Hydrostatic transaxle

A hydrostatic transmission located within an internal chamber formed by a surrounding housing member provided with an input power shaft connection and an output power shaft connection and whereby a portion of said housing member protrudes into said internal chamber to divide said internal chamber into a pump chamber and a motor chamber, said portion includes within its internal structure a plurality of fluid power transmitting passages;

• a hydraulic pump disposed in said pump chamber and coupled to said input power shaft connection and a hydraulic motor disposed in said motor chamber and coupled to said output power shaft connection, said hydraulic pump and said hydraulic motor each being provided with fluid coupling surface and each said fluid coupling surface having a respective pair of arcuate-shaped ports;
• said hydraulic pump having a swash-plate and an adjacently disposed cylinder barrel and where said cylinder barrel can be said to reside in a location between said input power shaft connection on the one hand and said swash-plate on the other hand, said cylinder barrel being formed with first and second end faces and containing an array of generally axially arranged cylinders, a piston disposed in each cylinder and said each cylinder terminating in a port at the first end face of said cylinder barrel, the pistons protruding from said cylinders at the second end face of said cylinder barrel to operatively connect with said swash-plate;
• wherein the rotating axis of said hydraulic motor can be said to be disposed parallel and offset with respect to that fluid coupling surface engaging said cylinder barrel on said piston side of said the first end face of said cylinder barrel.

A hydrostatic transmission located within a chamber formed by a surrounding housing member provided with an input power shaft connection and an output power shaft connection and comprising a hydraulic pump coupled to said input power shaft connection and a hydraulic motor coupled to said output power shaft connection;

• said housing member having within its internal structure a pair of fluid power transmitting passages allowing fluid communication between said hydraulic pump and said hydraulic motor, said hydraulic motor having a thrust-plate member having an inclined operational surface or capable of being inclined to a plane normal to the axis of rotation of said hydraulic motor and an adjacently disposed cylinder barrel, said cylinder barrel having a plurality of generally axially extending bores therein each defining a cylinder, a piston within each said bore, said cylinder barrel including a base having ports therein in communication with the respective said cylinders, said base having a planar outer surface;
• a fluid coupling surface provided by said housing and formed with arcuate-shaped ports and where said pair of fluid power transmitting passages connect with a respective one of said arcuate-shaped ports;
• and wherein said planar outer surface of said base faces and engages said fluid coupling surface such that said arcuate-shaped ports are adapted to register with successive said ports in said base of said cylinder barrel upon rotation between said cylinder-barrel and said fluid coupling surface.

A hydrostatic transmission located within a chamber formed by a surrounding housing member provided with an input power shaft connection and an output power shaft connection and comprising a hydraulic pump coupled to said input poster shaft connection and a hydraulic motor coupled to said output power shaft connection;

• said housing member including a portion protruding into said chamber to provided a fluid coupling surface formed with arcuate-shaped ports and including within its internal structure a pair of fluid power transmitting passages allowing fluid communication between said hydraulic pump and said hydraulic motor;
• said hydraulic motor having a thrust-plate member having an inclined operational surface or capable of being inclined to a plane normal to the axis of rotation of said hydraulic motor and an adjacently disposed cylinder barrel, said cylinder barrel having a plurality of generally axially extending bores therein each defining a cylinder, a piston within each said bore, said cylinder barrel including a base having ports therein in communication with the respective said cylinders, said base having a planar outer surface and where said pair of fluid power transmitting passages connect with a respective one of said arcuate-shaped ports;
• and wherein said planar outer surface of said, base faces and engages said fluid coupling surface such that said arcuate-shaped ports are adapted to register with successive said ports in said base of said cylinder barrel upon rotation between said cylinder-barrel and said fluid coupling surface.