This allows the reversing tractor to contact the trailer bolster plate, to permit it to slide up onto the ramp, to raise the nose of the trailer, and allow the kingpin to be aligned with the access opening into the open jaws of the fifth wheel. The ramp is the welded steel component that slopes upward from the rear of the tractor frame toward the fifth wheel plate. When a trailer’s upper coupler plate and front underbody area displays excessive damage, you can often blame an incorrect fifth-wheel pick-up ramp. Other problems could include a rotary operating rod that has slipped out of its track, a rod assembly that has not been properly adjusted, or lock arm indentations that are worn at the mating surfaces of the rear jaw.
#Repair on nuway trailers fifth wheel driver#
This can be caused when a jaw opening is spread too far apart in a high-coupling attempt and a driver still forces the kingpin lock in place. The end result affects the tractor’s ride height, which thrusts up against the nose of the trailer. Kingpins can also apply upward pressure on the jaws if air bags on a tractor aren’t properly inflated. At the very least, the constant to-and-fro movement between the fifth wheel jaws and the trailer kingpin would buck the connection, wearing the kingpin and jaws. If there was a lot of slack, a trailer could be dropped as the truck bounces down the road. The jaw must retain its hold and allow rotation around the kingpin for turns. Since we don’t want to lose trailers on the road, the fifth wheel jaws have to be adjusted to ensure a secure clamping force to provide minimal slack between the fifth wheel and the trailer. You can also face problems if the jaws are adjusted too tight. Here, all you need to do is slowly back a tractor into the trailer to relieve the pressure.
This can be caused when you park on an incline, and the mass of the trailer and its kingpin applies pressure against the lock jaw of the fifth wheel. Other issues can surface and make it difficult to uncouple the trailer.Ĭonsider cases when the kingpin applies longitudinal pressure to the jaw. Other problems can include a top plate that has been damaged just below the jaw pin a rotary operating rod that has slipped out of its track a shim which is far thicker than the recommended spec’s or a missing handle accelerating spring.īut don’t think that the issues are limited to coupling. Packed snow, ice or dirt can also restrict the workings of the lock, and be a problem around the fifth wheel shims, backing plate and buffing rubber. A bent cover plate can interfere with the movement of the lock, while a jammed safety latch can also cause grief. Just try to couple smoothly if you’ve a bent lever bar, lock arm, or operating rod. Then again, bumps, bends and jams are other sources of problems. So too can you have problems if the jaw opening has spread too far apart because someone tried to couple to the trailer when the kingpin was sitting too high. (The remedy here is to check the adjustment using a new SAE kingpin or special test gauge.)īut an inexperienced mechanic, a worn kingpin, or even problems with a fifth wheel’s adjustment mechanism could all be the cause of initial trouble.
#Repair on nuway trailers fifth wheel series#
For example, you can over-adjust for trailer kingpin slack on an ASF Simplex Series Slack-Free design. One source of trouble can be a jaw pin that has over-adjusted for kingpin slack, although the make and model of fifth wheel will determine the cause of this problem. As simple as a fifth wheel can appear to be, problems experienced as you couple or uncouple to a trailer can be linked to an array of issues.
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