Thanks . It was fun building this trailer. I started with a standard full frame and ended up with a deluxe 1/4 frame
Here it is now that I have all the arms made and lift motor installed. The arms work perfect and Incan get a hair over 45 deg lift . The rear 1/4 frame stays level the whole time the box is raising. I set up the arms so it puts a little rake into the 1/4 frame so it leans forward putting more weight on the drives. This will help with traction after the load comes out. It was a fin balancing act to get the arms to work and keep things level.
The tractor 5th wheel now has an aluminum plate under it so the plastic does not bend when lifting the loaded box. I also had to "bar" the 5th wheel so it stays level as the arms need to pivot at the front. I plan to taper the front of the arms before final assembly so the trailer sits lower up front yet still have a slight rearward slant just like the real ones often do.
The down side is I don't think the screw drive is going to work.it currently has a 4:1 reduction with a integy 85 turn motor. It will barely lift itself at the start of its travel. Once it gets going it is fine but it's stressed even with the 4:1...
I was going to buy the rc4wd 16:1 and see how well that does before investing in a hydraulic cylinder and pump kit.
Thanks for looking