Abstract: A hydraulic system for a working machine includes a first electric machine connected to a first hydraulic machine; a second electric machine connected to a second hydraulic machine, an output side of the second hydraulic machine being connected to an input side of the first hydraulic machine; at least one hydraulic consumer hydraulically coupled to an output side of the first hydraulic machine via a supply line and configured to be powered by the first hydraulic machine; and a valve arrangement arranged between the hydraulic consumer and the first and second hydraulic machines, wherein the valve arrangement is configured to control a return flow of hydraulic fluid from the hydraulic consumer to either the input side of the first hydraulic machine or an input side of the second hydraulic machine based on a requested output pressure from the first hydraulic machine.

Abstract: A hydraulic actuator arrangement (1) is described comprising a hydraulic actuator having a pressure chamber (2), a cylinder (3) in a cylinder housing (4), and a piston (5) connected to a piston rod, a hydraulic pump (7) connected to the pressure chamber (2) and an electric motor (8) driving the hydraulic pump (7), wherein the pump (7) and the motor (8) are arranged within the actuator. Such an actuator arrangement should have many application possibilities. To this end, a hydraulic pressure amplifier (10) is arranged between the hydraulic pump (7) and the pressure chamber (2).

Abstract: A closed-loop hydraulic circuit includes a piston chamber housing a piston rod and a ram piston coupled to an end of the piston rod, and a pump in fluid communication with the piston chamber at first and second hydraulic ports. Pumping a hydraulic fluid to the first hydraulic port causes a forward stroke of the ram piston and the piston rod, and pumping the hydraulic fluid to the second hydraulic port causes a return stroke of the ram piston and the piston rod within the piston chamber. An accumulator is in fluid communication with the pump and the piston chamber, and a 3-2 valve is actuatable between a first position, where pressurized hydraulic fluid is conveyed from the accumulator to the pump during the forward stroke, and a second position, where excess hydraulic fluid is conveyed from the first hydraulic port to the accumulator during the return stroke.

Abstract: A motor oil pump assembly includes: a motor component; an oil pump component, where the oil pump component is supported on an end cover of the motor component; an inner sound insulation enclosure, where the inner sound insulation enclosure encloses the oil pump component, and the inner sound insulation enclosure and the oil pump component define an inner sound insulation cavity filled with low-pressure oil; and a pre-tightening buffering component, where the pre-tightening buffering component is pressed between an upper end cover of the oil pump component and the inner sound insulation enclosure, and the pre-tightening buffering component is in communication with a high-pressure cavity of the oil pump component.

Abstract: A modular electrohydraulic actuator including an electric motor, a hydraulic pump driven by the electric motor, and a hydraulic actuator in fluid communication with the hydraulic pump. The hydraulic actuator includes a hydraulic cylinder supporting a pressure sleeve in which a piston and rod is adapted for reciprocating motion in response to a supply of pressurized fluid to a first side or a second side of the piston, wherein at least one of the electric motor, hydraulic pump, hydraulic cylinder, piston, piston rod or the pressure sleeve supported in the hydraulic cylinder is selectively removable and replaceable with a different component to vary at least one performance characteristic of the electrohydraulic actuator.

Abstract: A hydraulic system includes: a single-rod hydraulic cylinder; a variable displacement pump driven by a rotating machine; a rod-side supply line and a head-side supply line that connect the pump to the hydraulic cylinder; a first tank line that is branched off from the rod-side supply line and connects to a tank; a second tank line that is branched off from the head-side supply line and connects to the tank; and a flow rate adjuster. The flow rate adjuster is configured to: switch a delivery capacity of the pump to a first setting value when a pressure of the head-side supply line is higher than a pressure of the rod-side supply line; and switch the delivery capacity of the pump to a second setting value less than the first setting value when the pressure of the rod-side supply line is higher than the pressure of the head-side supply line.

Abstract: A hybrid actuator, having a central longitudinal axis, may include a housing defining a central cavity. The hybrid actuator may also include a piston disposed within the central cavity, the piston comprising a piston head that divides the central cavity into a pressure chamber and an annular chamber. The piston houses a pump configured to pump fluid through a port defined in the piston head between the annular chamber and the pressure chamber to extend a piston rod of the piston from the central cavity, according to various embodiments.

Abstract: An electro hydrostatic actuator comprises a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator. The pump comprises an inlet and an outlet for the hydraulic fluid and an active flow path arranged therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path arranged to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet.

Abstract: An electro hydrostatic actuator comprising a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator, the pump comprising an inlet and an outlet for the hydraulic fluid and an active flow path configured therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path configured to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet. The hydraulic pump is a rotary piston pump comprising a pump barrel driven to rotate by a motor shaft.

Abstract: A hydraulic charging and driving system (4), aircraft employing the same, and corresponding methods, for extending and retracting a hydraulic actuator (2), comprising: a motor assembly (22); and an accumulator assembly (20), the motor assembly (22) and the accumulator assembly (20) being hydraulically coupled to each other; wherein the motor assembly (22) is arranged to recharge the accumulator assembly (20) with hydraulic fluid at a relatively slow rate that is slower than the rate at which the accumulator assembly (20) is arranged to discharge when actuating the hydraulic actuator (2). The system may further comprise a selector valve (24). The accumulator assembly (20) may comprise an accumulator chamber (30), and a compression means (32) provided within the accumulator chamber (30). The motor assembly (22) may comprise a motor (42) arranged to vary a volume of a hydraulic charging chamber (38) of the motor assembly (22).

Abstract: A hydraulic adjusting device, in particular for use in a power plant and/or a wind power plant, includes a double-acting adjusting cylinder that has an adjusting function for a working operation and for a special operation. The double-acting adjusting cylinder is configured to be pressurized with a working pressure medium. In order to satisfy the adjusting function in the special operation, the double-acting adjusting cylinder is further configured to be connected to a pressure medium reservoir that has a pressurized gas isolated from the working pressure medium. The adjusting cylinder has a working chamber configured for the adjusting function of the special operation, the piston area of which is coupled to a piston arrangement of the adjusting cylinder that is configured for the working operation or is configured to be coupled to the piston arrangement.

Abstract: Various embodiments related to hydraulic actuators and active suspension systems as well as their methods of use are described.

Abstract: Actuator arrangement for a drive train, which has at least one friction clutch for transmitting drive torque and has a transmission. The friction clutch can be actuated by means of a hydraulic clutch cylinder, which is connected directly to a pump port of a pump driven by an electric motor in order to actuate the friction clutch, such that the friction clutch can be actuated by varying the speed of the pump. The actuator arrangement has a parking lock actuator device for actuating a parking lock arrangement of the drive train. The parking lock actuator device has at least one hydraulic parking lock cylinder, which can be connected to the pump, such that the parking lock arrangement can be actuated by varying at least one of the direction of rotation or the speed of the pump.

Abstract: A thrust apparatus for a rod string. The apparatus has a stationary frame, a thrust frame with a rod gripper, two hydraulic cylinders and two rams in fluid communication with the hydraulic cylinders. During low-load operations, the hydraulic cylinders act alone, providing the load to the grippers to pull or push the rod string. When higher loads are required, a check valve is activated, allowing fluid from the hydraulic cylinders to activate the rams. The rams provide additional force to the grippers, and may be activated without mechanical or significant hydraulic changes to the apparatus.

Abstract: The subject matter of this invention is a telescopic actuator with tubular cylinders which at the same time function as pistons, used to move/shift/translocate pieces of devices especially while emergency opening damaged movable elements/components. It has a bushing body (1) connected with a head (5) attached to its free end and the head has a control segment (10) and the systems feeding the actuator with pressure agent/factor, created in the form of at least one gas generator (9); and by the fact that the bushing/sleeve body (1), the first cylindrical piston (2) and another cylindrical piston (3) have at least one ring groove situated on the surface mating with another tubular element near the head faces of those tubular elements.

Abstract: A cylinder device (1) according to the present invention includes: a cylinder (2); a piston (3) slidably inserted into the cylinder (2); a rod (4) inserted into the cylinder (2) and connected to the piston (3); a rod-side chamber (5) and a piston-side chamber (6) partitioned by the piston (3) within the cylinder (2); a first on-off valve (9) provided in the middle of a first passage (8) allowing the rod-side chamber (5) to communicate with the piston-side chamber (6); a second on-off valve (11) provided in the middle of a second passage (10) allowing the piston-side chamber (6) to communicate with the tank (7); and a pump (12) for supplying liquid to the rod-side chamber (5).

Abstract: Provided is a method of and valve assembly for dumping excess fluid during retraction of a cylinder actuator. The method includes pumping fluid with a pump from a piston side of the cylinder to a rod side of the cylinder; opening a first check valve with relatively high pressure fluid from a downstream side of the pump to allow flow into the rod side of the cylinder; and opening an extend relief valve via a first spool with fluid from the downstream side of the pump to allow excess fluid at an upstream side of the pump to return to a reservoir at relatively low pressure.

Abstract: The invention relates to an electrohydraulic actuator comprising a body (1) that defines a cylindrical cavity (2) in which a piston (3) slides in leaktight manner and divides an inside volume of the cavity into two chambers (A, B) of variable volume, the piston being associated with at least one rod (4) passing in leaktight manner through an end wall of the cavity, the actuator including a bidirectional pump (5) having two ports (P1, P2), each connected to one of the chambers, an electric motor (8) for selectively driving the pump in one direction or the other, the pump being placed inside the piston of the actuator so as to move together therewith.

Abstract: A hydraulic system for a marine engine has a fluid reservoir, a bi-directional pump, a valve assembly, and a hydraulic actuator. The valve assembly includes: first and fourth apertures fluidly communicating with the pump, second and third apertures fluidly communicating with the actuator, and a fifth aperture fluidly communicating with the fluid reservoir. Operating the pump to supply hydraulic fluid to the first aperture causes hydraulic fluid to flow from the pump to the actuator and from the actuator to the fluid reservoir, and causes the actuator to move in a first actuator direction. Operating the pump to supply hydraulic fluid to the fourth aperture causes hydraulic fluid to flow from the pump to the actuator and from the actuator to the pump, and causes the actuator to move in a second actuator direction opposite the first actuator direction.

Abstract: A hydraulic actuator assembly includes an actuator, a first sink subsystem in fluid communication with an upper working chamber of the actuator, a second sink subsystem in fluid communication with a lower working chamber of the actuator and a source subsystem in fluid communication with both the upper and lower working chambers of the actuator. A low pressure accumulator is in fluid communication with the upper and lower working chambers, the first and second sink subsystems and source subsystem. A high pressure accumulator is in fluid communication with the first and second sink subsystems and the source subsystem. The hydraulic actuator assembly can generate passive or active forces with or without energy recuperation.

Abstract: A hydraulic manifold pump comprising a housing in which is located a first hydraulic circuit and a second hydraulic circuit. A bidirectional motor connectable to the first hydraulic circuit and the second hydraulic circuit, the bidirectional motor being able to activate the first hydraulic circuit when operable in a first direction, and being able to activate the second hydraulic circuit when operable in a second direction. The hydraulic manifold pump further compromises a hydraulic actuator having two hydraulic chambers being connectable to the first hydraulic circuit and to the second hydraulic circuit, and both the first and second hydraulic circuits being connected to and able to vent into a fluid reservoir.

Abstract: A hydraulic circuit comprises a hydraulic cylinder, an accumulator, and a bi-directional variable displacement hydraulic pump for managing flow between a head side of the hydraulic cylinder and both of a rod side of the hydraulic cylinder and the accumulator.

Abstract: A system and method for performing a floating function in an earthmoving implement of an earthmoving machine without physically connecting chambers within a hydraulic actuator that is adapted to raise and lower the earthmoving implement. The system includes a device for delivering a pressurized fluid to and receiving pressurized fluid from the actuator, a valve for compensating for differences in volume between chambers of the actuator, and an electronic control circuit that includes electronic sensors for sensing the pressures in the chambers of the actuator, and a controller for receiving outputs of the sensors. The controller calculates an amount of the pressurized fluid that, when delivered to or received from the actuator, achieves a substantially constant pressures in the chambers of the actuator and enables the earthmoving implement to float regardless of motion of the actuator.

Abstract: A hydrostatic drive with first and second hydraulic pumps and a dual-acting hydraulic cylinder. The dual-acting hydraulic cylinder has a first working chamber defined by a first piston surface and a second working chamber defined by a second piston surface. The first working chamber is connected to first connections of the first and second hydraulic pumps. The second working chamber is connected to a second connection of the second hydraulic pump. A second connection of the first hydraulic pump is connected to a hydraulic fluid reservoir. The ratio of the first piston surface to the second piston surface differs from the ratio of the total delivery volume of the two hydraulic pumps relative to the delivery volume of the second hydraulic pump. A tapping valve for removing hydraulic fluid is provided for the volumetric flow equalisation.

Abstract: A hydraulic circuit for actuation of a hydraulic working cylinder (1) having a one-sided piston rod (1a), comprising a reversible pump (4) whereby both sides of said pump are connected via a supply line (5) and a first two-way valve (6) to the tank (7) containing hydraulic medium and through releasable control check valves (8) to the working cylinder (1). Both sides of the arrangement are further connected respectively to a hydraulic closeable valve (21, 31) through a discharge line (20, 30) and also to the tank (7) through a replenishing suction line (22, 32) having a corresponding suction valve (9). Each of said hydraulic closeable valves (21, 31) is controlled by the pump (4) through a second two-way valve (4).

Abstract: The invention relates to a hydraulic drive, comprising a hydraulic cylinder (1), divided into a first operating pressure chamber (4) and a second operating pressure chamber (5), by an operating piston (3). The hydraulic drive further comprises a closed hydraulic circuit (39), with a first hydraulic pump (43), connected to the first operating pressure chamber (4) via a first working line (7), by means of a first connector (10) and to the second operating pressure chamber (5) via a second working line (13), by means of a second connector (12). In addition, an open hydraulic circuit (40) is provided, with a second hydraulic pump (8), connected to the first operating pressure chamber (4), by means of a third connector (11). A fourth connector (14) on the second hydraulic pump (8) is connected to a hydraulic reservoir element (75).

Abstract: The present invention relates to an actuation device for the actuating of an adjustment surface of an aircraft such as an elevator, a rudder or the like, of landing gear or another aircraft or surface vehicle actuator, comprising an electrohydraulic actuator having a servo control cylinder, a pump for pressure fluid action on the servo control cylinder as well as an electric motor for the actuation of the pump, with the electric motor having a liquid cooling. In accordance with the invention, the actuation device is characterized in that a leak flow of the pump is guided over a leak passage through the electric motor to cool the electric motor.

Abstract: A stand pipe is disposed so as to be fitted with the inner periphery surface of a piston rod with a hollow structure and a reservoir is incorporated into the inside of the stand pipe, whereby it becomes possible to reduce the size of an EHA device. Besides, since the reservoir is separated from both an annulus-side oil chamber and a bore-side oil chamber, a stable reservoir performance can be exhibited without being influenced by a fluid pressure resulting from an external force. Moreover, as a result of installation of the stand pipe, a difference between the amount of fluid required per unit stroke in the annulus-side oil chamber and that in the bore-side oil chamber becomes smaller, so that the required volume of the reservoir oil chamber can be reduced and it is possible to constitute an efficient EHA device with little difference between the energy consumption during compressing and that during extending.

Abstract: A dual mode hydraulic actuator, comprising: a housing; a rod secured to a piston, the rod and piston being slidably received within the housing; a first chamber positioned on one side of the piston; a second chamber positioned on another side of the piston; a sealed reservoir; a fluid disposed in the first chamber, the second chamber and the reservoir; a bidirectional pump for moving the fluid between the first chamber, the second chamber and the sealed reservoir; a bi-mode control valve for providing selective fluid communication between the first chamber, the second chamber and the sealed reservoir, wherein the bi-mode control valve is spring biased into a neutral position wherein fluid communication between the first chamber, the second chamber and the sealed reservoir is prevented; and wherein the bi-mode control valve is capable of being manually manipulated into a manual mode position wherein fluid flow from the first chamber to the second chamber is provided and fluid flow from or to the sealed reservo

Abstract: A hydraulic system and work machine are provided, the hydraulic system including at least one hydraulic cylinder with a first port and a second port connected by a first fluid passage. A first pump, which is a bi-directional hydraulic pump is positioned within the first fluid passage, and a second pump is positioned in parallel with the first pump and disposed within a second fluid passage. An accumulator fluidly connects with the second fluid passage.

Abstract: A power steering system includes a reversible-type oil pump supplying hydraulic fluid to first and second pressure chambers of a hydraulic power cylinder through first and second passages and having first and second discharge ports, and a branch passage conveying part of hydraulic fluid discharged from the discharge ports of the oil pump to the outside of the pressure chambers of the power cylinder, wherein the branch passage has a passage sectional area greater than a total leak sectional area of the oil pump.

Abstract: A piston and cylinder assembly having a cylinder with a piston and a connected piston rod. The piston defines opposed chambers wherein a compensating device is disposed in at least one of the chambers. The compensating device includes a capsule of an elastic material containing a gaseous medium which is compressed comparable to the volume displaced by the piston rod when fully retracted. When the piston rod is in its protracted position, the compensating capsule expands so that the pressure within the hydraulic chamber of the cylinder reaches a value that will minimize the absorption of any air into the cylinder and not overload the bearing seal through which the piston rod extends.

Abstract: An electrohydraulic actuator (10) includes a fluid-powered actuator (11) having a piston (15) in a cylinder (16). The piston divides the cylinder into two opposed chambers (18, 19). The actuator includes a fixed-displacement reversible motor-driven pump (13) having a first port communicating with one of the chambers and having a second port communicating with the other of the chambers in a closed hydraulic system. A pre-charged accumulator (14) communicates with the pump first port. One of the actuator chambers is maintained at a fixed pre-charged pressure of the accumulator, and the operation of the pump controls the pressure in, and volume of, the other chamber.

Abstract: An oil pressure operated pump for marine steering gears includes a multiple piston oil pressure operated pump controlled by a steering wheel, a valve housing mounted under the pump, a bottom cover closing the valve, the valve housing and the cover each including channels, threaded holes for reciprocal fastening thereof, non-threaded bores for oil pressure connections, a valve set lodged in the valve housing for non-return and adjustment of oil flow, the valve set including a generally parallelepiped shaped tubular shell having a generally external square shape, a central tubular through-hole, and lathe-turned ducts, a double acting oil pressure cylinder including a shaft movable in the central tubular through-hole for controlling a direction of an engine or rudder of a boat, and valves for controlling fluid flow and thereby movement of the shaft.

Abstract: A novel bi-rotational pump adapted to pump fluid in either of two directions by reason of construction inclusive of passageways and an array of check valves and pilot pistons which cooperate in one direction and in another way in the other direction.

Abstract: A cylinder driving system capable of reducing the number of hydraulic devices and the amount of energy loss and an energy regenerating method thereof are provided. To this end, the system includes i) a hydraulic cylinder, ii) a hydraulic pump having three suction/discharge ports of a first port for supplying oil to a bottom chamber of the hydraulic cylinder or draining oil from the bottom chamber, a second port for draining oil from a head chamber of the hydraulic cylinder or supplying oil to the head chamber, and a third port for draining oil from a tank or supplying oil to the tank, the suction rate or the discharge rate in the first port being the sum of the respective discharge rates or suction rates in the second port and the third port, and iii) a driving source for driving the hydraulic pump.

Abstract: A hydraulic swinging-leaf door drive for swinging doors includes an actuating piston, which acts on a drive shaft. A hydraulic pump acts on the actuating piston by way of a hydraulic circuit. The hydraulic circuit is designed as a closed circuit.

Abstract: A hydraulic system for an actuator provides staged operation during extend and retract. A pair of reversible pumps are conjointly driven by a reversible motor. A relief valve in the retract circuit directs fluid to tank when fluid pressure increases above a predetermined value. An unloader valve in the extend circuit is responsive to pressure at a first stage pump to direct flow to tank when the pressure increases above a second predetermined value. A non-return check valve connected between the pumps in the extend circuit closes the flow circuit to the second stage pump during high loads, so that the flow from the second stage pump goes to tank, and the return flow from the actuator goes only to the first stage pump. The non-return check valve is responsive (via a signal line to the retract circuit portion) to the pressure in the extend and retract circuit portions.

Abstract: An electrohydraulic actuator comprising: a hydraulic actuator comprising a piston secured to a member to be controlled and capable of moving in a cylinder under drive from a hydraulic fluid; a hydraulic pump feeding both faces of the piston with hydraulic fluid via channels integrated in the walls of the cylinder; an electric motor immersed in the hydraulic fluid, and controlled and powered electrically by an electronic control unit, driving the hydraulic pump in rotation; and a hydraulic accumulator for compensating variations in the volume of the hydraulic fluid; the hydraulic actuator, the hydraulic pump, the electric motor, and the hydraulic accumulator having a common axis of symmetry and being mounted in alignment in a common housing that is leaktight to the hydraulic fluid, thereby forming an axially symmetrical self-contained hydraulic assembly.

Abstract: A compact hybrid actuator has a fluid pump (20) arranged to supply fluid to an actuator (44). The pump has at least one electrically-powered solid-state pump driver (21) provided with a displacement element (22). The position of this displacement element modulates the volume of a fluid chamber (23). A driven valve (24) is operatively arranged to control the flows of fluid with respect to the pump chamber, and has one member (29) movable relative to a body (28) to modulate the opening of ports (25, 26) so as to form at least one three-way valve. A valve driver (31) is operatively arranged to operate the driven valve. Electrical power is provided to each valve and to the valve driver so as to operate these various elements in synchronism with one another. The improved pump driver and driven valve may be operated at frequencies in excess of 1 kHz.

Abstract: The present invention provides a hydraulic actuator suitable for use in marine and other harsh environments. In the presently preferred embodiment, the hydraulic actuator includes a motor that is coupled to a pump assembly that is configured to displace hydraulic fluid. The hydraulic actuator also includes a cylinder bore that has an upper chamber and a lower chamber which are separated by a movable piston member. Pressure actuated valves are used to regulate the flow of high pressure hydraulic fluid to the cylinder bore. The pressure actuated valves are actuated in response to pressure generated by the pump assembly.

Abstract: A hydraulic system for an actuator provides staged operation during extend and retract. A pair of reversible pumps are conjointly driven by a reversible motor. A relief valve in the retract circuit directs fluid to tank when fluid pressure increases above a predetermined value. An unloader valve in the extend circuit is responsive to pressure at a first stage pump to direct flow to tank when the pressure increases above a second predetermined value. A non-return check valve connected between the pumps in the extend circuit closes the flow circuit to the second stage pump during high loads, so that the flow from the second stage pump goes to tank, and the return flow from the actuator goes only to the first stage pump. The non-return check valve is responsive (via a signal line to the retract circuit portion) to the pressure in the extend and retract circuit portions.

Abstract: A hydraulic manipulator having an ergonomic handle and good transmission behavior. There is an input drive element of the manipulator which is a hydraulic pump with two conveyance directions. The input drive movement is introduced on the drive shaft of the hydraulic pump as a rotary movement. This device is used in hydraulic manipulators with an input drive element for introducing an input drive movement into a closed hydraulic circuit and a control element for an output drive movement from the hydraulic circuit.

Abstract: The invention relates to a hydraulic drive with a plurality of hydraulic consumers also comprising a differential cylinder which are located in particular on a plastics injection-molding machine. There are a first hydraulic machine and a second hydraulic machine, which can both operate as pump and as motor. A first of the two hydraulic machines is connected to a tank by means of a second port and rests against a pressure line by means of a first port, which pressure line can be connected to that working chamber of the differential cylinder which is remote from the piston rod via a shut-off valve. The second hydraulic machine is likewise connected to the pressure line by means of a first port and can be connected, by means of a second port, to a tank via a nonreturn valve which opens toward the second port and to the piston-rod-side working chamber of the differential cylinder via a shut-off valve.

Abstract: A hydraulic system manifold having a body, a counterbalancer in the body and a flow controller in the body is disclosed. The body has first and second pump ports, first and second cylinder ports, first and second compensator ports and first and second supply conduits in communication with the first and second pump ports, the counterbalancer and the flow controller. The counterbalancer is in communication with the first and second supply conduits and the cylinder ports, to communicate hydraulic fluid between the first and second supply conduits and the first and second cylinder ports while counterbalancing hydraulic fluid pressure in the first and second supply conduits. The flow controller is in communication with the first and second supply conduits and the compensator ports, to control the flow of hydraulic fluid between the compensator ports and the first and second supply conduits to supply and store hydraulic fluid in a volumetric compensator in communication with the compensator ports.

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: A machine, in particular an industrial truck, is provided with a hydraulic system that has at least one reservoir (1) for hydraulic fluid and at least one hydraulic pump (5). The hydraulic pump (5) is located inside the reservoir (1). A priority valve (8a) is connected to the hydraulic pump (5) by a flange connection. An electric drive motor (3) of the hydraulic pump (5) can also be located inside the reservoir (1).

Abstract: A hydraulic piston pump 1 includes a distributing valve 11 having a pair of arcuate or circular ports 11a and 11b formed through it. The arcuate port 11b is shorter circumferentially than the arcuate port 11a to reduce, by a predetermined amount, the amount of pressure oil to be discharged from and sucked into the pump through it. The valve 11 also has a pair of tank ports 11c and 11d formed through it circumferentially on both sides of the shorter port 11b. The circumferential dimensions of the tank ports 11c and 11d correspond to the predetermined amount of oil.

Abstract: In a hydraulic cylinder actuation system for a crane having a conventionally charged main hydraulic pump, a supplemental pump or "charge boost" pump is provided. To efficiently achieve fast actuation speeds of the cylinder, the charge boost pump provides supplemental charge flow in response to a need in the system. The charge boost pump is driven independently from the main pump or may be driven by the main pump if the main pump is equipped with drive thru capability to provide a variable output and preferably includes a load sensing means for controlling the output.

Abstract: A hydraulic system manifold having a body, a counterbalancer in the body and a flow controller in the body is disclosed. The body has first and second pump ports, first and second cylinder ports, first and second compensator ports and first and second supply conduits in communication with the first and second pump ports, the counterbalancer and the flow controller. The counterbalancer is in communication with the first and second supply conduits and the cylinder ports, to communicate hydraulic fluid between the first and second supply conduits and the first and second cylinder ports while counterbalancing hydraulic fluid pressure in the first and second supply conduits. The flow controller is in communication with the first and second supply conduits and the compensator ports, to control the flow of hydraulic fluid between the compensator ports and the first and second supply conduits to supply and store hydraulic fluid in a volumetric compensator in communication with the compensator ports.