Automatic transmission for electric wheelchairs.

A new infinitely variable automatic transmission called the RESATRAN that automatically changes its speed ratio in response to load torque being transmitted is presented. A prototype has been built and tested on a conventional three-wheeled electric motor propelled wheelchair. It is shown theoretically that more than 50 percent reduction in power during hill climbing may be expected when a transmission-equipped wheelchair is compared to a direct-drive vehicle operating at the same voltage. It is suggested that with such a transmission, wheelchairs can use much smaller motors and associated electronic controls, while at the same time gaining in efficiency that results in longer operating distances for the same battery charge. Design details of the transmission and test results are presented. These results show a substantial reduction in operating current and increased distance of operation over a test course.