The authors describe the main features of the internal spur gear including gear and pinion dimensions.
A new mechanical gearing system based on an internal spur gear attached
to each of the electric wheelchair's rear wheels, and accompanying
pinion drive gears, is offered as an alternative drive type to the worm
and worm wheel drive unit
Internal Gear Pinion Drive Operation Manual, Lab Instructor Guide and Student Workbook. Internal Gear Pinion Drive for Educational Vocational, Didactic Technical Training Equipment Labs.