Abstract: The present invention provides a hydraulic circuit for a crane wherein a switching valve is provided between a plurality of motor circuits connected in series within the same actuator group, and at the time of simultaneous operation of the motor circuits, the switching valve is switched from a first position to a second position whereby the series connection between the motor circuits is cut off, and they are driven by each of separate hydraulic sources, thereby enabling prevention of pressure interference at the time of simultaneous operation of the motor circuits within the same actuator group without increasing hydraulic sources.

Abstract: The system controls the position of a pneumatically operated valve using an electrical control signal from a controller. A pilot circuit of the system has multiple piezo valves that are subject to electrical signals from the controller to provide pneumatic output signals to a volume booster circuit of the system. Relatively small volume pneumatic pilot signals from the piezo valves are used to determine the opened or closed state of higher volume valve assemblies of the booster circuit which connect or disconnect the actuator of the valve to be operated with a source of pressurized gas. Both the piezo valves and the booster valve assemblies are subjected to gas at the same operating pressure, but the surface area of pistons in the booster valve assemblies exposed to the piezo valves is substantially larger than the surface area of the pistons exposed to operating pressure such that the pneumatic signals shift the pistons even when pressure is the same on both sides thereof.

Abstract: A line vent arrangement is provided to selectively vent pressurized fluid from an actuator in an electro-hydraulic system when an engine of a machine has been shut down. This is accomplished by providing a pressure storage arrangement in parallel with a source of pressurized pilot fluid and an electrically controlled valve that is movable to a position to connect the pressure storage arrangement to the electro-hydraulic directional control valve when the engine of the machine has been shut down.

Abstract: An actuation arrangement for displaced components on vehicles, particularly trunk lids, convertible tops, engine hoods or the like, includes at least one supply line for the pressurized medium and one essentially non-pressure connection line to a reservoir for the working medium or a pump arrangement being functionally of the same kind, at least one preferably hydraulic working cylinder, and at least one control valve controlling the supply of a working medium in at least one working chamber of the working cylinder.

Abstract: A hydraulic control circuit for a hydraulic actuator, including a high-low pilot valve having a sensing port for connection to a flow line. A single pressure line connects the high-low pilot to a hydraulic actuator. A second line connects the high-low pilot to a reservoir. A normally closed relief valve is connected to the single pressure line for relief of excessive pressure. A normally closed override valve is connected to the single pressure line for manual override of circuit controls. A pump is connected to the single pressure line for pressuring the single pressure line. The hydraulic control circuit has a normally open time out valve on the single pressure line, the time out valve being set to close a pre-set time interval after being manually activated, to isolate the high-low pilot, from the single pressure line to the hydraulic actuator, until the time out period has elapsed. The override valve is connected to the single pressure line between the time out valve and the hydraulic actuator.

Abstract: When a working implement comes close to a cab during operation, for efficiency, the operation should continue insofar as possible yet it is essential the working implement be prevented from striking the cab. To that end, a pilot pump oil line capable of supplying pilot pressurized oil to a solenoid proportional pressure reducing valve in a state where a control member is not manipulated, is provided in a stick contraction-side pilot oil line. When the working implement enters an interference prevention area, defined around the cab, the stick is automatically moved out so that the operation can continue yet the working element avoids the interference prevention area.

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

Abstract: The invention relates to a gear control system for a synchro-shuttle gear (1) or powershift gear (2) in particular in machines, comprising switching elements for a forward drive (SEV1, SEV2) or reverse drive (SER) and switching devices for actuating a shift valve (SV1) to select the direction of travel. A control valve (SV2) is provided between the switching elements for forward drive and reverse drive and the shift valve capable of being actuated by the switching devices to select the direction of travel, said control valve (SV2) can be actuated via a further switching device. The control valve can be used as a neutral-position or idling valve in a synchro-shuttle gear or as a reversing valve for the switching elements for forward drive in a powershift gear.

Abstract: The present invention relates to a backpressure control circuit for a hydraulic drive device, which reduces the loss in drive power and which can suppress cavitation. Thus, the backpressure control circuit for hydraulic drive devices is a hydraulic drive circuit: for supplying to a hydraulic motor pressurized oil discharged from a hydraulic pump through a direction changeover valve, which is switched upon receipt of a pilot pressure; and for permitting at the time of braking by the hydraulic motor, a throttle valve to throttle return oil from the hydraulic motor and oil discharged from the hydraulic pump to generate a backpressure to supply pressurized oil to the hydraulic motor via a check valve for prevention of cavitation.

Abstract: A hydraulic valve control system that includes a plurality of digitally actuated magnetically-latchable four-way valves that directly or indirectly control the position of a hydraulic actuator. The digitally actuated magnetically-latchable four-way valves are controlled by a controller that can control the valves in accordance with a servo routine. The servo routine may include the computation of a plurality of cost functions and the selection of an action that corresponds to the lowest cost.

Abstract: A hydraulic pressure-control valve for controlling a pressure to be supplied to a frictional engaging element such as a start clutch in an automatic vehicle transmission, including a first pressure-regulating valve connected to a hydraulic pressure source and connected to the frictional engaging element through a second passage, and a solenoid for displacing the first-pressure-regulating valve.

Abstract: The proposal is for a control for the scoop flap (1) of a construction machine, especially an excavator, with at least one distributing regulator (9) acting with at least one hydraulic cylinder (4) to which hydraulic control pressure can be applied via at least one electrically actuated valve of at least one control device. When an actuating component (17) is triggered, the control device acting electrically therewith, the valve (10, 11) and via it the distributing regulator (9) and the hydraulic cylinder (4) are actuated according to a predeterminably timed current ramp (22).

Abstract: A fail-safe closure system for one or a plurality of springless process valve actuators is disclosed. An accumulator is provided with an urging means, such as a spring for pressurizing fluid stored therein. A source of pressurized fluid is also provided. Supply pressurized fluid is applied to an opening chamber of one or a plurality of process valve actuators while a flow path is opened to a vent from the closing chamber of the one or more actuators. For closing the actuator or actuators, a flow path is established by which pressurized fluid from the accumulator is applied to the closing chamber of the actuator or actuators while the opening chamber is vented. Control valves are arranged so that if or when they fail, they fail in a position which allows the process valve actuators to close as described.

Abstract: A hydraulic control valve (10; 110) which acts as a hydraulic flow amplifier. An obturator (34; 134) is slidable towards and away from a valve seat (36; 136) to controllably vary throughflow from an inlet (S; P) to an outlet (T; S). The obturator (34; 134) is mounted on a piston (30; 130) which is slidable in dependence on the excess of the difference between inlet and outlet pressures over control pressure in a control chamber (42; 142). The control chamber (42; 142) is fed with hydraulic fluid bled from the source (S; P) via a controlled leak (48+50; 148+150) which is self-regulating in dependence on throughflow-controlling movement of the piston/obturator (34/30; 134/130) in a sense which provides negative feedback. The control chamber (42; 142) is drained through a fluid conduit (54; 154) incorporating an externally-controllable fluid flow restriction (56; 156) which serves as the control input to the control valve (10; 110).

Abstract: A governor for air compressors of vehicles, that serves to control additional devices, especially energy-saving devices. From an inlet connection supplied from the compressed air supply, a pilot valve designed as a round slide valve with a small cross section is controlled. The pilot valve monitors the supply of compressed air to a switching piston for a double valve with a large cross section. The double valve is supplied with compressed air from the inlet connection and causes an outlet connection connected with the additional device to be charged with air or cut off from the air. The switching piston is connected with a valve tube of the round slide valve in such fashion that this valve, during switching processes, is moved in a direction opposite to that of regulating piston of the pilot valve, so that a precise switching of the governor that reflects the pressure differential is achieved at the upper and lower pressure limits.

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

Abstract: Control apparatus is provided for pneumatically operating a sliding door on a marine vessel. A dual pneumatic system provides for a first pressure to operate the switching mechanisms of the control apparatus, while a second lower pressure provides for operation of a pneumatic cylinder to achieve door travel. Operation of the door may be controlled from either side of the door. Upon loss of pneumatic pressure, the control apparatus provides for relieving of the pressure to allow manual operation of the door. In a manual state of operating, flow controls are provided to regulate door travel in accordance with external force applied to the door. Controlled low pressure maintains the door in an open or a closed position.

Abstract: A fail-safe second stage valve for controlling actuator movement upon power loss in a multiplexed fluid power control system. The second stage valve is interposed between a corresponding actuator and a fluid multiplexer to operate generally as integrating or amplifying device which regulates flow to the actuator. The second stage valve is provided with a dampening mechanism in the form of a bleed port to reduce fluid flow to the actuator. The bleed port bleeds off accumulated fluid received by the second stage valve over a predetermined range of valve positions. This changes the position of the valve and thereby reduces flow rate to the actuator. The multiplexed fluid power control system using the fail-safe second stage valve controls the flow to the corresponding actuator upon electrical power loss. The actuator may be used to open and close variable stator vanes in an aircraft gas turbine engine.

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

Abstract: The present invention provides a servo-actuator capable of operating in both the Fail Safe and Fail Operate modes. In the Fail Safe mode, a pretensioned spring member moves a jet pipe in the servo-valve to cause said actuator rod to move in a first direction upon loss of electric power. A mechanical feedback means coupled to said spring member and said actuator rod opposes the force applied by the spring so that when a force equilibrium is reached the actuator rod will be at a predetermined position.

Abstract: An electrohydraulic displacement controlled valve module is disposed in a bore of a valve body for controlling fluid flow between first and second ports. A main valve element slideably disposed in the bore is biased to a closed position blocking communications between an annular groove of the valve element and the second port. An actuating chamber defined at one end of the valve element receives pressurized pilot fluid for urging the main valve element toward an open position communicating the first and second ports through the annular groove. A passage communicates the actuating chamber with a control chamber disposed at the other end of the valve element through an orifice. A poppet is disposed within the control chamber and is biased into sealing engagement with an annular valve seat of an outlet port by a feedback spring disposed between the valve element and the poppet.

Abstract: A fluid joining device for construction vehicles is disclosed. The device has a bypass line control valve which is mounted to a second center bypass line of the second pump. The bypass line control valve normally opens the second center bypass line but selectively closes the second center bypass line in response to a pilot pressure. A second pilot line control valve is mounted to a second pilot line and controls the second pilot line in response to an outside signal. The second pilot line extends from the first pilot line control valve and selectively drives the first pilot line control valve. The device selectively performs the fluid joining function in accordance with operational conditions of the actuators, thus smoothly operating the actuators and improving operational effect of the construction vehicle.

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

Abstract: A control device for a travelling system in construction vehicles is disclosed. The control device applies the pilot pressure of the pilot pump to the spool of the directional control valve separately from the travelling control pedal, thus automatically controlling operation of the directional control valve. However, the manual control mode performed by the travelling control pedals has priority over the automatic control mode. The control device has a proportional control valve, which applies the pilot pressure of the pilot pump to the spool in response to an input current signal. A pressure sensor checks the pilot pressures, which are generated by both the travelling control pedals and the proportional control valves and act on the spool. A controller receives a signal indicative of the pilot pressures checked by the pressure sensor and outputs the current signal to the proportional control valve.

Abstract: A control method and a device to control construction equipment attachments include during manual operation, the pilot pressure discharged from a pilot pump is fed from a manual operation valve through an electromagnetic change valve to a main control valve. During automatic operation, the pilot pressure from an automatic-mode selecting valve is fed through an electromagnetic proportional control valve as well as the electromagnetic change valve, all of which are controlled by a controller, to a main control valve. When the operation range is restrictively set during manual operation, the pilot pressure output from the manual operation valve is fed through the electromagnetic proportional control valve as well as the electromagnetic change valve to the main control valve. Both the main control valve and the electromagnetic proportional control valve are controlled by control signals from the controller.

Abstract: It is possible for the present invention to operate with the optimal control to prevent a ram from overshooting in a case that a load acting on the ram is decreasing rapidly, like a stamping machining process. Linking a hydraulic circuit which consists of a hydraulic pump 3 and a hydraulic cylinder 2 to make the ram 1 for the hydraulic press equipment move upward and downward and a full-bridge hydraulic circuit with four proportional sheet valves V1 through V4, the working timings of the proportional sheet valves V1 through V4 are controlled by a NC controller 9. In the normal operation, operating the proportional sheet valves V2 and V3 with the turn-on-off control system and with the meter out control system, oil pressure PU acting on the upper chamber 2U of the hydraulic cylinder 2, driving the ram 1 by the piston 10 moving downward, a work is stamped out. The NC controller 9 detects the running by inertia of the ram 1 in the instance of having stamped out a work in the stamping out machining process.

Abstract: A switching device controlling at least one hydraulically operating apparatus has two check valves working in opposition to one another in a feed conduit and a discharge conduit, respectively. The conduits are connected to the operating apparatus, as well as to a pilot valve. Two openable nonreturn valves are connected parallel to the two check valves. The control line of one openable nonreturn valve is connected to the blocking connection of the other openable nonreturn valve. The switching device is especially for controlling a hydraulic cylinder to provide a float setting at low cost, with reliable operation, and with few components.

Abstract: Apparatus and method for controlling equipment of driving a ram of a hydraulic press. Four proportional sheet valves PA, PB, TA and TB are connected with a hydraulic circuit, in which a hydraulic cylinder 2 for driving a ram 1, a hydraulic pump 3 and so on are set up, a so as to form a full-bridge hydraulic circuit. A compression proportional sheet valve PAp and a hydraulic pump 40 are connected as a hydraulic power source with high pressure and small flow rate parallel with the sheet valve PA being in the oil supply position side in the hydraulic circuit. An NC controller controls timing of turn-on of the proportional sheet valves PA, PB, TA and TB as well as change of the valves PA and Pap by PWM signal to pilot valves of the sheet valves PA, PB, TA and TB. The valves PA and TB are turned on in the down stroke of the ram 1, the valves PB and TA are turned on in the up stroke of the ram 1, and the valve Pap is turned on in the compression stroke.

Abstract: A control system is provided for use in a hydraulic system to provide a simple arrangement with a limited number of elements that bypasses the system flow in the event of an electrical malfunction in the system and further allows other hydraulic circuits to operate even if one or more of the hydraulic circuits have experienced an electrical malfunction. The subject arrangement uses an electro-hydraulic fluid flow control valve mechanism in conjunction with directional valve mechanisms that have at least three functional positions and are controlled by associated electrically controlled displacement control mechanisms in response to receipt of electrical signals from an electrical controller.

Abstract: A hydraulic control device having a directional valve by means of which the direction of movement and the speed of a hydraulic consumer, especially a mobile working device can be modified. The hydraulic control device has a hydraulic pre-control device by which a control pressure can be applied, via a first control line, to a first control chamber and, via a second control line, to a second control chamber of the directional valve, and having valve arrangement in a first control line by which a largely free flow of control oil is admitted to a first control chamber and by which, by a throttling of the discharge of control oil, the movement of a control slide of the directional valve can be damped.

Abstract: To provide a burglarproof device for a hydraulic machine which has a high degree of security against burglary, ensures high safety, and can be simply installed in a location where the device is hard to find for burglars, a solenoid valve 23 of a burglarproof device 20 is installed in a pilot primary pressure line 3 between a pilot hydraulic pump 1 and a pilot valve device 4. Unless ten numeral keys 21a of a key input device 21 are depressed in the order of the password, an unlocking electronic circuit 22K does not generate an unlock signal and the solenoid valve 23 keeps the pilot primary pressure line 3 cut off. Therefore, a pilot primary pressure from the pilot hydraulic pump 1 is shut off and, even with a manual lever 4c of the pilot valve device 4 operated, no pilot secondary pressure is produced and a main control valve 6 is kept standstill. As a result, a hydraulic cylinder 8 is not operated and the hydraulic machine is unable to move.

Abstract: A control logic for a multiple use hydraulic system includes a selector switch having a first position connecting a battery to a treadle switch operable to energize a solenoid pilot valve for communicating pilot fluid to an end of a first directional control valve. The selector switch has another position connecting the battery to a bi-directional push button switch operable to selectively energize a pair of solenoids of a second pilot valve. Energizing one of the solenoids moves the second pilot valve in one direction to communicate pilot fluid to an end of the first and a second control valve. Energizing the other solenoid moves the second pilot valve in the opposite direction to communicate pilot fluid to the other end of the control valves. The selector switch has a third position connecting the battery to a pair of pressure switches connected to a pair of lines connecting a manually actuated pilot valve to a pair of solenoid blocker valves.

Abstract: A switching valve has a control rod with a pilot chamber at each of its ends. For each pilot chamber, there is a first passageway connected to a pressure line and communicating with the pilot chamber. A second passageway is connectable to return. A relief valve has a valve member biased to close an orifice to close communication between the pilot chamber and the second passageway. The valve member has an open position in which the pilot chamber is connected to return via the second passageway to allow shifting of the control rod. In a first embodiment, the pilot chamber is continuously in communication with pressure via the first passageway, and the valve member is opened by this pressure in response to connection of the second passageway to return. In another embodiment, the second passageway is continuously in communication with return, and the valve member is mechanically moved into its open position by an operator in response to pressure acting on the operator.

Abstract: An operating valve assembly with a pressure compensation valve, comprises a spool for selectively establishing and blocking communication between a pump port, an output port and a main tank port, being disposed within a spool bore of a valve body, and a pressure compensation valve being provided between the output port and the actuator port. The pressure compensation valve has a piston pressed in the closing side by a load pressure acting on a compensation pressure acting portion, and a valve provided integrally with the piston for selectively establishing and blocking communication between the output port and the actuator port, and actuated for opening by the output port pressure acting on a portion to be compensated, the compensation acting area being equal to the area to be compensated.

Abstract: A turning-purpose hydraulic circuit characterized in that a discharge passage (20a) of a hydraulic pump (20) is connected to a variable relief valve (21) and a pump port of a directional switching valve (22); a first actuator port and a second actuator port (25, 26) of the said directional switching valve are connected to a turning-purpose hydraulic motor (27); the pilot pressure of a pilot valve (33) is introduced into pressure chambers (31, 32) for controlling a spool in the said directional switching valve and is also introduced into a pressure chamber (40) for controlling a set pressure in the said variable relief valve; a metering-in side portion (42) along which a pressurized oil flows from the said pump port of the said spool to the first or second actuator port is formed with a portion having a configuration such that a flow force may not be produced thereat; and a metering-out side portion (45) along which the pressurized oil flows from the first or second actuator port of the said spool to a tank po

Abstract: A three position four way directional control valve having a single spool is typically used for controlling fluid flow from a pump to a cylinder and from the motor to a tank. The present invention includes a pair of electrohydraulic control valves with one of the control valves controlling pump-to-cylinder communication between a pump and the rod end and head end chambers of a hydraulic cylinder while the other control valve controls cylinder-to-tank communication between the rod end and head end chambers and the tank. Each of the control valves includes a displacement controlled proportional valve for controlling the position of a pilot operated valve member. Actuation of the hydraulic cylinder requires moving the valve member of one control valve to control pump-to-cylinder communication to one of the chambers while simultaneously moving the valve member of the other control valve for establishing cylinder-to-tank communication between the other chamber and the tank.

Abstract: A method for controllably moving an implement is provided. The implement is connected to a work machine and is movable between first and second implement positions in response to operation of a hydraulic actuator. The method includes a joystick with first and second positions and a neutral position. The joystick is normally biased in a neutral position and is movable between the first and second positions. The method senses the position of the joystick and responsively generates a joystick position signals The joystick maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick is released from the detent position in response to receiving a release detent signal. The method senses the position of the work implement with respect to the work machine. The method provides hydraulic fluid flow to the hydraulic actuator in response to a magnitude of an electrical valve signal.

Abstract: A two stage valve assembly responsive to signals from a control system for supplying pressurized fluid to two load lines. The first stage includes a motor that directs pressurized fluid from a jet pipe toward a receiver assembly having two receiver ports and a bleedoff area disposed between and separating the receiver ports. The second stage assembly includes two spool/sleeve assemblies that control the flow of pressurized fluid to and from the two load lines. A drain line from the receiver assembly includes a pressure relief valve, which insures that both spool/sleeve assemblies will be servo-controlled at all times. Cartridges may be inserted in the spool/sleeve assemblies to linearize the relationship between input current from the control system and the output force of an unequal area actuator connected to the load lines.

Abstract: An electrohydraulic steering system has a pair of proportional valves for controlling displacement of a steering valve for normal steering functions. The proportional valves are selectively energized by a position sensor in response to rotation of a steering wheel. However, should an electrical malfunction occur, rotation of the steering wheel beyond the normal operating range causes a steering control member to mechanically move an armature of the proportional valves through a spring to provide mechanical/hydraulic steering. Making the armatures of the proportional valves responsive to a mechanical input through the springs provides a simple, cost effective mechanical/hydraulic backup for the primary electrohydraulic steering control.

Abstract: When an operator makes the reversing-lever operation by operating a control lever 4A in a direction x.sub.2 in the event a solenoid proportional valve 91A of a directional control valve 8A is failed to be left open, an operation position sensor 30A.sub.2 outputs a low-level signal and operation position sensors 30A.sub.1, 30B.sub.1, 30B.sub.2 output high-level signals. Therefore, an AND circuit 6b.sub.2 outputs a low-level signal and an AND circuit 6b.sub.1 outputs a high-level signal, whereupon a switch signal is output from an amplifier 6h to a solenoid switching valve 121 for shifting it to a right-hand position shown in FIG. 1 so that a pilot line 51 is kept communicated with a reservoir 97. No switch signal is output from the amplifier 6h to a solenoid switching valve 122 for holding it in a left-hand position shown in FIG. 1 so that the pilot line 52 is kept communicated with a pilot pump 96.

Abstract: A variable priority device for a swing motor in heavy construction equipment including a variable orifice device installed in an arm cylinder-side parallel oil passage of an parallel oil passage for supplying oil pumped by a single pump to a swing motor and an arm cylinder, the variable orifice device serving to perform a switching operation between an orifice state and an orifice release state in response to a pilot pressure for moving the spool of a swing motor control switching valve.

Abstract: A hydraulic system for a construction machine includes a pump for delivering fluid under pressure from a fluid reservoir to at least first and second main valves. First and second input devices are included for producing first and second control signals that are indicative of a desired operation of the hydraulic system. A controller responsive to at least the first and second control signals is provided and produces a compensating signal in response to the first and second control signals. The second main valve is operated in response to both the second control signal and the compensating signal.

Abstract: A valve control unit includes a main hydraulic oil circuit and a pilot oil circuit. The main circuit includes a main pump, a main valve downstream from the main pump, and a hydraulic actuator downstream from the main valve. The pilot oil circuit circulates pressurized pilot oil to control the main valve and includes a pilot oil pump, an automatic control switching valve downstream from the pilot oil pump, a manual limit switching valve downstream from the pilot oil pump, a manual control switching valve downstream from the manual limit switching valve, and a pilot oil chamber downstream from the manual control switching valve. The pilot oil chamber is located near the main valve such that the flow of pressurized pilot oil moves the main valve.

Abstract: A pneumatically operated fastener driving device is provided including an inlet head valve structure mounted within a housing for movement between (1) a closed position sealing a piston chamber from communication with a main air pressure reservoir and (2) an open position enabling the main air pressure reservoir to communicate with the piston chamber, and an outlet head valve structure mounted within the housing for movement separate from the inlet head valve structure between (1) a closed position sealing the piston chamber from communication with an exhaust opening and (2) an open position enabling the piston chamber to communicate with the exhaust opening. The inlet and outlet head valve structures include first and second reservoir pressure responsive surfaces respectively.

Abstract: A controller for a hydraulic motor (11) comprises a directional valve (12) for communicating hydraulic pressure fluid from a pressure source (10) to the motor (11), a pilot pressure operated activating device (13, 14), pilot valves (17, 18) connected to the activating device (13, 14) and to the pressure source (10), and a manually operable activating lever (15) mechanically connected to the directional valve (12) via a coupling (24, 55, 56). A pressure fluid operated actuator (25, 47, 48) is associated with the coupling (24, 55, 56) to shift the coupling when pressurized from an engaged condition and a disengaged condition, and a mode shifting valve (19) is connected both to the actuator (25, 47, 48) and to the pilot valves (17, 18) and is arranged to pressurize simultaneously the pilot valves (17, 18) and the actuator (25, 47, 48) of the coupling (24, 55, 56) to avoid double activation of the directional valve (12).

Abstract: Material such as trash or refuse is packed in a container by opposed hydraulic packing and ejecting cylinders. Each cylinder is controlled by a hydraulic control valve with the control valve controlling the ejecting cylinder being, in effect, operated by the control valve for the packing cylinder. This is accomplished by sensing the pressure applied to the packing cylinder and when the pressure reaches a predetermined level, a pilot dump valve, in the ejecting cylinder is opened to allow the piston in the ejecting cylinder to retreat. When the pilot pressure drops below the predetermined level, the pilot dump valve closes, allowing the packing cylinder to exert additional packing force. In this way the piston in the ejecting cylinder inches back and the material is intermittently packed. An anti-cavitation check is provided so as to fill the chamber of the ejecting cylinder as the piston retracts.

Abstract: A hydraulic recovery device in a hydraulic system having a pump (1) driving a plurality of actuators through a plurality of control valves (2, 3), the hydraulic recovery device comprising a variable resistance valve (6, 60) in a first line being controlled by a control signal (Px), a third line, a check valve (7) disposed in the third line for allowing the hydraulic fluid to flow only in a direction from the first line toward the second line.

Abstract: A hydraulic control valve apparatus including a flow control valve having a pair of variable throttles, a feeder passage, a pair of load passages, directional control valve devices comprise a seat valve having a seat valve body movably disposed in a housing to form an auxiliary variable throttle in the feeder passage, and a control variable throttle (33) formed in the seat valve body for changing an opening area in accordance with an amount of movement of the seat valve body; (b) a pilot line (24, 29-31, 35-37) for communicating a portion (7C) of the feeder passage upstream of the auxiliary variable throttle with a downstream portion (7A, 7B) of the feeder passage through the control variable throttle to determine the amount of movement of the seat valve body in accordance with a flow rate of the hydraulic fluid passing through the pilot line; and (c) pilot flow control (400; 401; 403; 405; 406; 407; 408) having a pilot variable throttle (45) disposed in the pilot line and input (800; 52-59; 159, 54-59; 231A,

Abstract: In a pneumatic control circuit, five three-port, two-position, directional control valves, three of which have manual controls, and two shuttle valves are arranged for controlling a first pneumatic device and a second pneumatic device in an operating mode wherein the second pneumatic device cannot be readily enabled before the first pneumatic device is enabled. A first control valve having a manual control is arranged to control the first pneumatic device. A second control valve having a pilot valve is arranged to control the second pneumatic device. A pilot control valve having a manual control is arranged to connect the first control valve to the pilot valve of the second control valve via a shuttle valve. A holding control valve has a cam control, which is operated by the second pneumatic device, and has an outlet connected to the pilot valve of the second control valve.

Abstract: The present invention relates to a hydraulic circuit and to an apparatus for generating pressure which use a positive-displacement pump provided with a flywheel, one-way valve for discharging the delivery of the pump into a tank, a pilot line for a first valve, delay valve for delaying the opening of the first valve, and second valve for actuating the opening of the first valve by closing the pilot line and connecting the delay valve to the tank and for actuating the closure of the first valve, connecting the pilot line to the delay valve.