Abstract: A two-speed differential adapted for use in motor vehicle driveline applications. The two-speed differential is capable of selectively transferring power to either a first drive mechanism for establishing a first drive speed ratio or a second drive mechanism for establishing a second drive speed ratio. The selected drive mechanism then transmits power to an output mechanism for subsequent transmission to the driving axles of the motor vehicle while permitting speed differentiation therebetween. In one aspect of the present invention, the first drive mechanism provides a "direct drive" speed ratio and the second drive mechanism provides an "overdrive" speed ratio. In another aspect of the present invention, the first drive mechanism provides a "direct drive" speed ratio and the second drive mechanism provides an "underdrive" speed ratio.

Abstract: A two-speed differential adapted for use in motor vehicle driveline applications. The two-speed differential is capable of selectively transferring power to either a first drive mechanism for establishing a first drive speed ratio or a second drive mechanism for establishing a second drive speed ratio. The selected drive mechanism then transmits power to an output mechanism for subsequent transmission to the driving axles of the motor vehicle while permitting speed differentiation therebetween. In one aspect of the present invention, the first drive mechanism provides a "direct drive" speed ratio and the second drive mechanism provides an "overdrive" speed ratio. In another aspect of the present invention, the first drive mechanism provides a "direct drive" speed ratio and the second drive mechanism provides an "underdrive" speed ratio.

Abstract: The present invention provides a method and apparatus for controlling the hydraulic line pressure in an automatic transmission for a vehicle in response to the torque transmitted through the transmission such that a minimum hydraulic line pressure is provided to the frictional elements to achieve a no-slip condition through the transmission increasing transmission efficiency, thereby increasing the fuel economy of the vehicle. Hydraulic line pressure is controlled by activating a solenoid activated valve which allows fluid recirculation from the high-pressure side of the hydraulic pump to the low-pressure side of the pump. Control signals are generated based on engine speed, turbine speed, output speed (vehicle speed), hydraulic line pressures, driver selected gear, the operating gear and the torque converter operating condition for energizing the solenoid-actuated valve.