A
system according to this invention for transmitting power hydraulically to and from the wheels of a motor vehicle includes an accumulator containing fluid at relatively
high pressure, a reservoir containing fluid at lower pressure, and a pump / motor driveably connected to the wheels and having an inlet, an outlet, and a variable volumetric displacement for pumping fluid between the accumulator and the reservoir. A first circuit connects the inlet to the reservoir and the outlet to the accumulator. A second circuit, which connects the inlet to the accumulator and the outlet to the reservoir, includes a first path having a low flow rate capacity, a second path having a higher flow rate capacity. A controller switches between pumping operation and motoring operation, opens and closes the first path during motoring operation, and reduces the displacement before switching between pumping operation and motoring operation. The first path includes a first valve responsive to the controller for opening and closing a connection between the accumulator and the inlet, and a first orifice arranged in series with the first valve having a relatively low flow rate capacity. The second path, arranged in parallel with the first path between the accumulator and the inlet, includes a second valve responsive to the controller for opening and closing a connection between the accumulator and the inlet, and a second orifice arranged in series with the second valve having a higher flow rate capacity than that of the first orifice.