Hydro-mechanical continuously variable transmission for producing high torque output

A transmission for a vehicle comprising:

• an engine drive shaft configured to be driven by an engine;
• a planetary gear unit configured to be driven by power from the engine and to provide power to drive a transmission output shaft;
• a hydrostatic drive unit configured to be driven by power from the engine and to drive a primary hydrostatic drive shaft;
• an engine clutch configured to be driven by the engine to drive an input sun gear of the planetary gear unit while engaged;
• a secondary hydrostatic drive shaft configured to be driven by the primary hydrostatic drive shaft and to drive a ring gear of the planetary gear unit;
• a hydrostatic output clutch configured to be driven by the secondary hydrostatic drive shaft and to provide power to drive an output sun gear of the planetary gear unit while engaged;
• a high torque clutch configured to be driven by a planet carrier of the planetary gear unit and to drive the transmission output shaft;
• a low torque clutch configured to be driven by the output sun gear of the planetary gear unit and to drive the transmission output shaft;
• and
• a controller configured to cause the hydrostatic output clutch and the high torque clutch to be engaged and to cause the engine clutch and the low torque clutch to be disengaged to cause the planetary gear unit to operate in a hydrostatic differential mode while the vehicle is not moving, or while the vehicle is moving at low speeds.