Abstract: An electronic steering control system for controlling the lateral movement of a vehicle powered by a pair of hydrostatic drive devices.

Abstract: An improved compact design for a hydrostatic transmission having a hydraulic pump and hydraulic motor mounted on a center section in a housing, wherein the pump and motor are mounted at generally right angles to one another, and the longitudinal axis of the input shaft is located between a first and second parallel planes located at respective ends of the motor shaft and the longitudinal axis of the motor shaft is located between a third and fourth parallel planes located at respective ends of the pump shaft.

Abstract: A dual tandem pump apparatus having a pair of coaxially arranged pump shafts and a separate input shaft that is not coaxial with the pump shafts. The trunnion arms for the two pumps may be mounted in different locations to increase application flexibility. Charge pumps may be mounted on end caps secured to the housing or may be driven directly by the input shaft. A coupler or bevel gear arrangement is used inside the pump housing to drive the pump shafts from the input shaft.

Abstract: A transaxle comprised of a hydrostatic transmission mounted in a transmission housing and having a pair of hydraulic pumps and hydraulic motors operatively connected together through a center section mounted in the housing. First and second axle housings are mounted on opposite ends of the transmission housing, with output axles mounted in the axle housings and connected to the respective hydraulic motors.

Abstract: A bypass mechanism is provided for use in a hydrostatic transmission, to enable the user to open or close a valve between the two pressure sides of the hydraulic circuit of the transmission. An electrical mechanism is positioned to open or close the valve based on a signal which may be generated by a switch associated with the hydrostatic transmission.

Abstract: A hydraulic motor assembly having a motor and gear reduction set mounted in a housing. The housing may be formed of separate components, including the external surface of the ring gear and the hydraulic motor port block. The motor assembly may also include pressure relief valves or neutral valves in the motor port block and a brake assembly mounted in the port block or on the motor housing to provide braking for the output axle.

Abstract: A hydrostatic drive device comprising a hydrostatic transmission mounted in a housing and a single output shaft driven by the hydrostatic transmission and extending out of the housing. The hydrostatic transmission has a center section mounted entirely within the housing and a rotatable hydraulic pump and a rotatable hydraulic motor mounted on the center section and connected through hydraulic porting in the center section. A pump shaft extends into the housing to drive the pump block, and the longitudinal axis of the output shaft is perpendicular to the longitudinal axis of the pump shaft.

Abstract: A utility vehicle is disclosed within. The utility vehicle comprises a front axle, a pair of rear axle shafts, a seat for at least two occupants positioned between the front axle and the rear axle shafts, a load bed positioned over the rear axle shafts, a prime mover with a prime mover output shaft with a pulley attached to the end of the prime mover output shaft. Further, the vehicle has a hydraulic drive system that has a hydraulic pump driven by a pump input shaft, a hydraulic motor located within a common housing with the hydraulic pump, and gears and a differential located in the common housing with the hydraulic pump and the hydraulic motor. The prime mover output shaft and the pump input shaft are parallel to the front axle and the rear axle shafts.

Abstract: An axle driving apparatus having a housing having two members joined along a joint surface and a hydraulic axial piston pump and motor mounted on a center section located in the housing, wherein the pump and motor are mounted perpendicular to one another. The motor is engaged to a fixed thrust bearing located in the housing and the center section is located entirely between the joint surface and the thrust bearing.

Abstract: A drive apparatus for a zero turn vehicle or similar application comprising a pair of pumps mounted in a common housing and having coaxial input shafts and an input shaft mounted in the common housing perpendicular to the two pump shafts. A pair of center sections or end caps including hydraulic porting are mounted to opposite ends of the common housing, and each center section has a hydraulic motor mounted thereon external to the common housing.

Abstract: An improved valve for use in a hydrostatic drive apparatus for a vehicle such as a zero turn vehicle. For each hydraulic drive system in the vehicle, a valve is located between the high and low pressure sides of the closed hydraulic circuit connecting the hydraulic pump and motor. The valve opens when the pressure rise rate in the high pressure side reaches a set level to minimize pressure spikes in the high pressure side and thus improve performance of the vehicle. A valve block may be used to mount the valve, and a second valve may also be included therein to connect the two pressure sides of the hydraulic circuit in a similar manner when the vehicle is operated in reverse.

Abstract: A dual pump apparatus having two pumps mounted in a housing, where the housing comprises two elements mounted on opposite sides of a hydraulic mounting member or center section. The pumps are mounted on one side of the hydraulic mounting member in a pump cavity, and the center section and second housing element form a gear cavity in which gears to connect the two pump input shafts are located. Various charge pumps or auxiliary pump configurations are disclosed, including one embodiment where the input shaft gears themselves may act as a charge pump for the pump assembly.

Abstract: A hydrostatic apparatus is disclosed. The hydrostatic apparatus comprises a pump, an input shaft, a fan and a fan shroud. The pump comprises a housing, an end cap, a first end and a second end. The input shaft extending from the first end and the second end of the pump. The fan is attached to one end of the input shaft. The fan shroud is also attached to the pump.

Abstract: A system for use with a vehicle such as a tractor having an output device such as a mower deck or snow thrower comprising a sensor positioned to detect the rotational direction of a shaft such as an output axle. The operational status of the output device can be changed depending on the rotational direction of the shaft.

Abstract: An improved valve for use in a hydrostatic drive apparatus for a vehicle such as a zero turn vehicle. For each hydraulic drive system in the vehicle, a valve is located between the high and low pressure sides of the closed hydraulic circuit connecting the hydraulic pump and motor. The valve opens when the pressure rise rate in the high pressure side reaches a set level to minimize pressure spikes in the high pressure side and thus improve performance of the vehicle. A valve block may be used to mount the valve, and a second valve may also be included therein to connect the two pressure sides of the hydraulic circuit in a similar manner when the vehicle is operated in reverse.

Abstract: A circuit for use with an apparatus such as a tractor having an output device such as a mower deck or snow thrower, comprising a user operated switch and a position sensing switch to detect the rotational direction of a shaft such as an output axle, so that the operational status of the output device may be changed depending on the rotational direction of the shaft.

Abstract: A method for use with an apparatus such as a tractor having an engine and an output device, such as a mower deck or snow thrower, comprising the steps of determining a rotational direction of a rotatable shaft as one of a forward direction and a reverse direction and selecting the operational status of the output device as one of an engaged state and a disengaged state, where the operational status is in the disengaged state when the shaft rotates in the reverse direction and is in the engaged state when the shaft does not rotate in the reverse direction.

Abstract: A utility vehicle incorporating a frame, a load bed mounted at the rear of the frame and front and rear axles secured to the fame, has an engine mounted to the frame between the front and rear axles, a mechanical gear box secured to the frame and a differential mounted in the gear box and engaged to and driving the rear axles. A hydraulic pump housing is secured to the frame and has a pump input shaft extending therefrom. A hydraulic motor housing is secured to the frame and hydraulically connected to the pump. A motor output shaft, driven by the hydraulic motor, extends out of the motor housing and is engaged to a gear box input shaft.

Abstract: A transaxle comprised of a hydrostatic transmission mounted in a transmission housing and having a pair of hydraulic pumps and hydraulic motors operatively connected together through a center section mounted in the housing. First and second axle housings are mounted on opposite ends of the transmission housing, with output axles mounted in the axle housings and connected to the respective hydraulic motors.

Abstract: A hydraulic motor assembly having a motor and gear reduction set mounted in a housing. The housing may be formed of separate components, including the external surface of the ring gear and the hydraulic motor port block. Pressure relief valves or neutral valves may be located in the motor port block.