Abstract: A working cylinder (A) having at least one working chamber (6, 7) defined by the cylinder barrel (1), at least one of the end sections (2, 3) and a piston (4), at least one supply port (9a, 9b) and a exhaust port (12a, 12b) for the working medium. The exhaust port (12a, 12b) has a valve (13a, 13b) that may be regulated by the pressure of the working medium, which is applied at the supply port (9a, 9b) in order to obtain a smaller dimension of at least the valve and to better utilize the already existing space, specifically within the cylinder, and to better and more efficiently adjust the output capacity of the individual elements. A valve (V), particularly a switch valve (W) of a rocker valve design has therefore at least one inlet (16) and at least one outlet (17a, 17b) for the working medium, as wells as at least one control port (18).

Abstract: A hydraulic control system (1) has a hydraulic motor (10), which is connected with a control valve (2) via two working lines (8, 9), the control valve (2) being connected with a low-pressure connection (T) and, via a compensation valve (4), with a high-pressure connection (P), to ensure that a return compensation valve (14, 15) is arranged in each working line, each return compensation valve (14, 15) having a nominal flow line (29), which extends unintersectedly in relation to the nominal flow line (28) of the compensation valve (4).

Abstract: An insert or cartridge that fits into a cavity in a valve body provides a check valve function and an anti-cavitation function and a pressure relief function. This insert is substantially circular and has an internal cavity with a valve assembly that has two pairs of valve seats, one pair of valve seats providing the anti-cavitation function and the other pair of valve seats providing the pressure relief function. The outside of the insert itself engages with a sealing surface in the cavity in the valve body to provide the check valve function.

Abstract: A damper valve (70) located between a control valve (18) and a power steering motor (22) in a hydraulic power-assisted steering system (10). The damper valve (70) comprises a housing (72) having axially opposite first and second end portions (76 and 78) and an intermediate portion (80) interposed between the first and second end portions (76 and 78). The first end portion (76) is for fluid communication with the control valve (18) and the second end portion (78) is for fluid communication with the power steering motor (22). A flow restricting element (114) is located within the housing (72) and is movable through portions of the housing (72) including the intermediate portion (80) by fluid flow through the housing (72). The damper valve (70) further includes a biasing element (106) for restraining movement of the flow restricting element (114) toward the first end portion (76) of the housing (72).

Abstract: A hydraulic valve having a main body in which is formed a pressurized-fluid inlet opening; a first conduit communicating hydraulically with a user device; a second conduit communicating hydraulically with the user device, and at least one spool for regulating pressurized fluid flow to and from the user device; the spool having a longitudinal axis, and the position of the spool being regulated by an actuating device; the hydraulic valve being characterized in that the actuating device has a guide member for preventing the spool from rotating about the axis; the actuating device also having a cable, e.g. a Bowden-type cable, for moving the spool in two opposite directions defined by the longitudinal axis.

Abstract: A hydraulic valve arrangement includes a control valve (3), which, in a first operating position (5), connects a motor connection (21) with a pump connection, in a second operating position (6), connects a motor connection with a tank connection, and, in a locking position (4), disconnects the motor connection (21) from the pump and tank connection. A locking valve (19) is coupled between the control valve (3) and the motor connection (21), dividing the motor line (22) into a first section (23) allocated to the control valve (3) and a second section (24) allocated to the motor connection (21). For the locking valve (19), a pressure release valve (20) in the shape of a seated valve is provided that is fixed to the housing thereby improving control accuracy.

Abstract: A damper valve (70) located between a control valve (18) and a power steering motor (22) in a hydraulic power-assisted steering system (10). The damper valve (70) comprises a housing (72) having axially opposite first and second end portions (76 and 78) and an intermediate portion (80) interposed between the first and second end portions (76 and 78). The first end portion (76) is for fluid communication with the control valve (18) and the second end portion (78) is for fluid communication with the power steering motor (22). A flow restricting element (114) is located within the housing (72) and is movable through portions of the housing (72) including the intermediate portion (80) by fluid flow through the housing (72). The damper valve (70) further includes a biasing element (106) for restraining movement of the flow restricting element (114) toward the first end portion (76) of the housing (72).

Abstract: The invention concerns a hydraulic power-assisted steering system for motor vehicles, with a valve and two hydraulic lines leading from the valve to cylinders of a servo drive mechanism and with at least one steering damper, the steering damper having a basic body 4 which is arranged movably along a path in a working chamber 3 and delimits with an outer wall 2 of the working chamber 3 a first channel through which hydraulic fluid can flow.

Abstract: An assembly of a pair of electrically operated bidirectional proportional control valves and a four-way direction control valve governs the flow of fluid to and from a hydraulic cylinder. The four-way direction control valve alternately connects a pump supply line to one of a pair of intermediate conduits and a tank return line to the other intermediate conduit. That connection determines the direction of movement of the cylinder piston. The intermediate conduits are coupled to chambers of the cylinder by a separate one of the proportional control valves which meters the fluid flow to or from the respective chamber. Thus the proportional control valves control the rate of piston movement.

Abstract: A hydraulic circuit system having a load sensing system including a hydraulic pump, a plurality of hydraulic actuators driven by a hydraulic fluid delivered from the hydraulic pump, a plurality of control valves disposed between the hydraulic pump and the plurality of acutators, a signal detecting hydraulic line to which a signal pressure based on a maximum load pressure among the plurality of hydraulic actuators is introduced, and pump control means for controlling a delivery pressure of the hydraulic pump to be held higher than the signal pressure by a predetermined value.

Abstract: A tilt control device for a fork lift truck comprises a tilt spool for operating the tilt cylinder, a pilot operation type flow rate control valve connected to the hydraulic pump via the tilt spool and adapted to be switched between a fully opened position and a half opened position which are different in opening from each other in response to addition/deletion of a pilot pressure, a pilot operation type logic valve disposed between the rod side oil compartment of the tilt cylinder and the flow rate control valve and adapted to permit hydraulic oil to flow into the rod side oil compartment and to be operated so as to open/close relative to hydraulic oil flowing out of the rod side oil compartment in response to the addition/deletion of the pilot pressure, and an electromagnetic switching valve for controlling the addition/deletion of the pilot pressure to the flow rate control valve and the logic valve.

Abstract: The invention concerns a hydraulic valve arrangement with locking function. It has a control valve (9), which in two operating positions (11, 12) connects one motor connection (A) with a pump connection and a second motor connection (B) with a tank connection and vice versa, and in a locking position (10) separates both motor connections (A, B) from pump and tank connection. Further, there are two lock valves (16, 17), each connected between the control valve (9) and one of the motor connections (A, B).

Abstract: In a power steering apparatus provided with a damper valve, a second valve apparatus of the damper valve is provided with a valve plate in contact with and apart from a partition member so as to open and close a through flow passage provided in the partition member, and a fluid storing recess portion is provided in a contact area between the partition member and the valve plate.

Abstract: The invention provides a method and apparatus for controlling in a path-dependent manner the force generated by a piston. A first piston travels in a first cylinder—divided into a first and second chamber by the first piston—together with a pressure fluid. A second cylinder is provided in which a second piston travels. Like the first cylinder, the second cylinder is also divided by the second piston into a first and a second chamber, in this case by the second piston. The first and second pistons are coupled mechanically. The pressure in the second chamber of the second cylinder is regulated such that it is always equal to the counterpressure in the first chamber of the second cylinder and the second chamber of the first cylinder.

Abstract: In a power steering apparatus provided with a damper valve, the damper valve holds a partition member between a cap and the housing.

Abstract: A main passage communicated to a pump passage or a tank passage by switching operation of a spool valve is provided with an operation check valve permitting communication only to a cylinder. A puppet in the operation check valve is provided with an orifice communicating the main passage with a pilot chamber of the operation check valve. The pilot chamber is communicated with the main passage through an electromagnetic on/off valve. Further, the pilot chamber in the operation check valve is communicated through a bypass passage with the main passage, and the bypass passage is provided with a manually operable opening/closing valve.

Abstract: An LUDV-circuit for controlling at least one of a lower-load consumer and a higher-load consumer is disclosed, wherein a metering orifice and a downstream pressure compensator for maintaining constant the pressure drop across the metering orifice constant are associated with each consumer. The pressure compensator of the lower-load consumer is associated with a bypass channel capable of being controlled open, whereby the pressure compensator of this consumer may be bypassed.

Abstract: A hydraulic cylinder in which the cylinder head contains the main control valve for the cylinder. In one fluid path from the main control valve to an area located on one side of the cylinder's piston, fluid is directed through a transfer tube that extends through the center of the piston and terminates within a hollow ported section of the piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves are located in different passages that extend to areas located on opposite sides of the piston. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve. In the preferred embodiment, electrical wiring to the cylinder head travels through one of the fluid hoses connected to the cylinder.

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

Abstract: Disclosed is an actuator control circuit which adopts a meter-in control system to control the displacement speed of a piston of a pneumatic cylinder and which is provided with a first pressure control valve to be in a free flow state when compressed air is supplied to the pneumatic cylinder and a second pressure control valve for retaining discharge pressure of compressed air discharged from the pneumatic cylinder to be a previously set predetermined pressure.

Abstract: A speed controller has a pilot check valve having a first body which has a first fluid inlet/outlet port defined in an end thereof and a pilot port defined in an opposite end thereof. A flow control valve has a second body integral with the first body. A pipe joint has a third body which has a second fluid inlet/outlet port defined in an end thereof and, the third body being integral with the second body. A flow adjustment screw is disposed in the flow control valve and extends into a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port, for adjusting a rate of flow of a fluid under pressure in the fluid passage. A valve body is disposed in the pilot check valve for opening a fluid passage which interconnects the first fluid inlet/outlet port and the second fluid inlet/outlet port in response to a pilot fluid pressure supplied from the pilot port.

Abstract: A quick coupler for coupling an implement to a work machine is provided with a control system that substantially prevents inadvertent and unintended release of the implement from the machine. Inadvertent and unintended release of the implement is prevented by requiring two separate switches to be actuated to release the implement. Actuation of one switch supplies pressurized fluid to a fluid circuit connected to an actuator operable to release the implement from the machine. However, the pressurized fluid supplied in response to actuation of the one switch is not sufficient to activate the actuator. Concurrent actuation of a second switch raises the pressure of the fluid supplied to the actuator fluid circuit to a level sufficient to activate the actuator, thus releasing the implement.

Abstract: The invention provides a hydraulic control system capable of preventing an objective from crashing even if a load supporting passage is fractured or the like during a crane operation for moving down the objective with a hydraulic shovel. When a pilot pressure for switching a control valve 2 to a downward position b is less than a predetermined value, only first selector means switches, and when the pilot pressure exceeds the predetermined value, second selector means as well as the first selector means switches.

Abstract: The present invention relates to control of a hydraulic piston/cylinder unit, in particular a multi-disc clutch having a control valve which can be moved into an open and a closed position, a first connecting line connected to the hydraulic piston/cylinder unit and a second connecting line connected to a pressure feed. The first and second connecting lines are in communication with the control valve. The first connecting line is designed such that when subjected to pressure, a force acting in the closed position can be generated on the control valve. The control further possesses a first control line which is in connection with the control valve such that when subjected to pressure, a force acting in the open position can be generated on the control valve. Furthermore, a restrictor element is provided whose inlet can be connected to the pressure feed and whose outlet is in communication with a pressure store and the first control line.

Abstract: Directional control valves are arranged with restrictable center passageways connected in series to a fixed displacement pump and with restrictable power and exhaust passageways straddling loads connected in parallel to the same fixed displacement pump. Pressure responsive valves located between the loads and the restrictable exhaust passageways reduce interactions between the loads. Another pressure responsive valve located between the fixed displacement pump and the restrictable center passageways maintains an appropriate division of flow between the restrictable center passageways and the restrictable power and exhaust passageways.

Abstract: In a check valve assembly and a valve assembly employing such a check valve assembly, a topping piston may be taken into contact with a main poppet to raise the main poppet from its seat. The main poppet is designed without significant area difference from the valve seat and the topping piston is actuated through a pilot valve, so that the process of raising the main poppet from the valve seat is controllable.

Abstract: A hydraulic valve arrangement with locking and floating function, with a control valve (9), which, for two operating positions (11, 12) connects one motor connection (A) with a pump connection and a second motor connection (B) with a tank connection and vice versa, in a floating position (13) connects both motor connections (A, B) with the tank connection and in a locking position (10) separates both motor connections (A, B) from the pump and tank connections. Further, there are two closing valves (16, 17), each being connected between the control valve (9) and a motor connection (A, B) and each having a piston loaded by a spring and limiting a spring chamber, the spring chambers being pressure releasable. Characteristic of this valve arrangement is that lifting valves (18, 19) are provided for the pressure release, which valves are operated by a control pressure depending on the position of the control valve (9). This improves the operating reliability.

Abstract: In an electrohydraulic clamping module for a clamping element of a tooling machine comprising a pressure regulating valve in a flow line towards said clamping element is provided for regulating the clamping pressure. A pressure surveying sensor is integrated into said pressure regulating valve surveying said clamping pressure. Said pressure regulating valve is a leakage-free seat valve having a closure member which can be moved in relation to a stationary valve seat and can be adjusted by means of a control piston which is displaceable by the regulated pressure downstream of said valve seat and in closing direction of said closure member counter to a regulating force. Said pressure surveying sensor can be actuated by said control piston.

Abstract: A valve assembly for actuation of a user and a method for actuation of the valve assembly, wherein a supply throttle device and a drain throttle device may be actuated independent of each other, is disclosed. In the case of single-action users, the drain throttle device is actuated such that the open cross-section of the drain throttle is maximum upon attaining the desired volumetric flow of hydraulic oil, so that the energy losses in the drain conduit are reduced to minimum.

Abstract: A fluid control system provides a float capability for a double-acting actuator. The system includes pilot operated check valves disposed between the double-acting actuator and first and second ports of a pilot operated directional control valve. The directional control valve and the check valves are cooperatively operable under first and second pilot signal conditions to extend and retract the double-acting actuator. The system includes a valve arrangement connected to the check valves and the directional control valve for producing the first and second pilot signal conditions thereon, including also directing the first pilot signal condition to the second pilot signal condition when the first pilot signal condition reaches a predetermined signal strength, to initiate a float capability.

Abstract: A fluid control circuit providing a float capability for a double-acting actuator having first and second actuating chambers is provided. The fluid circuit includes signal controlled load check valves disposed between the actuating chambers and a directional control valve. The directional control valve is movable from a centered, neutral position towards first and second operative positions and a float position. The directional control valve and the load check valves are cooperatively operable in one operable position to allow fluid flow from the first actuating chamber to the exhaust port, and fluid flow from the pump port to the second actuating chamber. In the float position of the directional control valve, both of the signal controlled load check valves are opened to allow open fluid flow between the first and second actuating chambers thus allowing the tool attached to the actuator to float.

Abstract: A fluid control system including a control valve providing a simple, easy to use regeneration capability in association with a pump, a tank, and a double acting actuator having a first actuating chamber and a second actuating chamber. The control valve has a first actuating chamber port connected to the first actuating chamber, a second actuating chamber port connected to the second actuating chamber, a tank port connected to the tank, a first pump port and a second pump port. The control valve includes a connecting passage connecting the first pump port and the second pump port to the pump, and is operable in a first position to allow fluid flow from the pump through the first pump port and the first actuating chamber port to the first actuating chamber and fluid flow from the second actuating chamber through the second actuating chamber port and the tank port to the tank.

Abstract: A control for a power transmission has a neutral idle circuit comprised of a signal valve, a control valve and a shuttle valve. The signal valve supplies a bias pressure to the control valve, which has an output control pressure proportional to the input torque to the transmission. The output control pressure and transmission line pressure act on the shuttle valve to direct the control pressure to a clutch in the transmission when the output pressure is below a predetermined percentage of the transmission line pressure and to direct line pressure to the clutch when the predetermined percentage is exceeded. This permits the clutch to be controlled at or below a slipping engagement state.

Abstract: A controlled float circuit is provided for controlling a load free of requiring flow from the source of pressurized fluid even when the float mode is activated with the load above the ground. The subject invention includes having a load lowering check valve arrangement disposed adjacent an actuator having first and second inlet ports with a pilot operated check valve disposed between the second inlet port and a location downstream of the load lowering valve. A first normally open electrically controlled valve is disposed in the pilot conduit leading to one end of a directional control valve and a second normally closed electrically controlled valve disposed between a source of pressurized pilot fluid and the pilot stage of the pilot operated check valve. Engagement of the float mode of operation blocks pilot flow to one end of the directional valve and opens the pilot operated check valve.

Abstract: For supplying a large volumetric flow into a particular hydraulic actuator without requiring a directional control valve to be large-sized and without making large a pressure difference between a pump discharge pressure and a load pressure or reducing the pressure loss when a large volumetric flow is flushed out into a tank, a flow control apparatus in a hydraulic circuit is designed to supply a pressurized discharge fluid from the hydraulic pump (10) via a directional control valve (15) and a pressure compensation valve (18) to a plurality of hydraulic actuators (16) which are arranged in parallel to one another, the apparatus in its construction including an auxiliary control valve (30) for supplying the pressurized fluid to a particular one of the hydraulic actuators (16), which is supplied with the pressurized discharge fluid from the hydraulic pump (10) via the said auxiliary directional control valve (30) and the directional control valve (15), or whose return fluid out of that particular hydraulic actu

Abstract: The invention relates to a damper valve arrangement, which can be combined with a servomotor of a hydraulic power steering system to form a steering damper. For calibration purposes, the damper valve arrangement has a bypass duct with a calibratable throttling resistance.

Abstract: A spool valve assembly (11) including a valve spool (33) defining a Raise position (R) operable to provide fluid communication from an inlet port (21) to a work port (25), and a Neutral position (N) blocking such flow. The spool valve (33) has a Lower position (L) in which return flow from the work port (25) flows past a pilot operated check valve (77) is then metered by a metering notch (75) defined by the valve spool. The valve spool (33) also has a separate Float position (F) in which the inlet port (21), the work port (25) and the return port (23) are interconnected. In the Float position (F), fluid at the valve spool (33) is in communication with the return port (23) through a back-pressure valve (59), which may be manually adjusted to control the back-pressure on a work implement (15) as it is permitted to "float".

Abstract: A pair of directional control valves 8 and a pair of hold check valves 9 are disposed respectively between a pair of metering notches 6, which are formed in a land 4-1 of a spool 2 and have functions of both flow rate control and direction control, and a pair of actuator ports A, B. Each hold check valve comprises a valve body 90 in the form of a hollow spool having a seat portion 12 formed on an outer periphery and being subject to a pressure developed in an outlet passage 10 communicating with one of the actuator ports to act in the valve-closing direction. Each flow distribution valve comprises a valve body 80 being slidably fitted in the valve body 90 and having a front surface positioned to face an inlet passage 7 communicating with the metering notch and a rear surface positioned to face an control pressure chamber 30 communicating with a signal detecting hydraulic line.

Abstract: The invention relates to a hydraulic power steering system for motor vehicles, in the case of which the manual steering wheel is normally connected only by way of a control system with respect to the drive with a servomotor operating the steered vehicle wheels. In the event of a malfunctioning of the control system, a hydraulic forced coupling is automatically established between the servomotor and a hydraulic delivery unit which is constantly forcibly coupled with the steering handle, in order to form a "hydraulic linkage".

Abstract: A pilot operated check valve is provided for use in controlling the hydraulic leg 14 of a hydraulic mine roof support, the valve having means 23 to connect a leg extension port 18 to a return port 17 within the valve, when the valve is used to lower the leg 14. This provides more rapid operation than with prior art arrangements in which released pressure from the leg has to return from an extension port back to a remote spool valve controlling leg extension before reaching a return line.

Abstract: In a hydraulic control system including a valve device B for controlling a hydraulic fluid supplied from a hydraulic pump A to a hydraulic cylinder C, the valve device comprises a spool 16 slidably fitted into a valve body 1, and a non-leak valve 27 for controlling communication of an actuator passage 19. The non-leak valve comprises a main valve section 40 including a seat valve 41 provided in the valve body, and a pilot control section 60 including a pilot poppet valve 61 provided in an end cover 31. The seat valve is controlled in proportion to an opening of the pilot poppet valve, and a relief valve 55 for preventing the hydraulic cylinder from being subject to an overload is built in the seat valve. The non-leak valve thus fulfills a load holding function and an overload relief function. By arranging the non-leak valve and the spool in two lines, the valve device can be made more compact.

Abstract: In order to achieve repeatable, consistent operation of a counterbalance valve, a poppet valve element within the valve has a radial bore therein in communication with a control fluid port and an axial bore therein which receives a rod that is anchored to a poppet valve cage that surrounds the poppet valve element. The poppet valve element is urged by a spring into engagement with a valve seat and pilot pressure is applied in opposition to the spring. By virtue of this arrangement, control fluid pressure is applied via the rod directly to the valve body in which the poppet valve element and cage are mounted. By changing the diameter of the rod and axial bore through the poppet valve element which receives the rod, the relief set pressure can easily be changed.

Abstract: A travelling control circuit for a hydraulically driven type of travelling apparatus is provided. The circuit has a hydraulic pump, left and right hand side directional control valves provided parallel to each other in a discharge path of the hydraulic pump, a left hand side first and second circuit and a right hand side first and second circuit. Furthermore, the output sides of the left hand side and right hand side directional control valves are connected with a left and right hand side travelling purpose hydraulic motor, respectively. In addition, a pressure compensating valve is provided with each of the first and second circuits to control the opening between an inlet port and an outlet port in response to a difference in pressure between a self load pressure and a maximum load pressure of the load pressures of the left and right hand side travelling purpose hydraulic motors, thereby compensating a pressure in the fluid.

Abstract: A directional control valve unit includes a first actuator port connected to a raising side chamber of a working machine cylinder. In addition, a second actuator port is connected to a lowering side chamber of the working machine cylinder. A regeneration passage makes the second actuator port communicate with a regeneration port through a check valve. A main spool is adapted to supply a pressure oil to the second actuator port and to make the first actuator port communicate with a tank port and the regeneration port by moving the main spool in one direction. The directional control valve unit also includes a switching device for switching the maximum moving distance of the main spool in the one direction in a plurality of stages.

Abstract: An apparatus selectively supplies a source of pressurized fluid to a load device and selectively exhausts pressurized fluid from the load device. The apparatus includes a first housing for defining a longitudinally extending aperture communicating through first, second, and third passages with spaced first, second and third external surface portions of the first housing. A valve spool is engageable within the first aperture for longitudinal movement between a first position communicating the second passage with the third passage and a second position communicating the first passage with the second passage. The valve spool is normally biased toward the first position. Modular port members are connectable to the first, second and third spaced external surface portions for connecting the first passage to a source of pressurized fluid, the second passage to the load device, and the third passage to an exhaust port.

Abstract: A control valve is provided for use in a hydraulic steering system of an agricultural vehicle of the type having a steering valve of the reactive type for controlling the supply of hydraulic fluid to hydraulic cylinders having opposed working chambers serving to move the steerable vehicle wheels in opposite directions. The control valve is connectable between the steering valve and the hydraulic cylinders and has a first setting in which fluid flow in both directions between the steering valve and the working chambers of the hydraulic steering cylinders is possible at all times and a second setting in which return flow of hydraulic fluid from any one working chamber of the hydraulic cylinders to the steering valve is only possible when a positive pressure is present at the outlet of the steering valve connected by the control valve to the opposed working chamber of the hydraulic cylinders.

Abstract: A pressure compensation valve unit comprises a check valve which is pushed in an opening direction thereof by an inlet side pressure and in a closing direction thereof by an outlet side pressure and a pressure reducing valve actuating to establish communication between the inlet side and the outlet side and block the communication therebetween, pushed in the blocking up direction by a pressure in a pressure receiving chamber to push the check valve in the closing direction thereof, pushed in the communication direction with a highest pressure in a plurality of pressures by a pressure selective receiving means, and communicating the outlet side with the pressure chamber, and a pressure oil supply system is provided with the pressure compensation valve unit of the structure described above.

Abstract: The present invention proceeds from a control arrangement for at least two hydraulic consumers which has a positive displacement pump the setting of which is variable by a load-sensing regulator which can be acted on via a load-signaling line by the highest load pressure, on which a maximum-pressure and an output regulation are superimposed, two displaceable metering diaphragms a first one of which is connected between the positive displacement pump and a first hydraulic consumer and the second between the positive displacement pump and a second hydraulic consumer, and two pressure compensators a first one of which is arranged behind the first metering diaphragm and the second behind the second metering diaphragm and the regulating pistons of which can be acted on, in opening direction on a front side, by the pressure behind the corresponding metering diaphragm and in closing direction on the rear side by the pressure in the load-signaling line.

Abstract: A pilot pressure operated directional control valve is provided in which a housing is formed therein with a spool having a plurality of ports. The spool bore has a spool fittingly inserted therein so as to be slidably displaceable therein and the spool is slidably displaced both by a spring and under a pilot pressure led into a pressure receiving chamber. Also a spring box is attached to an end surface of the housing in a longitudinal direction of the spool. The spring box is provided with a hollow portion which contains the spring while forming a pressure receiving chamber, as well as a pilot pressure fluid inlet that communicates with the hollow portion and is open in the longitudinal direction of the spool.

Abstract: A hydraulic elevator up direction control system is provided that has a circulating valve connected between the supply and the return of a source that normally supplies pressure to the cylinder of an elevator. The circulating valve is controlled by a computer regulated stepless variable solenoid valve that influences the pilot fluid pressure in the operating chamber of the circulation valve to control the size of the opening of the circulating valve and thereby the volume of fluid passing through the circulating valve. This affects inversely the volume of fluid passing through a fluid flow measuring valve, to the cylinder, to provide selectably variable up speeds of travel facilitating a fast, smooth, accurate ride of the elevator car as it approaches a stopping point relative to an upper floor of a building. Such operation is substantially independent of the system pressure and fluid viscosity. A selectably variable speed down direction control system operates on largely the same principle.