just need advice:(

It's the same principle because you have two pivot points. One at the pintle hitch and the other is the turn table under the pup's front wheels.

 

That dude has too much freaking time on his hands!

 

My 2 cents, Put your hands at the bottom of the steering wheel , want the trailer to move right , turn steering wheel right while backing , turn left ? Turn wheel left while backing.

 

That won't work for a truck and pup setup.

 

Im sure there is an app for this....

http://www.google.com/patents/US5348332

 

Try and visualize what the dolly tounge will do as the rear of the truck changes direction while going in reverse. Then try and visualize how this movement will affect the dolly 5th wheel pivot, and how this will then act like a normal truck/trailer back. So, with your additional pivot point, your initial tractor turn will be opposite of how it is with a typical tractor-trailer rig.

Imagine the beginning of the back should be handled no differently then how you would steer to back your car. But be sure to make subtle changes to truck direction heading.

 

What type of truck?

 

Mentioned earlier it's a long tractor with a pup trailer hooked up with a dolly/pintle at the rear. Something like this I think...

 

Excattly only with tanks instead of dump boxes.