Older trailers do not have spring brakes. This means that if the air supply in an older trailer's air tank has leaked away, there will be no working brakes connected to the trailer and its wheels will turn freely.

The trailer will not have brakes.

The trailer will stop normally.

The trailer will not have brakes.

Positioning the weight of a load on one side of a trailer may cause the trailer to lean to that side, increasing the risk of a rollover during turns and lane changes.

May add extra support during turns.

May be easier to steer during turns.

Fully-loaded rigs are more vulnerable to rolling over than empty rigs because the weight of the cargo gives the vehicles higher centers of gravity.

Are more likely to roll over than empty rigs.

Usually are very responsive to steering.

Are more likely to roll over than empty rigs.

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.

It prevents a vehicle's wheels from locking up.

It allows a vehicle's wheels to lock up.

It prevents a vehicle's wheels from locking up.

It makes turning a vehicle easier.

You should always steer gently and smoothly while pulling a trailer. Making sudden steering moves could cause the trailer to tip over.

Make sudden turns with the steering wheel.

Push the accelerator to the floor when starting from a stop.

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.

The tractor protection valve will close.

The service brakes will activate.

The tractor protection valve will close.

The rear trailer will detach from the combination.

Combination Vehicles Practice Test | Oklahoma 2025 #2

Train for FREE online with our Oklahoma 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 OK combination license in 2025, 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 | Oklahoma 2025 #2

1 . Older trailers are not equipped with spring brakes. This means that if the air supply for a vehicle's air braking system leaks away:

2 . If a load is placed on one side of a trailer, the trailer:

3 . Fully-loaded rigs:

4 . During a trip, landing gear should be:

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

6 . When driving while pulling trailers, you should:

7 . If the emergency air line loses pressure:

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