ELDT - Entry Level Driver Training Entry Level Driver Training Coupling and Uncoupling 1 — Questions and Answers
Question 1: When connecting air lines to a trailer during coupling, which hose should be connected first?
- Either hose — the order does not matter
- The emergency (blue) glad hand first (Correct answer)
- The service (red) glad hand first
- Both hoses must be connected simultaneously
Correct answer: The emergency (blue) glad hand first
The emergency (blue) glad hand should be connected first. If the service line were connected first and the emergency line were left disconnected, the trailer brakes would release, creating a runaway hazard. Connecting emergency first keeps the trailer brakes applied until the system is fully connected.
Question 2: What should you do with the tractor parking brakes before beginning the uncoupling process?
- Release them so the tractor can roll away freely
- Apply them to hold the rig in place (Correct answer)
- Set only the trailer brakes, not the tractor brakes
- Brakes are not required if the vehicle is on level ground
Correct answer: Apply them to hold the rig in place
The tractor parking brakes must be applied before uncoupling begins. This prevents the tractor from moving unexpectedly while you are disconnecting the kingpin, air lines, and electrical connections, which could cause serious injury.
Question 3: Before backing under a trailer to couple, you should inspect the fifth wheel plate and ensure it is:
- Dry with no lubrication to maximize friction
- Properly lubricated to allow smooth coupling and reduce wear (Correct answer)
- Tilted upward at the rear to guide the kingpin
- Removed and reinstalled after the kingpin is seated
Correct answer: Properly lubricated to allow smooth coupling and reduce wear
The fifth wheel plate must be properly lubricated before coupling. Adequate lubrication reduces wear on both the fifth wheel and the kingpin, ensures the kingpin seats correctly, and allows proper trailer articulation during turns.
Question 4: After fully coupling a tractor to a trailer, what is the correct procedure for raising the landing gear?
- Raise it only halfway so it can be quickly lowered if needed
- Leave it in its current position until you reach your first stop
- Raise it completely and secure the crank handle (Correct answer)
- Landing gear must be removed before driving
Correct answer: Raise it completely and secure the crank handle
Landing gear must be raised completely before driving. Partially raised landing gear can strike the ground on dips or bumps, causing loss of control or structural damage. The crank handle must also be stored securely so it cannot fall and become a road hazard.
Question 5: During the uncoupling process, when is the correct time to disconnect the air lines and electrical cord?
- Before lowering the landing gear
- After the tractor has driven away from the trailer
- After the landing gear is down but before releasing the fifth wheel (Correct answer)
- It does not matter — disconnect them in any order
Correct answer: After the landing gear is down but before releasing the fifth wheel
Air lines and the electrical cord should be disconnected after the landing gear is lowered and supporting the trailer but before releasing the fifth wheel latch. This sequence ensures the trailer is stable before you remove connections, and prevents the lines from being dragged when the tractor pulls away.
Question 6: What does it indicate if the kingpin does not lock into the fifth wheel jaws when you back under the trailer?
- This is normal — drive forward slowly to seat it
- The coupling is complete and no further action is needed
- The trailer may be too high, too low, or the fifth wheel jaws may be worn or damaged (Correct answer)
- You should increase reverse speed to force the kingpin into place
Correct answer: The trailer may be too high, too low, or the fifth wheel jaws may be worn or damaged
If the kingpin fails to lock, the trailer is likely set at the wrong height, or there may be a defect in the fifth wheel jaws or the kingpin itself. Never force a coupling or assume it seated correctly — inspect the height, the fifth wheel condition, and the kingpin before attempting again.
ELDT - Entry Level Driver Training Entry Level Driver Training Coupling and Uncoupling 1
When connecting air lines to a trailer during coupling, which hose should be connected first?