Multi-mode starter-generator device transmission with single valve control

A power system for a work vehicle, comprising:

• an engine;
• an electric machine;
• a combination starter-generator device, having:
• a gear set configured to receive rotational input from the electric machine and from the engine and to couple the electric machine and the engine in a first power flow direction and a second power flow direction, the gear set configured to operate in one of multiple relatively high-torque, low-speed start gear ratios in the first power flow direction, including a first start gear ratio corresponding to a cold engine start mode and a second start gear ratio corresponding to a warm engine start mode, the gear set further configured to operate in a relatively low-torque, high-speed gear ratio in the second power flow direction corresponding to a generation mode;
• a first clutch assembly coupled to the gear set, wherein the first clutch assembly is engaged during the cold engine start mode to result in the gear set operating according to the first start gear ratio, disengaged during the warm engine start mode to result in the gear set operating according to the second start gear ratio, and engaged in the second power flow direction;
• a second clutch assembly coupled to the gear set, wherein the second clutch assembly is disengaged during the cold engine start mode to result in the gear set operating according to the first start gear ratio, engaged during the warm engine start mode to result in the gear set operating according to the second start gear ratio, and engaged in the second power flow direction;
• and
• a third clutch assembly that is engaged in first power flow direction during the cold engine start mode and the warm engine start mode and is disengaged in second power flow direction during the generation mode;
• and
• a single control valve fluidly coupled to selectively apply a fluid pressure to the first clutch assembly and to the second clutch assembly.