Abstract: An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to input pressure plus a constant margin. A pressure compensation systems requires that a load-dependent pressure be provided to the pump input through a load sense circuit. A reciprocally spooled, multi-ported isolator transmits the load-dependent pressure to the pump input but prevents fluid in the load sense circuit from leaving the load sense circuit and flowing through a relatively long conduit leading to the remotely located pump. In a multi-valve array, at least one valve section has a backflow-preventing shuttle valve which prevents backflow through the pressure compensation system if a main relief valve is operative.

Abstract: A fluid control valve includes an adjustable soft start capability. The fluid control valve isolates an input port and connects an outlet port to an exhaust port when the fluid control valve is in its closed position. A system is provided for locking the fluid control valve in the closed position. When the fluid control valve is moved to an open position, the exhaust port is isolated and full communication between the input port and the outlet port is delayed by a piston which continues to block fluid flow between the input port and the outlet port. An adjustable by-pass passage bleeds pressurized fluid from the input port around the piston to the outlet port until a specified pressure is built up at the outlet port. When the pressure at the outlet port reaches the specified pressure, the piston is moved from a position which blocks the flow from the input port to the outlet port to a position which allows full communication between the input port and the outlet port.

Abstract: A control valve (10) is provided for mobile or stationary hydraulic equipment for automatically increasing or decreasing speed of a prime mover in response to operation of a hand lever to extend a hydraulic cylinder. A prime mover speed control valve (42) is integrated with a spool (12) in a single housing (10) for the purpose of simultaneously controlling the supply of fluid to a hydraulic cylinder (16) and to a cylinder (61) controlling prime mover speed. When the spool (12) is in the "CYLINDER EXTEND" or "NEUTRAL" position for the implement cylinder, a hydraulic control signal is provided from port (55) to the prime mover control cylinder (61) to signal increased prime mover speed and increased output from a hydraulic pump (17). When the spool (12) is in the "CYLINDER RETRACT" position for the implement cylinder (16), the spool (12) blocks the signal from port (55) while allowing fluid to drain from the implement cylinder (16) to a reservoir (29).

Abstract: A direction control valve is formed by providing a main spool for establishing and blocking communication between an inlet port, first and second actuator ports and first and second tank ports. A pressure compensation valve comprising a check valve portion and pressure reduction portion is provided for compensating the pressurized fluid with a load pressure and supplying it to the inlet port. A plurality of valve blocks are connected to each other with respective first and second tank ports and respective pump ports in fluid communication. A pump port of one of the valve blocks is connected to a main inlet port, and a tank port of one of the valve blocks is connected to a main tank port. Thus, a hydraulic circuit for distributing a pressurized fluid from a single hydraulic pump to a plurality of actuators is provided.

Abstract: A hydraulic pilot valve has a joystick which is normally maintained in a neutral position by coil springs acting on plungers which engage corresponding first cam surfaces of a cam fixed to the joystick. The plungers are each connected to respective valve members which are stroked to open the pilot valve when the plungers are depressed. When the joystick is pivoted to depress one of the plungers so as to stroke one of the valve members, that valve member is held stroked by an magnetic detent. The joystick may then be released and the valve member will remain in its stroked position. When the joystick is moved back towards a neutral position, a second cam surface on the joystick engages an outer end portion of the depressed plunger and applies an axial force to the plunger. This disengages an armature component of the magnetic detent from an electromagnetic component. A spring then pushes the plunger to its neutral position where the plunger holds the valve member operated thereby closed.

Abstract: A multiple valve includes first and second valve units respectively having first and second valve bodies. The first and second valve bodies have respective spool bores therein; and a respective spool is inserted in the spool bore of each of the first and second valve bodies. The first and second valve bodies of the first and second valve units also have inlet ports, tank ports, and first and second blocks having mounting holes, the blocks and a respective valve body being fixedly coupled together by means of stud bolts. The first block has a first threaded hole on one side surface thereof for receiving the stud bolt, and a second threaded hole on another side surface thereof for receiving a cover bolt. A pump passage, a main passage and a tank passage extend between the one side surface and the another side surface of the first block, and a stud bolt extends through the second block and is engaged with the first threaded hole.

Abstract: An improved pre-detent tactile feedback assembly for a fluid control valve is provided. The pre-detent tactile feedback assembly includes an elastic member seated within an annular groove formed in the bore of a plunger valve assembly. Preferably, this elastic member is a garter type spring. When the plunger is moved from an opened to a closed position, a portion of the plunger contacts the elastic member, urging the elastic member outwardly into the groove. The additional force required to urge the elastic member into the groove provides a "feel" force to the control lever. Preferably, the groove is positioned within the bore so that this "feel" force is sensed just prior to actuation of an associated detent assembly.

Abstract: A control means for a hydraulic motor connected to an external load comprises a directional valve (10) for selectively feeding hydraulic fluid to the motor from a pressure source and including load pressure sensing means (24, 25) connected to a load compensating valve (15) located upstream of the directional valve (10) for adjusting automatically the feed pressure in relation to the actual load pressure. The load compensating valve (15) includes a valve spindle (28) with opposite end surfaces (29, 30), one of which is exposed to the load pressure whereas the other is exposed to the feed pressure, and a selectively activatable feed pressure reducing means (38, 43; 50-57) for increasing the bias force acting on the load compensating valve spindle (28) in the closing direction of the latter in relation to the bias force acting in the closing direction of said valve spindle (28).

Abstract: A method for controlling a hydraulic motor with a hydraulic valve comprising an inlet section which includes a pump and tank connection and a maneuvering section having a slide (B1) and a load signal system (L1, L2, L3). The hydraulic valve also includes two regulating constrictions (S3, S4) which can be connected to and from a motor (C), such as a hydraulic piston-cylinder device. The maneuvering slide (B1) also includes a load level detecting constriction (S2) and a load signal drain (S5), and the pump generates an idling pressure. When maneuvering the maneuver slide (B1), the load signal Ps of the load signal system is increased by a further constriction (S1) located between the pump connection and that side of the load detecting constriction (S2) that has the higher pressure during the maneuvering process.

Abstract: A universal hydraulic stop valve has housing having check valves in a check valve bore. A needle in needle bore has spaced apart seals which may alternately seal against valve seats on adjustable knobs, with movement of the needle, which may be mechanically linked to a machine element moved by a hydraulic actuator. The universal hydraulic valve sets accurate starting and stopping positions, and also provides for gradual feathered stops.

Abstract: Hydraulic actuators are fed by a single flow-rate generator, each being connected to it through a proportional directional valve, the unit including a device for detecting the highest of the pressures prevailing upstream of the throttle provided by a controlled spool in the respective proportional directional valves, and, in each of these an actuation device to cause the compensating spool to respond to the highest of the upstream pressures thus detected.

Abstract: A hydraulic circuit including a pressure compensating valve, which aims at preventing the delay in operation of the valve due to the time required for the inflow of fluid in amount corresponding to stroke volume thereof, thereby improving the response of thereof. This hydraulic circuit includes a pressure compensating valve (3) provided between the delivery side of a hydraulic pump (1) and the inlet of a directional control valve (4), the pressure compensating valve (3) being arranged to be urged by the pressure applied to first pressure receiving portion (6) to position (D) where the area of opening thereof is kept maximum, and also urged by the pressure applied to second pressure receiving portion (8) to position (E) where the area of opening thereof is kept minimum, the portions (6) and (8) being connected with the outlet and inlet sides of the valve (4).

Abstract: A bleed valve apparatus for the fresh water system of a camping vehicle. The apparatus is interposed between a garden hose and the female hose coupling of the plumbing system of the camping vehicle. The apparatus includes a housing which contains three ends, one of which has a mating coupling for the camping vehicle plumbing system. A second end may be coupled to the garden hose. The third end is isolated from the other ends by a water valve which may be opened to allow the apparatus to serve as an outdoor faucet at the camping vehicle or to serve to allow water to drain from the camping vehicle plumbing when the user of the camping vehicle desires to disconnect from the external water system provided through the hose. The configuration of the apparatus allows a garden hose to be routed from the camping vehicle to a water hydrant with few required bends along the hose.

Abstract: A fluid flow control assembly for controlling the flow of fluids to and from a number of tanks, and for controlling the communication of that flow. Raw material, product, CIP solution and drain conduits pass near to the tanks. The fluid flow control assembly which is the subject of this invention includes three sets of valves. One set of valves regulates the flow of raw materials from the first conduit into the tanks. Another set of valves regulates the flow of product out of the tanks into the second conduit. A third set of valves regulates the flow of CIP solution out of the tanks into the third conduit. Each set of valves prevents flow of fluid into or out of its respective conduit when desired, such that one of the tanks can be being filled at the same time another of the tanks is being emptied of product and a third one of the tanks is being flushed with CIP solution.

Abstract: Hydraulic actuators are fed by a single flow-rate generator, each being connected to it through a proportional directional valve, the unit including at least one auxiliary valve fed by the flow-rate generator and producing a pressure which is normally equal to a regulation pressure increased by a constant, and in each proportional directional valve an actuating device causes the compensating spool to respond to the pressure produced by the auxiliary valve.

Abstract: A valve for slowly starting an actuator includes a block having an inlet port, an outlet port, and a passage providing communication between the inlet and outlet ports. A first valve body is disposed in the passage for selectively opening and closing the passage, and a second valve body is disposed downstream of the first valve body with respect to the passage for selectively opening and closing the passage. A needle valve is disposed in the block parallel to the second valve body between the passage and the outlet port for restricting the fluid under pressure discharged from the outlet port. The second valve body has a passage defined therein and communicating from one end to the other end thereof, and first and second pressure-bearing surfaces on the one and other ends, respectively, the first pressure-bearing surface is wider than the second pressure-bearing surface.

Abstract: A valve control system for controlling the operation of a pressure fluid-activated device such as a hydraulic cylinder includes a valve housing having an internal, sealed valve chamber therein. A valve spool is slidably disposed for lengthwise movement within the valve chamber, the valve spool having a valve member for selectively admitting a pressure fluid through passages in the vale housing. A movable handle for manual operation of the valve is connected to the valve spool by a connecting mechanism, whereby movement of the handle causes lengthwise movement of the valve spool relative to the valve housing. A neutral-centering tactile feedback mechanism applies a return force to the handle when the handle is in an operative position. The return force varies in proportion to the pressure of the pressure fluid within the valve, which pressure actuates the device. The feedback mechanism ceases to apply the return force when the handle returns to a neutral position.

Abstract: A pressure compensating hydraulic directional valve comprising: a body provided with a movable slide; a passage through the body for connecting a distribution chamber associated with the slide to working orifices, the distribution chamber being selectively connectable to an admission orifice by the slide when moved; a load sensing line channel combined with means for selecting the maximum pressure selected from the pressure in the channel and the pressure of the fluid in the valve; and pressure compensating means placed in the passage and responsive to the difference between the pressure in the passage and the pressure in the channel to generate a fixed pressure drop in the pressurized fluid flowing through the passage towards the working orifices, the pressure compensating means being combined with the maximum pressure selecting means in such a manner that if the pressure in the channel is greater than or equal to the pressure of the fluid from the slide, then no communication exists between the passage and

Abstract: A pneumatic control valve system has a modulating valve and a piston. When the operator depresses the piston, pressure is communicated to a switching piston moving that piston to a switched position so that pressure is communicated to a switching outlet. The switching piston retains this switched position when the first piston is released. When the modulating valve is opened to communicate pressure to a work port, pressure is also communicated to the switching piston in order to move the switching piston back to its unswitched position whereat the switching outlet is vented. The switching piston allows the control of another function.

Abstract: A pilot-actuated, pressure-compensated flow and directional control valve assembly (11) is provided in which a main valve spool (95) is positioned in response to a pressure differential between a pilot chamber (119) and a reaction chamber (117). Flow of fluid from an inlet port (29) is controlled by means of a pilot valve assembly (97), into the pilot chamber (119), while fluid flows out of the pilot chamber (119) through a fixed orifice (67) to a pump load sense port (61). The main valve spool (95) acts as an inlet compensator. If the pressure at a load L is above inlet pressure, the main valve spool (95) acts as an inlet check, preventing reverse flow. If there is a higher load pressure at another load circuit in the system, such as a steering valve S, there will be an increase in pressure in the reaction chamber (117), thus closing off the main spool (95), reducing the flow from the inlet port (29) to the work port (47), and giving more priority to the steering valve S.

Abstract: A hydraulic remote control distributor valve device comprises a flat body (1) having two main assembly faces (3) to enable a multiple hydraulic remote control block to be built up, and two side faces and a bottom face (5) that are narrow and on which orifices are located for receiving link couplings for hydraulic connection with a source of hydraulic fluid under pressure and with a component to be controlled. Two outlet orifices (A, B) are situated on the bottom face of the body (5) and the width e of the bottom face (5) is less than the diameter d of the link couplings suitable for fixing on the outlet orifices. The two outlet orifices (A, B) are disposed asymmetrically relative to the median plane (M) of the body (1) that extends perpendicularly to the main faces and to the bottom face (5), said orifices being offset relative to the plane (M) by an offset 1 that is equal to or greater than 1/2.sqroot.(d.sup.2 -e.sup.2).

Abstract: In a piezoelectric valve the actual control member (7) is formed by a displacer fluid motor (9) though which the fluid stream (5) flows. A piezoelectric actuating element (8) is disposed in the region of a displacer element (1), which can be moved by the fluid stream (5) and belongs to this fluid motor (9), and acts exploiting the inverse piezo effect during electric actuation to at least indirectly block or release this displacer element (1). The fluid motor (9) is formed preferably by a rotating piston machine, such as a gear pump.

Abstract: An operation valve having a pressure compensation valve of relatively simple non-complicated internal body structure. In the valve body, a load pressure introducing passage, a check valve and a restriction are formed inside the spool comprising the operation valve. An intermediate pressure between an inlet pressure and an outlet pressure of the compensation valve which is arranged in the valve body, may be supplied to a pressure receiving section of the pressure compensation valve through an oil hole of the spool. The operation valve with the pressure compensation valve is of simple construction and may be easily manufactured.

Abstract: A hydraulic pilot valve unit constructed with an aim of controlling the flow rate of fluid under pressure in proportion to the stroke of the operating lever, irrespective of the speed of operation of the lever, and adapted for use in supply of pilot fluid under pressure by a pilot fluid actuated type changeover valve or the like arranged to be actuated for switch-over by pilot fluid under pressure. This hydraulic pilot valve unit includes valve spools 23 each being slidably movable between a first position where the pilot fluid under pressure supplied by a pilot pressurized fluid supply pump (27) is allowed to flow into outlet ports (26) formed in the valve body (1), and a second position where the outlet ports are allowed to communicate with a reservoir port (30) formed for drainage purposes.

Abstract: The present invention comprises a lightweight, portable, adjustable, reusable, preassembled, hydraulic expandable shoring shield for providing safety to personnel working in below-grade excavations. The Shoring shield comprises specially designed solid aluminum extruded sheeting sections forming the walls, each mounted with a top cap and lower skid, the walls are provided with a static expandable telescoping structural framework for holding the walls opposed, and also are provided with hydraulic cylinders for expanding the space enclosed between the walls, the framework and cylinders thus cooperate in combination with an armored manifold for routing fluid to the cylinders.

Abstract: A pressure compensating type hydraulic valve wherein a pressure compensation can be made according to the movement of the movable portion of a hydraulic actuator, and the movable portion of the actuator can be stopped against load pressure when it is located at its neutral position. This pressure compensating type hydraulic valve is arranged such that a spool (24) is moved in a valve hole (16) so as to allow a first actuating port (21) and a second actuating port (22) connected with pressure receiving chambers (13.sub.1, 13.sub.2), respectively, defined on both sides of a movable portion (13.sub.

Abstract: There is disclosed a direction selector valve having function of detecting load. The valve is used in a hydraulic system. A spool has two passage holes extending axially partially through the spool from both side ends. These two passage holes have their respective high-pressure holes. When the spool is in its neutral position, the high-pressure holes are closed off by spool hole walls between bridge ports and actuator ports. The two passage holes further include low-pressure holes which are in communication with tank ports via load check valves mounted in the passage holes, respectively. Guide holes are formed near the front end of one passage hole and in communication with a load-sensing port. A restriction portion is formed on the outer surface of the spool adjacently to the guide holes to control the flow from the load-sensing port to the tank ports. First guide holes and second guide holes which are close to each other are formed near the front end of the other passage hole.

Abstract: An active hydraulic pressure control system includes a sensor, a valve, a controller and an actuator. In accordance with a broad aspect of the present invention, the controller determines a pressure differential between the pressure sensed by the sensor in a high pressure supply line of a hydraulic system and a predetermined pressure. In response to such pressure differential, the actuator drives the valve which has a variable flow orifice to communicate hydraulic fluid between the high pressure supply line and a reservoir of hydraulic fluid to eliminate the pressure differential.

Abstract: Pressure compensating valves located downstream of the directional control valves are useful in providing load independent, proportional flow control hydraulic systems and normally serve as load checks. The subject load check and pressure compensating valve is designed for use in a hydraulic system in which the pressure of a common pressure signal directed to all the pressure compensating valves of the system is limited to a predetermined maximum level. The pressure compensating valve includes a valve element disposed downstream of a metering orifice, a separate load piston disposed in end-to-end relationship with the valve element in a common bore and a pressure compensating spring disposed in a chamber behind the load piston and biasing the load piston and valve element to the load check position.

Abstract: A multi-valve, multi-port, relay device used in a control system for sequentially pressurizing a first reservoir before a second and depressurizing the second reservoir before the first. A piston valve configuration for blocking a second outlet permitting an external pressure supply source to pressurize an external reservoir via a first outlet. The piston is biased in the second outlet blocking position by a spring having a force preselected by the operator via an adjustment screw. A pressure force greater than the piston spring biasing force opens the piston valve configuration. When open, the piston valve configuration and a check valve configuration cooperates to block flow out of the first outlet, but permit flow out the second outlet to a second external reservoir, until full pressurization. An overpressurization feature enables the bleed off of pressure increases associated with thermal expansion of the working fluid.

Abstract: A hydraulic control system for driving a plurality of actuators basically includes directional control valves, and pressure compensation valves, and at least one detection valve, the directional valves and the pressure compensation valves both corresponding in number to the actuators. These valves are mounted or incorporated in a body. The body has a plurality of regions corresponding in number to the actuators. Each of the regions of the body has a first hole, and a second hole substantially perpendicularly intersecting the first hole. A load pressure chamber for receiving a load pressure of the corresponding actuator is formed at the intersection between the first and second holes of each region. A spool of the directional control valve is received in the first hole. A balance piston of the pressure compensation valve is received in that portion of the second hole disposed on one side of the load pressure chamber.

Abstract: A fluid controller (11) is provided of the type including a primary, rotatable spool valve (35) and a relatively rotatable follow-up sleeve valve (37). The spool and sleeve define a main fluid path in response to relative rotation, the main fluid path including flow through a fluid meter (17). In accordance with the invention, the spool and sleeve are also moveable axailly relative to each other to define a separate fluid path, in parallel with the main fluid path, the parallel fluid path preferrably excluding the fluid meter (17). Axial actuation of the spool and sleeve relative to each other may be accomplished by controlling fluid pressure in a pair of axial fluid chambers (69, 83). The control of the fluid pressure may be accomplished by any suitable electrohydraulic means (95) or hydromechanical means (181).

Abstract: There is provided control apparatus for controlling fluid flow between a bidirectional motor, a pump and a container, and includes a control valve that has a slide operative between neutral and first and second operative positions. A compensating valve is provided in the supply conduit that holds the upstream pressure drop at the control valve substantially constant and is controlled by load pressure sensing circuitry. The load pressure circuitry includes two branches that are connected through a change over valve to the compensating valve. There is provided an over pressure valve and a throttle point in each branch, each branch being connected to a load pressure sensing orifice of the control valve housing and fluidly connected through the slide to one of the housing motor orifices, the one depending upon whether the slide is in its first or in its second position.

Abstract: A four way directional control valve comprises a valve body having a sleeve formed therein, a spool slidable in the sleeve, two output ports, a pump port and two tank ports formed in the valve body so that the output ports can be a pressure side and an exhaust side by operation of the spool. The four way directional valve further comprises a communicating passage formed in the valve body to provide communication of the output ports with each other, a fixed orifice disposed in the communicating passage, a control passage, formed in parallel with the communicating passage, a control spool disposed in the control passage movable in response to a differential pressure between the output ports to block the communicating passage.

Abstract: Several individually operable push buttons are provided to initiate an OFF function, defrost, air conditioning and various air directions and other functions of an automotive heating, ventilating and air conditioning system. Each push button has a carriage adapted to be fitted on one side with an optional leaf spring contactor engageable with fixed contact members. The opposite side of the carriage is fixedly fitted with a compressible silicone rubber or other resilient valve member in sealing engagement with a port plate to carry out vacuum valving functions. Each carriage is guided by a tongue-and-slot guiding arrangement, whereby sealing pressure is applied between the valve member and the port plate. Each carriage has a rearwardly projecting tongue, slidably received in a slot formed in flange structure on the port plate. The front portion of each push button is also slidably guided to maintain the sealing pressure.

Abstract: Load sensing hydraulic systems conserve energy by generating only the fluid flow demanded by the system and at a pressure only slightly greater than the highest load pressure of the system. Optimizing the operating characteristics of the system for certain applications also caused the variable displacement pump to go to its maximum displacement setting with the excess fluid generated thereby not doing any useful work. The load sensing hydraulic system includes a flow control valve connected to a directional control valve and has an operating position in which fluid exhausted from a hydraulic jack is transmitted therethrough to a tank. A signal valve is disposed in a control pressure signal line for controlling fluid flow therethrough from a supply conduit to one end of the flow control valve. When the signal valve is blocking fluid flow through the signal line, the flow control valve is in the above-noted operating position.

Abstract: A rotary piston valve arrangement, for a pneumatic settling tank, including rotary piston valves disposed in a common housing, with a first rotary piston valve being designed for the control of an additive stroke, and a second rotary piston valve being designed for the control of a discharge position. To reduce the amount of air required for controlling the settling tank, an element is provided for periodically shutting off the passage of air between the air inlet opening of the first rotary piston valve and the settling chamber during the time interval of an intake position of the first rotary piston valve and a simultaneous discharge position of the second rotary piston valve.

Abstract: An apparatus for filling a liquid friction pump with a liquid comprises a metering pump and plug connector means for connection to the liquid friction coupling. During a testing of the filling ratio of the liquid friction pump it may be necessary not only to supply viscous liquid to said coupling but also to withdraw viscous liquid from such coupling. For that purpose the plug connector means are preceded by a manifold, which communicates with two nonreturn valves, which normally prevent a flow of liquid from said manifold through said valves. A discharge line from the metering pump communicates with a first of said nonreturn valves. The second nonreturn valve is incorporated in a return line leading from said manifold to a reservoir, from which the metering pump is adapted to suck liquid. Said second nonreturn valve is adapted to be opened preferably by the application of pneumatic pressure for a flow in said return line from said manifold through said second valve to said reservoir.

Abstract: A ball valve includes a valve casing accommodating therein an upstream ball seat and a downstream ball seat and defining a cavity between the two ball seats, a ball provided with a through hole, accommodated in the cavity and brought into sealing contact with the two ball seats at the outer periphery thereof, a valve stem having one end thereof fixed to the ball, a valve handle fixed to the other end of the valve stem, a check valve accommodated in the through hole of the ball and biased toward the upstream side, a path formed on the ball and, when the ball valve is closed, causing the downstream side and the cavity to communicate with each other, and a connection port formed on the valve casing so as to communicate with the cavity and having a free end thereof connected to one end of a nipple having the other end thereof covered with a cap. The ball opens and closes the ball valve through the valve stem by a rotating operation of the valve handle.

Abstract: Vibration equipment bases which are isolated from the floor by air bags are made self-leveling by interposing a valve between each of the air bags and a pressurized air supply and each of the air bags and the atmosphere, the valve being sensitive to height of the base in air flow controlling relation to and from the bags to adjust their inflation and thus the height of the base.

Abstract: Flow amplified control systems are useful in pilot operated steering systems. The load responsive flow amplified control system includes a directional control valve movable to an operating position to direct fluid from the operating fluid circuit through a variable orifice to a steering motor and to direct control fluid from a control fluid circuit through another variable orifice to be combined with the fluid going to the steering motor. The operating fluid circuit and the control fluid circuit are provided with fluid from a common variable displacement pump. The directional control valve is moved to an operating position by the control fluid acting thereon and is pressure compensated insofar as the flow of control fluid passing through the another variable orifice such that a substantially constant predetermined pressure differential exists across the another variable orifice.

Abstract: A four way directional control valve comprises a valve body having a sleeve formed therein, a spool slidable in the sleeve, two output ports, two pump ports and a tank port formed in the valve body so that the output ports can be a pressure side and an exhaust side by operation of the spool. The four way directional valve further comprises a communicating passage formed in the valve body to provide communication of the output ports with each other, a fixed orifice disposed in the communicating passage, a control passage, formed in parallel with the communicating passage, a control spool disposed in the control passage movable in response to a differential pressure between the output ports to block the communicating passage.

Abstract: Two control valve housings each have a longitudinal bore receiving a valve spool. The housings are clamped together by two pairs of bolts located one on each side of the bores. Formed on one of the parts at the interface of the two parts and at opposite sides of each bolt is a pair of roughened surface areas which are prepared by milling or stamping. By means of such a surface preparing method projections are created which are deformed and serve as spacers between the two parts when they are clamped together. The two parts then touch themselves only in the roughened surface areas. Thus, when the two parts are clamped together any distortion in the area of the longitudinal bore is avoided and the valve spool can move in the longitudinal bore, noneffected by the force acting on the two parts.

Abstract: An individual segment flow regulator is shown having a two landed spool and two landed bore, all with the same nominal diameter, a plug, a spring and a sensing passage from the main spool of the valve. Supply oil entering between the two lands of the bore is separated from a sensing pressure by one spool land which is slidable within the bore. The other spool land meters the supply fluid. The metering land of the regulator spool opens away from the valve bore land to allow supply fluid through and can shut off the supply. A spring chamber above the spool senses the load pressure which opens the metering spool, thereby increasing the flow and therefore the pressure drop across the main spool area opening. Feedback pressure developed at the bottom of the metering land of the spool is used to close down the regulator spool as the flow, and therefore the pressure drop, across the main spool increases beyond the pre-load force of the bias spring.

Abstract: A flapper actuated pilot valve is shown is which the output pressure from the valve is dependent upon and proportional to the force exerted by the flapper. The valve includes a valve body with upper and lower chambers and an interconnecting gas passage. A spring-biased poppet in the lower chamber has a primary sealing surface for sealing off the lower chamber and a secondary sealing surface which is contacted by a flapper element located in the upper chamber. The flapper element has an interior bore leading to an exhaust port in the upper end of the flapper element which extends through an opening in the valve body. The flapper element also extends through a central opening provided in a cupped seal in the upper chamber. The cupped seal and primary and secondary sealing areas of the flapper element cooperate to provide and outlet gas pressure which is proportional to the external force supplied by the flapper upon the flapper element.

Abstract: A hydraulic servo system to control flow rate of working fluid to a hydraulic motor as a function of command includes a spool-type pilot valve with manual or electrohydraulic structure for positioning the pilot valve and control conduits connecting the pilot valve to a flow control valve having lands and chambers between the lands for directing flow to the hydraulic motor, the flow control valve having a cylindrical cavity at one end and being exposed to full system pressure at the other end, a shuttle valve coaxially positioned with respect to the flow control valve having an axial extension extending into the cylindrical cavity, a spring in the cavity which tends to urge the flow control valve in a direction to oppose the system pressure, with control passages connecting opposite sides of the shuttle valve with the flow control valve chambers causing the shuttle valve to select the higher pressure in the flow control valve chambers and causing the spool to seek a position providing the desired flow rate.

Abstract: Actuator control system includes two parallel connected orifices between a pair of fluid passages providing communication between an actuator and a flow control valve. Relief valves in series with the respective orifices block fluid flow through the orifices at low differential pressures between the fluid passages, thereby preserving the original high pressure gain of the control valve in a region about valve null. At higher differential pressures outside the valve null region, the relief valves open to permit restricted flow through the respective orifices to reduce the pressure gain of the control valve in a region outside the valve null region, which effectively reduces the stiffness of the control valve.

Abstract: A proportional type hydraulic distributor incorporates a distributor slide valve including a feed chamber. It is provided with a pressure compensator device for regulating the feed pressure to the feed chamber according to the output (load) pressure of the slide valve. This device includes an inlet channel, an outlet channel communicating with the feed chamber and a stator communicating with the inlet and outlet channels. A compensator slide valve slides in a housing in the stator. A spring exerts an axial force on the compensator slide valve in the same direction as the force exerted on it by the output pressure and in the opposite direction to the force exerted on it by the feed pressure. An annular obturator member on the compensator slide valve isolates the inlet and feed channels and is acted on by a return spring on the compensator slide valve. The latter has a recessed part on which the obturator member slides without clearance.

Abstract: A gas spring with a piston rod slidably received in a cylinder which defines a chamber in which a gas is compressed when the rod is forced into the cylinder. The gas spring can be operated with either an external source of gas or as a precharged and self-contained unit by changing first and second valves assemblies either of which can be installed in the same cavity in the cylinder. If desired, a check valve can control the bleeding of gas under pressure in the cylinder back to the entrance of the cavity containing one of the valve assemblies through which the cylinder is filled with gas.

Abstract: A pendant for controlling the energization of pneumatic motors that position an overhead crane trolley and raise and lower an object supported by a hoist mounted on the trolley is disclosed. The pneumatic pendant includes a moisture-proof housing (11) and a plurality of manually actuated pneumatic control valves mounted in the housing. The control valves include a start/stop valve (69) and direction valves (119a-d) for directing forward and reverse air pressure to the crane trolley motor, and up and down air pressure to the hoist motor.