If you do not know whether or not a trailer is equipped with ABS, look under the vehicle for the electronic control unit and wheel speed sensor wires coming from the back of the brakes.

Look under the trailer for wheel speed sensors coming from the back of the brakes.

Remove a tire and look for the ABS sensor on the axle.

Trailers can overturn as a result of the "crack-the-whip" effect. The last trailer in a combination is the most prone to tip over due to this effect. Drivers should be aware of the rearward amplification of their specific vehicles and drive accordingly.

Be more effective than braking.

Before a trip, be sure to inspect all couplings. There should be no space between the upper and lower fifth wheel.

A maximum of two inches of space

Tractors without semi-trailers are referred to as bobtail tractors. Operating a bobtail tractor requires drivers to exercise caution.

A tractor attached to two trailers

A tractor protection valve keeps air in a tractor or truck air brake system should the trailer break away or develop a bad leak. The valve will close automatically if the pressure drops to an unsafe level.

A valve to keep air in the brake system should there be a bad leak

A valve that prevents a truck from being stolen

A valve that prevents the driver from driving too fast

A tractor protection valve keeps air in a tractor or truck air brake system should the trailer break away or develop a bad leak. The valve will close automatically if the pressure drops to an unsafe level.

Keeps air in the truck braking system if the trailer develops a leak.

Ensures that oil adequately lubricates the engine.

Protects the tractor from exceeding a set speed.

Keeps air in the truck braking system if the trailer develops a leak.

The trailer hand valve (also referred to as the trolley valve or Johnson bar) is a mechanism that works the trailer brakes. It should only be used to test the brakes. Using it while the vehicle is being driven could cause a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

Should only be used to test trailer brakes.

Should be used when parking uphill.

Combination Vehicles Practice Test | Virginia 2024 #2

Train for FREE online with our Virginia CDL combination vehicle test. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a VA combination license in 2024, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that DMV requirements for issuing a combination license may vary from state to state.

Number of Question 20

Passing Score 16

Number of Tests 20

Combination Vehicles Practice Test | Virginia 2024 #2

1 . If unsure if a trailer has an Anti-Lock Braking System (ABS), you can:

2 . The "crack-the-whip" effect can:

3 . How much space should be between the upper and lower fifth wheel?

4 . What is a bobtail tractor?

5 . What is a tractor protection valve?

6 . The tractor protection valve:

7 . A trolley valve:

See the exact questions that will be on the 2024 DMV exam.

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