2015 • Robotics • Digital Fabrication
The Hand Drive employs a dual ratchet mechanism that converts back-and-forth rowing motions into forward or backward wheelchair movement. One ratchet is spring-engaged by default, transmitting force from the rowing handles to the wheels for forward motion using larger muscle groups than traditional hand-rim pushing. A brake lever on the handlebar allows the user to disengage the forward ratchet and engage the reverse mechanism, enabling backwards travel through the same rowing motion. The design is optimized for fused deposition modeling 3D printing, with nearly all components printable on consumer-grade machines. The open-source files and assembly instructions make the system accessible globally at less than 1% the cost of commercial alternatives. The rowing motion keeps hands cleaner and provides better ergonomics by distributing force across back and arm muscles rather than relying solely on hand and wrist strength. 
