CDL AIR BRAKES PRACTICE TEST - IOWA
6.
If your vehicle is equipped with air brakes, loss of air pressure in the
emergency line causes:
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the speed of your vehicle to increase.
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the trailer emergency brakes to come on.
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the trailer spring brakes to come on.
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7.
The safety valve is usually set to open at:
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150 psi.
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100 psi.
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200 psi.
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8.
The air brake lag distance at 55 mph on dry pavement adds about:
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32 feet.
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75 feet.
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60 feet.
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9.
When parking a trailer without spring brakes, it is very important for safety that you use wheel chocks. Why?
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You may not notice a major leak in the service line until you try to put the brakes on.
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if you don't use wheel chocks, supply air will be sent to the service line instead of going to charge the trailer air tanks.
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The air could leak out of the trailer air tank, releasing its emergency brakes.
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10.
A broken exhaust system:
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poses no threat to the driver.
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can let poisonous carbon monoxide to leak into the cab.
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can improve fuel efficiency.
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