Abstract: A drive wheel with an integral fan mountable as a unit to a shaft of a hydraulic power unit for rotation therewith. Fan blades extending from the drive wheel circulate air when the drive wheel is rotated. One or more passageways extending through the drive wheel can be provided to allow air to flow axially therethrough to be circulated around the hydraulic unit. A fan assembly for a hydraulic power unit is also provided including a fan element and a rotatable shroud attached thereto.

Abstract: A hydraulic axle combination includes a housing having first and second pump chambers containing spaced, axially aligned, first and second hydrostatic pumps with respective pump shafts and input gears; first and second hydraulic motors connected with respective first and second pumps via intermediate manifold blocks thereby enabling closed-loop internal drive systems between the associated pumps and motors and forming first and second independent hydrostatic transmissions wherein the hydraulic motor output shafts serve as first and second axle shafts; an input shaft, extending between the two transmissions, includes a gear for supplying torque to and meshing perpendicularly with the pump shaft input gears and forming, therewith a T-shaped gear box, the housing optionally including: an internal sump serving as an integral combination fluid reservoir for the axle combination, at least one breather cap, a fluid filter assembly and a drain port and plug, all mounted in various housing sides.

Abstract: In a method for successively generating, on the inner peripheral surface of a ring, the individual profiles of a plurality of teeth of an internally toothed gear wheel: positioning the ring on a turntable; imparting complex motions, at a predetermined speed relationship therebetween, on the turntable; rotating a contoured grinding wheel, via both axial and radial feeding motions, as the grinding wheel enters into the inside of the ring for the tooth profile generation; keeping the tip radius of the grinding wheel at least substantially similar to the radius of the arc shape of each tooth; and continuously maintaining but a single contact line, between the grinding wheel and the ring inner peripheral surface, during the actual generation of the tooth profiles on the inner peripheral surface of the ring, with the complex motions including both, at least partially concurrent, angular and orbital movements, in the same angular direction.

Abstract: Improvement in a hydrostatic valve assembly for use in a hydrostatic transmission, for controlling fluid transfer between a first, second and third line, wherein two of the lines define first and second pressure lines within a closed loop circuit. The valve assembly comprises a valve body having ports in communication with the three lines; a spool bore and valve spool reciprocating therewithin, having first and second end portions joined by a connecting portion, and first and second bypass orifices within the valve spool; and dampers for centering the valve spool in a neutral position. The bypass orifices utilize increased cross-sectional areas that permit the passage of substantially the full flow of the charge pump, without using a charge pump relief valve, at a low pressure drop. A hydraulic system utilizing this valve assembly and a method for increasing the transmission efficiency, in the neutral mode, are also set forth.

Abstract: A vane pump assembly including a cam ring having an elliptical inner bore defining a hydraulic pumping chamber, the pumping chamber having an interior camming surface. The cam ring defines ports for admitting fluid into the pumping chamber. A rotor, within the cam ring, defines a plurality of radial vane slots. A vane assembly is supported in each vane slot to define vane buckets. Each vane assembly has an end dynamic vane seal for reducing leakage between the buckets. Front and rear side plates, separated by an annular spacer, enclose the pumping chamber. The pump assembly may also include floating front and rear rotor seals for reducing radially inward leakage. Each rotor seal is disposed within a groove formed in the rotor, wherein discharge pressure urges the rotor seals axially outward from the pumping chamber to create an effective seal against the respective side plate.

Abstract: Improvement in a combination valve including check valve and pressure relief valve portions for regulating fluid flow pressure and direction in a hydraulic circuit, wherein a valve seat includes, in addition to a central aperture, a plurality of peripherally-spaced axial cross-port orifice holes, of same or differing diameter and a plurality of intersecting, circumferentially-spaced, radial, semicircular holes; a spring cap including four adjoining axial portions of differing outer diameters, with a first portion being a protrusion that locates an end of a relief valve compression spring, a second portion having flat outer tool locating surfaces used for rotating the spring cap for axial adjustment relative to a valve stem, a third portion having a reduced radial wall thickness for easy crimping thereof relative to a valve stem, and a fourth portion having a coaxial recess for centering and physically retaining one end portion of a check valve compression spring.

Abstract: A hydrostatic transmission mountable to a frame of a vehicle for driving a left side or right side drive wheel. A motor portion of the transmission can extend outwardly from the frame and a pump portion can extend upwardly from the frame. The motor portion can be configured to be at least partially received within a wheel for direct mounting of the wheel to an output shaft of the motor. The pump portion can include an input shaft extending from a lower side thereof for connection to a prime mover, such as an internal combustion engine.

Abstract: A hydrostatic transmission including a hydraulic pump, a hydraulic motor, and an external manifold surrounded by and in contact with air for connecting the hydraulic pump and a hydraulic motor. The external manifold facilitates heat transfer from hydraulic fluid flowing therein to the surrounding air. The design of the hydrostatic transmission with external manifold also allows virtually any desired relative orientation of the pump and motor to be achieved by only changing the shape of the manifold.

Abstract: A housing for a motor having fluid passages integrated within. The passages include a first passage for receiving a fluid from outside the motor, a second passage for directing the fluid away from the motor, and at least one other passage from conveying the fluid to a set of components attached to the motor housing. The housing has at least one relief valve positioned within the fluid passages for diverting a portion of the fluid directly from the first passage to the second passage.

Abstract: A speed adjusting mechanism that includes a return to neutral feature for returning a control member of a pump to neutral after the control member has been moved to a forward or reverse position. The speed adjusting mechanism is characterized by the use of a torsion spring that enables the mechanism to be composed of just a few parts.

Abstract: A hydrostatic transmission including a pump and motor connected by supply and return lines. The hydrostatic transmission can be an integrated unit mountable to a vehicle frame as a unit. The motor portion of the transmission is configured to be at least partially received within a wheel to which an output shaft of the motor can be directed connected. Accordingly, the output shaft of the motor can be configured to function as a wheel axle.

Abstract: A normally engaged parking brake system for a mower that automatically disengages a parking brake when a steering arm is moved from a park position. Accordingly, the operator does not need to act to set or release the parking brake during normal operation. The system utilizes a hydraulic actuator that releases the parking brake when pressurized fluid is supplied thereto from a hydraulic pump of the mower. A manual pump, which can be configured to be operated by moving a steering arm of the mower, is provided for supplying pressurized fluid to the hydraulic actuator to release to brake in the event the hydraulic pump is not operating.

Abstract: A compact dual hydraulic pump unit having a low profile configuration. The inlet and outlet ports of the pumps may be located on opposite transverse sides of the unit for easy connection to adjacent motors coupled to the drive wheels of a vehicle.

Abstract: A hydraulic unit including an integrated fluid cooler. The fluid cooler includes a flow-through type heat exchanger. The hydraulic unit can include a pump, a motor, or both a pump and a motor. The fluid cooler can be carried by a housing of the hydraulic unit and a fan for moving air through the fluid cooler and circulating air over at least a portion of the housing of the hydraulic unit can be interposed between the fluid cooler and the housing. The fluid cooler can also be configured to function as a fan shroud. Fluid from the hydraulic unit as well as fluid from other sources can be circulated through the fluid cooler.

Abstract: An auxiliary pump assembly for a hydrostatic transmission that operates at a reduced pressure when the auxiliary circuit is not in use, and operates at an increased pressure when the auxiliary circuit is in use, thereby reducing the heat generated by the auxiliary pump. The auxiliary pump assembly can be used to supply low pressure makeup flow to a closed loop of a hydrostatic transmission. A combination valve including a bypass valve and a relief valve is also provided.

Abstract: A hydraulic axle combination includes a housing having first and second pump chambers containing spaced, axially aligned, first and second hydrostatic pumps with respective pump shafts and input gears; first and second hydraulic motors connected with respective first and second pumps via intermediate manifold blocks thereby enabling closed-loop internal drive systems between the associated pumps and motors and forming first and second independent hydrostatic transmissions wherein the hydraulic motor output shafts serve as first and second axle shafts; an input shaft, extending between the two transmissions, includes a gear for supplying torque to and meshing perpendicularly with the pump shaft input gears and forming, therewith a T-shaped gear box, the housing optionally including: an internal sump serving as an integral combination fluid reservoir for the axle combination, at least one breather cap, a fluid filter assembly and a drain port and plug, all mounted in various housing sides.

Abstract: In a method for successively generating, on the inner peripheral surface of a ring, the individual profiles of a plurality of teeth of an internally toothed gear wheel: positioning the ring on a turntable; imparting complex motions, at a predetermined speed relationship therebetween, on the turntable; rotating a contoured grinding wheel, via both axial and radial feeding motions, as the grinding wheel enters into the inside of the ring for the tooth profile generation; keeping the tip radius of the grinding wheel at least substantially similar to the radius of the arc shape of each tooth; and continuously maintaining but a single contact line, between the grinding wheel and the ring inner peripheral surface, during the actual generation of the tooth profiles on the inner peripheral surface of the ring, with the complex motions including both, at least partially concurrent, angular and orbital movements, in the same angular direction.

Abstract: In a variable displacement hydraulic pump having a housing with a multiplicity of interconnected surfaces, including opposed end surfaces and intermediate side surfaces, the improvement comprising the location of at least one case drain orifice in each of a plurality of differing ones of the surfaces in a manner such that at least one of the orifices is located in the vicinity of the top surface of the housing in any spatial orientation of the housing.

Abstract: Improvements in trunnion shaft-controlled swashplate axial hydraulic piston pumps as well as hydraulic systems used in hydrostatic transmissions utilized. e.g., in zero-turn-radius (ZTR) wheeled vehicles, such as grass mowers, with one embodiment thereof pertaining to, in combination, the noted pump, devoid of any internal servo control, and a reversible power actuator, for controlling the angle of the swashplate, externally affixed to the housing containing the pump and operatively interconnected with an end of the trunnion shaft extending from the pump housing, with the power actuator being one of a rotary actuator, a fluid power axial cylinder and a rotary electronic actuator.

Abstract: Improvement in a combination valve including check valve and pressure relief valve portions for regulating fluid flow pressure and direction in a hydraulic circuit, wherein a valve seat includes, in addition to a central aperture, a plurality of peripherally-spaced axial cross-port orifice holes, of same or differing diameter and a plurality of intersecting, circumferentially-spaced, radial, semicircular holes; a spring cap including four adjoining axial portions of differing outer diameters, with a first portion being a protrusion that locates an end of a relief valve compression spring, a second portion having flat outer tool locating surfaces used for rotating the spring cap for axial adjustment relative to a valve stem, a third portion having a reduced radial wall thickness for easy crimping thereof relative to a valve stem, and a fourth portion having a coaxial recess for centering and physically retaining one end portion of a check valve compression spring.