Here’s an early (1990) build from the master builder down under. Ian Drysdale conjured up this interesting bike utilizing hydraulic drive on both wheels and, just for good measure, hydraulic steering on both wheels, as well. Powered by a 2 stroke engine, Ian named this the Drysdale Dryvtech 2x2x2.
Ian explains the drive system:
The pump pressurizes oil to around 4500psi which is then directed to hydraulic motors located in each wheel hub which convert the high pressure oil’s energy into rotary motion. By freezing time for an instant you can visualize one piston in the pump directly applying force onto a piston in a wheel motor via a long column of oil. Oil is effectively incompressible- so for a split second you can imagine the oil as a solid steel bar causing one pump piston to push on one motor piston. The speed of the bike is determined by the flowrate of the pump which is infinitely variable.
As for steering, there’s no direct mechanical connection to the wheels:
Turning the handlebars operates a hydraulic master cylinder which pressurises oil (separate from the drive system oil) and sends it down inflexible hoses to a ram (slave cylinder) mounted near the hub which moves the wheel. Both wheels are steered, but not together nor at a linear rate, while an accumulator (effectively a ‘hydraulic battery’) maintains steering system pressure.
There’s a LOT to look at here and understand and it was an early indicator that Ian was going to be building things a bit out of the ordinary. Reading through his extensive description of the bike, it does seem to have a few quirks. For instance, when the engine isn’t running, the wheels do not freewheel, they’re locked in place, which may be a bit inconvenient. There’s also the braking, which uses the hydraulic motors as brakes, something that didn’t work well and tended to blow out the seals.
On the whole, however, this is a veritable smorgasbord of mechanical wizardry in action. For a very detailed description and explanation of how everything works, the best place to look is on Ian’s website.
The bike was sold and went to the Donnington Motor Museum in the UK. The current owner, bought it a few years ago and took it back to Australia where it’s now for sale. It might be a nice opportunity for one of our many Aussie readers.