how to slide the fifth wheel
on a big rig truck

It's pretty simple to slide the fifth wheel on a big rig. There are a few important steps involved in moving the fifth wheel, in order to  transfer weight from the drive axles to steering axle, successfully.

If a truck driver isn't familiar with the method of moving the 5th wheel on his rig, he can easily damage it when maneuvering in tight spaces, so this is an essential skill for a trucker to learn.

Moving the Fifth Wheel on a Big Truck 

  • The first thing to do, when getting ready to make adjustments to it's position, is to lower the landing gear enough to take the weight and pressure from the fifth wheel and slider mechanism.

 This will make the adjustment easier on the truck, but yet not add so much ground pressure to the landing gear, that the legs begin to lift the drives off the ground and the truck looses traction. The trailer brakes must be locked.

  • Once the landing gear is lowered, the next step is to pop the pins on the slider. This is done by flipping the slider switch on the dash of the truck, forcing air pressure to push the pins on either side of the fifth wheel into the release position.

All truckers should know that it is important after flipping the switch, to get out of the truck and visually check both pins to ensure they have released properly.

TIP: Keep these pins lubricated with a spray lubricant, to keep them sliding freely. If these pins are stuck, it can be a nightmare, to get them to release.

What to do if the pins won't slide

If one of the pins does not slide out and release, gently rock the tractor back and forth to release the pressure on the pin, allowing it to slide.

If the pin still does not release, listen for an air leak. Air pressure can pop these pins out and if there is an air leak, there probably isn't enough pressure to allow the pin to release.

Once both pins are out, slowly and carefully move the tractor slightly forward or back, depending on where you need to move the weight.
If you need more weight on the steering axle to get as close to the 12,000 lb allowance as possible, gently back the tractor farther underneath the trailer.

Bear this in mind.... keep a close eye on the distance between the front face of the trailer and the back of the tractor. If you are too close with the tractor to the trailer, it will destroy the swing-dip clearance. If the tractor and trailer are too close to each other, they may hit, when taking a corner or going up a driveway.

Produce haulers need to take precaution when loading at produce docks, as they often have a steep dip in front of the loading dock, which can cause the truck and trailer to collide when backing in. You'll not want to explain the big dents in the back of the cab to the boss.

Pins on a Fifth Wheel

The general rule of thumb is every cog on the fifth wheel slider represents 100 lb. Howeve, do keep in mind, every rig is different.

For example, if 400 more lb. on the steering axle is needed, move the fifth wheel ahead four notches, reset the pins and recheck axle weights on a weigh scale. Ensure both slider pins are locked back in and the landing gear is rolled back up before heading back to the scale.

This procedure may take a few attempts to get it right, but it will save you time and trouble at the DOT highway scales, if you arrive there with your axle weights, CORRECT EVERY TIME.

The coops are not lenient when it comes to incorrect axle weights.

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