If your vehicle gets stuck on railroad tracks for any reason, you should immediately exit the vehicle and walk away from the tracks. Contact the proper emergency authorities.

Exit the cab and walk away from the tracks.

Sit in the cab and call for help.

Exit the cab and walk away from the tracks.

Motion for another driver to push your vehicle.

Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "emergency" position, the air supply will be stopped and the trailer emergency brakes will be applied.

The trailer emergency brakes will be applied.

The vehicle will increase speed.

The trailer emergency brakes will be applied.

The air supply to the trailer will increase.

Combination vehicles need more space on the road than other commercial vehicles because they are longer and need more space to turn and stop. It is especially important to properly manage space when you are operating a combination vehicle.

Need more space to turn and stop than other commercial motor vehicles.

Drive more slowly than other commercial motor vehicles.

Are heavier than other commercial motor vehicles.

Need more space to turn and stop than other commercial motor vehicles.

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.

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 a brake system if there is a bad leak.

Prevents a truck from being stolen.

Prevents a trailer from being accidentally released.

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.

Combination Vehicles Practice Test | Iowa 2024 #1 Page 2 of 3

Train for FREE online with our Iowa 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 IA 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 | Iowa 2024 #1 Page 2 of 3

8 . If your vehicle gets stuck on railroad tracks, you should:

9 . If an air supply control is in its "emergency" position:

10 . Combination vehicles need extra space on the road because they:

11 . The tractor protection valve:

12 . A tractor protection valve:

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

14 . In a double or triple combination, the ____ trailer should be directly behind the cab.

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

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