A transmission system includes planetary gearing with a ring gear, a plurality of planet gears, a carrier, and a sun gear, a forward clutch operatively connected between the ring gear and carrier, a reverse brake operatively connected between the carrier and a rotationally fixed location, and a control subsystem to switch the transmission system between forward and reverse operational modes in the which the ring gear and the sun gear rotate in the same or opposite rotational directions, respectively. A control subsystem actuation stroke can actuate both the forward clutch and the reverse brake based on a common control signal.

A drive assembly receives rotational power from an input shaft rotatable about a rotation axis. The drive assembly includes a drive housing to which is mounted a wheel bearing support of a wheel mount that is configured to rotate about the rotation axis on a wheel bearing assembly. A planetary set is coupled between the input shaft and the wheel mount to selectably cause rotation of the wheel mount. The planetary set substantially fits within axial borders of the wheel bearing support and within an inner radial dimension of the wheel bearing support.

A drive assembly receives rotational power from an input shaft rotatable about a rotation axis. The drive assembly includes a drive housing to which is mounted a wheel bearing support of a wheel mount that is configured to rotate about the rotation axis on a wheel bearing assembly. A planetary set is coupled between the input shaft and the wheel mount to selectably cause rotation of the wheel mount. The planetary set substantially fits within axial borders of the wheel bearing support and within an inner radial dimension of the wheel bearing support.

Methods for modifying certain prior art automatic transmissions to strengthen the transmission and eliminate a tendency of the transmissions to fail as well as components for doing the same. Some aspects also include kits for modifying a transmission to increase the strength of the transmission. In some examples, the hydraulic system of a General Motor's model number 4L80E transmission is modified so that an overrun clutch is engaged in more modes of operation than the original equipment prior art 4L80E transmission in order to minimize a tendency for an overdrive roller clutch to fail.

Methods for modifying certain prior art automatic transmissions to strengthen the transmission and eliminate a tendency of the transmissions to fail as well as components for doing the same. Some aspects also include kits for modifying a transmission to increase the strength of the transmission. In some examples, the hydraulic system of a General Motor's model number 4L80E transmission is modified so that an overrun clutch is engaged in more modes of operation than the original equipment prior art 4L80E transmission in order to minimize a tendency for an overdrive roller clutch to fail.

A first ring gear of a drive unit is connected to a second carrier and is mechanically connected to a counter shaft. A first sun gear is connected to a second sun gear and a first rotary electric machine. A first clutch selectively switches between a connection state and a disconnection state of the first sun gear and an engine. A second clutch selectively switches between a connection state and a disconnection state of a first carrier and the engine. A brake selectively switches between a fixed state and a release state of a second ring gear to and from a fixing member.

A first ring gear of a drive unit is connected to a second carrier and is mechanically connected to a counter shaft. A first sun gear is connected to a second sun gear and a first rotary electric machine. A first clutch selectively switches between a connection state and a disconnection state of the first sun gear and an engine. A second clutch selectively switches between a connection state and a disconnection state of a first carrier and the engine. A brake selectively switches between a fixed state and a release state of a second ring gear to and from a fixing member.

A hydraulic control device for an automatic transmission includes a shut-off valve arranged between a first pressure adjusting device and a respective shifting element cylinder of a plurality of shifting elements. In the first shifting position of the shut-off valve, the first pressure adjusting device is hydraulically connected to the respective shifting element cylinder through the shut-off valve. In the second shifting position of the shut-off valve, the shifting element cylinder is sealed by the shut-off valve relative to the first pressure adjusting device. The shut-off valve is an releasable check valve. The releasable check valve includes a check valve and an unblocking device. The unblocking device is actuatable by a control pressure from a second pressure adjusting device.

A hydraulic control device for an automatic transmission includes a shut-off valve arranged between a first pressure adjusting device and a respective shifting element cylinder of a plurality of shifting elements. In the first shifting position of the shut-off valve, the first pressure adjusting device is hydraulically connected to the respective shifting element cylinder through the shut-off valve. In the second shifting position of the shut-off valve, the shifting element cylinder is sealed by the shut-off valve relative to the first pressure adjusting device. The shut-off valve is an releasable check valve. The releasable check valve includes a check valve and an unblocking device. The unblocking device is actuatable by a control pressure from a second pressure adjusting device.

A system for locking and releasing a shifting position of a shifting element that is hydraulically actuatable by an actuating pressure is provided. The shifting element is arranged coaxially with a transmission shaft. The system includes a stop valve. The stop valve is subjectable to a control pressure that is separate from the actuating pressure of the shifting element. The stop valve is arranged radially inside the shifting element in the transmission housing.