Hydromechanical transmission

A variable ratio hydromechanical transmission for propelling a vehicle comprising:

• a hydrostatic transmission including a fixed displacement hydrostatic unit and a variable displacement hydrostatic unit fluidly connected to the fixed displacement unit in a closed loop circuit by a pair of conduits;
• the fixed displacement hydraulic unit including a rotating assembly therein having an axial opening therethrough defined by a hollow shaft member;
• a planetary gear set including a rotatable ring gear, a carrier plate assembly rotatable within the ring gear and having an output member thereon, a sun gear coupled for rotation with the hollow shaft member, and a plurality of planetary gears rotatably mounted on the carrier plate assembly and simultaneously mating with the sun gear and the ring gear so as to drive the output member;
• the variable displacement hydrostatic unit including an input shaft drivingly connected to the ring gear and adapted to be connected to a source of rotational power;
• the fixed displacement hydrostatic unit being located between the variable displacement hydrostatic unit and the planetary gear set;
• and
• the input shaft extending coaxially through the hollow shaft member of the fixed displacement hydraulic unit.