A transaxle for use as a drive apparatus of a vehicle is provided. The transaxle includes a main housing joined to a gear housing to enclose a transmission and a reduction gear set. The transmission includes a pump assembly and a motor assembly arranged in a parallel configuration on one side of a center section. A charge pump is contained within a pocket on an opposing side of the center section. A charge pump cover assembly secures the charge pump in the pocket and has a charge relief assembly that extends into a void volume defined by a ring gear of the gear reduction set. The gear reduction set drives an axle extending from the gear housing.

A transaxle for use as a drive apparatus of a vehicle is provided. The transaxle includes a main housing joined to a gear housing to enclose a transmission and a reduction gear set. The transmission includes a pump assembly and a motor assembly arranged in a parallel configuration on one side of a center section. A charge pump is contained within a pocket on an opposing side of the center section. A charge pump cover assembly secures the charge pump in the pocket and has a charge relief assembly that extends into a void volume defined by a ring gear of the gear reduction set. The gear reduction set drives an axle extending from the gear housing.

A hydraulic system includes a hydraulic gear pump with a first gear having a plurality of first gear teeth and a second gear having a plurality of second gear teeth. The hydraulic system also includes a control valve and a control circuit. The control circuit controls the pump to adjust at least one of a flow in the hydraulic system to a flow set point or a pressure in the hydraulic system to a pressure set point, and concurrently establishes an opening of the control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point. The control circuit establishes a position of a first tooth relative to a position of a second tooth to seal a fluid path from the outlet of the hydraulic gear pump to the inlet of the hydraulic gear pump.

A hydraulic system includes a hydraulic gear pump with a first gear having a plurality of first gear teeth and a second gear having a plurality of second gear teeth. The hydraulic system also includes a control valve and a control circuit. The control circuit controls the pump to adjust at least one of a flow in the hydraulic system to a flow set point or a pressure in the hydraulic system to a pressure set point, and concurrently establishes an opening of the control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point. The control circuit establishes a position of a first tooth relative to a position of a second tooth to seal a fluid path from the outlet of the hydraulic gear pump to the inlet of the hydraulic gear pump.

A method for controlling a hydrostatic drive, which has a driving engine, a hydraulic pump coupled to the driving engine and a hydraulic motor coupled to the hydraulic pump by way of a pressurized hydraulic work line, includes calculating a manipulated variable vector comprising at least one manipulated variable for the hydrostatic drive based on (i) an output torque setpoint value for a torque on a secondary shaft driven by the hydraulic motor, (ii) a rotational speed and torque of the driving engine emerging from a predetermined operating point characteristic for the driving engine, and (iii) volumetric and mechanical losses of at least one adjuster unit comprising the hydraulic pump and the hydraulic motor. The manipulated variable vector is used to control the hydrostatic drive.

A fluid-driven actuator system includes a fluid-driven actuator and at least one proportional control valve and at least one pump connected to the fluid-driven actuator to provide fluid to operate the fluid-driven actuator. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The fluid-driven actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to adjust at least one of a flow in the fluid-driven system to a flow set point and a pressure in the fluid-driven actuator system to a pressure set point and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of the flow to the flow set point and the pressure to the pressure set point.

A drive mechanism includes a pair of driven axles, a center section and a pump and a motor rotatably disposed on one side of the center section. A clutch mechanism is located adjacent an opposite side of the center section to drive the pair of axles. The clutch includes at least one clutch fork disposed adjacent to the center section and being rotatable along an axis of rotation that is perpendicular to the axes of rotation of the pump input shaft and motor output shaft, and also perpendicular to the axis of rotation of the axles.

A hydrostatic transmission system includes a fluid-driven motor and an integrated pump assembly connected to the fluid-driven motor to provide fluid to operate the fluid-driven motor. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The hydrostatic transmission system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the hydrostatic transmission system to an operational set point.

A working machine comprising: a ground engaging structure with a first and second axle, each mounting two wheels; a body supported on the ground engaging structure, a working arm mounted to the body; and a drive arrangement for moving the ground engaging structure to propel the working machine, the drive arrangement including a prime mover and transmission. The transmission comprises a hydraulic pump driven by the prime mover, a first high speed hydraulic motor to drive the first axle to permit the working machine to be driven at relatively high speeds in a first two-wheel drive operating mode, and a second low speed motor to be supplied with hydraulic fluid from the hydraulic pump to drive the second axle at relatively low speeds and configured to be driven in conjunction with the first motor in a second four-wheel drive operating mode.

A working machine comprising: a ground engaging structure with a first and second axle, each mounting two wheels; a body supported on the ground engaging structure, a working arm mounted to the body; and a drive arrangement for moving the ground engaging structure to propel the working machine, the drive arrangement including a prime mover and transmission. The transmission comprises a hydraulic pump driven by the prime mover, a first high speed hydraulic motor to drive the first axle to permit the working machine to be driven at relatively high speeds in a first two-wheel drive operating mode, and a second low speed motor to be supplied with hydraulic fluid from the hydraulic pump to drive the second axle at relatively low speeds and configured to be driven in conjunction with the first motor in a second four-wheel drive operating mode.