There was a recent article on Autoblog about the SmartDrive MX2, a device that attaches to conventional wheelchairs to provide power assistance. It’s a small electric motor, battery pack and drive wheel on a frame that attaches to the back of any manually powered wheelchair. The motor can either maintain a steady speed when a user cannot use both hands, such as when rolling a suitcase through an airport, or to power forward, like as when ascending a hill on a hiking trail.
The interesting thing is how similar the concept is to the Briggs & Stratton “Motor Wheel” which was introduced over a century ago.
The device was a small motor, gas tank and drive wheel attached to a steel chassis that could easily be attached to a bicycle. The Briggs & Stratton Flyer was a four-wheeled buckboard car with a Motor Wheel on the back, creating an early version of what now might be called a go-kart, although it was for personal transportation rather than joy-rides.