CDL Practice Tests

Combination Vehicles Test

Learning Series

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Question #1 of 52

Combination Vehicles Test Question Image

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 and listen for air(Trailer hand valve must be on). If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly(s) are in the OPEN position.

This is how can you test the tractor protection valve.

This is how can you test the trailer emergency brakes.

This is how can you test that air flows to all trailers.

This is how can you test the trailer service brakes.

This is not a test.


CDL Practice Test (Home) | General Knowledge Test 1 (Learning)

General Knowledge Test 2 (Learning) | Air Brake Test 1 (Learning) | Air Brake Test 2 (Learning)

Combination Vehicles (Learning) | Hazardous Materials (Learning) | Doubles & Triples (Learning)

Tanker Test (Learning) | School Bus (Learning) | Passenger Vehicle (Learning)

Testing Series | CDL Training Information

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