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Arkansas CDL DMV Combination 1

Take 6 practice tests for CDL is the best way to prepare for your Arkansas DMV exam is by taking our free practice tests. The following question are from real Arkansas DMV practice test. More than 95% people pass a DMV exam when practice at DMV Practice Test.

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1. What is a tractor protection valve?
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.

2. In a combination rig, it is best to make:
Quick, sudden stops.
Sharp turns.
Quick accelerations.
Slow, planned stops.

When driving a combination vehicle, it is important to brake well in advance and look far ahead of your vehicle to avoid the need for sudden stops. Making habits of these actions will help you prevent your trailer from jackknifing.

3. What is off-tracking?
When a vehicle’s front wheels follow a different path than its rear wheels
When a vehicle's wheels all follow the exact same path
When a load shifts during a turn
When a vehicle's wheels run over a curb during a turn

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is known as off-tracking, or "cheating."

4. When braking while pulling a trailer equipped with anti-lock brakes, you should:
Pump the brakes.
Use extra braking force to ensure the brakes kick in.
Brake as you would without anti-lock brakes.

When driving a tractor-trailer combination that is equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would if the vehicle was not equipped with ABS.

5. A driver should test the tractor protection valve by:
Pulling the yellow, diamond-shaped knob.
Releasing air with the brake pedal.
Unlocking the trailer doors.

You should test the tractor protection valve by allowing the air supply to properly charge, turning off the engine, then releasing air from the system by pressing the brake pedal several times. The tractor protection valve should move into its emergency position when psi drops to an unsafe level.

6. Pushing in the trailer air supply control will:
Supply the trailer with air.
Deactivate the air brakes.
Prevent the vehicle from skidding.

Push in the trailer air supply control to supply the trailer with air. Pull out the trailer air supply control to turn off the air supply and activate the emergency brakes.

7. When should the trailer hand valve be used?
Only when the trailer is carrying a load
Only to test the trailer’s brakes
Only in inclement weather when the trailer may skid

The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. Using it while a vehicle is in motion could cause a skid.

8. What happens when the wheels of a trailer lock up?
The trailer will often continue to move in a straight line.
The trailer may disengage.
The trailer may swing around.
Steering will become easier.

A trailer may swing out and strike other vehicles if its wheels lock up. This is especially likely with lightly-loaded trailers.

9. During a trip, which shut-off valves should be open?
All shut-off valves should be open.
The rear shut-off valves should be open.
All shut-off valves should be in the open position, except the rear shut-off valves.
No shut-off valves should be open.

When starting a trip, be sure that all shut-off valves are in the open position, except for the last valves on the rear trailer. It is important that air reaches the brakes on all trailers and that the air is not able to escape from the back of the vehicle.

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

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.

11. If color-coded, which color is used to identify service lines?

Air lines are sometimes color-coded to help drivers avoid mistakes when coupling glad hands. Typically, blue is used for service lines and red is used for emergency lines.

12. When lightly loaded, combination vehicles:
Should not be driven.
Have reduced braking capabilities.
Will not rollover.
Should be loaded with most of the weight in the rear of the trailer.

When a combination vehicle is lightly loaded, it may have poor traction. It is very easy for wheels to lock up on lightly-loaded vehicles when they are being stopped.

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

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.

14. The service air line is attached to the:
Relay valves.
Supply line.
Emergency air line.
Steering wheel.

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.

15. An air supply control in its "emergency" position will:
Turn on the air supply.
Apply the trailer emergency brakes.
Prevent a skid.
Accelerate the 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.

16. If the emergency air line loses pressure:
The service brakes will activate.
The tractor protection valve will close.
The rear trailer will detach from the combination.

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.

17. Before beginning a trip, you should:
Leave the service line valve open.
Remove the relay valves.
Close the emergency line valve.

Before a trip, you should ensure that air reaches all air brakes on all trailers by opening up the rear emergency line and service line shut-off valves and listening for escaping air. Close both shut-off valves before beginning to drive.

18. Rollovers happen when:
Drivers turn too quickly.
Drivers turn too slowly.
It is raining.

Rollovers occur when drivers turn or change lanes too quickly.

19. Which of the following types of vehicles is most prone to the “crack-the-whip" effect?
An automobile
A three-axle tractor
A bobtail tractor
A triple combination

Double and triple combinations are the most vulnerable to turning over as a result of the "crack-the-whip" effect.

20. If a load is placed on one side of a trailer, the trailer:
May lean during turns.
May add extra support during turns.
May be easier to steer during turns.

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.

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