CDL Combination Vehicles Practice Test

Instructions:

This practice test consists of 20 multiple-choice questions designed to help you prepare for the CDL Combination Vehicles endorsement test. Choose the best answer for each question.

1. What is the most common cause of trailer jackknifing?

A) Turning too sharply
B) Over-acceleration
C) Braking too hard on slippery surfaces
D) Driving too slowly

2. What should you check for when inspecting the coupling system during a pre-trip inspection?

A) Ensure the fifth wheel is properly greased and locked onto the kingpin
B) Make sure the kingpin is loose in the locking jaws
C) Verify that the fifth wheel is tilted away from the cab
D) Check that the fifth wheel is resting on the trailer landing gear

3. When backing a trailer, which side is the safest to back towards?

A) Blind side (passenger side)
B) Sight side (driver’s side)
C) It doesn’t matter
D) Backing straight is safest

4. When should you use the trailer hand valve?

A) During normal driving
B) When parking the trailer
C) To test the trailer brakes
D) During emergency stops

5. Why should you use caution when parking a trailer that is not attached to a tractor?

A) The trailer brakes might not hold
B) The trailer can roll away if not properly secured
C) The trailer may lean or tip over
D) All of the above

6. Which part of the kingpin should be inspected for wear?

A) The top flange
B) The shank
C) The head
D) The locking groove

7. What is the main purpose of the glad hands?

A) To connect the electrical lines between the tractor and trailer
B) To connect the air lines between the tractor and trailer
C) To lock the fifth wheel in place
D) To secure the trailer to the landing gear

8. How can you prevent a trailer from rolling over on a sharp turn?

A) Speed up through the turn
B) Keep the load centered and reduce speed
C) Make sure the load is stacked high
D) Apply the trailer hand valve while turning

9. What should you do if the service air line comes apart while driving?

A) The trailer brakes will lock up automatically
B) You will have normal braking ability
C) The trailer emergency brakes will apply
D) The tractor brakes will fail

10. What is off-tracking?

A) When the trailer swings wider than the tractor during a turn
B) When the trailer follows a different path than the tractor during a turn
C) When the trailer wheels lock up during braking
D) When the tractor and trailer are not aligned properly

11. Why should you never unlock the pintle hook with the dolly under the rear trailer?

A) It could cause the dolly to be damaged
B) It might cause the trailer to roll over
C) It could make the landing gear collapse
D) The dolly tow bar might fly up

12. When coupling, why should you ensure that the fifth wheel is tilted down towards the rear of the tractor?

A) To allow easier access to the kingpin
B) To prevent damage to the kingpin or fifth wheel
C) To ensure the trailer will not roll away
D) To make it easier to attach the glad hands

13. How often should you check the mirrors when driving a combination vehicle?

A) Every 5-8 seconds
B) Every 10-12 seconds
C) Every 12-15 seconds
D) Only when changing lanes

14. Why is it important to drain the air tanks regularly in combination vehicles?

A) To remove condensation that can freeze and cause brake failure
B) To reduce pressure in the system
C) To increase the braking power
D) To prevent overfilling

15. What happens if the trailer is overloaded?

A) It will increase stopping distance
B) It could cause a rollover
C) It may lead to a mechanical failure
D) All of the above

16. When should you test the trailer brakes?

A) After you have started driving
B) Before starting your trip as part of the pre-trip inspection
C) When you arrive at your destination
D) Only if you suspect a problem

17. What is the purpose of the trailer air supply control valve?

A) To control the flow of air to the service brake chambers
B) To apply and release the trailer emergency brakes
C) To control the air pressure in the tractor tires
D) To drain moisture from the air tanks

18. Why is it important to avoid sudden movements when driving combination vehicles?

A) Sudden movements can cause the load to shift
B) It can lead to a trailer jackknife
C) It can result in a rollover
D) All of the above

19. What should you do if you notice your trailer begins to skid while driving?

A) Apply the brakes harder to stop the skid
B) Let off the brakes to regain traction
C) Steer in the opposite direction of the skid
D) Accelerate to pull out of the skid

20. What is the correct way to couple a trailer?

A) Back up quickly to latch the fifth wheel
B) Back up slowly until the fifth wheel just touches the trailer
C) Position the tractor and trailer in a straight line before coupling
D) Raise the trailer until it is slightly above the fifth wheel

Answer Key:

This practice test is designed to provide an accurate assessment of your knowledge of combination vehicles, which is crucial for passing the CDL Combination Vehicles endorsement test. Review each question and answer carefully, and make sure you understand the reasoning behind each correct answer. For more resources and study materials, visit FreightRelocators.com.

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