Abstract: A hydraulic control device for a hydraulic motor having a working pressure line connecting a source of pressure with the motor and containing a non-return valve from which a bypass line branches off to communicate with the fluid reservoir or tank; a three-way flow controller is connected to the tank and is in communication with a two-way flow controller; characterized in that a single measuring orifice is common to several pressure balances with a single porportional magnet provided in the working pressure line.

Abstract: The invention relates to a coaxial multi-function insertable hydraulic distribution cartridge valve including various inlet and outlet ports (P1,X1,R1,S1,s1,D1,B1), a first compensating slide (N1) urged towards a position of full opening by a first spring (r1), a second internal slide (J1), concentric with the first, providing the principal regulation of the oil inlet flow rate, urged by a second spring (r2), against the control pressure delivered by the inlet port (X1), towards the position of closure of the communication between the oil pressure inlet port (P1) and the outlet port (R1) delivering the actuating pressure, and isolating (C) check valve and a backfeed (G) check valve, which are urged by a third spring (r3) to return these two check valves into the position of closure of communication towards (S1) for the check valve (C) and towards (T1) for the check valve (G), a third balancing slide (E1) urged by a fourth spring (r4), against the pressure delivered by the balancing pressure port (B1) and the

Abstract: A directional control valve comprising a valve housing, tank-, user-, and pump-ports provided in said housing, a spool reciprocally mounted in said housing and adapted to connect and/or separate said ports, and a pilot controlled flow control valve within said directional control valve.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: A load responsive system including individual positive and negative load compensators, for control of positive or negative load and an external logic system for determination of whether the controlled load pressure is positive or negative. The deactivating valve deactivates the positive load compensator, when the negative load pressure exceeds a certain minimum predetermined level, preventing flow of fluid from the system pump to the system actuator controlling a negative load at a pressure higher than a certain predetermined level, and therefore preventing development of excessive pressure in the actuator, while also deactivating the negative load compensator below a certain minimum predetermined negative load pressure level and while the positive load is being controlled by the positive load compensator.

Abstract: A pressure compensated hydraulic valve (2) is provided with a housing (4) having a reciprocal spool (6) for communicating hydraulic fluid to work ports (8,10). Pressure compensating means (58) is provided in the same housing with the valve and senses work port pressure by hydraulic fluid flow through the spool from the work port and creates a substantially fixed differential pressure across the spool by controlling the pressure after the flow has passed through the spool.

Abstract: Into the housing of a multiway valve a pressure balance is incorporated, the end of the control piston subjected to the load report pressure facing a housing recess in which the load report pressure obtains while the opposite end of the control piston is subjected to the supply pressure and in the opposite sense to the supply pressure to the force of a spring. The valve has a simple structure.

Abstract: A compensated control valve assembly for control of fluid flow to and from a fluid motor, which may be of a cylinder type and is subjected to positive and negative loads. During control of negative load the controlled pressure level of a pressure reducing valve mechanism handling the fluid flow at negative load pressure is varied upstream of an outflow metering orifice arrangement, positioned at the outlet of the fluid motor, in response to pressure at the inlet of the fluid motor, while maintaining this controlled pressure constant at each specific level. The pressure differential across an inflow metering orifice arrangement, positioned at the inlet of the fluid motor, is maintained at a constant preselected level by a positive load pressure compensating control device.

Abstract: A control valve for limiting the flow rate of a fluidized medium to a hydraulic motor during start up of the motor so as not to induce loads which exceed predetermined torque limits of apparatus driven by the motor. The control valve includes a poppet which is spring biased to a seated closed position. Increasing inlet-to-outlet pressure differential unseats the poppet in a downstream direction uncovering bypass ports which allow an initial surge of fluid to the motor to accelerate the motor to a predetermined speed at a rate which does not exceed the torque limits. Further downstream movement of the poppet exposes greater cross-sectional areas of main inlet ports which permit additional modulated fluid flow to accelerate the motor to its operational speed. The rate of movement of the poppet in the downstream direction is limited by flow restrictor orifices which conduct fluid which is displaced from a chamber due to the downstream movement of the poppet.

Abstract: A compensated direction flow control valve assembly for control of fluid flow to and from a fluid motor, which may be of a cylinder type and is subjected to positive and negative loads. During control of negative load, the negative load compensating control varies the level of the pressure differential across a metering orifice, positioned at the outlet of the fluid motor, in response to pressure at the inlet of the fluid motor, while maintaining this pressure differential constant at each specific level. The pressure differential across a metering orifice, positioned at the inlet of the fluid motor, is maintained at a constant preselected level by the positive load compensator control assembly.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: A first path extends through the combined blocking and relief valve (10) from a first inlet/outlet port (44) to a first actuator port (88), and a second path extends from a second inlet/outlet port (46) to a second actuator port (82). The first path includes a spring biased poppet valve member (64) positioned to open in response to system pressure introduced into the valve (10) via the first inlet/outlet port (44). The second path extends between one end of a pilot piston (68) and one end of a relief piston (74). Pressure in the first path from port (44) acts on an area (A2) of the pilot piston (68) to produce a force on the pilot piston (68) tending to bias it away from the closure member (64). This same pressure is applied against an opposite side area (A5) on relief piston (74). This area (A5) is equal to the difference between the pilot valve area (A2) and the poppet valve area (A1) so that the pressure forces on the pistons (68) and (74) cancel each other out regardless of the pressure in the first path.

Abstract: A compensated direction flow control valve arrangement provided with a direction control spool for control of fluid flow to and from a fluid motor, which may be of a cylinder type and is subjected to positive and negative loads. During control of negative load the upstream of the outflow metering orifice, positioned at the outlet of the fluid motor, is maintained at a controlled constant pressure level by a pressure reducing valve handling the fluid flow at negative load pressure. The outflow metering orifice is made independent of the direction control spool and its effective flow area is made responsive and varies with the pressure at the inlet of the fluid motor. The pressure differential across a metering orifice, positioned at the inlet of the fluid motor, is maintained at a constant preselected level by the positive load compensator.

Abstract: A proportional hydraulic distributor with a hollow, cylindrical compensating slide, a seat at one end of the compensating slide, a reciprocable piston, an end of which is urged against the seat by a spring, a pressure assistance chamber surrounding the seat, and a choke connecting the entry pressure of the hydraulic distributor to the pressure assistance chamber. The balance of forces on the reciprocable piston and on the cylindrical compensating slide is equal to and oppositely directed with respect to the hydrodynamic drag force that develops during transitional phases of the operation of the hydraulic distributor.

Abstract: A hydraulic control apparatus has at least two meter-in and two meter-out poppet valves. In order to be compact and deal with a great flow rate, the apparatus is arranged such that a pair of meter-in poppet valves and load check valves are located in an upper horizontal plane, a pair of meter-out poppet valves and solenoid-actuated pilot valves are located in a lower horizontal plane, and a pair of a pilot valve associated with the meter-out poppet valve and a reducing valve associated with the meter-in poppet valve are located in a middle horizontal plane and are respectively disposed in opposed relationship to each other, and the load check valve is vertically located in parallel relationship with the meter-out poppet valve.

Abstract: A hydrostatic drive is provided having an adjustable pump connected with a pump servo positioned by a control pressure from a line connected between the consumer and an adjustable measuring restrictor which in turn is connected to a switching means which includes a plurality of hollow ended main spools in boreholes in a housing, and secondary spools in said hollow ends acting with radial passages in the main spool to form parallel connected restrictors.

Abstract: A hydraulic circuit breaker for use with a hydraulic device comprising a body having a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device and a return conduit for carrying hydraulic fluid away from the hydraulic device. A slide valve is mounted for movement in a first chamber of the body to define a supply orifice of variable area in the supply passage and a return orifice of variable area in the return passage. The slide valve is positioned in the body as a function of the pressure drop across at least one of the orifices. A pressure responsive member is mounted for movement in the body and moves in response to the pressure drop across the supply orifice reaching a predetermined value. A movable drive member extends into both of the chambers so that it can transmit at least some of the motion of the pressure responsive member to the slide valve to move the slide valve to close the supply and return orifices.

Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions and a variable displacement pump with loading sensing control for supplying fluid to said actuator. A pilot pressure operated meter-in valve is provided to which the fluid from the pump is supplied and pilot pressure is applied to the meter-in valve for controlling the direction and displacement of movement of the meter-in valve and the direction and velocity of the actuator. A pair of lines extends from the meter-in valve to the respective openings of the actuator and a pilot pressure operated meter-out valve is associated with each line of the actuator for controlling the flow out of the actuator when that line to the actuator does not have pressure from from the pump applied thereto.

Abstract: A load sensing circuit of a load responsive direction control valve including a device for sensing load pressure signals, identifying those load pressure signals as positive or negative and transmitting those identified positive or negative load pressure signals to the throttling compensator controls of the load responsive valve, while also transmitting the positive load pressure signal to the pump control. The identification and distribution of the load pressure signals to the controls of the load responsive circuit can take place with the direction control spool in its neutral position. Therefore such a load pressure sensing and transmitting circuit is capable of anticipating the command signal indicated control function.

Abstract: An arrangement for supplying pilot oil to a servo-valve arranged to activate a main valve of a hydraulic system. The hydraulic system also includes a hydraulic oil pump, a valve located between the pump and the main valve, a pressure reducing valve located between the pump and the servo-valve, and at least one auxiliary assembly is arranged to deliver an electric signal to electromagnetic means arranged to activate the servo-valve. In accordance with the invention, the valve located between the pump and the main valve is arranged to be substantially or fully closed when standing at a given, pre-determined pressure corresponding to the servo pressure required by the servo-valve in order to carry out its intended function, and is arranged to be open when the pressure slightly exceeds the aforementioned pre-determined pressure. An electromagnetically operable shunt valve is located between the pump and pressure reducing valve and, when open, to pass oil direct from the pump to a tank.

Abstract: A power steering system which includes an engine-driven pump, a fluid motor for supplementing manual steering torque, a fluid control valve for distributing fluid to the fluid motor, and a reaction device for applying hydraulic reaction or feeling to a steering wheel. A first flow control valve is utilized to deliver first fluid flow to a fluid control valve from the pump and to lead excess flow to a bypass passage. A second flow control valve is connected between the bypass passage and the reaction device to deliver second fluid flow to the reaction device and to lead excess flow to a reservoir. A magnetic pressure control valve is connected to the reaction device to control fluid pressure applied thereto in accordance with a predetermined vehicle operating condition, such as vehicle speed.

Abstract: An air pressure control system for use where a plurality of various sequential and repetitive air pressures are selectively required. A pilot air operated pressure regulator valve having a pilot air operator and a working air flow control valve are connected in series in a pressurized working air conduit between a source of pressurized air and an air cylinder. A pilot air pressure selector circuit means, for selectively and sequentially providing a plurality of pre-set pilot air pressures to the pilot air operator of the pilot air operated pressure regulator valve, includes a plurality of pressurized pilot air conduit means which are connected in parallel with each other, and with one end of each pressurized pilot air conduit means being operatively connected to the source of pressurized air and the other end thereof being operatively connected to the pilot air operator of the pilot air operated pressure regulator valve.

Abstract: An electrohydraulic servovalve which includes as an integral part thereof a monitor valve which senses the absence or lack of system pressure in the first or second stages of the valve and translates in the absence thereof to deactivate load control. The torque motor of the electrohydraulic servovalve is biased, electrically or magnetically, to provide a failure indication in the first stage of the valve in the absence of or excess of applied electrical signals to the torque motor.

Abstract: The valve disclosed herein functions, in one sense, as a flow matching device and, in another sense, as a reciprocative check valve. By employing the valve, a hydraulic system may be implemented in which filling and emptying of a variable volume load, such as a hydraulic piston may be accomplished through a single check valve structure at controlled flow rates.

Abstract: A valve device for controlling and monitoring an operating pressure in a hydraulically operated consumer arrangement, such as a tool chuck or head stock of a machine tool, includes a pressure reducing valve coupled to the consumer device and a servo valve connected to the pressure reducing valve for adjusting the operating pressure to a maximal allowable value. The servo valve is in turn connected to a flow monitoring device which upon reduction of operating pressure in the consumer device generates an electrical signal which is used for shutting off the consumer device.

Abstract: In a pneumatic nailer using compressed air for driving nails, a work chamber contains a drive piston and is in communication with a storage chamber for effecting the return of the drive piston after it has driven a nail. A valve unit controls the supply of additional compressed air into the storage chamber. A switching element is arranged to react when a predetermined compressed air pressure is exceeded for controlling the flow of compressed air through the valve unit to the storage chamber. The switching element can be a pressure limiting valve. The combination of the switching element and valve unit avoids unnecessary compressed air losses in the higher pressure operating ranges.

Abstract: A fluid driven pump comprising a pump housing defining a recess including therein a moveable wall which divides said recess into a variable volume driving chamber and a variable volume pumping chamber. The pump also includes a pressure inlet communicable with the driving chamber and adapted to communicate with a source of pressure which oscillates between an operating pressure and a pressure different from the operating pressure. The pressure inlet includes a one-way valve for permitting fluid under the operating pressure to communicate with the driving chamber to move the moveable wall in one direction when the driving chamber is in communication with the pressure inlet.

Abstract: The invention relates to a hydraulic control valve assembly for controlling a consumer unit such as a servomotor of a vehicle steering system. The valve assembly has a conventional port arrangement which includes two selectively pressurizeable and drainable motor ports connectable to a servomotor and supply and exhaust ports connectable respectively to a pump and a drain tank. A slide valve has a central wall section between two motor ports which completely block a central supply port when the slide valve is in a neutral position. Two metering control load sensing ports are on opposite sides of the supply port and when the slide valve is in a neutral position the load sensing ports are in throttling relation to the slide valve motor ports.

Abstract: A hydraulic directional valve for an open circuit and with outwardly adjustable flow regulating valve has a base housing which can be insignificantly changed for different switching of the flow regulating valve so that its adjusting device is always easily accessible, is provided with a bridge passage extending from its central circulating chamber and having two branches with enclosed a feed chamber and extend in auxiliary openings one of which receives a valve insert whereas the other receives a locking plug, and have a transverse opening which connects two constant flow chambers with one another and with an upstream opening of the feed passage from a first embodiment in which a blocking portion obtains the constant stream, and also have a throughgoing feed passage to form a second embodiment in which only one directional valve has the constant stream, and can be provided with different switching options of the flow regulating valve and conversion of the left and right arrangements so that the adjusting devi

Abstract: A pneumatic door control equipped with a door control valve for operating a door drive to an open or a closed position. The door control valve has an opening and a closing solenoid-operated pilot valve and an opening and closing spool valve, each operable to a passage or a vent position. A shuttle valve is part of the control valve and works in conjunction with an operator-controlled emergency valve to vent both spool valves simultaneously. A differential pressure switch is connected to the door drive to sense abnormal pressure expended in a door-opening or closing movement. Such an occurrence will output a signal to an electronic switching device which also monitors, via limit switches, whether a door is fully opened or fully closed. If excess pressure occurs during a door-closing movement, the switching device will trigger the control valve to reverse to the opening position.

Abstract: A hydraulic valve is provided which can be modified to provide priority compensation, parallel pressure compensation, inlet check functions and a float function by changing a flow through inlet valve portion in the inlet chamber of the valve.

Abstract: A hydraulic valve is provided which can be modified to provide priority compensation, parallel pressure compensation, inlet check functions and a float function by changing a flow through inlet valve portion in the inlet chamber of the valve.

Abstract: A valve combining in a single unit a multiplicity of functions including isolation, thermal and pressure relief, return check and bypass. The valve includes a pair of spool valves, one slidably positioned within the other, disposed with a bore in a housing and interconnected with system pressure and return and an appropriate control valve.

Abstract: A valve assembly (16) for use in a fluid system (10) includes a flow control valve (82) which controls fluid flow between a fluid inlet port (34) and a fluid supply passage (36) in response to the load requirements. A main control spool (96) is selectively movable between a neutral position and first and second actuated positions. A load sensing passage (78) communicates a load signal from an actuator (26) to the spring chamber (50) of the flow control valve (82). A drain passage (80) communicates the load sensing passage (78) with the reservoir (14) when the main control spool (96) is in the neutral position. A blocking mechanism (138) blocks the load sensing passage (78) when the main control spool (96) is in the neutral position and opens one of the inlet port (34) and the supply passage (36) to the spring chamber (50) so that the flow control spool (82) is held in an open position.

Abstract: A fail-safe actuator mechanism has an actuator housing encapsulated within a tank which stores a pressurized fluid media. Ports of the actuator housing are put into selective fluid communication with both the interior and exterior of the encapsulating tank by a valve at selective pressures.

Abstract: An electropneumatic door valve for use with pneumatic door operations as are used on mass transit vehicles. The single valve housing arrangement provides either a through passageway or a throttled passageway for pressurizing the opening or closing chamber of a pneumatic door drive unit. Provisions are also made to allow automatic reversal should the door become wedged, and to allow manual override should that operation be desired. Electrical pulses initiated by the vehicle operator trigger one of two solenoid valves which direct one of two operating pistons into a position to dictate which passageway will be established. Three vent passageways are provided to exhaust compressed air from any of the chambers which had been charged during a previous door operation.

Abstract: A direction flow control valve for control of positive and negative loads equipped with positive and negative load compensators, a single pilot valve stage responsive to positive and negative load pressure signals and control signal diverting valve operable to connect the pilot valve stage either to positive or negative load compensator in response to the type of load being controlled.

Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions and a variable displacement pump with loading sensing control for supplying fluid to said actuator. A pair of meter-in valves are provided to which the fluid from the pump is supplied and a pilot controller alternately supplies fluid at pilot pressure to a meter-in valve for controlling the displacement of movement of the meter-in valve and the direction and velocity of the actuator. Alternately pilot pressure from the pilot controller is applied simultaneously to both of the meter-in valves in conjunction with the venting of one of two load drop check valves to provide a regenerative mode.

Abstract: A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions, a pump for supplying fluid to said actuator, a pilot operated meter-in valve to which the fluid from the pump is supplied for controlling the direction of movement of the actuator, and pilot operated meter-out valves associated with each opening of the actuator for controlling the flow out of said actuator. The pressure of fluid being supplied to the actuator by the meter-in valve is sensed and caused to produce a force opposing the movement of the meter-out valve controlling flow from the actuator.

Abstract: A hydraulic system includes a pump, a reservoir, and an actuator system. A hydraulic circuit breaker is arranged to compare fluid flow to and from the actuator system and to shut off this flow in the event the flow to the actuator system is greater than the flow returning from the actuator system by more than a predetermined differential, thereby indicating a leakage condition. A hydraulic circuit breaker reset device is hydraulically connected to the actuator system and to the circuit breaker. When the circuit breaker is in a shut-off condition, the reset device continuously pressure tests the actuator system. If the pressure in the actuator system increases to indicate the absence of fluid leakage, the reset device responds to the pressure increase in the actuator system to provide a reset signal to the circuit breaker. After the circuit breaker is reset to its normal operating position, a timing piston returns the reset device to its normal operating condition.

Abstract: For supplying a compressible driving fluid, preferably air, under pressure from a source to a motor of the kind comprising a housing, in which a body is reciprocable between predetermined end positions while dividing the interior of the housing into two chambers alternatingly serving as fluid receiving chambers, a drive system composed of conventional valves and other circuit components is provided, which assures that the driving fluid is supplied to the pressure chamber at a reduced pressure during the finishing phase of each operating stroke of the motor. The source is presupposed to deliver the compressible fluid under a pressure substantially exceeding the fluid pressure required for driving the motor under its anticipated maximum load.

Abstract: In a pressure compensated flow control system a flow control valve has a valve element which is subjected to pulsating fluid pressure by which it is maintained in a state of dither about a mean position corresponding to the selected flow rate through the valve. The valve element is spring-biased towards a closed position and is displaced against the spring bias by an amount which is a function of the rate at which fluid is applied on one side of the valve element and the rate at which the fluid is bled away via an orifice.

Abstract: A 4-way, 3-position, on-off type electrohydraulic valve includes a pair of solenoid-operated inlet valves for controlling communication between a pump and a valve bore. A pair of adjustable check valves are positioned in opposite ends of the valve bore. A double-acting pilot return valve assembly is operably mounted in a central portion of the valve bore and is movable to engage and open one of the check valves to return fluid flow when pump pressure flows through the other check valve to a fluid motor.

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: An electro-hydraulic proportional actuator in which the actuator piston position is hydraulically controlled by fluid flow through solenoid valves operable by an electronic control system. An operator control provides an input voltage representing a desired piston position and a transducer generates a voltage representing the actual piston position. The difference between the input and output voltages generates a difference or error signal that is fed into a feedback system including a sample-and-hold circuit. A clock logic system is provided for transmitting the signal from the feedback system to the solenoid valves at predetermined intervals to activate either valve to move the actuator piston in either direction or to activate both valves to hold the piston at a desired position.

Abstract: A priority flow control system in which the priority feature is obtained by progressively lowering the pressure differential of nonpriority valves, once the maximum pump output is reached, so that all of the system valves always retain their compensated proportional flow feature.

Abstract: A dual input direction flow control valve responsive to a manual or an electrical control signal for control of positive and negative loads operated by a single pilot valve stage, which automatically maintains a relatively constant pressure differential across valve spool, while controlling positive and negative loads and which permits variation in the level of pressure differential in response to a pulse type control signal, while this pressure differential is maintained constant at each controlled level.

Abstract: A hydraulic valve mechanism has a housing with first and second bores, a control valve element in the first bore, a pressure compensation valve in the second bore, and a non-return valve cooperating with motor parts, wherein control edges for direction control are arranged on the control valve element only at one side of throttle means, the non-return valve is also arranged in the second bore of the housing, and the longitudinal valve element of the pressure compensation valve also forms a closing member of the non-return valve.

Abstract: A direction flow control valve for control of positive and negative loads operated by a single pilot valve stage, which automatically maintains a relatively constant pressure differential across valve spool, while controlling positive and negative loads and which permits variation in the level of pressure differential in response to an external control signal, while this pressure differential is maintained constant at each controlled level.

Abstract: A fully compensated direction flow control valve for control of positive and negative loads provided with a direction control and flow metering spool and a control which varies the level of the pressure differential controlled across the metering section of the spool in respect to the displacement of the spool from its neutral position.