AIR BRAKES CDL PRACTICE TEST - NORTH CAROLINA
6.
The application pressure gauge:
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shows how much air pressure is being applied to the brakes.
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stops the compressor from pumping air.
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protects the tank and the rest of the system from too much pressure.
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tells you how much pressure is in the air tanks.
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7.
The s-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. It is called the s-cam because:
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"S" stands for "Shoes".
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it is a safe-driving brake.
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it is shaped like the letter "S".
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it applies a "Shock" to the brakes.
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8.
Air tanks must be drained because:
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compressed air usually has some water in it. The water can freeze in cold
weather and cause brake failure.
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if one air system is low on pressure, the rear brakes will not be operating fully.
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if you don't drain the tanks yourself, your battery fluid may drain out.
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when you push the brake pedal, air is let into each brake chamber.
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9.
You are going down a steep grade. Once the vehicle is in the proper low gear, you should brake just hard enough to feel a slowdown, and then release the brakes when your speed has been reduced to ____ below your safe speed.
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10 mph
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5 mph
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15 mph
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20 mph
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10.
With the air pressure built up to governor cutoff, the maximum leakage rates per minute after the initial pressure drop are:
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4 psi for single vehicles and 2 psi for a combination of 2 vehicles.
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5 psi for single vehicles and 6 psi for a combination of 2 vehicles.
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1 psi for single vehicles and 2 psi for a combination of 2 vehicles.
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3 psi for single vehicles and 4 psi for a combination of 2 vehicles.
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