CDL Combination Vehicles Test 6 – Classic Mode

1. Before you back under a trailer, make sure the:

A Air brakes are off.
B Tractor protection valve is normal.
C Landing gear is up.
D Trailer brakes are locked.

2. If the service air line comes apart while you are driving a combination vehicle but the emergency line stays together, what will happen right away?

A Nothing is likely to happen until you try to apply the brakes.
B You'll come to a complete stop.
C The trailer's air tank will exhaust through the open line.
D The emergency tractor brakes will come on.

3. The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than ____ psi per minute.

A 2
B 3
C 4
D 2 1/2

4. In normal driving, some drivers use the hand valve before applying the brake pedal to prevent a jackknife. Which of these statements is true?

A It results in less skidding than using the brake pedal alone.
B It should not be done.
C It is the best way to brake and keep the truck in a straight line.
D It should only be used if you're aware of the dangers.

5. The driver crosses the air lines when hooking up to an old trailer. What will happen?

A If the trailer has no spring brakes, you can drive away, but you will not have trailer brakes.
B The brake pedal will work the trailer spring brakes instead of the air brakes.
C The hand valve will apply the tractor brakes instead of the trailer brakes.
D None of the above.

6. The hand valve should be used:

A To test the trailer brakes.
B Only when the trailer is fully loaded.
C Only in emergencies.
D Only with the foot brake.

7. The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than ____ psi per minute.

A 1
B 2
C 3
D 4

8. The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:

A You can set the fifth wheel for weight balance.
B The coupling is not right and should be fixed before driving the vehicle.
C The parking lock is off and you may drive away.
D The fifth wheel needs to be replaced.

9. You are driving a combination vehicle when the trailer breaks away, pulling apart both air lines. You would expect the trailer brakes to come on and:

A The trailer supply valve to stay open.
B The tractor to lose all air pressure.
C The tractor protection valve to close.
D The tractor protection valve to open.

10. Semi trailers made before 1975 that are equipped with air brakes:

A Often do not have spring brakes.
B Usually need a glad hand converter.
C Are easier to brake because they are heavier.
D Only were equipped with spring brakes.

End of Test #6

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