The objective of this project is to design and test an off‐road manual wheelchair. The design has four main subsystems: a supporting frame that is broken up into an upper and lower frame, a drivetrain to power the wheelchair, a braking system to ensure that it stops when desired, and a suspension system to absorb impacts from off‐road obstacles. The team modified an existing Silver Sport 2 wheelchair by breaking it into two parts: an upper frame and a lower frame. The upper frame consists of steel tubing for the arm rests, leg supports, seat attachments, and brackets. The lower frame consists of steel tubing for attaching wheels and brackets. The brackets are used for mounting the other subsystems. We evaluated the performance of the frame using Finite Element Analysis based on the forces from the user and the other subsystems. For stopping the wheelchair, our design replaces the existing parking brake lever mechanisms with a typical caliper braking system used on bicycles. In addition, dynamic analysis was conducted to find the appropriate size brake pads based on various stopping distances. The drivetrain sub‐system uses chains and sprockets similar to those seen on mountain bikes to propel the wheelchair. Lever bars have been added to create a mechanical advantage that allows for easier propulsion. Finally, the suspension system includes four springs and dampers mounted between the upper frame and the lower frame to minimize impacts on the upper frame and provide a comfortable ride for the user. Fully assembled, this wheelchair will provide a new opportunity for wheelchair bound people to recreationally explore off‐road terrains.
