[KarlInOhio]

A guy named Ferguson (he owned the Massey Ferguson tractor company) was showing off a car he had invented. The vehicle was powered by oil or similar fluid under pressure in a tank under the hood. Two hoses led to each wheel and the fluid was forced against an enclosed fan on each wheel. Then it was returned to the holding tank..when under braking the fluid reversed the jets and stopped the car.

You can't return the depressurized oil which has been used to drive the wheels to the pressurized tank without some mechanical pumping and therefore an outside energy source. Think of blowing up a balloon and using the pressurized air to do some work. The air you've used can't just return to the inside of the balloon because all of the air inside would push it back out. You could use the energy from braking to pressurize some of the oil and put it back into the tank, but you still have some permanent losses from friction and air resistance.

If you had a destination pressurized resevoir after each or all the wheels, the main resevoir could work until the secondaries reached the same pressure as the primary when you hit an equilibrium with no more power transfer - think of one ballon blowing up a second one while you took some of the energy from the transfer.

[norraad]

This similar to the hydroneumatic energy system introduced in the 1955 Citroen.

A wonderful little swash-plate rotor pump worked it up to almost 3000psi with reservoirs & auto valves, etc.

Aspects of this design are yet to be fully utilized our half a century later.

i.e. that little pump would be great as a fuel pump.

Run your injectors at 3000 psi instead of the 60~70 psi dribble.