Abstract: A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.

Abstract: A system includes a variable displacement pump (VDP) with a pump inlet and a pump outlet. The VDP is configured to receive a flow at the pump inlet at a first pressure and to outlet a flow from the pump outlet at a second pressure elevated relative to the first pressure. The VDP includes a variable displacement mechanism configured to vary the second pressure. A controller is operatively connected to a pressure sensor and to the variable displacement mechanism for control of the VDP. An output splitter is configured to split flow from the pump outlet to a first outlet branch and to a second outlet branch for supplying two different systems each having a different pressure schedule. The output splitter is operatively connected to the controller, which is configured to control the output splitter to regulate pressure in both of the first and second outlet branches.

Abstract: Disclosed is a hydraulic control apparatus including a flow-path selector valve that switches a supply flow path and a flow-path switching control unit that operates the same, a regeneration valve and a regeneration release valve capable of the regenerative operation, and a regeneration control unit that operates the same. The flow-path switching control unit makes the flow-path selector valve form a flow-path providing communication between first and second pumps in a combined operation state. The regeneration control unit judges the propriety of the regenerative operation on the basis of the second pump pressure which is the discharge pressure of the second pump in a single operation state and judges the propriety of the regenerative operation on the basis of whether or not the driving state of the work actuator is within an allowable range corresponding to the target work operation amount in the combined operation state.

Abstract: A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.

Abstract: A vehicular accessory system includes a first accessory pivotable in a first direction via pressurized fluid at a first actuator and pivotable in a second direction via pressurized fluid at a second actuator, and a second accessory pivotable in a third direction via pressurized fluid at a third actuator and pivotable in a fourth direction via pressurized fluid at a fourth actuator. A valve assembly is in fluid communication with the first, second, third and fourth actuators. Responsive to pivoting of the first accessory to a first fully pivoted orientation, the valve assembly automatically operates to supply pressurized fluid to the third actuator to pivot the second accessory in the third direction. Responsive to pivoting of the first accessory to a second fully pivoted orientation, the valve assembly automatically operates to supply pressurized fluid to the fourth actuator to pivot the second accessory in the fourth direction.

Abstract: In the event of a malfunction in the supply of hydraulic fluid to the a braking device actuating device a hydraulic system has a manually actuated emergency-operation valve arrangement which is formed in such a way that, after the manual actuation thereof, a fluid connection is created between a steering device actuating device and the a pressure chamber of the braking device actuating device. The emergency-operation valve arrangement has a valve block in which flow paths are formed which can be shut off by means of shut-off screws.

Abstract: Modular directional valve with two or more crossing elements (E1 . . . En) able, acting only on the entry side, to manage a variable displacement pump (PA) of the load sensing type. In particular, this management allows in a single drive, unlike the conventional crossing distributors, to make the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads. A compensated flow rate regulator is placed in the entry side so as to act only on the bypass line LC upstream of the first element (E1 . . . En) while a proportional choke is placed on the load line consisting of a 2-way 2-position tray.

Abstract: A hydraulic system for a work machine includes a first control valve to control a first hydraulic actuator, a second control valve to control a second hydraulic actuator, a first fluid tube connecting the first hydraulic actuator to the first control valve, and a second fluid tube connecting the second hydraulic actuator to the second control valve. A level control valve apparatus is connected to the first fluid tube and the second fluid tube. The level control valve apparatus is configured to control a leveling operation for the second hydraulic actuator. An accumulator apparatus is connected to the first hydraulic actuator. The accumulator apparatus communicates with the first fluid tube between the level control valve apparatus and the first control valve. Circuitry is configured to control the level control valve apparatus to stop the leveling operation when the accumulator apparatus is in operation.

Abstract: A hydraulic excavator drive system includes: a cylinder that drives a moving part that is an arm or a bucket. Hydraulic oil is supplied from a hydraulic pump to the cylinder via a control valve. A bypass line branches off from a rod-side supply/discharge line. The bypass line is blocked and opened by a restrictor. The restrictor is controlled by a controller such that, when the hydraulic oil is supplied to the cylinder through a head-side supply/discharge line, the restrictor blocks the bypass line if a pressure detected by a load detector is lower than a predetermined value, and opens the bypass line if the pressure detected by the load detector is higher than or equal to the predetermined value.

Abstract: An agricultural spreader system includes a first motor, a second motor, and a valve system coupled to the first motor and to the second motor. The first motor is configured to be driven by a working fluid and to drive a first spreader disc in rotation. The second motor is configured to be driven by the working fluid and to drive a second spreader disc in rotation. The valve system is configured to transition between a series flow arrangement and a parallel flow arrangement. The series flow arrangement is configured to direct the working fluid to the second motor through the first motor. The parallel flow arrangement is configured to direct a first portion of the working fluid to the first motor, and to direct a second portion of the working fluid to the second motor.

Abstract: A method for improving excavating operation characteristic and grading operation characteristic of an excavator is disclosed. A hydraulically controlled selector valve is added in a boom confluence control circuit of a hydraulic excavator, and a solenoid valve group is added in the boom confluence control circuit and the bucket/stick confluence control circuit. A controller sends a control signal to switch the solenoid valve group between a disconnected mode and a connected mode. The controller may send out a signal to disconnect the solenoid valve group, to restore a valve spool to a middle position, to restore a boom lifting confluence circuit, and to disconnect a bucket/stick swinging confluence circuit to perform a standard excavation mode. The controller may send out a signal to connect the solenoid valve group to disconnect a boom lifting confluence circuit and to increase a bucket/stick swinging confluence circuit to achieve a grading operation mode.

Abstract: A hydraulic fan powered in a branch of a vehicle-carried working load hydraulic circuit helps cool hydraulic fluid in a cooler. A switching block has a bypass mode which kicks in whenever sensed hydraulic fluid temperature indicates an overheat condition. The bypass mode shuts off hydraulic fluid to all the working loads of the system, while circulating hydraulic fluid as fast as possible through the cooler and running the cooling fan at a slower rate. After the hydraulic fluid cools below the overheat threshold temperature, a start button must be pressed before the switching block will again power the working loads and run the fan at a higher speed.

Abstract: A steam turbine system and method of operating a steam turbine system including a steam generator coupled to a high pressure section and a low pressure section. The steam turbine system may further include to a first portion of a drive shaft coupled to the high pressure section and a clutching device for releasably coupling to a power generator coupled to the first portion of the drive shaft. The steam turbine system may also include a second portion of the drive shaft for coupling to the power generator coupled to the low pressure section. The method may be implemented using a controller of the steam turbine system.

Abstract: A hydraulic system is disclosed having first, second, and third pumps. The hydraulic system may also have a first actuator connected to the first pump in closed-loop manner, a second actuator connected to the second pump in closed-loop manner, and a third actuator. The hydraulic system may further have a selector valve associated with the third pump, and a first switching valve associated with the third pump and the third actuator. The first switching valve may be movable between a first position at which the third pump is connected to the third actuator in a closed-loop manner to move the third actuator in a first direction, a second position at which the third pump is connected to the third actuator in a closed-loop manner to move the third actuator in a second direction, and a third position at which the third pump is connected to the selector valve.

Abstract: A system has a variable displacement pump that supplies pressurized fluid to power a plurality of hydraulic functions. Each hydraulic function has a control valve with a variable source orifice controlling fluid flow between the pump and a flow summation node, and a variable metering orifice controlling fluid flow between the flow summation node and a hydraulic actuator. Variable bypass orifices in the control valves are connected in series between the flow summation node and a tank. As the metering orifice in a control valve enlarges, the source orifice enlarges and the bypass orifice shrinks. This alters pressure at the flow summation node, which is used to control the output of the pump. Components are provided to give selected hydraulic functions different levels of priority with respect to consuming fluid flow from the pump.

Abstract: An accessory flow recovery system includes an inlet that receives a first fluid flow, and a pump with a pump inlet and outlet. The pump inlet receives the first fluid flow from the inlet and discharges a second fluid flow from the outlet. The accessory flow recovery system has an actuation unit for supplying a third fluid flow to accessory components, a metering system to regulate the flow rate of the second fluid flow based on a flow demand, and an inlet pressurizing valve coupled between the outlet and the metering system. The inlet pressurizing valve regulates the second fluid flow between the pump and the metering unit. The accessory flow recovery system further includes a return switch valve to direct the third fluid flow to the metering system when the recovery system is operating in one mode, and to the inlet when the system is operating in another mode.

Abstract: The present invention relates to a hydrostatic transmission closed circuit comprising a fluid tank (50), a hydraulic pump (12; 212), a first engine assembly (20; 220) and a second engine assembly (30, 40; 230), said first and second engine assemblies (30, 40; 230), each comprising at least one hydraulic engine, a booster pump (14; 214), an exchange unit (60; 260), said circuit being characterised in that it also comprises a supplementary boosting line (150; 350) which removes fluid at the outlet of the exchange unit (60; 260) and boosts the hydrostatic transmission circuit at the level of the series line (104; 204).

Abstract: [Problem] To provide a hydraulic drive system for a hydraulic excavator, which makes it possible to efficiently perform grading work by using residual energy of pressure oil in a hydraulic circuit although no attention has been paid to the residual energy in conventional technologies. [Solution] A hydraulic drive system for a hydraulic excavator is provided with a boom cylinder 1 and arm cylinder 2, a main hydraulic pump 4 for feeding pressure oil to both the cylinders 1,2, a directional control valve 7 for a boom and directional control valve 8 for an arm to control flows of pressure oil to be fed to the boom cylinder 1 and arm cylinder 2, respectively, and a reservoir line 8c connecting the directional control valve 8 for the arm with a working oil reservoir 6.

Abstract: Hydrostatic transmission apparatus for a vehicle having a front group of drive members and a rear group of drive members, a pump, a front motor and a rear motor contributing to driving respective ones of the front and rear groups of drive members; a first one of the motors and a second one of the motors connected to the first motor via a series duct also being connected to the main orifices of the pump, thereby constituting a closed transmission circuit; at least one pressure-limiting valve being interposed between the series duct and a low-pressure circuit, and being suitable for connecting the series duct to the low-pressure circuit while being controlled as a function of the high pressure of the pump. The pressure in the series duct is thus effectively limited to a pressure representative of the pressure necessary for driving the vehicle.

Abstract: A hydrostatic transmission apparatus having a main pump, two main ducts that are respectively a feed main duct and a discharge main duct for first and second hydraulic motors serving to drive two drive members of a vehicle that are situated one after the other. At least the first hydraulic motor is a dual motor made up of two elementary motors, a first one of which is connected via a series link to the second hydraulic motor. A link selector can take up a first position in which a series loop including said series link coexists with a direct loop for directly linking at least the second elementary motor to the two respective orifices of the main pump, and a second position in which at least one of said direct and series loops is bypassed by a bypass link having a constriction valve.

Abstract: Hydraulic transmission circuit with N hydraulic motors, wherein each motor comprises N sub-motors, all N2 sub-motors having the same cylinder displacement. The circuit comprises one common feed duct, adapted for receiving fluid under pressure, and to which one feed sub-motor of each motor is connected; one common exhaust duct, adapted for ejecting exhaust fluid, and to which one exhaust sub-motor of each motor is connected; N serial ducts, each serial duct connecting a feed, first sub-motor to an exhaust, N-th sub-motor via N?2 interposed sub-motors, these N connected sub-motors respectively belonging to the N motors. This circuit allows tight synchronization of the N hydraulic motors.

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: The invention relates to a hydrostatic multi-motor drive (1) with a hydraulic pump (2) and at least one first pair of hydraulic motors. The two hydraulic motors (6, 7) of the first pair of hydraulic motors are connected to one another in series by means of a first working line section (12). A bypass line (15) is provided which connects a first connection (11; 10) of the hydraulic motor (7; 6), which is upstream in relation to a volumetric flow generated by the hydraulic pump (2), to a second connection (9; 8) of the downstream hydraulic motor (7; 6). A first valve unit (18) which interrupts the first bypass line (15) is arranged in the bypass line (15). A first minimum pressure maintaining device (25; 26) for maintaining a minimum pressure at the upstream connection (11; 10) of the downstream hydraulic motor (7; 6) is also arranged in the bypass line (15).

Abstract: Improvements in a transmission are provided for transferring power from a power source to a work unit. The pump transfers energy received from the power source into a fluid or gas. The first turbine is fixed to output shaft, and a plurality of additional turbines are fixed on either one-way overrunning clutches or multi-disc clutches and these clutches are fixed to the output shaft and after each turbine is a multi-valves that discharges the fluid or gas. After all of the multi-stage turbines a first planetary gear set connects the transmission to the vehicle or work unit. The second planetary gear set is located between the last turbine and the first planetary gear set. During braking the planetary gear set reverses turning direction of the turbines and convert the turbines into pumps where they will pump low pressure fluid to a high pressure accumulator.

Abstract: A valve assembly couples a plurality of hydraulic actuators to a variable displacement pump and to a tank. A separate valve is associated with each hydraulic actuator and comprises a variable flow source orifice between the supply conduit and a summation node coupled to a pump control port, a variable metering orifice between the summation node and the associated hydraulic actuator, and a variable bypass orifice between the summation node and the tank. As a valve operates to enlarge the metering orifice, the flow source orifice also enlarges, and the bypass orifice shrinks. When the valve operates to shrink the metering orifice, the flow source orifice also shrinks and the bypass orifice enlarges. Those operations vary fluid flow in and out of the summation node, which alters pressure applied to the pump control, thereby causing the pump output to vary as required to drive the associated hydraulic actuator.

Abstract: A multi-speed jack, having a pump assembly including a pump block having a first cylinder and a second cylinder defined therein, a piston assembly movable within the pump block, the piston assembly having a first portion configured to sealably engage with the first cylinder and a second portion configured to sealably engage with the second cylinder, a reservoir for storing hydraulic fluid and coupled to the pump block so that when the piston assembly is moved in a first direction, hydraulic fluid in the reservoir is supplied to the first cylinder and the second cylinder, a lifting assembly having a ram chamber and a ram rod, the ram chamber coupled to the pump assembly and configured to receive fluid from the first cylinder and the second cylinder when the piston assembly is moved in a second direction so as to raise the ram rod and a bypass check valve provided in the first cylinder.

Abstract: A hydraulic control system for a swiveling construction machine includes at least one hydraulic travel motor, a first hydraulic actuation device, a second hydraulic actuation device and a hydraulic diverter valve assembly. The at least one hydraulic travel motor is configured to move the swiveling construction machine in a first travel speed and a second travel speed based on a variable pilot pressure signal. The first hydraulic actuation device is configured to actuate a first function of an implement. The second hydraulic actuation device is configured to actuate a second function of an implement. The hydraulic diverter valve assembly is configured to divert hydraulic power between the first hydraulic actuation device and the second hydraulic actuation device while maintaining operation of the at least one hydraulic travel motor in one of the first and the second speeds.

Abstract: A hydraulic drive system is mounted on a hydraulic excavator, and is provided with a directional control valve 23 for a boom, a directional control valve 24 for an arm, a boom control device 25 for selectively controlling the directional control valve 23 for the boom, and an arm control device 26 for selectively controlling the directional control valve 24 for the arm. The directional control valves 23, 24 control a boom cylinder 6 and an arm cylinder 7, respectively, which are driven by pressure oil delivered from a main hydraulic pump 21. The hydraulic drive system is provided with a communication control unit for communicating a rod chamber 6b of the boom cylinder 6 and a bottom chamber 7a of the arm cylinder 7 with each other when a stroke of the arm control device 26 has become a predetermined amount S or greater.

Abstract: Improvements in a turbo transmission are provided for transferring power from a power source to a work unit. The transmission includes an input shaft coupled to a power source and to a pump that is configured to rotate with the input shaft. The pump transfers energy received from the power source into a fluid or gas. The transmission includes an output shaft and a multi-stage turbine in line. The first turbine is fixed to output shaft, and a plurality of additional turbines are fixed on either one-way overrunning clutches or multi-disc clutches and these clutches are fixed to the output shaft and after each turbine is a multi-valves that discharges the fluid or gas. After all of the multi-stage turbines a planetary gear set connects the turbo transmission to the vehicle or work unit.

Abstract: An improved anti-cavitation hydraulic manifold for hydraulically coupling the hydraulic input and output of two, drive coupled, reversible hydraulic motors and a reversible source of hydraulic power for winding and unwinding systems is described wherein a stop confines a shuttle ball within each of two input/output (I/O) chambers receiving driving hydraulic input liquid from the reversible source of hydraulic power between an annular valve seat around a bypass passage communicating between the bases of the input/output (I/O) chambers and any ports penetrating into the respective input/output (I/O) chambers supplying high pressure or driving hydraulic input from the reversible source of hydraulic power where, responsive to supplied high pressure or driving hydraulic input to a particular I/O chamber, the shuttle ball in the chamber seats upon the particular annular valve seat translating a shuttle rod in the bypass passage unseating the particular shuttle ball from the annular valve seat around the passageway

Abstract: A hydraulic system for a machine is disclosed. The hydraulic system may have a pump, a tank, a first actuator with a head-end and a rod-end, and a first valve arrangement configured to control fluid flow from the pump to the first actuator and from the first actuator to the tank. The hydraulic system may also have a second actuator with a head-end and a rod-end, and a second valve arrangement configured to control fluid flow from the pump to the second actuator and from the second actuator to the tank. The hydraulic system may further have a third valve arrangement fluidly connected between the first and second valve arrangements to receive pressurized fluid from the pump in parallel with the first and second valve arrangements. The third valve arrangement may be configured to facilitate fluid regeneration of and supplemental flow to at least one of the first and second actuators.

Abstract: A hydraulic system includes first and second pumps, first and second motors, and three valves for selectively creating combined and basic hydraulic flow. The arrangement of valves permits combined flow to be provided to both motors in series to cause high speed operation of the motors, and permits combined flow to be provided to one motor and basic flow to the other motor. When applied to a vehicle, the arrangement provides a steerable high speed series arrangement of the vehicle's drive motors.

Abstract: The invention relates to a hydrostatic multi-motor drive (1) with a hydraulic pump (2) and at least one first pair of hydraulic motors. The two hydraulic motors(6, 7) of the first pair of hydraulic motors are connected to one another in series by means of a first working line section (12). A bypass line (15) is provided which connects a first connection (11; 10) of the hydraulic motor (7; 6), which is upstream in relation to a volumetric flow generated by the hydraulic pump(2), to a second connection (9; 8) of the downstream hydraulic motor (7; 6). A first valve unit (18) which interrupts the first bypass line (15) is arranged in the bypass line (15). A first minimum pressure maintaining device (25; 26) for maintaining a minimum pressure at the upstream connection (11; 10) of the downstream hydraulic motor (7; 6) is also arranged in the bypass line (15).

Abstract: A swing control circuit is provided separately from a hydraulic actuator control circuit. The swing control circuit includes a swing pump motor connected to closed circuits of a swing motor through a solenoid valve that serves as a directional control valve. A swing motor generator is connected to the swing pump motor. The swing motor generator is connected to an electric power storage device of a hybrid type drive system. An exterior-connecting passage for feeding hydraulic fluid to hydraulic actuators of a lower structure and a work equipment is drawn from a pipeline between the swing pump motor and the solenoid valve. A connecting passage solenoid valve is disposed in the exterior-connecting passage. The invention enables hydraulic energy generated in the swing system to be directly fed to the outside of the swing system.

Abstract: To permit using hold-side pressure oil in a first hydraulic cylinder for the acceleration of a second hydraulic cylinder upon performing a combined operation of the first and second hydraulic cylinders, a hydraulic drive system is provided with a main hydraulic pump 21, a boom cylinder 6 and an arm cylinder 7, a directional control valve 23 for a boom and a directional control valve 24 for an arm, and a boom control device 25 and an arm control device 26. The hydraulic drive system is also provided with a pressure oil feed means for feeding pressure oil in a rod chamber 6b of the boom cylinder 6 to an upstream side of the directional control valve 24 for the arm when a bottom pressure of the arm cylinder 7 has increased to a high pressure equal to or higher than a predetermined pressure. This pressure oil feed means includes a flow combiner valve 44 arranged in a reservoir line 42 which can communicate to the rod chamber 6b of the boom cylinder 6.

Abstract: An improved anti-cavitation hydraulic manifold for hydraulically coupling the hydraulic input and output of two, drive coupled, reversible hydraulic motors and a reversible source of hydraulic power for winding and unwinding systems is described wherein a stop confines a shuttle ball within each of two input/output (I/O) chambers receiving driving hydraulic input liquid from the reversible source of hydraulic power between an annular valve seat around a bypass passage communicating between the bases of the input/output (I/O) chambers and any ports penetrating into the respective input/output (I/O) chambers supplying high pressure or driving hydraulic input from the reversible source of hydraulic power where, responsive to supplied high pressure or driving hydraulic input to a particular I/O chamber, the shuttle ball in the chamber seats upon the particular annular valve seat translating a shuttle rod in the bypass passage unseating the particular shuttle ball from the annular valve seat around the passageway

Abstract: The invention relates to a hydrostatic vehicle drive system (1) comprising a first and a second hydraulic pump (2, 3), and a first and a second hydraulic motor (7, 12). Said hydraulic pumps (2, 3) and said hydraulic motors (7, 12) are coupled in such a way in a differential lock operation that a first connection (14) of the first hydraulic pump (2) is connected to a first connection (8) of the first hydraulic motor (7); a second connection (6) of the first hydraulic motor (7) is connected to a first connection (10) of the (10) of the second hydraulic pump (3); a second connection (9) of the second hydraulic pump (3) is connected to a first connection (13) of the second hydraulic motor (12); and a second connection (11) of the second hydraulic motor (12) is connected to a second connection (5) of the first hydraulic pump (2). The absorption volume of the first hydraulic motor (7) and the second hydraulic motor (12) can be respectively adjusted by means of an adjusting device (20, 21).

Abstract: A hydraulic drive unit is provided with a boom cylinder, an arm cylinder, a communication line communicating a rod chamber of the boom cylinder and a bottom chamber of the arm cylinder with each other, and a switching valve arranged on the communication line for communicating or shutting off the communication line in accordance with a rod pressure of the boom cylinder. When an arm-crowding single operation is performed and by its digging counterforce, a rod pressure of the boom cylinder rises to a high pressure of at least a predetermined pressure, the switching valve is changed over from a shut-off position to a communicating position to feed pressure oil from the rod chamber to the bottom chamber. The boom cylinder is hence caused to automatically extend, thereby avoiding lifting of a hydraulic excavator body.

Abstract: There is provided a flow divider system in a hydraulic circuit for a work machine including a boom cylinder and a bucket cylinder. The flow divider system divides a pressured oil drained from a one-boom cylinder into an other-bucket cylinder and a tank via a first orifice, a second orifice and a flow dividing valve, maintaining a specified pressure difference between pressures downstream the first and second orifices. The first and second orifice are configured of a variable orifice respectively, and in the event that the oil flow from the one-boom chamber decreases, respective opening degrees of the first and second orifices are controlled so as to be reduced. Accordingly, changing of a divisional ratio of oil flow can be suppressed properly regardless of a small oil flow drained from the boom cylinder.

Abstract: According to the present invention, an improved hydraulic transmission system is provided which includes a fluid supply adapted to supply a variable pressure hydraulic working fluid. Hydraulic users are connected to the fluid supply. A control is adapted to generate a control signal indicative of a desired flow rate of the hydraulic working fluid, and a second connection control is responsive to the control signal and is adapted to selectively connect the hydraulic users in series or in parallel according to the control signal.

Abstract: A hydraulic driving unit is provided with a directional control valve 23 and directional control valve 24 for controlling a boom cylinder 6 and arm cylinder 7, both of which are driven by pressure oil delivered from a main hydraulic pump, respectively, a boom control device 25 for selectively controlling the directional control valve 23 and an arm control device 26 for selectively controlling the directional control valve 24, and is mounted on a hydraulic excavator.

Abstract: The present invention relates to a hydraulic actuating device for a device having a first and a second hydraulically moveable component. This actuating device comprises a first and a second hydraulic actuator, respectively, for moving the first and second moveable components. The first and second actuators each have a housing in which there is a space in which a piston and piston rod assembly can move in a reciprocating manner, with a piston and a piston rod which is coupled to the piston and projects out of the housing. The piston delimits a first working chamber and a second working chamber in the housing. The housing is provided with a first and a second connection, which are respectively in communication with the first and second working chambers in order to supply and discharge hydraulic fluid in order to displace the piston and piston rod assembly.

Abstract: A small self-propelled loader has hydraulic drive motors and at least one work cylinder, and has a hydraulic system that efficiently utilizes the available horse power from an internal combustion engine on the loader. The engine drives a tandem pump and the flows from two sections of the tandem pump pass through a first diverter valve that permits using the flow from each of the pump sections to drive a respective one of the drive motors. The return or drain flow from valves controlling the drive motors is connected to a second diverter valve to selectively direct the drain flow from the drive motors for operating remote work cylinders. Alternately, the first diverter valve directs the output from one pump section to the work cylinders, so that when the loader is standing still or moving very slowly, the work cylinder has adequate flow, and flow from the other pump section is split to power the drive motors.

Abstract: A hydraulic circuit comprises first and second cylinders, and a piston disposed in each of the cylinders. A pump communicates with one side of one of the pistons, and a pressure relief valve has a position wherein the pump communicates with another side of the one piston and with the other piston.

Abstract: A regeneration method for a hydraulic system enables the fluid being forced from a first actuator to be used to power a second actuator. Often the force of the load acting on a hydraulic actuator is used to move the actuator into a given position which motion forces fluid from the actuator. Rather than simply draining that fluid to the system tank, the fluid is routed to a second actuator to be powered when the pressure of the fluid draining at the first actuator is greater than the pressure required to power the second actuator. At other times the draining fluid can be used to drive the pump which has been configured to operate as a motor thereby driving the prime mover connected to the pump. Alternatively the draining fluid can be routed to an accumulator where it is stored under pressure until needed to power an actuator of the system. A unique bidirectional pilot operated poppet valve.

Abstract: A hydraulic valve assembly includes a pilot operated proportional poppet valve in which the main poppet moves in response to pressure in a first control chamber. The pressure in a first control chamber is governed by a pilot poppet and movement of the main poppet controls fluid flow between a first inlet and a first outlet. A shadow poppet valve has a shadow poppet that controls fluid flow between a second inlet and a second outlet in response to pressure in a second control chamber. The first and second control chamber are connected together whereby the pilot operated proportional poppet valve and the shadow poppet valve open and close together. A unique hydraulic system utilizing a plurality of these hydraulic valve assemblies to operate two operators alternately in parallel or in series is described.

Abstract: A fluid control system (50) is provided for a work machine (10) having first and second compacting drums (14,16). First and second hydraulic motors (28,32) are connected in series and power first and second vibratory mechanisms (26,30) located within the first and second compacting drums (14,16). A control valve (60) supplies pressurized fluid to the first hydraulic motor (28). The pressurized fluid is transferred through a bypass circuit (74) around the second hydraulic motor (32). A sequencing device (80) closes the bypass circuit (74) transferring the pressurized fluid to the second hydraulic motor (32) after actuation of the first hydraulic motor (28).

Abstract: A hydraulic control circuit for, for example, working members of earth-moving machines such as backhoe loaders. A first and a second control section (9,10) are coupled to first and second linear hydraulic actuators (1,2; 3-8) through respective first a second hydraulic spool valves (21,22; 23-28), and supply (11) of a hydraulic fluid under pressure is connected in parallel with the two control sections (9,10) via a feed line (13). A load sensing circuit (16) is associated with the first and second spool valves. The control circuit includes a series-parallel connection circuit (36) of the load sensing circuit (16), and additional optional devices ensuring a higher operative functionality of the working members of the machine.

Abstract: A power machine has a base, an operator support portion, and a hydraulic slew motor coupled to move the operator support portion relative to the base. A boom, an arm, and a tool are all coupled to one another and to the operator support portion and are powered by hydraulic actuators. A slew valve is coupled to receive hydraulic fluid under pressure from a hydraulic power circuit and is also coupled to the slew motor to provide hydraulic fluid to the slew motor and receive hydraulic fluid from the slew motor. A first power actuator valve is coupled to receive hydraulic fluid from the slew valve and is coupled to provide hydraulic fluid to one of the hydraulic boom actuator, the hydraulic arm actuator and the tool actuator. The slew valve is coupled in series with the power actuator valve.

Abstract: A power machine includes a pair of traction motors to provide for travel of the machine. The power machine also includes a boom, an arm and a tool (such as a bucket). The power machine includes a hydraulic power circuit which has a valve stack that enables the boom and at least one of the arm and tool to be operated simultaneously.