CDL AIR BRAKES PRACTICE TEST - SOUTH CAROLINA
16.
The tractor protection valve:
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provides the air supply for the brake system.
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will close if you apply the parking brakes.
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will close automatically if the air pressure drops to a certain level.
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All of the above.
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17.
Why must air tanks be drained?
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Water can freeze in cold weather and cause brake failure.
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To keep from fouling the air compressor oil.
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Water and
oil reduce the air pressure.
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The low boiling point of water reduces braking power.
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18.
If your brakes fail while you are driving on a downgrade, you should:
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use an escape ramp if it's available.
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immediately start looking outside your vehicle for something to stop it.
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take the least hazardous escape route you can.
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All of the above.
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19.
If your vehicle catches fire, you should pull over:
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at a service station.
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near trees.
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near other vehicles.
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in an open area.
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20.
What should you do to test your vehicle's low air pressure warning signal?
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With the engine running, put the vehicle in a forward gear and attempt to drive forward.
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Pump the brakes until the air pressure drops below 80 psi.
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With the key in the "on" or "battery charge" position, rapidly apply and release the foot brake.
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Release the parking brake valve and the tractor protection valve and reduce the air pressure by stepping on and off the brake pedal.
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