The mock-up is constructed to showcase the mechanism by which the track slide design works to lift and lower the power wheelchair center-mounted footrest.
link to youtube video demonstrating use, and uses of several other designs:
Step 1: Materials
o Preferred with housing
o Spring force sufficient to move 5lb, 10 in. long mass
o Part used: Metal spring door closer (home depot)
"Features a non-handed design with adjustable closing tension. Easily mounts to the surface and can operate up to a 150 lb. load. (MFG Model # : KC10HD, MFG Part # : KC10HD)" - Homedepot.com
o part used: brass pull ring hand (McMaster Carr, part # 8482A421)
"retractable plunger, nonlck nose, 3/8 in- 16, w/o lock, 2.0 4.0 # end force" - Homedepot.com
o Length of cables allows stretch from spring plunger to hand operated lock release
o Hand-operated manual pull mechanism to lift spring plunger
o Tension such that the pin is moved with a deliberate hand motion
o Part used: Bike Brake ; Only handle and cable used
Two 80/20 aluminum bar segments
o 2 x 1 x (1 in. * height of seat well)
o 2 x 1 x 1 in.
hook - eye screw
Step 2: Mounting the Spring
Mount torsion spring to footboard (#1 in figure) using 1' screws.
Step 3: Mounting Board to Chair
Thread setscrew hole.
Drill one hole through the long face on top of small aluminum block, adjacent to face with three holes. Bit size to allow passage of torsion spring extender through small block.
Drill one hole on the same face, away from the center hole. Bit size matches that of spring plunger.
Thread spring plunger hole.
Assemble footboard with mounted spring to the small aluminum block with spring plunger (6) and secure to 80/20. It is recommended to attach a board to the opposite end of 80/20 to be laid on work surface for stability.
Step 4: Attaching Cable System
Pass the cable through the bracket. Using a sturdy connector (8), secure end of cable to top of spring plunger. Key ring was used.
Using an 80/20 fastener (9) secure the bracket to the side face of the longer 80/20 segment. Position such that cable is allowed to move during pull until connector meets bracket. Force of cable pull will lift plunger spring to remove locking mechanism and permit footrest to move.
Secure hook-eye screw (10) to outer face of long 80/20 and thread cable through such that it is guided up and around user legs.
Handle (11) can be laid next to the user when not in use.