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.
Auction is over and it’s unlikely you’ll ever see that one for sale again.
Yeti2bikes says
Ian Drysdale… You have vision brother!
Paulinator says
Interesting rig. Much easier to tap power with hydraulic flex-hoses than with any other mechanical means (with the exception of maybe flex-drive cables?). I could see torque limitations and power losses cutting into the performance, but a light-weight Rokon with taller / narrower wheels would go literally anywhere that a person may consider walking.
KGB says
4500 psi eh? Tell you what, if that system leaks in the right place, and close enought to you, it will easily drive hydraulic fluid deep into muscles. It’s an ugly bit of cleanup job in the ER.
WillyP says
Merry Christmas to Paul, your family, and fans of the Kneeslider!
Paul Yak says
This is the similar as Ohlins did for the 2WD experiment. They said it had great potential especially for less experienced than pro riders (ALL of us). Though big companies didn’t R&D any further.
With electronics available fairly cheaply at present, the 2wd/2wsteer could be made to work in really low friction conditions such as DAKAR Rally. ABS, Traction, Anti-Wheelie.
I think the way to market this is as an add-on for trail/road/MX bikes, attach to engine an have your own power take off for the hydraulics. Trying to change motorcycle manufacturing difficult, trying to make a load for us guys to attach to existing machinery to get better grip, safety in bad conditions PRICELESS!
Ian Drysdale says
Apologies for my late reply to this post, I’ve been crazy busy ( trips to China plus moving factories ), thanx for the nice comments.
I have been working on a new mechanical 2WD system for some years that will be a “kit” – my aim was to make it “bolt-on” with no frame or engine modifications required and I believe that I have achieved this. Its currently in “mock-up” stage, still several months from being testable, and them only if I can find the time to dedicate to it.
It will fit most 450 class bikes, but not all, for reasons I won’t go into at present.
Paul, pls note new website: http://www.drysdale-v8.com.au
Cheers IAN
Cheers IAN
Jax Rhapsody says
Pretty neat, I’ve been thinking about building a modern version of that halftracked minibike, since I figured out how it works. I have two ideas on a 3wd r/t, I don’t have the means to do.