Free CDL Practice Test

Correct!
C. lower the dolly support.

Explanation:
To use the tractor and first semitrailer combination to pick up the converter dolly when coupling twin trailers, position the combination as close as possible to the converter dolly. Move the dolly to the rear of the first semitrailer and couple it to the trailer. Lock the pintle hook. Secure the dolly support in the raised position. Pull the dolly into position as close as possible to the nose of the second semitrailer. Lower the dolly support. Unhook the dolly from the first trailer. Wheel the dolly into position in front of the second trailer in line with the kingpin.

In the handbook:
7.2.1: Coupling and Uncoupling - Coupling Twin Trailers

Correct!
A. release the pintle hook on the first semitrailer.

Explanation:
To uncouple twin trailers, uncouple the converter dolly after uncoupling the rear trailer. Lower the dolly landing gear. Disconnect the safety chains. Apply the converter gear spring brakes or chock the wheels. Release the pintle hook on the first semi-trailer. Slowly pull clear of the dolly. Never unlock the pintle hook with the dolly still under the rear trailer. The dolly tow bar may fly up, possibly causing injury, and making it very difficult to re-couple.

In the handbook:
7.2.2: Coupling and Uncoupling - Uncoupling Twin Trailers

Correct!
B. trailer hand brake.

Explanation:
Check the brakes on a double or triple trailer as you would any combination vehicle. You must make additional checks on your double or triple trailers. To check that air flows to all trailers (double and triple trailers) during your pre-trip inspection, use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for the air pressure to reach normal, then push in the red "trailer air supply" knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line. Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged. Close the emergency line valve. Open the service line valve to check that service pressure goes through all the trailers (this test assumes that the trailer handbrake or the service brake pedal is on), and then close the valve. If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly(ies) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work.

In the handbook:
7.4.1: Doubles/Triples Air Brake Check - Additional Air Brake Checks

Correct!
B. lower the dolly landing gear.

Explanation:
To uncouple twin trailers, uncouple the converter dolly after uncoupling the rear trailer. Lower the dolly landing gear. Disconnect the safety chains. Apply the converter gear spring brakes or chock the wheels. Release the pintle hook on the first semi-trailer. Slowly pull clear of the dolly. Never unlock the pintle hook with the dolly still under the rear trailer. The dolly tow bar may fly up, possibly causing injury, and making it very difficult to re-couple.

In the handbook:
7.2.2: Coupling and Uncoupling - Uncoupling Twin Trailers

Correct!
B. unhook the dolly from the first trailer.

Explanation:
To use the tractor and first semitrailer combination to pick up the converter dolly when coupling twin trailers, position the combination as close as possible to the converter dolly. Move the dolly to the rear of the first semitrailer and couple it to the trailer. Lock the pintle hook. Secure the dolly support in the raised position. Pull the dolly into position as close as possible to the nose of the second semitrailer. Lower the dolly support. Unhook the dolly from the first trailer. Wheel the dolly into position in front of the second trailer in line with the kingpin.

In the handbook:
7.2.1: Coupling and Uncoupling - Coupling Twin Trailers

End of sample test. Final Score: 0% Sign up now to get access to hundreds of test questions and pass your CDL written exam your first time... Guaranteed! Special! $3 off all CDL Prep Courses, plus 30 extra days free! $6.95 30 Days Access $17.00 60 Days Access $11.95 90 Days Access