An Improved Lever Drive Wheelchair Transmission

Principal Investigator/s: Michael L. Boninger, MD

Co Investigator/s: Rory Cooper, PhD, William Ammer, BS

9/2002-8/2004

While the traditional wheelchair design, employing pushrims for propulsion, is simple and reliable, it is unfortunately inefficient and injurious. Research conducted at HERL has shown that only about half of the force being applied to the pushrim produces useful torque. A lever drive wheelchair transmission has the potential to reduce all of the risk factors for wrist and shoulder injuries. In Phase I, a lever drive with a mechanical efficiency of over 90% has been demonstrated. The improvement in propulsion efficiency, coupled with the improved biomechanics of the lever drive, could substantially reduce new wrist and shoulder injuries, ameliorate existing injuries and allow some individuals the option of continuing to use a manual wheelchair. In this Phase II program, we will continue engineering development of the lever drive transmission begun in Phase I, incorporating shift-on-the-fly capability and dynamic breaking. Metabolic testing will be conducted on two models to document improvements in propulsion efficiency and in biomechanics.