Introduction: Instructions for Making a Four Bar Linkage Attachment for Center Mounted Footrest
Mid-drive power wheel chairs (PWC) have become more popular in recent years. However, due to the placement of the front casters, the traditional side-mounted footrests have been replaced by a single center-mounted footrest. Unfortunately, center-mounted footrests do not have a lift/lower mechanism that is easily operable by certain PWC users who transfer independently. Many PWC users have limited trunk strength and range of motion, decreased sensitivity in their lower body, and lack of fine motor function. This causes difficulty reaching the footrest to raise it. There is a need for a design solution that allows PWC users to independently lift and lower the footrest.
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Step 1: Replacing the Pin to Lock Bar Into Place
Replace hinge pin on existing footrest with round metal rod and drill set screws into the hinge to lock bar into place.
Step 2: Cut Two Plastic Pieces
Cut two plastic pieces approximately 4" by 1" by 1".
Step 3: Cut Two Wooden Bars.
Cut two wooden bars. One approximately 17" in length and the other approximately 5" in length. Width and depth should be 1" by 1".
Step 4: Drill Two Holes Into Both Ends of Each Plastic Piece
Drill two holes into both ends of each plastic piece. Three of these holes should be of slightly bigger size than normal size screws. They should be able to have a screw slip in and out. The fourth hole should be the size of the metal bar used in the hinge and should hold it firmly. Insert metal bar into this hole and drill set screw in plastic piece to hold metal bar in place.
Step 5: Drill a Hole in the 17" Wooden Bar
Drill a hole in the 17" wooden bar. Drill the 5" wooden bar into the top of the other side of the wooden bar.
Step 6: Connect Two Ends of Plastic
Connect other two ends of plastic pieces together with screw and nut as shown.
Step 7: Connect End of Wooden Bar
Connect end of wooden bar to plastic piece with screw and nut as shown.
Step 8: Adding Hinge to the Wooden Bar
A hinge can also be added to the wooden bar to allow for clearance when bar is in maximum vertical position.
Step 9: Making Case to House the Wooden Bar
A casing such as the one shown can also be made to house the wooden bar.