cdl practice test

Combination Vehicles CDL Test


Question #1 of 49

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), 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(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.



About this Combination Vehicles CDL Test

Our combination vehicle CDL practice test is graded for you at the end of the test based on the percentage of correct test answers. You will also be able to see user statistics which will show you how many people answered a particular combination vehicle question correctly or incorrectly. Take this practice test until you get a perfect score.



CDL Practice Test (Home) | General Knowledge Test | General Knowledge Test Part 2

True/False General Knowledge Challenge | Hazmat Test | Hazmat True/False Test | Air Brake Test

Air Brake Test (New) | Combination Vehicles Test | Doubles and Triples Test | Tanker Test

Pre Trip Inspection Test | Truck Driver Requirements | School Bus Test | Passenger Vehicle Test

Class A CDL Test #1 | Class A CDL Test #2 | Class B CDL Test #1 | Class B CDL Test #2

CDL Learning Series Tests (New) | Free CDL Training Information

Privacy Policy  |  Contact


© 2017 CDLTEST.co