I saw the first working example of hydrostatic drive over 30 years ago. A hydraulic "motor" in each hub was light enough not cause any problems with unsprung weight.

Alas it appears that the only people who use hydrostatic drives today are the builders of those massive earth movers.

I think that the window of opportunity for this technology has come and gone. I suspect we'll see electric motors in each hub before hydraulic units.

L. J.

Yes, and to answer the question regarding "widespread acceptance", I doubt either one will have (or generate) much currency. The more complicated a system, the more things can break down, thus rendering simplicity an even greater virtue. As an example, power windows are nice, but give me hand cranks any day. At least if the handle breaks off, I can fit a vice-grip pliers on and keep the rain out.

Enviroman wrote: "The more complicated a system, the more things can break down, thus rendering simplicity an even greater virtue."

I agree. If you and I are correct, then simplicity and reliability will likely drive designers and manufacturers towards electrically driven cars.

I quickly pondered a four wheel drive system of both types and the regulators needed to provide differential speeds in turns and the slippage on snow, wheel to wheel.

Electric hubs won hands down.

When you consider that after 50 years, the automatic transmission continues to be the most costly item on the option list and the one most likely to fail, it adds further arguments for electric hubs and drive trains.

Detroit automakers are populated by a myopic leadership however. Common sense does not seem to play a part in their decision making.

L. J.

Depends on how you define your terms. If you believe that greed is good, then they probably ARE applying common sense.

A trend in the automotive world has been smaller faster spinning electric motors.

Ford and General motors used a direct drive starter motor, Chrysler used a smaller motor and a gear reducer to multiply the torque. Now all cars use this design. Electric door locks used to be solenoids, now they are very small electric motors and a plastic gear train. Plastic gears are cheaper than copper. I believe that improvements in electric motors will improve electric powered vehicles. I think hydraulics will remain as means to transmit power and motion

After studying hydraulic hybrids for my design project in university I have to say the only problem we found was the pressure storage needed to contain a significant amount of energy...assuming you want regenerative braking. Hydraulic drive by itself is good for routing power in places where typical drive shafts cannot go but the losses involved with fuild flow through pipes does reduce it's efficiency a bit.

What we did was figured out what off-the-shelf hydralic motor could be fit to the rear differential of a vehicle (rwd or awd of course) to be able to either capture/contribute power at that point. This way the wheel assemblies and the normal drive components under the hood remain intact and unchanged. A variable displacment hydraulic motor would be able to either drain kinetic energy from the vehicle by pumping hydralic fluid into a nitrogen filled (bladdered) accumulator. This pressurized fuid could then be bled back through the motor to contribute to the kinetic energy of the vehicle. Keeping the tanks nearby and using the maximum hose diameter and minimum length minimized the fuid losses. A well insulated accumulator would prevent the heated nitrogen (heated from the compression) from escaping. Variable displacement motors are already available and accumulators too...it all came down to how much pressure you could risk in a vehicle but this seems to be less of an issue with newer composites. I seem to recall 5000psi.

Would be fun to play around with given the time and components.

For more info see: www.innas.com

Lots more answers to find. Hydraulics are not so bad at all but new and further developed systems have a much better efficiency.