Patent ID: 8075435

Claim:
A dual mode EPPV transmission hybrid electric drive system for propelling a machine using a combination of power sources, the drive system comprising: an internal combustion engine having an engine output for providing rotational power; a first electric motor having an output for providing rotational power; a second electric motor having an output for providing rotational power; and a transmission for receiving rotational power from the internal combustion engine, first electric motor, and second electric motor, and for combining the received rotational power into a transmission output power for propelling the machine, the transmission including: a first planetary gear set including a first sun gear linked to a first ring gear via a pinion on a first carrier, the first ring gear receiving rotational power from the engine output and the first sun gear being rotationally fixed to the first electrical motor; a second planetary gear set including a second sun gear linked to a second ring gear via a pinion on a second carrier, the second carrier being rotationally fixed to the first carrier and to a transmission output, and the second ring gear being rotationally fixed to the second electrical motor; and a first clutch selectively linking the first sun gear to the second sun gear and a second clutch selectively braking the second sun gear such that when the first clutch is engaged, the transmission exhibits a first mode of power transmission characteristics and when the second clutch is engaged the transmission exhibits a second and distinct mode of power transmission characteristics.