Design of a modular multi-speed inner transmission for medical aids

This study presented a modular multi-speed inner transmission for medical aids. The proposed inner transmission can be directly applied to existing wheelchairs. A 5-link, 2-degree-of-freedom (DOF) epicyclic gear train is selected as the main body of the inner transmission, which provides a four-speed gear including a high-speed gear, a direct-drive gear, a neutral gear and a reverse gear. The power-flow path at each gear stage is also analyzed. The schematic diagram of a multi-speed inner transmission is presented for suiting to install on a wheelchair.