Abstract: A center section/motor sub-assembly for use in a hydrostatic transmission includes a center section having a pump running face for interfacing with a pump, and a motor running face for interfacing with a motor. The center section and the motor are configured for the hydraulic separating forces of the motor to be reacted only into the center section. The center section has two internal passages between pump kidney ports and motor kidney port, and the motor kidney ports are raised in elevation relative to the pump kidney ports. The internal passages run parallel to each other as they rise in elevation. A hydrostatic transmission includes the sub-assembly enclosed by a housing, in combination with a pump and output shaft assembly. For installation, the output shaft assembly is configured as a separate component from the sub-assembly of the center section and the motor.

Abstract: A zero turn mower vehicle 10 includes left and right hydrostatic transmissions 11a, 11b driving wheels 15a, 15b. The transmissions 11a, 11b each include a swashplate type axial piston hydraulic pump 17 having a swashplate 22. A system 12 and method controls each pump 17. A controller 31 receives input signals and provides output signals to electric motors 33a, 33b to control each swashplate 22. Operator interface input devices 30a, 30b provide inputs to controller 31. Angle sensors 35a, 35b provide additional inputs to controller 31. Displacement amplifiers 36a, 36b amplify displacement of each swashplate 22, and torque amplifiers 34a, 34b amplify torque of electric motors 33a, 33b.

Abstract: A center section/motor sub-assembly for use in a hydrostatic transmission includes a center section having a pump running face for interfacing with a pump, and a motor running face for interfacing with a motor. The center section and the motor are configured for the hydraulic separating forces of the motor to be reacted only into the center section. The center section has two internal passages between pump kidney ports and motor kidney port, and the motor kidney ports are raised in elevation relative to the pump kidney ports. The internal passages run parallel to each other as they rise in elevation. A hydrostatic transmission includes the sub-assembly enclosed by a housing, in combination with a pump and output shaft assembly. For installation, the output shaft assembly is configured as a separate component from the sub-assembly of the center section and the motor.

Abstract: A zero turn mower vehicle 10 includes left and right hydrostatic transmissions 11a, 11b driving wheels 15a, 15b. The transmissions 11a, 11b each include a swashplate type axial piston hydraulic pump 17 having a swashplate 22. A system 12 and method controls each pump 17. A controller 31 receives input signals and provides output signals to electric motors 33a, 33b to control each swashplate 22. Operator interface input devices 30a, 30b provide inputs to controller 31. Angle sensors 35a, 35b provide additional inputs to controller 31. Displacement amplifiers 36a, 36b amplify displacement of each swashplate 22, and torque amplifiers 34a, 34b amplify torque of electric motors 33a, 33b.