Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump flow control responding to highest system load. Each direction flow control valve is equipped with a load responsive negative load control to control a constant pressure differential at the motor exhaust. The negative load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A fluid controller is disclosed of the type including a primary valve member, and a follow-up valve member. The controller includes a load signal port and a load signal chamber. Fluid is communicated from the inlet port to the load signal chamber, and the valve members define a neutral orifice communicating between the load signal chamber and the return port when the valving is in neutral. The valving defines operating orifices communicating fluid from the load signal chamber to the main fluid path, downstream of the main flow control orifice, when the valving is shifted away from neutral. The operating orifices have a smaller orifice area when the valving approaches maximum deflection. The result is a substantially higher differential operating pressure, and a higher flow rate than would otherwise be possible at that particular valve deflection.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The system is powered by a single fixed or variable displacement pump. The valve maintains a selected constant flow level during control of positive loads and automatically blocks pump flow to the actuator in presence of a negative load, providing the actuator inlet flow requirement from the valve exhaust manifold. The direction and flow control valve is equipped with a load responsive control which during control of positive load maintains a constant low pressure level at the actuator outlet and retains its control characteristics in a system in which multiple positive loads are simultaneously controlled.

Abstract: A fluid power device such, for example, as one for opening and closing clam shell gates is operated by a ram under fluid pressure. A tank is provided for storing fluid under pressure and by a system of valving extension of the ram, as for a gate opening operation, is inhibited until enough fluid under pressure is stored in the tank to assure completion of reverse operation of the ram to close the gates.

Abstract: A direction control valve of pressure compensated or load responsive type for use with positive or negative load controllers which maintain a constant pressure differential between selected valve chambers. Controllers are connected to the valve bore by pressure sensing passages which are blocked in the neutral position of the valve spool. Displacement of the valve spool from its neutral position in a sequential manner connects first a valve load chamber to the pressure signal passage and the valve controller and then upon further displacement of the valve spool connects the load chamber with one of the other valve chambers. The sequence of these connections and distance of travel of valve spool to accomplish these connections can be varied.

Abstract: The disclosure is directed to a closed center, pressure compensated hydraulic system which uses a multiple section hydraulic control valve in conjunction with a variable output hydraulic pump. The hydraulic control valve has a plurality of independently operable power spools each of which is used to control the flow of hydraulic fluid to a separate hydraulic actuator and load. Each valve section includes an automatic spool positioner which enables the operator to move the valve handle to a preselected position, the power spool thereafter being retained in such position until the actuator completes its stroke. After completion of the stroke, the automatic spool positioner causes the power spool to return to the neutral position. The multiple section hydraulic control valve also includes means for selecting the highest demand or work port pressure, and for controlling the variable output pump as a function of this selected pressure.

Abstract: A hydraulic valve system particularly adapted for controlling a hydraulically powered elevator. The system involves essentially a bypass valve which selectively bypasses hydraulic fluid from the pump directly back to the tank during the up mode operation, thereby controlling the up speed of the elevator; and a down valve which selectively controls the escape of fluid from the elevator jack back to the tank, thereby controlling the down speed of the elevator. The down valve also serves as a check valve for retaining fluid pressure in the jack. Both the bypass valve and the down/check valve are each controlled by closely integrated cylinder-and-piston arrangement, with pressure to the cylinder being controlled by a control valve structurally interlinked to the respective piston. The bypass valve also serves as a check valve between the jack and the tank during the down mode of operation. The cylinder-and-piston control for the bypass valve makes possible an initial limit opening of the bypass valve, i.e.

Abstract: A hydraulic control arrangement for at least two hydraulic consumers, comprises two pressure compensated multiple position valves, respectively coordinated with the two consumers, and each including a pressure compensating control member which controls a control conduit coordinated with a reversing or unloading valve, which, depending on its position and those of the multiple position valves control flow of pressure fluid from a pump over the multiple position valves to the respective consumer or to a return conduit. This will assure that even during parallel operation of both consumers, the output of the pump will be adjusted to the consumer load in such a manner that energy losses are substantially avoided and control of the two consumers independent from each other is assured.

Abstract: A hydraulic valve system particularly adapted for controlling a hydraulically powered elevator. The system involves essentially a bypass valve which selectively bypasses hydraulic fluid from the pump directly back to the tank during the up mode operation, thereby controlling the up speed of the elevator; and a down valve which selectively controls the escape of fluid from the elevator jack back to the tank, thereby controlling the down speed of the elevator. The down valve also serves as a check valve for retaining fluid pressure in the jack. Both the bypass valve and the down/check valve are each controlled by closely integrated cylinder-and-piston arrangement, with pressure to the cylinder being controlled by a control valve structurally interlinked to the respective piston. The bypass valve also serves as a check valve between the jack and the tank during the down mode of operation. The cylinder-and-piston control for the bypass valve makes possible an initial limit opening of the bypass valve, i.e.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive pressure control which automatically regulates valve inlet pressure to maintain a constant low pressure level at the motor exhaust and a load responsive negative load control to control a constant pressure differential at the motor exhaust. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive pressure control which automatically regulates valve inlet pressure to maintain a constant low pressure level at the motor exhaust and a load responsive negative load control to control a constant pressure differential at the motor exhaust. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A load responsive fluid power multiple load control system using a first type of load responsive direction control valves responding to upstream pressure differential between inlet and load chambers together with a second type of load responsive direction control valves responding to down stream actuator pressure or pressure differential. Load pressure signals are phased by check valve logic system to the output flow control of fixed or variable displacement pump which maintains a constant pressure differential between pump discharge pressure and highest of the load pressures.

Abstract: A pressure responsive check valve permits fluid flow therethrough in a first direction and blocks fluid flow therethrough in the reverse direction until the fluid pressure at the blocked side exceeds a preselected pressure level at which time the check valve is controllably opened for reverse flow therethrough.

Abstract: Instrumentality for use in multiple spool control valve assemblies including a high pressure pilot operated relief valve that exhausts fluid from the chamber being protected through a pair of exhaust passages simultaneously. A pressure responsive flow restricting valve maintains a constant pressure differential on the control spools across the open center flow passages of open center valves. A low pressure regeneration circuit includes provisions for preventing excessive pressure and consequent seal blow-out in the return passages of a control valve assembly. Each of these instrumentalities is capable of being disposed in an end plate section of universal configuration for section control valve asssemblies.

Abstract: A self-depressurizing hydraulic control valve having a sliding-type metering valve to control the flow of hydraulic fluid through the valve and also a shutoff valve to stop the flow automatically. The shutoff valve is responsive to the rate of flow of fluid through the control valve and stops the flow when the flow rate decreases to a preselected value. When the shutoff valve closes, the control edges of the metering valve are no longer exposed directly to high pressure fluid, and quiescent leakage across the edges is practically eliminated. Thus, electrochemical erosion of the metering edges resulting from such leakage is substantially reduced.

Abstract: A direction flow control valve for control of positive and negative loads equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between inlet pressure and load pressure. The load responsive control of the direction flow control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a single load responsive controller which automatically regulates fluid flow into and out of the fluid motor to maintain a constant pressure in front of a variable flow controlling orifice, during the control of both positive and negative loads. The load responsive controller of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A pressure compensating valve spool assembly for a hydraulic flow control valve the spool assembly being slidably positioned in the central bore of a valve housing for movement from a neutral position wherein fluid will flow through the valve assembly to reservoir to operative positions in either direction to provide fluid communication between fluid inlet passages to one of a pair of cylinder passages in the valve housing, the other of said cylinder passages being connected to one of the pair of reservoir passages. The valve spool assembly includes a symmetrical valve spool having valve members at each end which are responsive to variations in the pressure relation between inlet pressure and cylinder pressure to control the fluid flow rate to the cylinder passage. Any excess flow is bypassed to reservoir at minimum pressure loss.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive pressure control which automatically regulates valve inlet pressure to maintain a constant low pressure level at the motor exhaust and a load responsive negative load control to control a constant pressure differential at the motor exhaust. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A compressed air-operated motor driven from a rechargeable compressed air supply tank. The motor has sets of symmetrically opposing cylinders having spring-biased air admission valves and containing drive pistons connected to a crankshaft. The supply tank is connected to the admission valves through respective pilot valves of a pair controlled by relay poppet valves alternately opened by a rotating cam driven by the crankshaft. The pilot valves control the delivery of compressed air alternately to two cylinder groups comprising alternately oppositely located cylinders, so that their pistons act to drive the crankshaft in a common direction by alternate power pulsations.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive pressure control which automatically regulates valve inlet pressure to maintain a constant low pressure level at the motor exhaust and a load responsive negative load control to control a constant pressure differential at the motor exhaust. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A pressure operated shut-off valve for controlling a pneumatic circuit for instance a supply passage of a pneumatic tool, in response to the motive air supply pressure. The valve comprises a valve body that is continuously biased in its closing direction by a spring means and in its opening diection by the motive air supply pressure. If the air pressure drops below a predetermined minimum value the valve is automatically shifted to a closed position by the load of the spring means. A valve body controlled passage means supplies pressure air to the rear end of the valve body as the latter occupies its closed position, thereby making the closed position stable.

Abstract: An hydraulic power system comprising a dual acting work piston adapted to be operatively connected to an external mass to be moved, the piston being instantly directionally responsive to a pair of control valves adapted to be sequentially opened and closed to actuate the work piston for movement in opposite directions, the control valves each having a series of sequentially acting valve elements which control fluid flow to and from the work piston, the system forming an hydraulic closed loop which is completely filled with fluid during both charging and discharging, the work piston and control valves working at all times against solid columns of fluid under controlled positive pressures, the system being capable of developing accelerating forces having a magnitude up to 500 G's and of being operated both directly or remotely utilizing electronic, mechanical or hydraulic actuating means with no appreciable phase lag between initial actuation and the completion of the work stroke.

Abstract: A control valve having a rotor for communicating outlet port or ports selectively to fluid drain port or to inlet port so as to change flow direction of fluid to be supplied to fluid operated apparatus. The control valve comprises first and second pistons inserted in a hollow space of the rotor and a compression spring arranged between the pistons. At the operation position(s) of the rotor or the valve, the first piston which is biased by the compression spring oscillatingly blocks and reopens fluid passage formed within the rotor outside the first piston for communicating the inlet port to the outlet port(s) under the influence of the compression spring and fluid pressure of the outlet port(s) from which fluid is constantly drained with a small rate through the valve. Fluid pressure of the outlet port may be varied by varying the force of the compression spring by an advance of the second piston.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump flow control responding to highest system load. Each direction flow control valve is equipped with a load responsive negative load control. The negative load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust while maintaining a constant pressure in front of a variable flow metering land.

Abstract: A load responsive direction and flow control valve for use in a fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads in parallel or series type circuits, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. When controlling positive or negative loads the valve maintains a constant pressure differential across a flow control metering orifice utilizing a single load responsive controller, first by throttling fluid entering the inlet chamber and then by throttling the fluid leaving the outlet chamber. The load responsive controller blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. When controlling positive or negative loads the valve maintains a constant pressure differential across a flow control metering orifice utilizing a single control slide member, first by throttling fluid entering the inlet chamber and then by throttling the fluid leaving the outlet chamber. The valve may be used with fixed displacement pumps, fixed displacement pumps equipped with differential pressure relief valves, with variable pumps equipped with pressure compensators and variable pumps equipped with differential pressure compensators.

Abstract: A servoactuator for stopping a ram in its existing position or retracting the ram at a fixed rate to a locked position.

Abstract: A hydraulic valve includes a valve body which is provided with a fluid inlet chamber, a pair of user chambers arranged for communication with users of the fluid admitted into the valve body and a pair of return chambers for recovering fluid from the users and recycling the fluid to a source of the same. The valve body further includes a longitudinal passage which connects the various chambers. A spool is slidably mounted in the longitudinal passage and, depending upon the position thereof, permits a user chamber to communicate with the fluid inlet chamber while the corresponding return chamber is sealed from the user chamber or permits the user chamber to communicate with the corresponding return chamber while the user chamber is sealed from the fluid inlet chamber. A flow channel extends across the width of the valve body and opens to either side of the latter. The flow channel is arranged for communication with the source of the fluid and with the fluid inlet chamber.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. When controlling positive or negative loads the valve maintains a constant pressure differential across a flow control metering orifice utilizing a single control slide member, first by throttling fluid entering the inlet chamber and then by throttling the fluid leaving the outlet chamber. The valve may be used with fixed displacement pumps, fixed displacement pumps equipped with differential pressure relief valves, with variable pumps equipped with pressure compensators and variable pumps equipped with differential pressure compensators.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The system is powered by a single fixed or variable displacement pump. The valve maintains a selected constant flow level during control of positive loads and automatically blocks pump flow to the actuator in presence of a negative load, providing the actuator inlet flow requirement from the valve exhaust manifold. The direction and flow control valve is equipped with a load responsive control which during control of positive load maintains a constant low pressure level at the actuator outlet and retains its control characteristics in a system in which multiple positive loads are simultaneously controlled.

Abstract: An electric and hydraulic servomechanism controlling device comprises a pressure governor valve, a hydraulic servomechanism actuated by the supply of the line pressure regulated by said pressure governor valve, and a change-over valve for shifting an oil passage that connects said pressure governor valve and hydraulic servomechanism. The change-over valve serves also as a pressure reducing valve thereby reducing not only the capacity but also the size of the necessary solenoid.

Abstract: A system for supplying pressurized fluid from a pressure source to a fluid-operated power device comprises an actuator, a sole first pressure conduit leading from the source to the actuator and at least two second pressure conduits leading from the actuator to the power device. The actuator comprises a cylinder and a piston arranged for simultaneous reciprocation and rotation in the cylinder. The reciprocation of the piston is effected by the fluid pressure introduced periodically into the cylinder through the first pressure conduit. The rotation of the piston is effected by the cooperation of a pin affixed to the cylinder wall with a helically extending groove in the cylindrical piston face.

Abstract: The invention relates to a hydraulic control valve assembly, or a plurality of control valve assemblies, for controlling one or more consumer units such as hydraulic motors. Each valve assembly has conventional supply and exhaust ports for selectively and alternately pressuring and exhausting two ports to which a consumer unit is connected. Each valve assembly has pressure sensing control ports which sense pressure in the consumer unit ports. Conduit means connected to the control ports include a pressure differential regulator which shunts the supply pressure and which reacts to pressure supplied to the consumer unit to control the regulator. In a preferred embodiment comprising a plurality of control valve assemblies and associated consumers and a common pressure differential regulator, the individual sensing conduits of all control units are connectable at one end to the return conduit in the neutral position and are combined at the other end to form a collecting sensing conduit.

Abstract: A hydraulic control system for use with double-acting shifting rams in a mine working.The system has a pump for supplying pressure fluid and main and return feed lines or conduits connected to the pump and laid along the working. An adjustable pressure-regulating device or devices serves to provide fluid at variable pressure in a further feed line or conduit.Each ram has its working chambers connected to a control device which is in turn connected to the main and further feed lines or conduits and to the return line or conduit. The devices can each be set to various positions to operate the rams in order to extend one of the rams its associated device is set to connect the working chamber used for extension (having the larger piston working surface area) to the further feed line or conduit, and to connect the other working chamber used for retraction (having the smaller piston working surface area) to the to the main feed line or conduit.

Abstract: A controller for fluid pressure operated devices such as hydrostatic power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member, and further comprising a fluid meter including a metering member coupled to the follow-up valve member. The controller is of the 5-port type, having a load signal port for communicating a steering load signal and maintaining a constant pressure drop across the main control orifice of the controller. The primary and follow-up valve members define a central reference plane oriented generally perpendicular to the axes of rotation of the valve members and the various ports and passages defined by the valve members are arranged in somewhat of a mirror image of each other about the reference plane.

Abstract: An injection molding machine wherein the ram in the injection cylinder can be moved at several speeds and can be subjected to different fluid pressures by an apparatus having a two-way valve whose inlet is connectable to one or more pumps by way of discrete check valves and whose outlet is connected with a chamber of the injection cylinder by a conduit containing an electrically adjustable pressure relief valve. The valve member of the two-way valve is movable between a first position in which it completely seals the inlet from the outlet and several second positions in which it acts as a flow regulating means to permit the fluid to flow from the inlet to the outlet at a selected rate. The valve member is movable by a solenoid-operated pilot valve which cooperates with a stop extending into the path of movement of the valve member and being movable axially by a reversible motor which is controlled by the programming system of the injection molding machine.

Abstract: A multiple control valve device for connection in parallel between a single fixed displacement pump and one or more oil actuators to control operation of all or a number of the actuators simultaneously. The pump can supply sufficient oil at an optimum pressure which is the highest loading pressure required among the working actuators. At the same time the desired controlled oil flow rate can be held to the desired value for each working actuator by this device. Also this valve device has stepless speed changing control, provides a self-depressing function of pump pressure loading, and can also have the function that a pressure rise or a pressure variation in the actuators can be treated automatically.

Abstract: A servoactuator for stopping a ram in its existing position or retracting the ram at a fixed rate to a locked position.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. System is powered by a single fixed or variable volume pump. The direction flow control valve is equipped with a load responsive control which automatically regulates pump discharge pressure to maintain either a constant low pressure level or low pressure differential at the motor exhaust. The pump discharge pressure is either regulated by bypassing of excess flow to reservoir, or by a special load responsive control, which varies the pump displacement. Direction control valve may also be equipped with a control responsive to load pressure for controlling negative loads and an inlet pressure throttling control for simultaneous control of multiplicity of loads.

Abstract: The piston of a fluid ram is provided with an end of stroke braking means comprisng a pusher adapted to contact the end wall of the ram cylinder as the piston approaches the end wall to restrict the flow of fluid from the outlet chamber of the ram to an outlet part. As the ram moves nearer the end the pusher opens a valve in the piston to connect the inlet chamber of the ram to the outlet part.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. When controlling positive or negative loads the valve maintains a constant pressure differential across a flow control metering orifice utilizing a single control slide member, first by throttling fluid entering the inlet chamber and then by throttling the fluid leaving the outlet chamber. The valve may be used with fixed displacement pumps, fixed displacement pumps equipped with differential pressure relief valves, with variable displacement pumps equipped with pressure compensators and variable displacement pumps equipped with differential pressure compensators.

Abstract: A pressure compensating valve spool for a hydraulic flow control valve, the valve spool being slidably positioned in the valve for movement from a neutral position wherein fluid will flow through the valve to operative positions in either direction to provide fluid communication from a fluid inlet passage to one of a pair of cylinder passages, the other of said cylinder passages being in fluid communication with a tank passage. The valve spool includes fluid pressure compensating members positioned within each end of the valve spool to vary the fluid flow rate to the cylinder passages, the fluid flow rate being varied to maintain a constant pressure differential between the pressure in the fluid inlet passage and the pressure of the fluid in the valve spool.

Abstract: A reversing slide valve for a hydraulic motor is operated by a pilot slide in a common valve body with the main slide, the latter being biased toward an intermediate position by springs and entraining the pilot slide when moving from the intermediate to either terminal position. Friction rings prevent movement of the pilot slide with the main slide when the latter returns to its normal intermediate position under spring bias. The pilot slide directs pressure fluid to compartments in the valve body partly bounded by end faces of the main slide in such a manner that the main slide is moved from its intermediate position into the terminal position remote from the last-occupied terminal position whenever pressure fluid is supplied to the valve after an interruption of fluid supply.

Abstract: The invention relates to a control valve assembly for a hydrostatic control system such as power steering assembly. A common control valve assembly of this type has relatively rotatable inner and outer elements connected respectively to a vehicle steering wheel and a servomotor. Paired holes in the inner and outer element permit the flow of fluid therethrough when the unit is in its neutral position with the paired holes in respective registration. In hydrostatic steering system of this type impact is sometimes applied to the steering wheel when the working motor connected to the steered wheels is suddenly loaded, e.g. when the wheels strike a stone. Such impacts on the steering wheel are avoided by providing a one-way valve in a section of the working path through which fluid flows to the working motor. Pressure regulating valve means, excess pressure valve means and emergency control valve means are associated with the one-way valve assembly.

Abstract: An improved differential pressure regulator valve for a hydrostatic transmission control system wherein the valve regulates high fluid pressure versus low fluid pressure and produces a pressure differential that in turn controls the transmission. The regulator valve includes a valve body whose bore is in communication with both first and second sets of fluid inlet and outlet ports, with the valve bore containing a spool assembly that includes first and second cooperating spool members, with the second spool member being operable to control the fluid flow between the first inlet and outlet ports or the second inlet port and the first outlet port. Means, including a passage connecting the first outlet port with a spool port, fluidly unbalances the second spool member by applying the pressure of fluid in the first outlet port to one end of the second spool member in opposition to the biasing action of a regulating spring.

Abstract: A hydraulic control arrangement for control of fluid flow to a consumer device and comprising a three-position valve having a valve member movable between a neutral position closing at least one conduit leading to the consumer device and two working positions in one of which it connects the consumer device with a source of pressure fluid and in the other of which it connects the consumer device with a return flow conduit leading to a reservoir, a reversing valve for connecting the source of pressure fluid directly to the return flow conduit and a control conduit connected with the reversing valve. A throttle is provided in the control conduit which produces a pressure difference which can act on the valve member of the reversing valve to move the latter against the force of a spring, and the arrangement includes further means for control of the consumer device independent of the load pressure acting thereon.

Abstract: A valve section which establishes priority flow in a valve assembly having a plurality of directional control open-center valves each for controlling flow between an associated hydraulic motor and a common power passage from a single source of motive fluid, wherein flow to one of the motors is afforded priority during simultaneous operation of it and another motor. The associated valve section of the priority motor having a conventional load check valve opened by pressure in the common power passage while the load check of the non-priority valve section is opened by pilot pressure in its open-center passage.

Abstract: The valve arrangement includes four main control valves connected in a bridge circuit connected, at one end of a first diagonal, to a source of fluid under pressure and, at the other end of the first diagonal, to a fluid reservoir. Opposite ends of a second diagonal of the bridge are connected to inlet and outlet ports of the operated device. The arrangement includes two pressure adjusting valves, each connected to a respective pair of main control valves. In one bridge circuit, the main control valves are pressure limiting valves and each pair of main control valves includes one main control valve in one branch of the bridge circuit and another main control valve in the other branch of the bridge circuit.

Abstract: A direction and flow control valve for use in a central fluid power load responsive system having plurality of loads. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. System is powered by a single variable volume pump equipped with a load responsive control, which automatically maintains pump discharge pressure at a level higher than the pressure required by the system's largest load. Each direction and flow control valve is equipped with a differential pressure regulating control, which is responsive to the load pressure for controlling the negative loads and preferably a second differential pressure regulating control for controlling the positive loads.