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10 Cards in this Set
- Front
- Back
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The air brake system on a commercial motor vehicle is comprised of three separate systems. Can you name them?
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The correct answer is:1) Service Brake System - This is the brake system that is controlled by the brake pedal during normal driving. 2) Parking Brake System - This keeps the vehicle from rolling while parked. 3) Emergency Brake System - This uses parts of each of the two previous systems in order to stop the vehicle in the event of a brake failure.
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How often should the air tank be drained in the air brake system?
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The correct answer is:If it is a manual drain valve, it should be drained of water and contaminants at the end of every day’s driving.
Explanation:Water and compressor oil collect in the tank and can cause freezing. |
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At what PSI does the air compressor “cut out”?
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The correct answer is:The air compressor will shut down or “cut out” when the pressure in the air tank reaches about 125 PSI. It will start building pressure again if the pressure drops to about 100 PSI.
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What is a foundation brake?
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The correct answer is:The foundation brake is the component found at each wheel, most commonly comprised of an S-cam drum brake and brake shoes.
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What is an s-cam?
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The correct answer is:It is literally an “S” shaped device that, when turned or pivoted, forces the brake shoes apart where they then come in contact with the brake drum, to create friction that will slow the vehicle.
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What are spring brakes?
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The correct answer is:Spring brakes are a part of the emergency and parking brake systems. They are engaged automatically, via spring power, if the air pressure drops below 20-45 PSI.
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Which knob in the cab of the truck controls the parking brakes? |
The correct answer is:The diamond-shaped, yellow knob controls the parking brakes.Explanation:When pressed in, this knob releases the air pressure, allowing the spring brakes to be applied.Report a problem
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How can you check to see if the spring brakes are operating properly?
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The correct answer is:Chock the wheels, release the parking brakes, and shut the engine off. Step on and off the brake pedal to release the air pressure built up in the system. The parking brake or spring brakes should automatically come on when the air pressure falls to between 20-40 PSI.The knob on the dash will pop out if they are working properly.
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What is a “dual air brake” system?
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The correct answer is:This is the type of air brake system that relies on two separate sets of air tanks, lines, and hoses to manage a single set of brake controls. Typically, one set controls the brakes on the rear axles and the other set operates the front axle brakes.
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How quickly should a vehicle build air pressure?
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The correct answer is:The pressure should build from 85 to 100 PSI in about 45 seconds
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