ADA Wheelchair Lift 

This product was intended to be retrofitted into existing "tilt-up dock height" buildings to provide wheelchair access to the main entrances. These kind of buildings are very common - they typically are the big, low concrete slab buildings where the one main floor is raised up about four feet off the ground so it's the same height as the inside bed of big trucks. Usually at these buildings, there is a small set of stairs at the front door you walk up to go in the main door.

After the Americans With Disabilities Act went into affect, the owners of these buildings had to provide wheelchair access to their tenants in these buildings when there was a change in tenancy. The simple solution would have been to add a wheelchair ramp up to the front door. However, the slope of these ramps has to be fairly shallow and it would have made the ramp some 48 feet long. Even with it doubled back on itself, it still would wipe out four or five parking spots.

The other alternative was to build a small elevator in essence. That's where I came in. This particular client came to Teague and we designed for him this mini-elevator. It only lifted up four feet and the "car" was three feet wide and five feet long. But it would have worked.

Unfortunately, the client canceled the project. It turns out it would have been too expensive to build this lift. It was going to be cheaper for him to take existing "home" lifts similar to this and modify them to meet the necessary codes.

Still, it was a fun design project. The design we came up with used a large 220V AC motor of about 2 horsepower that would turn a set of four "Acme screws" to raise and lower the wheelchair platform. It was also designed to be modular so the two side frames, the platform and the motor drive frames could be built as subassemblies in the factory and delivered to the site in a full size pickup instead of a large truck. The final assembly would take place on-site. Think of the Ikea "knock down" furniture approach and you've got the idea.

We did all the design on Pro/Engineer and fully detailed it and made a complete set of drawings. Once the client got the pricing, he decided to put a stop to the project and we wrapped it up.

Here are some more images of the product. Click on any of the images to see a bigger version:

This shows the entire assembly from a Pro/Engineer screen shot. The wheelchair platform is the large white "pan". It goes up and down with the side frames and door to keep you from falling off. The motor and drive system is on the dark red frame in the back. (This view is a back view). The person enters the platform at ground level via the small white swing out door on the platform. What is not shown here are the cosmetic side panels and clear plastic windows.

This is a closeup of the drive system. The big yellow can is the 2 HP electric motor. It goes into a green two-way power splitter. Each output of the splitter drives a 90 degree coupler (in violet) that drives the long green drive shafts. Each of the two drive shafts have worm gears that turn the vertical Acme shafts (bright blue). The platform is raised and lowered by "Acme nuts" that travel up and down the Acme shafts as they turn. These nuts are tied to the platform and convert the rotation of the shafts into vertical motion. Lots of parts, but fairly simple in principle. Most of these powertrain components are off the shelf commercial parts. Some are stock parts with some modifications while a few are fully custom fabricated.

Last updated: November 09, 1996