With apologies to LittleB for hijacking his thread:
Converting a motorcycle/ATV lift to a real platform type lift only requires that you replace the top and bottom horizontal members with longer ones.
Most lifts of this type have a lifting area of about 12" by 16" and use a jack to control the diagonal dimension of a parallelogram. If you change the length of the top and bottom members, the same work is accomplished, almost. In truth, when the jack starts up the leading member (closest to the jack) starts up first and helps the trailing member to get started. When you increase the length of the top and bottom members this "help" is diluted by the length of the top member. In other words, the leading member on a stock machine advances five or six degrees ahead of the trailing member and helps to pull it up. Unfortunately when the length of the top member becomes 8' those five or six degrees become one or two degrees. The end result is that the jack ends up pulling against the frame as if it's trying to crush the bottom member. The solution is to not allow the top member drop all the way down. I accomplished this by adding two 2X4 posts to the back corners of the top frame. This added two inches to the height of the platform but allowed the jack to pull against a diagonal instead of straight ahead force. Look for the posts, they're there. The all thread is 1/2' and I used metal plates to distribute the forces to avoid splitting the wood members.
Ckeck it out:
Hope this helps.
KZCSI
Post edited by: KZCSI, at: 2007/07/24 19:15