hydralic 4WD

DanJR1 · 6 Jul 2004, 11:22 (Ref:1027902)

you know that Yamaha are running a 2WD drive bike now using hydralics, would it be possible to run the system on a car? you could possibly run it on a lotus elise or caterham or maybe a WRC car! it would get rid of the propshaft and most that gear you need, might save weight?

egomeister · 6 Jul 2004, 12:05 (Ref:1027955)

Such a solution would be unlikely to save weight as you would require quite a volume of hydraulic fluid (not light!) and all the pumping/power transmission ancilliaries. The only real benefit I can see on a car would be that you could choose where the fluid is packaged in the car rather than having a propshaft straight down the middle of the car.

Morris 1100 · 6 Jul 2004, 12:38 (Ref:1028011)

There would be less power loss using electric motors than hydraulics but it would work but they are not as efficient as direct drive.

Cameron Winton · 7 Jul 2004, 11:35 (Ref:1029094)

Anyone see new Scientist two weeks ago? It had an interview with the Chief engineer at Liebherr - the producers of the worlds largest dump truck (it's very large!)
It uses a diesel electric system similar to that used on some train locomotives. Big diesel engine runs big generator. Big generator powers big electric motors in each wheel hub.
Theoretically, high voltage AC transmission is the most efficient (approx 98%) power transfer system. Compare that to the losses in a mechanical 4WD system (around 25%) and you will see it makes sense. Hydraulic power transmission is also a lot more efficient than gears etc but has higher losses than electrical transmission.
The big problem with all this is scale. It appears that the complexity & weight of non-mechanical transmission systems becomes a problem with small vehicles.
The clever thing with WRC cars would be to integrate all the hydro electrical control of power transmission with the actual transmission itself - classic Chapman in using one component to do many jobs