The combination vehicle Practice test will examine your knowledge of driving combinations, combination vehicle air brakes, antilock brake systems, coupling and uncoupling, and inspecting combinations. In order to receive your combination vehicle endorsement, it is required that you pass the state’s official CDL written Knowledge exam.
If you have ABS brakes, you can expect your braking distance to be shortened by...?

Question 1 of 30

The service air line is usually colored...?

Question 2 of 30

Having ABS brakes allows you to...?

Question 3 of 30

The tractor protection valve should be checked with...?

Question 4 of 30

When a tractor and trailer are connected properly, there should be what space between the upper and lower fifth wheel?

Question 5 of 30

All air tanks in an air brake system should be drained of oil and moisture at least...?

Question 6 of 30

In the coupling system, the locking jaw should be around...?

Question 7 of 30

The first thing to do before testing trailer service brakes is to check for...?

Question 8 of 30

The sliding fifth wheel on the combination vehicle must be...?

Question 9 of 30

If a trailer is too high when you try to couple, what might happen?

Question 10 of 30

When connecting a tractor to a trailer, you should have your transmission in...?

Question 11 of 30

You must remember that converter dollies and trailers were not required to have spring brakes if they were built before...?

Question 12 of 30

You should always test the trailer brakes before driving with the hand valve or by pulling the air supply control. This is particularly important on...?

Question 13 of 30

You should always make sure when driving that your landing gear is...?

Question 14 of 30

Your trailer and converter dolly will have mandatory ABS brakes if they were built after...?

Question 15 of 30

When you have connected the tractor and trailer, you can check the system for crossed air lines by applying the brakes and...?

Question 16 of 30

Before lowering your landing gear, you should check...?

Question 17 of 30

When checking your air brakes, it is essential that...?

Question 18 of 30

If you identify a damaged air or electrical line in your inspection, you should...?

Question 19 of 30

If you have the trailer air supply knob in and the handbrake on but cannot hear air escaping from either line at the shutoff valve at the rear of the last trailer, you should first check...?

Question 20 of 30

When beginning to connect a tractor to a semitrailer, you should start with the tractor positioned...?

Question 21 of 30

If you are towing a three trailer combination, the order of the cutout cocks/shutoff valves, going from the tractor backwards, should be...?

Question 22 of 30

If the fifth wheel plate is not greased as required on a tractor semitrailer combination, it could cause...?

Question 23 of 30

If you are not sure whether or not your trailer has ABS brakes, you can find out by...?

Question 24 of 30

If you have ABS only on your trailer and you lose steering control, you should...?

Question 25 of 30

You will know you have connected your hose couplers incorrectly if...?

Question 26 of 30

The foot pedal on a tractor-trailer combination applies air to the service brakes...?

Question 27 of 30

Air is supplied to the emergency supply lines by...?

Question 28 of 30

For your brakes to work properly, air supply must reach...?

Question 29 of 30

Before you connect hose couplers 'glad hands' you should...?

Question 30 of 30



Studying and applying oneself is the only way to successfully learn the information you need to know to pass all testing required to obtain your CDL. We are here to help.

Don’t hesitate to take advantage of our practice tests in each category specific to your needs. We wish you the best of luck in your endeavors and are pleased to be of assistance.


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