A fluid transfer coupling comprises a first shaft assembly a second shaft assembly, and a seal assembly. The first shaft assembly comprises a first shaft and an annular fin attached to the first shaft, the annular fin having one or more internal passages extending therethrough. Each internal passage connects a centre portion of the first shaft to a radially outwardly facing side of the annular fin. The second shaft assembly comprises a second shaft and an annular trough extending radially outwardly of the second shaft.

A method of controlling the electric current of a linear solenoid valve by performing pulse width modulation on a coil current for energizing a linear solenoid of the linear solenoid valve to adjust the hydraulic pressure of a working oil in a hydraulic clutch for transmitting and interrupting the rotational drive power from a power source to a drive wheel of a vehicle. The method includes setting the period of the pulse width modulation to a shorter value as the degree to which the hydraulic clutch is engaged increases from a disengaged state thereof. Here, the period of the pulse width modulation may be set in accordance with the variation of a duty ratio depending on the hydraulic pressure corresponding to the degree to which the hydraulic clutch is engaged.

A method of controlling the electric current of a linear solenoid valve by performing pulse width modulation on a coil current for energizing a linear solenoid of the linear solenoid valve to adjust the hydraulic pressure of a working oil in a hydraulic clutch for transmitting and interrupting the rotational drive power from a power source to a drive wheel of a vehicle. The method includes setting the period of the pulse width modulation to a shorter value as the degree to which the hydraulic clutch is engaged increases from a disengaged state thereof. Here, the period of the pulse width modulation may be set in accordance with the variation of a duty ratio depending on the hydraulic pressure corresponding to the degree to which the hydraulic clutch is engaged.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

A vehicle drive includes a speed change mechanism connected to a rotary electric machine; an output member connected to the speed change mechanism and wheels; an engagement device changes a state of engagement between an input member connected to an engine and the speed change mechanism; a hydraulic pump driven by the engine or the rotary electric machine; a first pressure control device that controls pressure supplied from the pump and supplies the pressure to the speed change mechanism; a second, separate hydraulic pressure control device that controls the pressure supplied from the pump and supplies the pressure to the engagement device; and a case that houses the rotary electric machine, speed change mechanism, engagement device, and pump. At least the engagement device is housed in a space formed by the case, and the second hydraulic pressure control device is provided at a part of the case forming the space.

Apparatus, system and method for providing supplementary power. A vessel is configured to receive and contain hydraulic fluid, where the vessel includes a piston configured within the vessel to be vertically displaced by the hydraulic fluid and provide pressure from the weight of the piston to a fluid supply line. A solenoid valve is operatively coupled to the fluid supply line; and connected to a flywheel power supply that includes a flywheel and a hydraulic drive adapter, wherein the hydraulic drive adapter is operatively coupled to the solenoid valve via the fluid supply line. A signal is received indicating a power outage, where the solenoid valve is further configured to open in response to the signal and provide the hydraulic fluid pressurized by the piston to the hydraulic drive adapter and causes the flywheel to operate and provide the supplementary power.