Although coupling and uncoupling tractors and trailers is a regular occurrence for truck drivers, it isn’t for most vehicle technicians. Careless technicians can be a danger to others as well as themselves. When done improperly, coupling/uncoupling can present serious hazards, possibly resulting in a tractor runaway or trailer rollaway situation that could result in costly equipment damage or serious, and even fatal, injuries.
Charles Rosato, field service manager, Fontaine Fifth Wheel (www.fifthwheel.com) – a world-wide manufacturer of fifth wheels, offers these basic bests practice for proper coupling and uncoupling.
COUPLING
- The fifth wheel release (pull) handle needs to be extended and the lock is open.
- Ensure that the fifth wheel jaw and wedge are out of the throat and the pull handle is in the extended position.
- Make sure the fifth wheel is at the proper height in relation to the trailer. Back the tractor up toward the trailer and stop just before the fifth wheel reaches the front of the trailer. Suspension airbags should be fully inflated.
Get out of the cab and make sure the fifth wheel is at the proper height to slightly lift the trailer when backed under it. To establish proper coupling height, raise or lower the trailer by adjusting the landing legs.
- Slowly ease the tractor backward until the fifth wheel connects with the trailer’s kingpin.
- Verify that there is no space between the top of the fifth wheel and the trailer’s kingpin plate. If there is space, the kingpin is not coupled.
In that case, slowly ease the tractor forward until the fifth wheel comes out from under the trailer. Inspect the filth wheel for any damage. If damage is found, repair or replace the fifth wheel before attempting to re-couple to the trailer.
Repeat the coupling procedure until there is no space between the fifth wheel and the trailer’s kingpin plate.
- Be sure the pull handle is fully retracted (is in the closed position) and the fifth wheel jaw and wedge are in a closed position across the throat of fifth wheel.
Use a flashlight and go under the trailer and look into the back of the throat. The locking mechanism should be engaged across tile entire fifth wheel throat and secured to the trailer’s kingpin.
- Connect the air and electrical lines.
- Raise landing gear all the way up and secure the crank handle, if so equipped.
UNCOUPLING
- Make sure that the trailer is positioned on a level surface that is firm enough to will support the weight of the trailer.
- Lower the trailer’s landing legs.
- With the trailer brakes locked, release the tractor brakes and back slowly into the trailer to ease the pressure on the fifth wheel locking jaw.
-Engage the parking brake while the tractor is pushing against the trailer’s kingpin.
- Lower the landing legs.
- Disconnect the air and electrical lines from the trailer.
- Release the fifth wheel lock by pulling the release handle.
- Slowly pull out from under trailer until the fifth wheel clears the trailer’s kingpin.
- Dump the air from the tractor suspension (if so equipped) and drive carefully away from under the trailer.
Do not dump suspension airbags prior to opening the fifth wheel lock. This will cause a difficult to open condition and possibly damage the fifth wheel lock.
