FREE CT CDL Combination Test - Practice Test 2024

1. You are coupling a tractor to a semi-trailer. After checking the trailer height but before supplying air to the trailer, you should:

connect the air lines to the trailer.
inspect the fifth-wheel.
lock the trailer brakes.
raise the front trailer supports.

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

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

3. Which of these statements about brakes is true?

Brake fade does not result from excessive heat.
To stop, the brake shoes and linings are pushed against the outside of the drum.
The lighter the vehicle, the more heat the brakes absorb to stop it.
None of the above.

4. If you unlock the pintle hook with the dolly still under the rear trailer:

the dolly tow bar may fly up.
your vehicle might roll away.
steam and boiling water can spray under pressure.
the brakes could be damaged by the combined forces of the springs and the air pressure.

5. If during vehicle inspection a tire is too hot to touch, you should:

remain stopped until the tire cools off.
make sure there is enough engine oil on the tires.
immediately decrease air pressure.
let air out.

6. You are coupling a semi-trailer to your tractor but have not yet backed under. The trailer is at the right height when:

the locking jaws are around the head of the kingpin.
it will be raised slightly when the tractor is backed under it.
the end of the kingpin is even with the top of the fifth wheel.
None of the above.

7. In vehicles with air brakes, the tractor protection valve:

keeps air in the tractor or truck brake system.
provides the air pressure used to operate trailer brakes.
is used to connect the service and emergency air lines from the truck/tractor to the trailer.
carries air, which is controlled by the trailer hand brake or the foot brake.

8. A high center of gravity means:

the spring brakes will come fully on.
a rollover is less likely.
you'll have better traction.
you are more likely to tip over.

9. The best way to test the trailer service brakes is to:

accelerate to the maximum possible speed, then apply the trailer brakes fully.
put the handbrake on when there are no vehicles around you.
pull forward quickly, then apply the trailer brakes with your hand control.
None of the above.

10. Before leaving your vehicle unattended, you should:

CONNECTICUT CDL COMBINATION PRACTICE TEST