We all have dreams. But those dreams generally don't involve reinventing the motorcycle with a fetishistic devotion to hydraulics. Ian Drysdale is the exception, and his two-wheel-drive, two-wheel-steer, hydraulically-driven Dryvtech 2x2x2 is proof you can build your dreams. And now you buy it.
This freak of engineering excess popped up a few years back when it was bought from the Donnington Motor Museum in the UK and shipped to its current owner in Australia. But Drysdale's obsession to create a hydraulically-driven, 2WD bike started in the late 80s and was eventually completed several years later. And it's utterly fucking nuts.
To begin with, the custom-built 250cc 2-stroke single doesn't drive the wheels – at least, not in the traditional sense. The engine drives a hydraulic pump rather a gearbox, with oil pressurized inside to 4,500 PSI. That hyper-pressurized oil is then sent through metal tubes and pushed into two radial hydraulic motors – hub-mounted on each wheel – where it spins the five pistons inside to power the wheels.
Think of it like an electric motor, but rather than spinning a rotor, it uses the oil to spin pistons. By varying the flow rate of the oil, it can then speed up or slow down the wheels. It also allows an infinitely variable torque split between the front and rear wheels, essentially analog torque vectoring. And just like an electric motor, it can also act as the brakes, which is exactly what it does rather than use discs or drums.
But driving the wheels is only part of this mutant's hydraulic repertoire – pressurized fluid is also used to steer each wheel independently.
There's no mechanical connection between the handlebars and the wheels. Instead, turning the bars pressurizes oil in a hydraulic master cylinder, sends it down a set of lines to a slave cylinder, which then applies force to push the wheel left or right. The steering attitude is different at each end, allowing the front wheel to turn while the rear stays straight – a plus if you don't want to highside this beast at 80 MPH.
Obviously, this level of complexity and lunacy creates some… issues. Without the hydraulic pump being driven, the Dryvtech would be damn-near impossible to steer. And Drysdale admits the same goes for the wheels, which won't spin when the engine is off. Also, y'know, leaks. But as a functional, ridable experiment and a testament to engineering over common sense, you have to give the guy credit. If you want to get into the details, he's published an exhaustive breakdown, and if you want it, the bidding starts at $10,000 AUS.