Abstract: An infinitely variable hydromechanical crossdrive steering transmission having a multiple of forward and reverse ratio ranges and a separately selectable low ratio range in both forward and reverse. The forward and reverse ratio ranges are enabled to shift between ratio ranges in a synchronous manner in both speed and torque, thus smoothly propelling the vehicle from rest through the multiple transmission ranges to maximum speed in a stepless manner.

Abstract: An infinitely variable hydromechanical crossdrive steering transmission having a multiple of forward and reverse ratio ranges and a separately selectable low ratio range in both forward and reverse. The forward and reverse ratio ranges are enabled to shift between ratio ranges in a synchronous manner in both speed and torque, thus smoothly propelling the vehicle from rest through the multiple transmission ranges to maximum speed in a stepless manner.

Abstract: To control transmission ratio of a continuously variable hydrostatic transmission including an input shaft, an output shaft, a hydraulic pump unit driven by the input shaft, a grounded hydraulic motor unit, and a wedge-shaped swashplate drivingly, pivotally connected to the output shaft and positioned to accommodate pumped hydraulic fluid exchanges between the pump and motor units. A ratio controller is provided having a pair of hydraulically actuated, differentially sized pistons coupled by a linkage mechanism to pivot the swashplate in opposite transmission ratio-changing directions. The smaller piston is incorporated internally of the output shaft, while the larger piston, of an annular shape, coaxially surrounds the output shaft. The linkage mechanism has geometry effective to translate axial forces exerted by the pistons into amplified ratio-changing moments exerted on the swashplate.

Abstract: In a multi-range, continuously variable transmission, input engine power is split between a belt-type, continuously variable transmission unit and a system of interconnected planetary gears. This gear system then combines the split power received from the engine and the transmission unit output to produce a transmission output for propelling a vehicle in multiple forward ranges and one reverse range, each range of continuously variable speed produced by stroking the transmission unit. Synchronous shifting between ranges is achieved by selectively clutching or braking elements of the planetary gear sets at appropriate stroke settings of the transmission unit, such that the vehicle may be smoothly accelerated from rest to maximum speed.

Abstract: A multi-range, synchronous shifting, hydromechanical transmission according to the present invention is suitable for application in an automotive drivetrain including a high speed engine. The transmission receives split power inputs from the engine; one input being geared down to a suitable lower speed for driving a continuously variable hydrostatic transmission unit, while the other input drives a counter shaft from which mechanical outputs are take at different speed ratios. A planetary gear set, driven by the hydrostatic transmission unit output, is shiftable to provide either a narrow continuously variable speed hydrostatic output, range suitable for transmission operation in low output ranges or a wide continuously variable speed hydrostatic output range suitable for transmission operation in high output ranges.

Abstract: A hydromechanical transmission receives split power inputs from a vehicle engine, one split input driving a hydrostatic power unit and the other split input driving a mechanical power input. The infinitely variable hydrostatic power output is combined in the mechanical power unit with multiple ratios of its split input power to achieve multiple ratios of hydromechanical output power for smoothly propelling a vehicle from rest through multiple transmission ranges to maximum speed, with synchronous shifting between ranges. The hydromechanical transmission is particularly applicable to off-road vehicles, such as agricultural tractors.

Abstract: A hydromechanical transmission receives split power inputs from a vehicle engine, one split input driving a hydrostatic power unit and the other split input driving a mechanical power input. The infinitely variable hydrostatic power output is combined in the mechanical power unit with multiple ratios of its split input power to achieve multiple ratios of hydromechanical output power for smoothly propelling a vehicle from rest through multiple transmission ranges to maximum speed, with synchronous shifting between ranges.

Abstract: A continuously variable hydrostatic transmission includes axially aligned input and output shafts journaled by a transmission housing and respectively coupled to a prime mover and a load. The input shaft drives a hydraulic pump unit, while a hydraulic motor unit is grounded to the transmission housing. A wedge-shaped swashplate is pivotally connected to the output shaft in operative position to accommodate pressurized hydraulic fluid exchanges between the pump and motor units. A controller is coupled to adjust the angular orientation of the swashplate relative to the output shaft axis and thus set the transmission ratio. A hydraulic circuit, connected into the hydraulic motor unit, is selectively operable to vent high and low fluid pressure sides of the swashplate to atmosphere, thus imposing a neutral transmission ratio condition regardless of the transmission ratio set by the controller.