Abstract: A pair of zero-turn, hydrostatic transaxles (HZTs) that may be joined to form an integrated, zero-turn, hydrostatic transaxle. Each of the hydrostatic transaxles are further comprised of a casing carrying a hydraulic pump driven by an input shaft, a hydraulic motor driven by a the hydraulic pump through porting contained within a center section, and an axle shaft driven by the hydraulic motor. The hydrostatic transaxles are joined along an interface extending generally perpendicularly to the axle shafts.

Abstract: A variable relief valve is inserted in a hydraulic piping for connecting a first pump/motor to a second pump/motor. The variable relief valve is controlled such that when shifting the transmission from forward to reverse or vice versa, a relief set pressure of the variable relief valve is reduced in response to switching of a forward/reverse shifting clutch mechanism and after completion of the switching of the forward/reverse shifting clutch mechanism, the relief set value is increased.

Abstract: A pump and motor distribution valve formed by a hydraulic closed circuit for connection between a pump and a motor. In a hydraulic non-stage transmission CVT including a swash plate plunger type hydraulic pump P and a swash plate plunger type hydraulic motor M connected to each other through a hydraulic closed circuit, a pump swash plate member is driven to rotate. A pump cylinder and a motor cylinder are connected to each other and disposed in a connected state on an output shaft. A motor swash plate, restricted in rotation, is oscillated, and the swash plate angle can be regulated variably. A pump-side spool rotatable as one body with the pump swash plate member and a motor-side spool maintained fixedly are inserted in a valve hole formed in the output shaft to penetrate through the output shaft in the axial direction. A hydraulic closed circuit includes the spools and a plurality of communication oil passages formed in the pump cylinder, the motor cylinder and the output shaft.

Abstract: A hydraulic stepless transmission comprises a first hydraulic system. Formed in a cylinder block are first and second plunger holes that contain first and second plungers, respectively, a hydraulic closed circuit that connects the first and second plunger holes, and distributing valve holes that contain distributing valves, which switch flow direction of hydraulic fluid in the circuit. A shaft and cylinder block synchronously rotate, with the first and second plunger holes formed in parallel to the shaft, respectively, and the swash plate of the second hydraulic system is rotatably supported around the shaft. The first and second plungers are urged toward the swash plates by springs provided in the corresponding first and second plunger holes, respectively.

Abstract: An axle driving apparatus in which a hydraulic pump and a hydraulic motor which constitute a hydrostatic transmission are disposed on a center section. In a horizontal portion of the center section are provided a pair of linear oil passages in parallel to each other. A pair of arcuate ports are provided on a pump mounting surface formed on the horizontal portion of the center section. The pair of arcuate ports are substantially perpendicular with respect to the direction in which the oil passages extend. The axis of slanting movement of a movable swash plate of the hydraulic pump extends laterally of the vehicle body on which the axle driving apparatus is provided. The rotating direction of an arm provided on a control shaft for slantingly operating the movable swash plate is coincident with the operating direction of a control rod connected with a speed changing member. Thus, the link mechanism for connecting the speed changing member and the control arm for the movable swash plate is simplified.

Abstract: Disclosed is a vehicle. The vehicle comprises a first hydraulic pump, a first hydraulic motor, a first axle shaft, a second hydraulic pump, a second hydraulic motor, a second axle shaft, a first bypass, a first linkage, a second bypass and a second linkage. The first hydraulic motor is connected to the first hydraulic pump by a first hydraulic porting. The first axle shaft is driven by the first hydraulic motor. The second hydraulic motor is connected to the second hydraulic pump by a second hydraulic porting. The second axle shaft is driven by the second hydraulic motor. The first bypass is associated with the first hydraulic porting. The first linkage is connected to the first bypass. The second bypass is associated with the second hydraulic porting. The second linkage is connected to the second bypass. The first bypass and the second bypass are actuated substantially simultaneously by a single actuating mechanism.

Abstract: A hydraulic continuously variable transmission has a variable displacement type first hydraulic system having a first plunger and a plunger abutting section which actuates the first plunger, and a second hydraulic system having a second plunger and provided with an output rotary section which rotates with abutment on the second plunger. A cylinder block rotates about an axis and has a first plunger hole and a second plunger hole which respectively retain the first and second plungers. A hydraulic closing circuit connects the first and second plunger holes and circulates a working oil between the first and second plunger holes. The continuously variable transmission has a distributing valve for controlling circulation of the working oil in the hydraulic closing circuit, a valve hole, formed in the cylinder block, for retaining the distributing valve, and a shaft which penetrates the cylinder block.

Abstract: To reduce the projection of a swash plate servo mechanism in the radial direction, and to make a hydraulic continuously variable transmission compact, a swash plate plunger pump includes a pump casing provided with an input driven gear. A pump cylinder and a motor cylinder are connected to a transmission output shaft, and a motor pivot member provided with a motor swash plate member is supported to be pivotally movable. A motor servo mechanism includes a ball screw shaft, a ball nut to which an end portion of the motor pivot member is connected, and a swash plate control motor to rotate the screw shaft. A swash plate control motor, located on the side of a hydraulic pump relative to the input driven gear, is mounted to the outside surface of a transmission housing close to the center axis side of a transmission output shaft.

Abstract: A two piece center section assembly for mounting inside the housing of a hydrostatic drive apparatus is disclosed. The assembly includes separate pump and motor support portions where the check valve is formed between the two pieces. Fasteners extend through the two pieces and into the housing for the drive apparatus to secure the assembly thereto without the need for additional fasteners. The need for additional sealing material between the pump and motor portions can also be reduced by the use of raised portions on the mating surfaces between these two portions.

Abstract: A hydrostatic transmission comprising a housing formed with a fluid sump, a center section disposed within the fluid sump, a hydraulic pump mounted on the center section, and a hydraulic motor mounted on the center section. A fluid passage is formed in the center section for hydraulically connecting the hydraulic pump with the hydraulic motor. A bore is open at an outer surface of the center section in communication with the fluid passage. An output operation device is provided for controlling discharged fluid of the hydraulic pump. The output operation device is moved to an operational position from a neutral position. A piston having an outer surface is reciprocally inserted into the bore so as to be allowed to project outward from the center section. A valve is disposed within the bore for opening and closing the bore to and from the fluid passage. The valve is biased to be closed by a spring disposed between the valve and the piston.

Abstract: An axle driving apparatus wherein a hydraulic motor and a hydraulic pump for a hydro-static-transmission are housed in a transmission casing of the axle driving apparatus and a center section for connecting the hydraulic motor and hydraulic pump is disposed in the transmission casing, the center section being fixed at the butt joint portion at the transmission casing, and an oil passage from the hydraulic pump to the hydraulic motor at the center section is bent at a right angle so as to extend the motor shaft in parallel to the axles, so that the rotation direction of the motor shaft conventionally changed by bevel gears is changed by the oil passages in the center section.

Abstract: A hydraulic drive circuit comprises a source of fluid flow, at least one hydraulic actuator and a rotary flow divider which operates in conjunction with valve means to provide intensified flow to the at least one hydraulic actuator.

Abstract: A hydraulic continuously variable transmission includes an axial plunger pump including a pump cylinder provided with pump plunger holes, and pump plungers fitted in the pump plunger holes. The transmission also includes an axial plunger motor including a motor cylinder provided with motor plunger holes, and motor plungers fitted in the motor plunger holes. A distribution valve of a closed hydraulic circuit is provided for connecting the axial plunger pump and the axial plunger motor to each other. Pump openings are provided at end portions of the pump plunger holes for discharging a hydraulic fluid pushed out by sliding movements of the pump plungers in the pump plunger holes. The pump openings are located opposite to end faces of the pump plungers, and the pump openings are smaller than the pump plunger holes and offset to the side of the rotational axis of the pump cylinder.

Abstract: In order to provide a rotationally balanced hydraulic swash plate plunger unit, a swash plate plunger pump casing is provided with an unbalanced flange to balance a casing which has a swash plate member therein, without requiring a separate counter weight. A hydraulic swash plate plunger pump includes a pump swash plate member, installed in the pump casing and rotatably supported in an inclined manner therein, and a pump cylinder having a plurality of pump plungers slidably disposed therein. An unbalanced five-sided flange portion is formed integrally with the outer wall of the pump casing, to rotationally balance the entire unit.

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 check and high pressure relief valve that is able to perform the function of a hydrostatic high pressure relief valve and a check valve. The new valve has two poppets separated by a spring that are within two seats within a guide and secured by a plug. By adjusting the seats the relief pressure setting is set. The dual check and high pressure relief valve has three separate passageways that allow fluid flow between different combinations of the passages depending upon the function desired within the hydrostatic circuit. A dashpot is also included between the two poppets to provide positive dampening of the system.

Abstract: A powertrain unit includes a hydraulic continuously variable transmission including a transmission housing, and a dipstick for checking an oil level in the housing. The width of the powertrain unit is reduced by positioning the dipstick laterally inside the housing. The hydraulic continuously variable transmission includes a fixed-displacement swash plate plunger pump and a variable displacement swash plate plunger motor, which are connected through a closed hydraulic circuit. The outer circumference of a portion of a pump casing of the plunger pump for is reduced in diameter to form a reduced diameter portion. The dipstick is positioned so that a gauge portion thereof extends from an area near the outer circumference of the reduced diameter portion down to the bottom of the transmission housing.

Abstract: A pressure-control device (20) includes a controllable variable-displacement reversible hydraulic motor (21) having a pressure port (22) and a return port (23); a source of pressurized fluid (Ps); a fluid return (R); and a pressure regulating valve (24) operatively interposed between the source, return and pressure port. The pressure regulating valve is operatively arranged to maintain a predetermined pressure at the pressure port regardless of the direction of flow through the pressure port.

Abstract: A hydrostatic transmission comprising a housing formed with a fluid sump, a center section, a hydraulic pump, and a hydraulic motor. A fluid passage is formed in the center section. A bore is open at an outer surface of the center section in communication with the fluid passage. An output operation device is provided for controlling discharged fluid of the hydraulic pump. A piston having an outer surface is reciprocally inserted into the bore so as to be allowed to project outward from the center section. A valve is disposed within the bore. The valve is biased to be closed by a spring disposed between the valve and the piston. A member interlocks with the output operation device so as to contact with the outer surface of the piston.

Abstract: An axle driving apparatus in which a hydraulic pump and a hydraulic motor which constitute a hydrostatic transmission are disposed on a center section. In a horizontal portion of the center section are provided a pair of linear oil passages in parallel to each other. A pair of arcuate ports are provided on a pump mounting surface formed on the horizontal portion of the center section. The pair of arcuate ports are substantially perpendicular with respect to the direction in which the oil passages extend. The axis of slanting movement of a movable swash plate of the hydraulic pump extends laterally of the vehicle body on which the axle driving apparatus is provided. The rotating direction of an arm provided on a control shaft for slantingly operating the movable swash plate is coincident with the operating direction of a control rod connected with a speed changing member. Thus, the link mechanism for connecting the speed changing member and the control arm for the movable swash plate is simplified.

Abstract: A hydrostatic transaxle axle assembly for a vehicle has the housing formed by three housing members, two of which are preferably separable on a parting plane coincident with the longitudinal axes of the axle shafts. One of the housing members is provided with an opening to allow a portion of one of the other housing members to extend through, and the extending housing member contains within its interior a number of internal fluid passages for fluidly connecting the hydraulic pump to the hydraulic motor.

Abstract: A variable speed control for closed loop hydrostatic drive has a variable displacement, pressure compensated, hydraulic piston pump of nominal capacity and a hydraulic motor of similar capacity with reversible inlet and outlet ports, connected to the pump inlet and outlet ports to operate in a closed loop for bidirectional rotation according to the pressure differential across the motor ports, and a proportional control valve, having a nominal flow capacity of no more than one-tenth the given pump output capacity, interposed between the pump and the motor to restrict and regulate oil flow through the relatively low pressure side of the loop for smooth, slow speed motor rotation, with a controller, connected to control the proportional valve for selection of a flow rate within its nominal capacity.

Abstract: A hydrostatic transaxle axle assembly for a vehicle has the housing is formed by three housing members, two of which are preferably separable on a parting plane coincident with the longitudinal axes of the axle shafts. One of the housing members being provided with an opening to allow a portion of one of the other housing members to extend through, and where the extending housing member contains within its interior a number of internal fluid passages for fluidly connecting the hydraulic pump to the hydraulic motor.

Abstract: A bypass mechanism for a hydrostatic transaxle comprising a casing in which is carried a hydraulic motor that rotates on a motor running surface of a center section. The bypass mechanism includes a bypass actuator having a first end that extends from the casing and a second end that extends through an opening in the center section adjacent to the motor running surface. Connected to the bypass actuator is a bypass arm that is adapted to rotate the bypass actuator to lift the hydraulic motor from the motor running surface of the center section. A first retaining ring attached to a first groove formed in the bypass actuator adjacent to an exterior surface of the casing and a second retaining ring located in a housing bore adjacent the first retaining ring maintains the position of the bypass mechanism relative to the transaxle components.

Abstract: A hydrostatic transmission including a fluid motor and a variable displacement fluid pump in fluid communication with the motor and having a first and a second, greater, fluid displacement rate. The pump is mounted on a block having an outer surface, a passage through which fluid flows from the pump to the motor, and a first and a second fluid bleed hole extending from the passage to the outer surface. The passage and a sump external to the pump are in fluid communication through the bleed holes and the void of a sliding element disposed within a bore in the block when the pump is operating at its first rate and the sliding element is in a first position. The first bleed hole and the sump are substantially out of fluid communication when the pump is operating at its second rate and the sliding element is in a second position.

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: Distributing valves of a swash plate type hydraulic drive transmission can make a cylinder block smaller and reduce the number of processes and the number of parts. Distributing valves alternately switch, corresponding to the axial reciprocating motion of plungers, communication and cutoff between communication passages communicated to oil chambers opening to the inner surface of cylinder holes and low pressure ports and high pressure ports communicated to a low pressure oil passage and a high pressure oil passage opening to the inner surface of the cylinder holes.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side in a hydraulic circuit. The combination check valve and pressure relief valve includes a valve plug, a valve guide moveably positioned in relation to the valve plug, a valve stem engaged to the valve guide, a check compression spring attached to the valve stem and positioned between the valve guide and the valve plug, a valve seat carried by the valve stem, and a relief compression spring positioned between the valve seat and the valve guide.

Abstract: The displacement of fluid translating devices are normally controlled by changing the angle of an eccentric or a cam plate to change the pumping stroke of the pistons within the device. In the subject arrangement, the displacement of the fluid translating device is controlled by controlling the flow being delivered into or away from each of the associated pressure chambers defined therein by the respective ones of a plurality of pistons. By not permitting the flow from every piston to be directed into useful work, the volume of fluid being directed into or away from the fluid translating device can be altered. Likewise, the direction of fluid flow within the fluid translating device can be selectively changed thus permitting the subject fluid translating device to be capable of pumping or motoring in both directions of flow relative to the first and second inlet/outlet ports thereof.

Abstract: A hydrostatic transmission comprising a housing formed with a fluid sump, a center section, a hydraulic pump, and a hydraulic motor. A fluid passage is formed in the center section. A bore is open at an outer surface of the center section in communication with the fluid passage. An output operation device is provided for controlling discharged fluid of the hydraulic pump. A piston having an outer surface is reciprocally inserted into the bore so as to be allowed to project outward from the center section. A valve is disposed within the bore. The valve is biased to be closed by a spring disposed between the valve and the piston. A member interlocks with the output operation device so as to contact with the outer surface of the piston.

Abstract: An hydraulic pressure control system in the hydrostatic system of a split torque transmission uses a shunt circuit to redirect hydraulic fluid in a loop between a first pump and a second pump or motor. The shunt is opened by restricting a variable area or valve in the primary loop and opening a variable area or valve in the shunt. Adjusting the openings of the valves prevents overloading of the engine, lugging under instantaneous loads and overspeed due to backloading.

Abstract: A method for providing a bypass for a hydraulic circuit in a hydrostatic transmission enables the user to open or close a bypass between the hydraulic circuit of the transmission and a hydraulic fluid sump. The method uses an electromechanical valve mechanism, and provides an electrical signal thereto to open the bypass and divert the hydraulic fluid from the circuit to the sump.

Abstract: A housing for a hydrostatic transaxle is provided wherein the housing has a chamber in which is disposed a hydrostatic transmission and a chamber in which is disposed an axle shaft that is engaged to the hydrostatic transmission. The housing is also provided with a plurality of caps to cover the chambers.

Abstract: A hydrostatic transmission including a fluid motor and a variable displacement fluid pump in fluid communication with the fluid motor and having a first and a second, much greater, fluid displacement rate. The pump is mounted on a block having a cylindrical surface, a passage through which fluid flows from the pump to the motor, and a fluid bleed hole extending from the passage to the cylindrical surface. The passage and a sump external to the pump are in fluid communication through the bleed hole and the void of an annular element disposed about and in sliding contact with the cylindrical surface when the pump is operating at its first rate and the annular element is in a first position. The bleed hole and the sump are substantially out of fluid communication when the pump is operating at its second rate and the annular element is in a second position.

Abstract: A pressure regulating valve is provided in a hydrostatic, continuously variable transmission having a hydraulic closed circuit including a hydraulic pump, a hydraulic motor, and a high pressure oil passage and a low pressure oil passage disposed between the hydraulic pump and the hydraulic motor. The pressure regulating valve is provided for relieving the hydraulic pressure in the low pressure oil passage into the high pressure oil passage when the hydraulic pressure in the low pressure oil passage exceeds a predetermined value. The present invention prevents excessive pressure in the oil passages, particularly in the normally low pressure passage that serves as a high pressure side during a speed reducing operation, e.g. an engine braking or reverse load situation.

Abstract: A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works includes a hydraulic boom hoist cylinder and a hydraulic circuit for controlling the hydraulic boom hoist cylinder. The hydraulic cylinder is pivotally connected to a mast on the upper works and pendently connected to the boom. The boom hoist cylinder preferably comprises two double-acting hydraulic cylinders. The hydraulic circuit includes a closed loop pump and a hydraulic controller connecting the closed loop pump and the double-acting cylinders such that fluid from the pump can be directed either to extend or retract the cylinders, with the hydraulic fluid exiting the cylinders being directed to return to the pump.

Abstract: Distributing valves of a swash plate type hydraulic drive transmission can make a cylinder block smaller and reduce the number of processes and the number of parts. Distributing valves alternately switch, corresponding to the axial reciprocating motion of plungers, communication and cutoff between communication passages communicated to oil chambers opening to the inner surface of cylinder holes and low pressure ports and high pressure ports communicated to a low pressure oil passage and a high pressure oil passage opening to the inner surface of the cylinder holes.

Abstract: An improved hydrostatic transmission useful as a speed changing device having a single output shaft or a pair of outwardly extending shafts for use, for example, in small vehicles such as lawn and garden tractors. The hydrostatic transmission output may be mechanically coupled to the wheel driving axle by a gear or chain drive, or alternatively may have such means included in the same housing package containing the hydrostatic transmission. When a differential action is needed between the drive wheels of the vehicle, the differential may then also be included in the same housing package. In whichever of such configurations, the hydrostatic transmission comprises a radial piston pump fluidly coupled to a single or twin larger displacement axial piston motor of the swash-plate type by means of a fluid coupling valve supported by the housing.

Abstract: A hydrostatic transmission design incorporating a unique housing shape and configuration, including a vertical split of the two casing elements, which are shaped to conform to the internal components of the transmission. The center section of the transmission has a unique configuration including a trunnion mounted swash plate, means for mounting the center section to the transmission and a motor output shaft mounted below the pump running surface. The transmission also includes an expansion chamber, preferably secured externally to the sump, having a tube mounted therein to transfer hydraulic fluid between the chamber and the sump.

Abstract: The inventive hydrostatic gear unit (1) comprises a hydraulic pump (2) and an adjustable hydraulic motor (6) which is connected to the hydraulic pump (2) via operating lines (4, 5). A drive control valve (3) is arranged in the operating lines (4, 5) for adjusting the delivery volume of the hydraulic medium flowing from the hydraulic pump (2) to the hydraulic motor (6). An adjusting device (7) is used to adjust the displacement volume of the hydraulic motor (6). The adjusting pressure of the adjusting device (7) is controlled via a control valve (24). A pilot control (12) is also provided which produces a control pressure in accordance with a transmitter (11). Said control pressure acts on the drive control valve (3) for adjusting the delivery volume flowing from the hydraulic pump (2) to the hydraulic motor (6). Said control pressure also acts on the control valve (24) for adjusting the displacement volume of the hydraulic motor (6).

Abstract: The object of the present invention is to simplify a structure for supporting a distributor valve and to reduce the weight thereof in a hydrostatic continuously variable transmission. A U-shaped clip is placed into a groove made on the head portion of a distributor valve and the distributor valve is passed in this state through the elongated hole of an expansion ring and the clip ring is engaged with the expansion ring whereas the inner peripheral surface of a slip ring is engaged with the head portion of the distributor valve.

Abstract: A hydraulic vehicle drive, having a closed hydraulic circuit consists of a variable displacement pump and one or several hydraulic motors. The variable displacement pump is driven by a diesel engine. During the braking or pushing operation of the vehicle, the hydraulic motor becomes a pump and drives the variable displacement pump which, in turn, acts as a motor upon the diesel engine and acts to accelerate the latter. Thus, the intended braking effect prevents the danger that the diesel engine will reach non-permissible high revolutions per unit time, which is particularly dangerous for diesel engines with turbochargers. In order to prevent non-permissible high revolutions per unit time, a pressure regulator acting as a throttle is placed in the return line between the hydraulic motor and the variable displacement pump. The valve throttles the rate of flow when the pressure of the hydraulic fluid in the line exceeds a certain desired value during the braking operation.

Abstract: In a direct drive type hydraulic pump, the displacement of the hydraulic pump is forcedly changed to a desired displacement according to an instruction of a channel different from a usual instruction, thereby changing to a desired displacement quickly with good responsivity. When an emergency brake switch is turned on, an emergency brake signal is entered an emergency brake control valve. Thus, an emergency brake signal pressure is entered a piston through an emergency brake signal oil passage, and a piston is forcedly positioned in a neutral position. In other words, the piston can be forcedly positioned in the neutral position according to the emergency brake signal regardless of the entry of a usual brake signal. Therefore, the displacement of the hydraulic pump can be forcedly changed to the neutral position (minimum displacement).

Abstract: To moderate the efficiency of engine braking when it is applied while a continuously variable transmission produces a large transmission ratio. Such a continuously variable transmission is constituted by a hydraulic pump having an input rotary member connected to an internal combustion engine of a vehicle, a hydraulic motor having an output rotational axis connected to a driving wheel. The hydraulic pump and hydraulic motor are coupled via a first oil passageway, which has a low oil pressure during the normal load operation of the engine but has a high oil pressure during the reverse load operation of the engine, and a second oil passageway, which has a high oil pressure during the normal load operation but has a low pressure during the reverse load operation, thereby forming a closed oil passageway circuit. At least the hydraulic pump or the hydraulic motor has a variable capacity.

Abstract: An assembly of valves controls hydraulic fluid flowing to several hydraulic actuators from a variable displacement pump that produces an output pressure equal to a control input pressure plus a predefined margin pressure. The control input pressure is a function of the greatest load pressure at the hydraulic actuators. Each valve has an associated pressure compensating valve which regulates the pressure differential across a metering orifice of each valve to a predefined level, usually the pump's margin pressure. A flow regulator is associated with at least one of the valves and reduces the output pressure from the pump to produce a reduced pressure that controls the associated pressure compensating valve. Operation of the flow regulator causes the pressure differential across a metering orifice of the associated valve to be less than the pump's margin pressure thus allowing adjustment of the fluid flow.

Abstract: An improved hydrostatic transmission which is compact, reliable and economical to manufacture, including a novel means for reducing the speed of the input to the transaxle using both hydraulics and mechanical gearing; an improved differential which is stronger and less complicated than prior art designs; a more effective and efficient means for braking the transaxle, an improved means for hydraulically bypassing the hydrostatic transmission and a unique check valve arrangement for maintaining oil pressure within the hydrostatic transmission.

Abstract: A hydrostatic transmission design incorporating a unique housing shape and configuration, including a vertical split of the two casing elements, which are shaped to conform to the internal components of the transmission. The center section of the transmission has a unique configuration including a trunnion mounted swash plate, means for mounting the center section to the transmission and a motor output shaft mounted below the pump running surface. The transmission also includes an expansion chamber, preferably secured externally to the sump, having a tube mounted therein to transfer hydraulic fluid between the chamber and the sump.

Abstract: The multiple pump apparatus includes first and second variable displacement closed circuit pumps. The multiple pump apparatus pressurizes fluid to be subsequently supplied to drive load devices. The first and second pumps each have fluid communication lines connected to load devices through flow control valves. Each of the pumps has a swashplate for varying its displacement. The swashplates are of the over-center type, enabling each pump to supply pressurized fluid in either direction, thus providing both forward and reverse function to the load devices. The first pump has its fluid communicating lines connected to fluid communicating lines between first and second two-position four-way flow control valves. The opposite side of the first flow control valve has fluid communicating lines connected to a load device which drives a harvesting mechanism, in this case a rotor motor.

Abstract: A control system for a hydraulic circuit having a tank, a pump, a supply conduit connected to the pump, a reversible hydraulic motor, an input conduit connected to the motor and an output conduit connected to the motor is disclosed which comprises a first, second, third, and fourth independently operable electrohydraulic metering valve, the second and third valves being disposed between the supply conduit, the first and second valves being disposed between the input conduit, and the third and fourth valves being disposed between the output conduit, a first pressure sensor connected to the supply conduit for sensing a pressure within the supply conduit, a second pressure sensor connected to the input conduit for sensing a pressure within the input conduit, a third pressure sensor connected to the output conduit for sensing a pressure within the output conduit, a speed and directional sensor connected to the motor for sensing the speed and direction of the motor, and a controller connected to the pump, the valv

Abstract: It is intended to provide a swash plate type continuously variable transmission capable of automatically affording a lock-up state in which second distributing valves are stopped at their stroke mid-point to cut off motor ports when a motor swash plate stands upright, even without using any special interlocking mechanism. Second distributing valves for bringing motor ports of motor cylinder bores into communication with a high-pressure oil path and a low-pressure oil path selectively in an alternate manner are arranged in parallel with the axis X of a cylinder block; a valve swash plate for reciprocating the second distributing valves is integrally combined with a motor swash plate on the same slant plane; and the motor ports are formed so as to be controlled selectively by the second distributing valves at respective positions 90.degree.