chance of the front wheels skidding.
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13.
A bridge formula permits less maximum axle weight for axles that:
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have a high center of gravity
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have poor weight balance
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are further apart than normal
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are closer together
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14.
Cargo should be properly covered:
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to block your view or someone else’s.
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to protect people from spilled cargo.
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to protect the weather from the cargo.
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All of the above.
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15.
What factors can cause brakes to fail or fade?
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Brakes out of adjustment
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Not relying on the engine braking effect
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Excessive use of the service brakes
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All of the above.
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16.
You are driving a modern truck with a manual transmission. When going down a hill you should usually:
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use a lower gear than would be required to go up the hill.
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downshift after your
speed has already built up.
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shift into neutral and coast.
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use the same gear you would use to go up the hill.
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17.
As part of your vehicle inspection, you are checking that air flows to all trailers. After using the trailer handbrake to provide air to the service line, you go to the rear of the rig. When you open the emergency line shut-off valve at the rear of the last trailer, you should hear:
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the service line valve close.
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air escaping from the open valve.
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a thumping sound.
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a mechanical vibration.
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18.
Which of the following is NOT part of testing the tractor protection valve?
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Charging the trailer air brake system.
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Stepping on and off the brake pedal several times to reduce the air pressure in the tanks.
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Shutting off the engine.
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Pulling forward slowly, then applying the trailer brakes.
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19.
When driving on slippery roads, you should NOT:
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watch far enough ahead to keep a steady speed.
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go slowly.
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try to anticipate stops early.
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use the engine brake.
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20.
Which of the following is NOT TRUE? When you drive a tractor-trailer combination with ABS, you should:
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drive slower to keep your vehicle in a straight line.
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brake the same way, regardless of whether you have ABS on the tractor, the trailer, or both.
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use only the braking force necessary to stop safely.
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monitor your tractor and trailer as you slow down, and if it is safe to do so, back off the brakes to stay in control.
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