Drysdale Dryvtech 2x2x2 Is a 2-Wheel Drive, 2-Wheel Steering Hydraulic Wonder

Drysdale Dryvtech 2x2x2 16 photos
Photo: Ian Drysdale
Drysdale Dryvtech 2x2x2Ian riding the Drysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2 in actiomDrysdale Dryvtech 2x2x2 steering systemDrysdale Dryvtech 2x2x2 steering with a 5-degree delay between the front and the rear wheelsDrysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2 has a 250cc 2-stroke engineDrysdale Dryvtech 2x2x2 front hub motor and steering ramDrysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2 exhaustDrysdale Dryvtech 2x2x2 rear wheelDrysdale Dryvtech 2x2x2Drysdale Dryvtech 2x2x2 has a simple set of controls
You have to admit that the title has already gotten more of your attention than you’d expect. It’s alright, the same thing happened to us when we stumbled upon the Drysdale Dryvtech 2x2x2. This bike prototype is so far out that it’s hard to even decide what to start with. A 2-stroke quarter-liter engine powering a high-pressure hydraulic pump which feeds power to two hydraulic hub motors and which also operates 2 steering rams… and everything on a motorcycle is definitely not a thing we see every day, is it?
The project is functional and is an emanation of Springvale, Victoria-based Drysdale Motorcycle Company, one of Australia’s most interesting bike-makers. And you should definitely know that company boss Ian Drysdale is in fact famous for the jaw-dropping V8 bikes he delivers.

Going fully-hydraulic

Ian thought about changing the main drive principle of a motorcycle to hydraulics and while this was at first a rather easy task, he thought to add two-wheel drive later introducing hydraulic steering and two-wheel steering in the game. The result is a peculiar, yet spectacular motorcycle which is as peerless as it is intriguing when you look at it the first time. Oh well, and the second and the third time and so on…

The principle is quite simple. The 250cc 2-stroke gas engine does not operate the transmission, but a bent-axis 9-piston radial pump. If you expect to see a traditional bike transmission you’ll be disappointed, as there is none aboard the Dryvtech 2x2x2. The pump pressurizes hydraulic fluid to 4,500 psi (310 bar), and this makes the Dryvtech 2x2x2 a piece of high-pressure hydraulic equipment.

The pump sends pressurized fluid to two radial motors mounted in the very hubs of the bike. Given the high pressures used, the lines are actual steel pipes. Two of the braided lines which can be seen in the photo are conveying lower-pressure fluid to the steering rams, while the third is a motor case drain.

You’ll obviously learn that there are no brakes aboard the Dryvtech 2x2x2. Well, there are no disc brakes, but the hydraulic motor acts like a braking system, much like regenerative brakes do on electric motorcycles.

Hydraulics is truly fun, even if this doesn’t seem like it

Some may think that a hydraulic drive system is weird, feels weird and has some sort of mysterious lag to it. This may be because of the progressive action of their car or motorcycle brakes, but the braking system is much different in certain aspect from hydraulic motors.

First off, we should remind everyone that hydraulic fluids are exceedingly stable and have virtual no compression factor. This means that a hydraulic system which contains no air bubbles or other fluids is technically incompressible. If you want, the pressurized fluid inside the pipes is as solid as metal. Think about the connection rods inside a gas-powered engine and you’re pretty much there.

If we could freeze time a bit, we could imagine the hydraulic pump connected to the hub motors of the Dryvtech 2x2x2 by means of a connection rod. Zero lag, zero “flabbiness” in the system, but a very responsive assembly which also provides infinitely-variable speed and torque delivery.

Using pressure-reducing valves, the torque can be controlled for each wheel in a parallel setup. Further developments could have the two hydraulic motors in a series setup, with the rear one first and the fluid then passing to the front hub, allowing the design to provide a different level of control over the torque deployment.

The bigger front wheel of the Dryvtech 2x2x2 is also helping prevent cavitation, which is the fastest and surest way to kill a hydraulic pump. High-pressure motors have a 5 percent internal leak when used close to their full capacity. Given the high psi values in the system, a 5% pressure difference may be enough to cause the cavitation effect with critical damage as a result.

Cavitation occurs when the pressure drops close to the vapor pressure limit inside a fluid, and vapor bubbles form. As the bubbles travel ahead and reach a high pressure area, they implode and send small shock waves which affect the surface of the pump and piping elements, destroying it in time.

Steering may seem weird, but you’ll get along

Ian says that a two-wheel steering motorcycle may be a little frightening the first times one rides it. There is no mechanical connection between the handlebars and the wheels, as everything is done by means of hydraulics. The two wheels are connected to the same system, but rotating the bars has its own way of making the wheels turn.

Normally, the rear wheel is “locked” and it starts turning only after you have rotated the bard past a certain degree. Even more, the steering ratio makes everything even weirder. For the first 5 degrees, the steering ratio is subunitary and the rider may feel the need to turn the bars more.

After this point, things return back to normal, with a 1:1 ratio, just like in the case of a normal fork. For the last 10 degrees, however, when the rear wheel steering kicks in fully, the Dryvtech 2x2x2 will provide more turn than a traditional bike for the same handlebar movement. Ian says riders will quickly get used to this system, and will most likely enjoy it more than traditional ones.

The 5-degree “delay” between the two wheels may feel weird, but it really does the job. With a 45-degree bar turning angle, the Dryvtech 2x2x2 provides 22 degrees of turn for both the front and the rear wheels. This offers a better turning circle than what a bar rotated at 45 degrees on a traditional bike would yield.

“The Dryvtech 2x2x2's drive itself is outstanding, with wheelspin virtually impossible even in sand or mud. The steering and drive combine to make it impossible to slide the back out – the bike will actually highside the rider in mud,” says Ian. Still, the system remains to be tested more extensively at higher speeds in the future. The experimental state of the bike and its limited braking capacity makes such type of tests an iffy matter now.

The all-hydraulic bike has some drawbacks

The Dryvtech 2x2x2 has certain drawbacks, and the biggest one seems to be that steering or moving it when the engine is shut down is impossible. The wheels could become mobile with a special bypass valve which would allow such a movement.

Braking still needs a lot of improvement, as the only method the Drysdale Dryvtech 2x2x2 uses now relies on routing the return oil through a pipe and a valve which restricts the flow and causes the motor to act as a pump. Ian is also thinking about adding a system which can store the energy accumulated during braking and use it to add a boost when needed. However, such a solution is very complex and bulky, but not impossible.

If you feel like adding a dash of experimentalist thrill to your life as a rider and want to throw a leg over the Drysdale Dryvtech 2x2x2, the bike is up for grabs on the Aussie eBay, with a bid starting at AU $10,000, which is $8,375 or €6,760. Read more about the Dryvtech 2x2x2 on Ian Drysdale’s dedicated website. And if you just want more bizarre, high-tech bikes, read this article on the amazing Geco, the shape-shifting motorcycle.
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