20 Tests

CDL Combination Vehicles Practice Test Online | Wyoming 2021

Train for FREE online with our Wyoming 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 WY combination license in 2021, practice as much as.. Read More

Train for FREE online with our Wyoming 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 WY combination license in 2021, 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.

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1 . What does an Anti-Lock Braking System (ABS) do?

An Anti-Lock Braking System (ABS) helps prevent wheel lockup during hard braking. If ABS detects impending lockup, it reduces braking pressure to a safe level.

2 . What does the trailer air supply control look like?

It is a circular orange knob. On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.

3 . When driving a combination rig, following distance should be:

Longer than when driving a single vehicle. In comparison to driving a single vehicle, you should maintain an extended following distance when driving a combination rig. Combinations require longer stopping distances than smaller vehicles.

4 . When driving a trailer with ABS, you should:

Try to not brakes as often as you would when driving a vehicle without ABS. When driving a tractor-trailer combination equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would if operating a vehicle without ABS.

5 . Using the trailer hand brake while experiencing a trailer jackknife will:

Continue the skid. If you are experiencing a trailer jackknife, you can help your tires regain traction by releasing the brakes. Using a trailer hand brake while experiencing a skid will only cause the skid to continue.

6 . If the emergency air line loses pressure:

The tractor protection valve keeps air in the trailer's braking system should the trailer break away or develop a leak. A loss of air pressure in the emergency line will cause the tractor protection valve to open and the emergency trailer brakes to activate.

7 . Before a drive, ensure that air flows to all trailers by:

Rolling each trailer down a hill and testing the brakes. Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.

Wait, before you go

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