CDL Combination Vehicles Practice Test 2

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The trailer protection valve is designed to close automatically if the air pressure reaches the range of

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20 - 45 psi. The trailer protection valve is designed to close automatically if the air pressures becomes too low (i.e., drops to a range of 20-5 psi)

You should always test the trailer brakes before driving by

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A or B. You should always test the trailer brakes before driving with the hand valve or by pulling the air supply control.

If you are parking a trailer without spring brakes, which of the following should you use?

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Wheel chocks. In trailers without spring brakes, the brakes will hold only as long as there is air pressure in the trailer air tank. If the air leaks away, there will be no brakes. Therefore, wheel chocks should be used to secur

Which of the following keeps air in the tractor of truck brake system in case there is a bad leak or a trailer break away?

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Tractor protection valve. The trailer protection valve's purpose is to keep air in the brake system in case the trailer breaks away or develops a bad leak. If the trailer protection valve malfunctions, then air could be drained awa

The coupling device used to connect the service and emergency air lines from the truck to the trailer is known as?

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Which of the following is a valve used at the back of a trailer that allows the closing of the air lines when another trailer is not being towed?

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Which of the following devices should you use to prevent water and dirt from getting into the coupler and air lines when they are not in use?

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How are the air lines color coded to keep them from getting mixed up?

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You could experience steering problems because of friction between the tractor and trailer if you do not lubricate which of the following?

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Fifth wheel plate. When coupling tractor-semitrailers you need to insure that the fifth wheel plate is greased as required so that friction between the tractor and trailer does not cause steering problems. Relay valves (which conn

If you are lowering the landing gear of a loaded trailer, you should

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Turn the crank in low gear a few extra turns after firm contact with the ground. If you turn the crank in low gear a few extra turns, it will lift some weight off of the tractor which will make it easier for you to unlatch the fift

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