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District Of Columbia CDL Permit Test - Air Brakes

Number of questions: 25
Passing score: 20
Directions: This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Washington D.C. Commercial Driver License Manual. Questions come from the chapter covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.
You have made error so far
Passing grade —
5 or fewer errors
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1.
Failing to drain the tanks in an air brake system can result in:
Water freezing and causing brake failure.
Squishy brakes.
Too much air collecting.
Too much fuel being carried.
2.
To ensure normal stopping power, drivers of vehicles equipped with a front brake limiting valve should:
Set the control to normal.
Set the control to the off position.
Set the control to neutral.
Keep the control at the halfway mark.
3.
What kind of force must emergency brakes use?
Air pressure
Mechanical
Heavy
Electrical
4.
During an applied leakage test, the maximum leakage rate for a triple combination vehicle is:
10 psi in a minute.
8 psi in a minute.
6 psi in a minute.
4 psi in a minute.
5.
Most heavy-duty vehicles use:
Single air brake systems.
Dual air brake systems.
Triple air brake systems.
Quadruple air brake systems.
6.
While driving downhill, you should brake until you reach a speed that is ____ below your safe speed, then release the brake pedal.
5 mph
10 mph
15 mph
20 mph
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