Help with some engineering issues on a folding tail gate ramp? Answered
I'm building a folding ramp to replace my tailgate on my truck. It's going to be used to load/unload a ztr lawn mower.
(It's been built primarily from discarded bed frames, with the addition of some expanded steel grating.)
Because these mowers are back heavy, and low to the ground, a longer ramp is needed than you need to load a conventional mower.
My solution is a spring loaded 8' ramp that is comprised of two 4' sections that fold down and out.
It functions, it fits, the mower goes up and down it ok.
The problem is that it is so heavy, that after it comes down about 2/3 of the travel, it is very difficult to control.
When it comes down hard, it puts tremendous stress on the center - where the two sections of ramp meet. It can be hard enough to break it.
I know my welding isn't the best, but that's really not the issue here. This is a design problem.
I'm going to post a few pictures, to better illustrate my situation, and to show some of the things I've tried to soften the blow.
The picture of the partially folded ramp was taken at the point where it begins to get difficult to lower without losing control.
So, to clarify, I need a way to lower and raise the ramp with more control, and or soften the blow towards the middle.
The springs I'm using are 140lb garage door extension springs, the largest springs available at any big box home center.
I need to get this finished yesterday, so I'm going to try some things while I'm waiting for a response, like move the springs back further in the bed to put more tension on the whole thing.
I'll also post this to the welding web forum, but I started here because I've got a lot of faith in the ingenuity of the instructables community.
If we get the bugs out of this thing and anyone wants it in instructable form, I'll do my best.
Thanks for reading the War and Peace of ramp questions.