2wd

2WD

Next stop, streetbikes?

Two-wheel-drive might not be a dirtbikeonly experiment. There are other technologies that may one day make 2WD attractive on the street as well. One is regenerative braking, now being contemplated for trucks and buses used in stop-and-go urban driving, Instead of throwing vehicle kinetic energy away as heat in

friction brakes, such systems employ hydraulic pumps at each wheel, generating brake torque by forcing fluid into a `high-pressure accumulator. If the pumps are already there to act as brakes, it would be tempting, under appropriate conditions, to use them also as motors, allowing front wheels to be powered. Given appropriate hardware and con trols, power could be sent to whichever wheel had traction. At present, hydrostatic drives like this have only moderate efficiency as compared with shaft or chain.

Too complicated? The Yamaha/Ohlins 2-Trac system used

on the tuning-fork company's Dakar Rally bikes is a hydraulic drive, and there is discussion of adopting it for production. So, too, is KTM con templating a small run of 2WD models that would make use of the Ohlins technology. Those systems consist of a chain that drives a hydraulic pump above the engine's gearbox, connected by pressure hoses to a hydraulic

motor located at one endothetrontaxie. Christinrsau mechanical AWD, as described in the accompanying article, is less complex but might not offer the ability to make on the-fly front-wheel-drive ratio changes, whereas Ohlins is working on such a feature with its hydraulic system.

A natural next step for two-wheel-drive would be to see how the concept works on a supermoto bike. If there are any potential advantages for this technology on pavement, that is probably where they will first be discovered.

Kevin Cameron