In 1921 a 7 hp type with a Coventry-Victor twin-cylinder engine ( capacity : 689 cc ) and friction drive was added for one year only followed in 1924 by a four-cylinder 10 hp type with a Dorman engine of 1, 094 cc, but very few were made.
22.
This can take one of three forms : integrated with the hub of hand-propelled wheels, so that any force on the pushrims is magnified by the drive system, or mounted under the wheelchair and controlled as for a powerchair, but with the motive force either transmitted to the main wheels via a friction drive system, or delivered directly through an auxiliary drive wheel.
