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Texas CDL DMV Combination 2

Take 6 practice tests for CDL is the best way to prepare for your Texas DMV exam is by taking our free practice tests. The following question are from real Texas 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 the truck from being stolen
A valve that prevents the driver from going too fast
A valve that prevents the trailer from accidentally being released

In a combination vehicle with air brakes, the tractor protection valve keeps air in the tractor or truck brake system in the event of the trailer breaking away or developing a leak.

2. To help prevent rollovers, you should:
Accelerate quickly after stopping.
Drive slowly around turns.
Keep the load near the back of the trailer.
Keep the load on one side of the trailer.

To lower the risk of a rollover, load your cargo as closely to the ground as possible. To further reduce this risk, take curves and corners slowly.

3. When coupling a trailer:
Make sure to couple matching glad hands.
Any glad hand can be connected to any other glad hand.
It is best to leave one glad hand unattached.
Only one set of glad hands should be connected.

When coupling, make sure you couple matching glad hands. They are often color-coded to help drivers avoid mistakes. Typically, blue is used for service lines and red is used for emergency lines.

4. Rollovers happen when:
A truck driver is driving too fast.
The driver of a vehicle in front of a truck is moving to slowly.
A truck driver is driving too slowly.
ABS is working effectively.

Rollovers happen when a vehicle is driven too fast. To reduce the risk of rollover, make sure the weight of cargo is loaded low to the ground, and that you take turns and curves slowly.

5. 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.

6. When driving a bobtail tractor, you should be aware that:
Bobtails stop very easily.
Bobtails cannot drive as fast as tractors with semitrailers.
Bobtails are more difficult to stop than tractors with semitrailers.
Bobtails are illegal in most states.

Bobtail tractors are tractors that are not attached to any semitrailers. When operating a bobtail, you should be aware that stopping can be difficult and that it will take a longer distance to bring the bobtail to a complete stop than it would a tractor attached to a loaded semitrailer.

7. Large combination vehicles take the longest amount of time to stop:
When fully loaded.
When partially loaded.
When empty.
When mostly loaded.

Large combination vehicles take longer to stop when they are empty than when they are loaded. The decreased weight causes a vehicle's wheels to have decreased traction on the surface of the road.

8. In a double or triple combination:
Cargo weight must be evenly distributed between all trailers.
The heaviest trailer should be positioned directly behind the cab.
The heaviest trailer should be positioned in the rear.
The weight of the trailers does not matter.

When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.

9. Before backing your tractor under the trailer, make sure your trailer brakes are:

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. Before backing your tractor under the trailer while coupling, make sure your trailer brakes are locked.

10. The best way to recognize that your trailer has begun to skid is by:
Seeing other drivers' faces.
Seeing it in your mirrors.
Feeling it.
Listening to the radio.

The earliest and best way to recognize the beginnings of a trailer skid is by seeing the trailer veer off-course in your mirrors.

11. Having ABS on only one axle:
Does not change braking in any way.
Is not possible.
Will allow the driver additional control over their vehicle when braking.
Will cause extra strain on the other axles.

Having an Anti-Lock Braking System (ABS) on only the trailer, or even on just one axle, will still provide a driver with additional control over the trailer when braking.

12. Pull out the trailer air supply control to test:
The parking brake.
The trailer emergency brakes.
The trailer service brakes.
The landing gear.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

13. When backing a trailer, how should you turn the steering wheel?
Turn the top of the steering wheel in the direction you want the trailer to go.
Turn the top of the steering wheel in the direction opposite of where you want the trailer to go.
It doesn’t matter.
It depends on where the trailer is being backed.

When backing with a trailer, turn the top of the steering wheel in the direction opposite of where you want to go. Once the trailer begins turning, you should then switch the direction of the steering wheel to follow the trailer.

14. After finishing a pre-trip inspection, you should:
Close the service line valve.
Remove the service line valve.
Leave the emergency line valve open.
Leave the rear shut-off valves open.

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 to listen for escaping air. Close both shut-off valves before beginning to drive.

15. One way to prevent a rollover is to:
Move cargo to the left side of the rig.
Keep cargo centered on the rig.
Move cargo to the right side of the rig.
Keep cargo as far from the ground as possible.

A rollover is more likely if cargo is unevenly loaded in a rig. To help prevent a dangerous rollover, it is important to keep a load as centered on the rig as possible.

16. Driving a combination vehicle ____ than driving a single vehicle.
Is easier
Requires more driving skill
Is better for training
Is safer in inclement weather

Driving a combination vehicle usually requires more skill than driving a single vehicle. Combination vehicles are generally longer and heavier than single commercial vehicles.

17. Simply changing lanes can cause:
A “crack-the-whip” effect, resulting in a rollover.
A trailer to straighten out.
Confusion over which lane the driver is hoping to use.
Other drivers to reduce their speed.

Due to the "crack-the-whip" effect caused by rearward amplification, changing lanes too quickly in a combination vehicle can result in a rollover.

18. A trailer will be most likely to swing around when:
It is full.
Traveling in a straight line.
It is empty.
The wheels are rotating.

An empty trailer will require a longer stopping distance than a loaded trailer. Additionally, a trailer is most likely to swing out and strike other vehicles when it is lightly loaded or empty.

19. Proper coupling technique:
Is the same on all vehicles.
Is essential to the safe operation of a vehicle.
Includes ensuring that the fifth wheel plate is not greased.
Can be learned over time.

Knowing proper coupling and uncoupling technique is fundamental to the safe operation of combination vehicles. Improper coupling can be very dangerous.

20. When driving a tractor-trailer equipped with ABS, you should:
Stop harder than you would otherwise.
Use extra braking force to ensure the ABS kicks in.
Brake as you normally would.
Brake using less pressure than you would otherwise use.

When driving a tractor-trailer combination equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would in a vehicle without ABS.

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