Flip Neck Box Mechanical RGN Question:

You should have your 5th wheel slid up alot farther when your detaching.
Too much weight hanging off the back end.
No reason not to run the rollers on top of the frame and 5th wheel slide.

When trying to pickup a heavy load,have the dog bones in the low position.
It will be easier to to get hooked up.
Air up and block the front of the the trailer.
Dump the air and pull the pin.
Pull out just enough to take the tension off the bones.
Rotate them to the high ride height.
And back into the pin.
If you're on soft ground,you may have to do this twice.

 

cutting that thin crossmember out in the fifth wheel slide was one of the first things I did.

 

This explanation is common sense, I never slide my fifth wheel loaded, I dropped the landing then dump the air suspension to take the weight off then slide or else you’ll bust the driveline. For your application, I would have done exactly what @Oxbow said if I was in your situation and I don’t even know set up nor done it. Only thing I’ve done is COZAD, and it’s close.

 

The only mechanical neck xl we have requires us to use 6 inch blocks under the front of the trailer deck when dropping or sliding the fifth wheel. But then once the fifth is in place for pulling the trailer there should be no need to slide it again.

 

When @ElmerFudpucker said that this Kenworth is too much truck for that trailer, I think he was suggesting that you will not be able to make full use of the truck. You might think that at least the truck is built for any weight that you are going to put on that trailer, and it certainly will, but it is so heavy ( I assume) that you penalize your self on what you can permit.

Different application and different laws in different states, but last week I hauled a 90k excavator on a 50 ton RGN and grossed about 132k. My tractor would be considered a light heavy haul tractor I suppose. It started life as a logging truck, has an 18 speed and 2 speed 46k rears, and a light tag axle but just a 12k steer.

The point behind this is that matching your equipment in order to maximize what you can haul is really important. Your situation makes me wonder if you could lose the drop axle, be able to put weight on the steer, and save 2000 pounds or so on your tare. Probably won't work, but an interesting thought.