Lot details
Registration No: NI-573
Frame No: N/A
Engine No: DT3-001
cc: 250
MOT Expiry Date: N/A

The concept of a two wheel drive motorcycle is one that has held a fascination for motorcycle engineers over the years and has resulted in production machines appearing. Perhaps the best known examples are the recently announced Yamaha system that has been applied to some of their off road machines with a degree of success and the Rokon motorcycle tractor. The Drysdale offered here took the concept to a much higher level incorporating not only two wheel drive but alo two wheel steering. The machine was conceived and built by the Drysdale Motorcycle Company of Dandenong, Victoria, Australia. Intended for desert use the prototype is reputed to have absorbed over 3,500 man hours in its design.
At the heart of the machine is a 250cc two stroke engine based on a 1977 Maico power unit, with new crankcases machined from solid by Drysdale. A spacer is fitted under the barrel in order to detuen the motor slightly. In order to achieve the two wheel drive required, the designers adopted an hydraulic system utilising a Vickers aerospace nine cylinder bent axis piston pump originally fitted to the North American Sabre jets land gear to provide the hydraulic pressure. The pressure provided by the pump is supplied to independent front and rear motors of a five cylinder design with a rotating housing and stationary shaft. Two drive options are available one in parallel split between the two motors giving a top speed of 50 kph and the second in with the two motors being driven in series resulting in a top speed of 100kph. A valve in the return to the main pump, activated by a right foot pedal provides the braking with the system acting on both wheels simultaneously. The steering system is again hydraulic utilising a pre-pressurised system that is independent of the transmission. A delay of 5 degrees has been designed into the steering box to enabling normal countersteering to be employed. Controls are restricted to the brake pedal previously mentioned, a left foot pedal that must be depressed and held down to keep the bike in drive and a conventional throttle mounted on the unconventional handlebars that were specifically designed to protect the riders hands.
This intriguing machine has been housed in the Donnington Grand Prix Collection for the last twenty years.