This is the set of plans for the construction of the ramp seen in the picture.
It is a shelf at the right held up by 4 4x4 posts that are bolted to the floor and the rafters. The ramp is made from 1-5/8 thick lumber held together for a surface that is 18 inches wide. It is reinforced by 2x4s to prevent sagging. The buggy in the picture weighs 1200 pounds with most of the weight in the rear. The ramps are hinged back from the left end to add length when lowered. The entire system is raised and lowered by a 12 volt winch mounted below the rafters over the shelf.