Abstract: Disclosed is a compressor including a cylinder, an upper flange and a lower flange respectively provided on an upper side and a lower side of the cylinder, and a main shaft having a sliding vane mounting portion. The sliding vane mounting portion of the main shaft is provided with at least two sliding vanes. Two rotary plates are provided. One rotary plate is provided between the sliding vane mounting portion and the upper flange, and another rotary plate is provided between the sliding vane mounting portion and the lower flange. Each of the rotary plates is fixedly connected with the main shaft and provided with exhaust openings in one-to-one correspondence with the exhaust sides of the sliding vanes and exhaust valves configured to control opening/closing of respective exhaust openings. The upper flange and the lower flange are both provided with exhaust passages corresponding to respective exhaust openings of each rotary plate.

Abstract: A drive assembly for a vehicle is provided, the vehicle having a frame, a prime mover and a pair of driven wheels. The drive assembly includes a transmission having a housing in which a pump and motor may be disposed. The transmission may be pivotally mounted to the frame and movable between at least two positions. The transmission may include an internal reduction gear assembly driven by a motor output shaft, a transmission output shaft disposed generally parallel to the motor output shaft and driven by the internal reduction gear assembly, the transmission output shaft extending from the transmission at both ends thereof. Each end of the transmission output shaft may drive an external reduction assembly supported in part by the frame, and the external reduction assemblies power at least a driven wheel of the vehicle.

Abstract: 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.

Abstract: A hydrostatic drive system for a vehicle (10) comprises an open circuit (100), a closed travel circuit (120), an electronic controller (320), and a main variable displacement hydraulic pump (102) driven by an internal combustion engine (12) equipped with a speed sensor (350). The main variable displacement hydraulic pump may be configured to supply hydraulic fluid to a hydraulic consumer (34, 44, 50) via a hydraulic supply line (106). A pressure relief valve (118) may be connected to a reservoir (300) and may be permanently connected to the hydraulic supply line of the open circuit. The electronic controller may be configured to run a strong braking mode in which the electronic controller at least partially increases the displacement of the main variable displacement hydraulic pump such that hydraulic fluid is discharged via the permanently connected pressure relief valve into the reservoir if the sensed engine speed is higher than a predetermined maximum engine speed.

Abstract: A hydrostatic transaxle for use as a drive apparatus of a vehicle is provided. The hydrostatic transaxle includes a main housing joined to a gear housing to enclose a hydrostatic transmission and a reduction gear set. The hydrostatic transmission includes an axial piston pump assembly and an axial piston 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.

Abstract: A hydraulic circuit. The circuit includes a high pressure line and a low pressure line, the pressure in the high pressure line being greater than the pressure in the low pressure line, a hydraulic machine having two ports designed to be connected to the high pressure and low pressure lines, a first of the ports being a hydraulic fluid intake port and the second of the ports being a hydraulic fluid discharge port The circuit includes a sequential connector designed to connect the ports of the hydraulic machine to the high and low pressure lines.

Abstract: A method for generating and verifying an output command for using in a power steering system is provided. The method receives, by a module having at least a primary processing path and a secondary processing path that is in parallel with the primary processing path, a set of input signals. In the primary processing path, the method generates a primary output command based on the set of input signals and sends the primary output command out of the module. In the secondary processing path, the method generates a first range of command values based on the set of input signals, determines whether the primary output command falls within the range of command values, and generates a fault signal based on determining that the primary output command does not fall within the first range of command values.

Abstract: A hydrostatic transmission comprises a hydraulic pump, a hydraulic motor, first and second main fluid passages fluidly connecting the hydraulic pump to the hydraulic motor so as to constitute a closed fluid circuit, a charge fluid passage, a plurality of first charge check valves and a plurality of second charge check valves. The plurality of first charge cheek valves are interposed between the charge fluid passage and the first main fluid passage so as to allow only flow of fluid from the charge fluid passage to the first main fluid passage when the first main fluid passage is hydraulically depressed relative to the charge fluid passage. The plurality of second charge check valves are interposed between the charge fluid passage and the second main fluid passage so as to allow only flow of fluid from the charge fluid passage to the second main fluid passage when the second main fluid passage is hydraulically depressed relative to the charge fluid passage.

Abstract: Hydraulic transmission apparatus including a pressurized fluid source and at least one hydraulic motor fed by said pressurized fluid source. The motor has two motor ducts for feed/discharge, and one casing duct. The motor can be operated in assisted mode, in which it generates torque or in unassisted mode in which it does not generate any torque and its pistons are maintained in the retracted position under the effect of the pressure in the casing duct. The apparatus further includes an accumulator suitable for feeding: the motor ducts during a stage of passing from the unassisted mode to the assisted mode in order to facilitate deployment of the pistons; and the casing duct during a stage of passing from the assisted mode to the unassisted mode in order to facilitate retraction of the pistons. This apparatus thus enables the motor to be positively clutched/declutched quickly.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a primary pump, a hydraulic actuator, and first and second passages fluidly connecting the primary pump to the hydraulic actuator in a closed-loop manner. The hydraulic system may also have a charge circuit, a makeup valve movable to selectively allow charge fluid from the charge circuit to enter the first or second passages, and at least one restricted pilot passage configured to direct pilot fluid to the makeup valve to move the makeup valve and allow the charge fluid into the first and second passages.

Abstract: A hydraulic transaxle comprises a transaxle housing, an axle, a hydraulic pump, a hydraulic motor, a hydraulic circuit, and a pair of auxiliary pumps. The transaxle housing defines a fluid sump therein. The axle is supported by the transaxle housing. The hydraulic motor is disposed in the transaxle housing so as to drive the axle. The hydraulic pump is disposed in the transaxle housing so as to supply hydraulic fluid to the hydraulic motor. The hydraulic circuit is disposed in the transaxle housing so as to fluidly connect the hydraulic pump to the hydraulic motor. The pair of auxiliary pumps are disposed in the transaxle housing so as to supply fluid from the fluid sump to outside of the transaxle housing.

Abstract: A hydraulic transmission system for a vehicle is provided. The system includes a main pump serving to feed with fluid at least one hydraulic motor for driving a vehicle mover member; an auxiliary pump, the main pump and the auxiliary pump being suitable for being actuated jointly; and a “bypass” connection between a delivery orifice of the auxiliary pump and an unpressurized reservoir. In addition, a first constriction is arranged on the bypass connection, and configured to maintain a pump protection pressure in a pump protection portion of the bypass connection. This pressure is applied to the main orifices of the main pump when said pump is actuated but is not delivering, thereby ensuring that the pump is protected.

Abstract: A control system for a hydraulic system comprises an electronic control module, an electronic system controller, a remote power module, and a solenoid valve. The electronic control module monitors torque output of an internal combustion engine, an electric motor and generator. The electronic system controller monitors torque demand of a first and a second hydraulic circuit. The remote power module is in electrical communication with the electronic system controller. The solenoid valve is in electrical communication with the remote power module. The solenoid valve connects to a combination valve and has a first open position and a closed position. The combination valve is in fluid communication with a first hydraulic circuit and a second hydraulic circuit. The solenoid valve moves to the open position in response to an output signal from the electronic system controller.

Abstract: A transmission comprises a casing, an output element, a hydrostatic stepless transmission unit (HST) and a forward/backward traveling direction selecting unit (reverser). The output element is supported by the casing. The HST is disposed in the casing so as to be driven by a drive source disposed outside of the casing. The HST includes a pump shaft and a motor shaft member. The pump shaft is drivingly connected to the drive source. The motor shaft member is fitted around the pump shaft coaxially to the pump shaft so as to be rotatable relative to the pump shaft, thereby constituting a hydraulic pump and a hydraulic motor centered on the pump shaft and the motor shaft member. An axially distal end of the motor shaft member is disposed on the axially proximal side of an axially distal end of the pump shaft so that axial ends of the pump shaft are the axially most distal ends of the HST in the axial direction of the pump shaft.

Abstract: A hydraulic transmission system for a zero-turn vehicle, comprises first and second transaxles each of which includes an axle, a casing supporting the axle, a fluid sump provided in the casing, first and second ports provided on the casing and opened outward from the casing, an HST circuit, a charge pump disposed in the casing, and a charge passage disposed in the casing to supply the HST circuit with fluid delivered from the charge pump. A first pipe connects the first ports of the transaxles, thereby making the flow of fluid from the charge pump of the first transaxle to the fluid sump of the second transaxle. A second pipe connects the second ports of the transaxles, whereby overflowing fluid of the fluid sump of the second transaxle is released to the fluid sump of the first transaxle via the second pipe.

Abstract: A pump displacement control cylinder is configured to control the displacement of a hydraulic pump according to pressure of hydraulic fluid and switches the discharge direction of the hydraulic fluid from the hydraulic pump according to the supply direction of the hydraulic fluid to the pump displacement control cylinder. A forward and backward progression switching valve is configured to switch the supply direction of the hydraulic fluid to the pump displacement control cylinder. A pressure control valve is configured to control the pressure of the hydraulic fluid supplied to the pump displacement control cylinder according to a command value input to the pressure control valve. A control section is configured to execute pump shuttle control which reduces the command value to the pressure control valve when switching between forward and backward progression using a forward and backward progression operation member.

Abstract: A hydraulic fluid cooling system for a pair of integrated hydrostatic transmissions includes a common reservoir holding hydraulic fluid and having hydraulic lines connecting the common reservoir to each integrated hydrostatic transmission, a hydraulic fluid reservoir inside each integrated hydrostatic transmission, and a pump for pumping fluid from each transmission's hydraulic fluid reservoir to the other transmission. An auxiliary hydraulic circuit is between the pair of integrated hydrostatic transmissions. The system pumps hydraulic fluid from one of the integrated hydrostatic transmission to the auxiliary hydraulic circuit, and the return line from the auxiliary hydraulic circuit may be connected to the other integrated hydrostatic transmission.

Abstract: A flow management system capable of providing adjustable hydraulic fluid flow or pressure at a common line to supply bidirectional pumps in electro-hydrostatic actuation systems and conditioning re-circulated hydraulic fluid. The system enables flow sharing between multiple actuation systems and minimization of energy consumption by a power-on-demand approach and/or electrical energy regeneration while eliminating the need for an accumulator. The system has particular application to electro-hydrostatic actuation systems that typically include bi-directional electric motor driven pumps and unbalanced hydraulic actuators connected within closed circuits to provide work output against external loads and reversely recover energy from externally applied loads.

Abstract: A drive apparatus is provided with a center section in a housing and having a hydraulic circuit formed therein with pump and motor running surfaces for connecting a hydraulic pump to a hydraulic motor. A pair of cylindrical openings may be formed on the center section opposite the pump running surface, and a passage in the center section connects the pair of cylindrical openings to form a fluid gallery to provide hydraulic fluid to the hydraulic circuit through a pair of check valves. A pair of caps on the center section to close off the fluid gallery, and an external charge pump to provide charged fluid to the fluid gallery, may also be provided.

Abstract: A hydrostatic pump (1) with a variable delivery volume can be operated in a closed circuit. An electrically controllable actuator device (4) is provided for the control of the delivery volume of the pump (1). The electrically controllable actuator (4) has an electrically actuatable control valve device (6) which generates a positioning pressure which actuates a positioning piston device (5) which is in an operative connection with a delivery volume control device (3) of the pump. An electrical position feedback circuit (21) of the delivery volume control device (3) is provided and the actuator device (4) is provided with a switchable hydraulic neutral position control system (25), by means of which a restoring movement can be generated that acts on the positioning piston device (5) and places the delivery volume control device (3) into a neutral position.

Abstract: A hydraulic circuit including: at least one primary motor comprising at least first and second distinct sub-motors, the first sub-motor having a first main orifice, and the second sub-motor having a second main orifice; and at least one secondary motor; in which circuit said first main orifice of the primary motor(s) is connected to a first main orifice of the secondary motor(s) via a first series duct, and the second main orifice of the primary motor(s) is connected to a second main orifice of the secondary motor(s) via a second series duct. This configuration of circuit makes coupling possible between the primary motor(s) and the secondary motor(s).

Abstract: A hydraulic fluid cooling system for a pair of integrated hydrostatic transmissions includes a common reservoir holding hydraulic fluid and having hydraulic lines connecting the common reservoir to each integrated hydrostatic transmission, a hydraulic fluid reservoir inside each integrated hydrostatic transmission, and a pump for pumping fluid from each transmission's hydraulic fluid reservoir to the other transmission. Hydraulic fluid lines link each transmission's hydraulic fluid reservoir to the other transmission. The system pumps hydraulic fluid from the sump or reservoir of each integrated hydrostatic transmission to the other transmission, providing the cooling capacity of a non-loaded transmission to cool hydraulic fluid for a fully loaded transmission.

Abstract: A drive train for a motor vehicle has an internal combustion engine and a hydraulically shiftable transmission unit. The input of the transmission can be connected via a clutch arrangement to a crankshaft of the internal combustion engine. The output of the transmission can be connected to driven wheels of the motor vehicle. The crankshaft is connected to a pump shaft which drives a pump arrangement for a hydraulic arrangement, by means of which the transmission unit is shifted and/or lubricated. The pump shaft is connected to an electric machine. The pump shaft is connected to the crankshaft via a constrained motion mechanism. The electric machine is arranged in the axial direction between the constrained motion mechanism and a pump of the pump arrangement.

Abstract: A drive apparatus includes a pair of axial piston pump assemblies in an inline relationship, each pump assembly having an end cap mounted to a pump housing to form a sump. The pump assemblies are mounted to a gearbox at one end thereof, and an input shaft extends into both pump housings and the gearbox to drive the axial piston pumps and one of the gears. A power take off mechanism is also engaged to the gearbox at another end thereof and includes a drive shaft at least partially disposed in the gearbox and driven by one of the transmission gears, and an output shaft extending in the opposite direction from the drive shaft.

Abstract: A hydrostatic transmission having a hydraulic pump that is fluidly connected to a hydraulic motor. The transmission also has a pressure control valve that has first and second stages and is fluidly connected to the hydraulic pump. By utilizing the pressure control valve when the first stage of the pressure control is at a minimum pressure the second stage determines the minimum charge pressure setting for the hydrostatic transmission.

Abstract: A hydrostatic transmission includes a hydraulic pump, a hydraulic motor, and a center section. The center section is formed therein with first and second fluid passages connecting kidney ports opened at a pump mounting surface to kidney ports opened at a motor mounting surface. The first and second fluid passages include respective straight portions parallel to the pump mounting surface and the motor mounting surface. When the center section is viewed to face the motor mounting surface, the straight portions of the first and second fluid passages substantially entirely overlap each other. When the center section is viewed to face the pump mounting surface, the straight portion of the first fluid passage is disposed between both ends of the second fluid passage, so that the straight portion of the first fluid passage and the ends of the second fluid passage are aligned on a substantially straight line.

Abstract: A fluid passage member includes a pump mounting surface onto which a hydraulic pump having a rotary axis is mounted; first and second kidney ports opened at the pump mounting surface; a first fluid extraction port outwardly opened and connected to the first kidney port; a motor mounting surface onto which a hydraulic motor having a rotary axis is mounted so that the rotary axis of the hydraulic motor is parallel to the rotary axis of the hydraulic pump; third and fourth kidney ports opened at the motor mounting surface; and a second fluid extraction port outwardly opened and connected to the third kidney port.

Abstract: There is provided a multiple pump unit including a pump shaft, a first pump, a pump housing, a second pump and a fluid passage block connected to one end surface in an axis line direction of the pump housing. One or both contacting surfaces of the pump housing and the fluid passage block is formed with a concave portion for accommodating the second pump. The pump housing is provided with a suction fluid passage guiding hydraulic fluid to a suction opening of the first pump and a first pump discharge fluid passage having a distal end that forms a first pump discharge port. The fluid passage block is provided with a second pump discharge port having the second pump as a hydraulic source.

Abstract: A hydrostatic transaxle is provided for a vehicle having a first axle and a second axle. The hydrostatic transaxle comprises: a hydraulic pump; a first hydraulic motor drivingly connected to the first axle; a closed circuit fluidly connecting the hydraulic pump to the first hydraulic motor; and a fluid-supply switching device shifted between a supply position for supplying fluid from the closed fluid circuit to a second hydraulic motor, which is disposed on the outside of the hydraulic transaxle and is drivingly connected to the second axle, and a supply-stop position for stopping the supply of fluid from the closed fluid circuit to the second hydraulic motor. The first hydraulic motor is variable in displacement, and the hydrostatic transaxle further comprises a linkage system for associating the switching of the fluid-supply switching device between the supply position and the supply-stop position with an operation for changing the displacement of the first hydraulic motor.

Abstract: A drive apparatus includes a pair of axial piston pump assemblies in an inline relationship, each pump assembly having an end cap mounted to a pump housing to form a sump. The pump assemblies are mounted to a gearbox at one end thereof, and an input shaft extends into both pump housings and the gearbox to drive the axial piston pumps and one of the gears. A power take off mechanism is also engaged to the gearbox at another end thereof and includes a drive shaft at least partially disposed in the gearbox and driven by one of the transmission gears, and an output shaft extending in the opposite direction from the drive shaft.

Abstract: A drivetrain for use in a mobile vehicle is disclosed. The drivetrain may have a housing, a first hydraulic pump connected to the housing, and a second hydraulic pump connected to the housing. The second hydraulic pump may be in axial alignment with the first hydraulic pump. The drivetrain may also have a first motor fluidly connected to the first hydraulic pump, and a second motor fluidly connected to the second hydraulic pump. The first and second motors may have an axial direction substantially perpendicular to the axial alignment of the first and second hydraulic pumps.

Abstract: A transmission system of a vehicle comprises a pump, an auxiliary pump, and a transmission. The pump pressurizes transmission oil when an engine is operating. The auxiliary pump operably coupled to the pump and located parallel to the pump that pressurizes the transmission oil when the engine is not operating. The transmission selects a gear ratio based on the pressurized transmission oil.

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: An auxiliary oil pumping system for an automatic transmission includes an auxiliary oil pump, the auxiliary oil pump being separate from an internal oil pump of the transmission but connected to an oil circuit of the automatic transmission to circulate oil in the system. An oil pump motor is connected to the auxiliary oil pump and selectively connectable to a power source for driving the auxiliary oil pump when a vehicle engine is off and the internal oil pump is not operating.

Abstract: A clutch mechanism for a hydrostatic continuously variable transmission in which a high pressure oil path and a low pressure oil path are shortened to change-over a transmittance of power. A spring sheet is provided of which manufacturing and assembling are simple and the number of component parts is reduced. This clutch mechanism for a hydrostatic continuously variable transmission includes a cam plate member arranged at the end part of the transmission shaft, a roller engaged with the cam plate member and moved in a diametrical outward direction with a centrifugal force, a roller bearing member slid axially through an outward motion of the roller, a spring sheet member for biasing the roller bearing member toward the roller, and a spring sheet member for supporting the spring member. The spring sheet member is held by said cam plate member and said casing and is supported.

Abstract: A hydraulic system comprises a plurality of primary hydraulic circuits and a secondary hydraulic circuit for satisfying flow continuity of the primary hydraulic circuits.

Abstract: There is provided a hydrostatic transmission (HST) in which a hydraulic pump unit operatively driven by a driving power source and a hydraulic motor unit arranged spaced apart from the hydraulic pump unit and operatively driving a driving-wheel are fluidly connected by way of operation fluid lines so as to form a closed circuit. The hydraulic motor unit is provided with motor-side operation fluid passages forming one part of the operation fluid lines. A motor-side charge fluid passage having a first end opened to an outside to form a motor-side charge port and a second end fluidly connected to at least one of the motor-side operation fluid passages is also included. A check valve is interposed in the motor-side charge fluid passage so as to allow the fluid to flow from the motor-side charge port to one motor-side operation fluid passage while preventing reverse flow.

Abstract: There is provided a hydraulic pump unit of variable displacement type disposed away from a pair of hydraulic motor units which are capable of being independently arranged, the pump unit fluidly-connected to the pair of hydraulic motor units so as to change the outputs of the pair of hydraulic motor units in both forward and reverse rotation directions. The pump unit includes a hydraulic pump body operatively rotated and driven by a driving source, a pump case surrounding the hydraulic pump body, a capacity adjusting mechanism for changing the capacity of the hydraulic pump body, and a hydraulic servomechanism for transmitting an external input based on a manual operation to the capacity adjusting mechanism by utilizing a hydraulic force.

Abstract: A regenerative braking system for a work machine includes a ground driven hydraulic pump coupled to a drive system, the ground driven hydraulic pump being configured to absorb shaft power from the drive system by converting the shaft power into a hydraulic flow, and the ground driven hydraulic pump also being configured to provide shaft power to the drive system by converting hydraulic flow into shaft power. The regenerative braking system also includes a hydraulic circuit fluidly coupling the ground driven hydraulic pump. The hydraulic circuit is configured to selectively receive and store energy from the drive system via the ground driven hydraulic pump; transmit the energy back to the drive system via the ground driven hydraulic pump; and direct hydraulic flow from the ground driven hydraulic pump to a hydraulic system of the work machine when an output of the main hydraulic pump drops below a desired level.

Abstract: A clutch mechanism for a hydrostatic continuously variable transmission has a hydraulic circuit including a high pressure oil path for feeding working oil from a hydraulic pump to a hydraulic motor and a low pressure oil path for feeding working oil from the hydraulic motor to the hydraulic pump. The clutch mechanism is located between the hydraulic pump and the hydraulic motor. A clutch valve is arranged on the transmission shaft and is slid by a centrifugal governor to cause the oil paths to be shortened. A cam plate member is arranged on the transmission shaft. A roller is engaged with the cam plate member and is moved outwardly in a diametrical direction by a centrifugal force. A roller bearing member receives a roller pressing force through outward motion of the roller. A pressure plate and shaft of the roller bearing member are separately formed and thereafter integrally formed.

Abstract: The invention relates to a connection block for a hydrostatic piston machine which is provided for simultaneous operation in a first hydraulic circuit and a second hydraulic circuit. A first working pressure duct (60) and a second working pressure duct (61) are formed in the connection block, via which ducts respectively a first and a second working line (7, 8) of the first hydraulic circuit can be connected to respectively a first and a second kidney-shaped control port of a control plate (52) of the hydrostatic piston machine. Furthermore, a third working pressure duct (62) and a fourth working pressure duct (63) are formed in the connection block (25), via which ducts respectively a third and a fourth working line (7?, 8?) of the second hydraulic circuit can be connected to respectively a third and a fourth kidney-shaped control port (70?, 71?) of the control plate of the hydrostatic piston machine.

Abstract: There is provided a pump unit configured to be capable of transmitting a rotational power from a driving power source which is operatively connected thereto to an actuator through a pair of hydraulic fluid lines. The pump unit includes: an input shaft; a hydraulic pump main body; a PTO shaft; a PTO clutch mechanism; an auxiliary pump main body; a suction line; a discharge line; a charge line; a PTO hydraulic fluid line; a pressure-reducing valve; and a resistance valve. The PTO hydraulic fluid line and the charge line are fluidly connected to the primary side and a secondary side of the pressure-reducing valve, respectively.

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 hydraulic drive device including a center section for rotatably mounting a hydraulic pump and hydraulic motor on respective running surfaces. The center section further includes a pair of ports connecting the running surfaces, where the ports are not located in the same plane but are rather offset from one another with respect to the pump running surface, so that one of the ports is closer to the pump running surface than the other port.

Abstract: An embodiment of the present invention involves a zero turn drive apparatus. The zero turn drive apparatus has a housing, which has a first and a second end. The housing has a first end cap mounted on the first end of the housing, and a second end cap mounted on the second end of the housing. A hydraulic pump is rotatably mounted on each end cap, and each hydraulic pump is driven by a pump input shaft. A gear chamber is interposed between each pump. A power take off mechanism is engaged to the housing, and an output shaft extends from the power take off mechanism. An input shaft, which is engaged to each of the pump input shafts, extends into the power take off mechanism and is selectively engaged to the output shaft.

Abstract: An axle driving apparatus comprising a common housing in which a hydraulic pump and a hydraulic motor fluidly connected with each other and an axle driven by the hydraulic motor are disposed, At least one of the hydraulic pump and the hydraulic motor is variable in displacement and has a capacity changing device for changing its capacity. A hydraulic actuator is provided in the housing for controlling the capacity changing device. A control valve for hydraulically controlling the hydraulic actuator is provided in the housing. A center section for fluidly connecting the hydraulic pump and the hydraulic motor with each other is fixedly disposed in the housing and a driving part of the hydraulic actuator and the control valve are incorporated in the center section. A rotary member operatively connected to a human-operated traveling control member provided on a vehicle is rotatably supported by the housing.

Abstract: A hydraulic system having at least one hydraulic valve for controlling a transmission, in particular a continuously variable transmission. The hydraulic valve is controlled by a pilot circuit including at least one control element having a variable flow resistance and one control element having a constant flow resistance. The control element having a variable flow resistance is connected upstream of the control element having a constant flow resistance.

Abstract: A charge pump for hydraulic drive device such as a hydrostatic transmission or integrated hydrostatic transaxle using hydraulic porting having first and second pressure sides mounted in a sump to connect a hydraulic pump and motor. The charge pump comprises a body connected between the first and second pressure sides of the porting to pull hydraulic fluid from a charge sump to the low pressure side of the porting, when the second pressure side is under low pressure.

Abstract: A charge pump is provided with two independent outlets that can satisfy the pressure requirements of both a charge circuit and an auxiliary circuit. Preferably, the charge pump is a multiple roller vane pump that has at least one inlet and two outlets independent of each other. The first outlet is in fluid communication with a charge circuit, and the second outlet is in fluid communication with an auxiliary circuit. Because the two outlets are independent of each other, the roller vane pump is able to satisfy the pressure requirements of both the charge and auxiliary circuits. Preferably, the two outlets are diametrically opposed to each other, thereby reducing the load on the driveshaft. Additionally, the roller vane pump may include a second inlet independent of the first.

Abstract: A charge pump design for a hydraulic drive apparatus such as a hydrostatic transmission, integrated hydrostatic transaxle or pump having a rotatable pump cylinder block mounted in a sump and connected to a hydraulic circuit by means of a center section or the like. A fluid gallery for charge fluid is in communication with the hydraulic circuit and the charge pump is mounted adjacent to and is driven by the pump cylinder block to provide hydraulic fluid from the sump to the fluid gallery. The charge pump can be of many different styles such as a gerotor, a centrifugal pump or a flexible impeller style.