FREE District of Columbia CDL Combination Test 2024 (Practice Test)

1. On front tires, tread should be at least:

2. When checking the air and electric lines to the trailer, be sure that the air lines are properly connected to the gland hands, and are:

secured with enough air leaks for turns.
secured with enough slack for turns.
properly greased.
None of the above.

3. _________ can make vehicle handling unsafe.

4. When the wheels of a trailer lock up, the trailer will tend to swing around. This is more likely to happen when:

the trailer is fully loaded.
the trailer is overloaded.
the trailer is empty or lightly loaded.
None of the above.

5. If the spring brakes do not release when you push the trailer air supply control, you should:

check the air line connections.
pump the brakes.
rev or lug the engine.
check the electrical cables.

6. If you try to couple when the trailer is too low:

the tractor could roll away.
it might not couple correctly.
the tractor may strike and damage the trailer nose.
All of the above.

7. As you approach off ramps and on ramps, remember:

that the posted speed limit may not be safe for larger vehicles.
to always brake and turn at the same time.
that downgrades make it easier to reduce speed.
to maintain your highway speed.

8. Most heavy-duty vehicles use:

9. To prevent rollover, you should:

drive slowly around corners.
drive on the shoulder of the road when possible.
turn the engine off while turning.
drive in the left lane.

10. It's very important to distribute the cargo so it is:

DC CDL COMBINATION TEST - PRACTICE TEST