Abstract: A method of assembling an air pump in a tire is provided including: opening an axial air passageway of an elongate flexible air tube at one end; inserting one by one a plurality of one-way check valves into the air passageway from the one end to form an axial array of spaced apart check valves along the air passageway, each check valve having an external nominal width greater than a nominal width of the air tube passageway; establishing a press fit engagement between each check valve and air tube internal sidewalls defining the air passageway to place each check valve at a respective preferred position within the air passageway; retaining the check valves in the respective preferred positions within the air passageway by radial pressure from the air tube internal sidewalls and closing the one end of the flexible air tube.

Abstract: A vented pressurized gas-powered actuator includes a housing having a central longitudinal axis and an inner surface. At least one vent groove extends from the inner surface in a direction away from the axis. The at least one groove has a first end spaced apart from a first plane extending perpendicular to the axis, and a second end spaced apart from a second plane extending perpendicular to the axis. The groove second end is closer to the second plane than to the first plane.

Abstract: A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.

Abstract: Provided is an electro-hydraulic control system (10) for controlling the movement of a third structure (18) of an engine using a power actuator (26) mountable to the third structure (18), a telescoping fluid porting tube (24) for porting a fluid to the power actuator (26) and a control valve (22) for controlling the flow of movement to effect the movement of the third structure (18). In this way, the third structure (18), such as a nozzle slat of an engine, may be moved via a compact and lightweight electro-hydraulic system.

Abstract: A vacuum lock having a main body portion, a cylinder and a piston is described. The cylinder is disposed within the main body portion and has an opening. The cylinder has one or more sealing rings disposed on an inside surface and an air vent opposite the opening. The vacuum lock can further include a piston adapted to fit in the cylinder and guides. The vacuum lock can also include a valve coupled to the air vent.

Abstract: An object of the present invention is to provide a hydraulic cylinder enabling a reduction in a stress generated by the pressure of hydraulic fluid at a welded portion of a case containing a damping valve. A piston (5) coupled with a piston rod (6) is slidably inserted in a cylinder (2, 3) sealingly containing hydraulic fluid. A joint (17) is attached to the side wall of an outer cylinder (3) of the cylinder. A damping force is generated by controlling a flow of the hydraulic fluid caused by a sliding movement of the piston in the cylinder by a damping force generating mechanism (19) contained in the joint (17). A valve case (18) of the joint (17) has a reduced diameter at a connection portion (23) welded to the outer cylinder (3). The reduced diameter is smaller than the diameter of the damping force generating mechanism (19) contained in the valve case (18).

Abstract: A cylinder head for a compressor includes a closure device that can be adjusted between an unactuated position (off-load) in which the compressor delivers air and an actuated position (off-load) in which the compressor is running in an idle mode, a pneumatic control device having a control cylinder and a control piston that can be moved in the control cylinder, a spring device that prestresses the closure device into the unactuated position (on-load), and a driver configured to couple the control piston to the closure device. The closure device closes a compressed air passage in the unactuated position (on-load) and clears the compressed air passage in the actuated position (off-load), and the driver is permanently connected to the closure device and can be driven by the control piston.

Abstract: A multiple valve compressor head having a casing defining an intake chamber in selective communication with a cavity through a plurality of one-way intake valves and an exhaust chamber in selective communication with the cavity through a plurality of one-way exhaust valves is disclosed. The casing further defines an inlet port for the entry of gas into the intake chamber and an outlet port for forcing out compressed gas from the exhaust chamber. In operation, the multiple valve compressor head is in operative engagement with a reciprocating diaphragm that draws the gas into the intake chamber and then the cavity during the intake stroke of the diaphragm, while expelling compressed gas from the cavity and through the outlet port during the exhaust stroke of the diaphragm.

Abstract: A hydraulic circuit capable of both a regeneration mode of operation and a full force mode of operation includes a poppet valve controlled by a control valve operating in conjunction with a shuttle valve. The opening of the poppet valve enables the regeneration mode of operation, and the closing of the poppet valve enables the full force mode of operation.

Abstract: A hydraulic fluid supply system includes an active pressure regulator or feed limit valve with a flow cut-off which may be used with dual clutch transmission hydraulic control systems. The supply system includes a pump, a filter, pressure relief and filter bypass valves, an accumulator, a system pressure sensor and the active feed limit valve. The active feed limit and flow cut-off valve includes an on-off solenoid valve and a spool or logic valve having an inlet port, an outlet port, a control port, a feedback port and an exhaust port. The inlet port is supplied with pressurized hydraulic fluid and the control port is supplied with hydraulic fluid from the solenoid control valve when it is energized. A valve spool having a pair of spaced-apart lands is biased toward the control port. One side of a check valve is in fluid communication with the feedback port.

Abstract: A hydraulic tensioning system (1) for a belt drive, including a cylinder (4) that is designed to receive a linearly displaceable piston (6), these elements together forming a piston-cylinder unit (3) and delimiting a pressure chamber (10) that is filled with hydraulic fluid. A relative movement between the piston (6) and the cylinder (4) causes the hydraulic fluid to be exchanged between the pressure chamber (10) and a storage chamber (12) or vice versa. At least one annular spring valve (14), which opens depending on the pressure, is positioned in an outflow section (17) for the hydraulic fluid between the pressure chamber (10) and the storage chamber (12) as a one-way valve.

Abstract: A vacuum pump for supplying a machine assembly with a negative pressure includes a housing and a housing cover surrounding a delivery chamber. The delivery chamber includes a low-pressure region having a working inlet connected to the assembly, and a high-pressure region having a working outlet. A delivery member moveable within the delivery chamber, which, when moved, suctions air into the delivery chamber through the working inlet and expel it at an increased pressure through the working outlet. An outlet valve is arranged at or downstream or the working outlet and at least makes it difficult for air to flow back into the delivery chamber. The delivery chamber is connected to the external environment of the vacuum pump via a ventilating connection in order to establish at least partial pressure equalization with the external environment when the delivery member is stopped and a negative pressure prevails in the delivery chamber.

Abstract: A pump piston device is for reciprocating movement in a pump cylinder. Between the pump piston and the pump cylinder, an annular space is formed which is defined by a first seal and a second seal, the annular space being pressurized, and the first seal and the second seal being in a common piece of material which constitutes the pump piston.

Abstract: An arrangement for a compressor (20) having a suction valve (36) and discharge valve (56) is provided. The compressor (20) includes a cylinder (24) having a diametral axis (33). A valve plate (28) is positioned to cover the cylinder (24). The valve plate (28) includes a suction port (32) positioned on the diametral axis (33) and a discharge port (34). A suction valve (36) having a first end (44) is coupled to the valve plate (28) and a second end (46) is movable between a first position, in contact with suction port (32), and a second position. The suction valve (36) is arranged such that it is on an angle relative to the diametral axis (33).

Abstract: A motor capacity change-over actuator 10 varies a capacity of a hydraulic motor 1 in accordance with the inflow/outflow of a working fluid into/out of a drive pressure chamber 72. A motor capacity change-over valve 20 supplies the working fluid to the drive pressure chamber 72 in a supply position H and discharges the working fluid from the drive pressure chamber 72 in a discharge position L. A flow control valve 15 is interposed between the drive pressure chamber 72 and the motor capacity change-over valve 20, and therefore a shock generated upon deceleration of the hydraulic motor 1 can be alleviated without being affected by leakage of the working fluid in the motor capacity change-over valve 20.

Abstract: An apparatus includes a first plurality of cylinders, each coupled to a shared first port by a separate first valve and to a shared second port by a separate second valve. Each first and second valve has a chamber to which pressure from either the associated cylinder or the respective port is dynamically applied to select different operating modes. Each one of a second plurality of cylinders is coupled to the first port by a separate third valve and to a shared third port by a separate fourth valve. Each third and fourth valve has a chamber to which pressure from either the associated cylinder or the respective port is dynamically applied to select different operating modes. Selecting an operating mode enables the apparatus to act as a bidirectional pump or a hydraulic motor. Selectively controller the valves can deactivate an individual cylinder, while other cylinders remain active.

Abstract: The invention relates to a double-acting pump system for use in moving a fluid. The pump system includes a means for inputting power at a location remote from the double-acting pump. The system allows for manual power input, such as through a local pumping unit. The double-acting pump may define an interior volume and include a first end chamber in fluid communication with the local pumping unit, a second end chamber in fluid communication with the local pumping unit, a central chamber having a separating section, and a driving element (e.g., a double-ended piston) slidably located within the interior volume of the double-acting pump. The separating section may include an inlet valve section (e.g., two inlet valves) and an outlet valve section (e.g., two outlet valves).

Abstract: A lockable lift assist assembly includes a piston assembly moveable between an extended position and a retracted position. A valve assembly is coupled in movement together with the piston assembly. The valve assembly is configured to selectively alter a flow of a hydraulic fluid through a fluid communication path established within the valve assembly to control movement of the piston assembly.

Abstract: A tool coupler assembly for a machine is disclosed. The tool coupler assembly may have a coupler frame, a first latch, a second latch, and a hydraulic actuator connected to move the second latch relative to the first latch and the coupler frame. The hydraulic actuator may have a first chamber, a second chamber, and a pressure valve with a check element movable to allow a flow of fluid into the first chamber based on a pressure of fluid in the first chamber, and a pressure regulating element movable to allow a flow of fluid out of the first chamber based on a pressure of fluid in the second chamber. The tool coupler assembly may additionally have a first pilot passage configured to communicate fluid from the second chamber with the pressure-regulating element, and a second pilot passage configured to communicate fluid from the first chamber with the pressure-regulating element.

Abstract: A reciprocating piston machine is proposed, in particular, for motor vehicles, comprising at least one piston movably supported within a cylinder bore, and comprising a valve device (1) interacting with the at least one piston, the device having a valve carrier (3) and an intake valve (5) provided with a number of valve fingers (7).

Abstract: A hydraulic circuit includes a control valve connected to a pump, a hydraulic reservoir, hydraulic work connections and a cylinder. A controllable check valve is connected between the work connections and the control valve. An overpressure safety device is connected between each work connection the corresponding check valve. In order to prevent sagging of a load on the cylinder, the overpressure safety device discharges hydraulic fluid between the check valve and the work connection to reduce an overpressure. The overpressure safety device includes an overpressure valve and a throttle connected downstream of this valve to throttle the flow of hydraulic fluid discharged through the overpressure safety device.

Abstract: An object of the present invention is to provide a hydraulic cylinder enabling a reduction in a stress generated by the pressure of hydraulic fluid at a welded portion of a case containing a damping valve. A piston (5) coupled with a piston rod (6) is slidably inserted in a cylinder (2, 3) sealingly containing hydraulic fluid. A joint (17) is attached to the side wall of an outer cylinder (3) of the cylinder. A damping force is generated by controlling a flow of the hydraulic fluid caused by a sliding movement of the piston in the cylinder by a damping force generating mechanism (19) contained in the joint (17). A valve case (18) of the joint (17) has a reduced diameter at a connection portion (23) welded to the outer cylinder (3). The reduced diameter is smaller than the diameter of the damping force generating mechanism (19) contained in the valve case (18).

Abstract: The invention discloses a valve arrangement for supplying pressure medium to a hydraulic load (2) having a directional valve (8), which has an inflow measuring diaphragm (10, 12) and a directional part (14, 16) flowing in the flow direction. The directional valve is associated with an individual pressure scale (18). In a return from the load, a load-lowering valve (44, 46) is provided, to which a pilot pressure is applied in the opening direction. According to the invention, said pilot pressure is tapped in channel between the pressure scale and the directional part.

Abstract: A variable rate suspension system for a boom sprayer including a lift assembly and chassis. The suspension system includes a needle valve fluidly connected to a hydraulic accumulator and a first and second lift arm cylinder. A control block provides hydraulic fluid to the system and lift arm cylinders. Dampening of vertical accelerations encountered by the chassis and transmitted to the boom sprayer through the lift assembly is controlled by adjusting the rate hydraulic fluid flows from the cylinders into the accumulator using the needle valve.

Abstract: A hydraulic system for controlling a belt-driven conical-pulley transmission. A pump draws a working medium from a working medium tank or through a cooler return valve from a cooler return line. The cooler return valve is a minimum pressure valve that holds closed a connection between the cooler return line and a pump inlet line through the cooler return valve, as long as the pressure in the cooler return line remains below a specified minimum pressure. The cooler return valve also opens the connection between the cooler return line and the pump inlet line through the cooler return valve as soon as the specified minimum pressure in the cooler return line is exceeded.

Abstract: An actuator using a fluid cylinder in which rigidity may be attained with a simple configuration, includes a fluid cylinder, a first choke valve device, and a second choke valve device. The first choke valve device is disposed between a fluid pressure source and a first chamber, and the second choke valve device is disposed between the fluid pressure source and a second chamber. An opening of a valve of a discharge valve mechanism included in each of the choke valve devices is set so as to be in inverse proportion to a target pressure in the chamber in which the fluid pressure is adjusted by the choke valve device.

Abstract: A hydraulic arrangement is provided for a tool locking device of a loader. The hydraulic arrangement comprises a hydraulic cylinder with first and second chambers, which cylinder has a first position for unlocking and a second position for locking, a first supply line hydraulically connected to the first chamber, a second supply line hydraulically connected to the second chamber and a control valve hydraulically connected to the first chamber. So as to prevent the faulty actuation of the hydraulic cylinder, it is proposed that the control valve has a first position and a second position, the control valve in the first position allowing hydraulic fluid to flow only in the direction of the first chamber and in the second position allowing hydraulic fluid to flow both to the first chamber and out of the first chamber and the control valve being controlled such that it assumes the first position when the hydraulic cylinder assumes its first position.

Abstract: The present application relates to a hydraulic system having a hydraulic supply, a consumer and having a control valve, which is in communication with the consumer by means of a first line and a second line, it being possible for the control valve to be switched into different positions, and the control valve connecting the hydraulic supply to the first line in at least one position. Furthermore, a first valve, which is in communication with the first line and the second line, is provided. Moreover, a third line, serving as a further return, which is in communication with the first valve and does not lead to or open out in the control valve, is also provided, the first valve being connected in such a manner that when pressure is applied to the first line it opens up a connection between the second and third lines.

Abstract: A progressive-starting unit for pneumatic circuits comprises a line inlet and a line outlet interconnected with each other by a regulating valve that is piloted by a pneumatic piloting inlet. The piloting inlet is controlled by the outlet of a progressive-starting device having an inlet connected upstream of said regulating valve. In this manner a progressive-starting unit is obtained which is insensitive to the conditions downstream of its line outlet.

Abstract: The invention relates to a device for adjusting the pressure in the chambers of a hydraulic jack comprising a hollow valve seat extending substantially longitudinally between two end sections, the body of the valve seat being connected to a source of pressurised fluid, each of the end sections of the valve seat being linked to a chamber of the hydraulic jack and adapted to receive a valve allowing to control the refilling with hydraulic fluid of said chamber of the jack, characterised in that a valve return spring is placed inside said valve seat and in that each of the ends of said valve return spring is attached to one of said valves.

Abstract: A piston is axially and reciprocatably accommodated in a cylinder, and a piston rod, fixed to the piston, penetrates a rod cover to protrude to the outside. Negative pressure supply paths, connected between expansion-contraction chambers and operation ports, are provided with negative pressure check valves allowing flow of air toward the expansion-contraction chambers and blocking reverse flow thereto. Exhaust channels, communicating with the expansion-contraction chambers and the outside, are provided with exhaust check valves allowing flow from the expansion-contraction chambers to the outside and blocking reverse flow thereto. The respective negative pressure supply paths come to a vacuum state due to the reciprocating of the piston.

Abstract: A shut-off valve apparatus has a valve body and a valve member coupled to the valve body. The valve member is movable between a first position blocking material flow through the valve body and a second position permitting material flow through the valve body. A pneumatic actuator receives pressurized air to move the valve member from the first position to the second position. A pneumatic exhaust controller controls the flow of pressurized air into and out of the pneumatic actuator.

Abstract: The safety valve comprises a body and an obturator movable in the body between a closed position (FIG. 2) and an open position (FIG. 3).

Abstract: A swing cylinder oscillation control circuit and valve for oscillating booms connects two hydraulic cylinders with a shuttle valve and two check valves to provide the higher cylinder pressure to a fluid inlet and a lower cylinder pressure to a fluid outlet of a fast-opening and a slow-closing check valve. The fast-opening and slow-closing check valve uses a poppet and spring to set a valve opening pressure and uses internal flow connections to a large diameter piston that works with mechanically adjustable piston and poppet strokes to control the time for valve closing.

Abstract: A piston position drift control for a free-piston device. The control includes a passage connecting internal volumes of the device, the passage being substantially shorter than an acoustic wavelength of the device; and a check valve in the passage for controlling fluid communication between the internal volumes, the check valve having an opening pressure not less than approximately 20% of a maximum pressure differential of the device at a maximum stroke. The control is passive, requires no active control once in service, provides low susceptibility to damage or fouling, and is amenable to adjustment or repair if needed. In addition, the control is small and inexpensive, and functions across the entire operational range of a free-piston device it supports. A related free-piston device including the piston position drift control is also provided.

Abstract: The present invention refers to a compressor head according to German Patent 199 27 458.4, wherein the valve elements are multiple-beak valves, the slot-shaped valve openings of which are arranged at right angles to each other.

Abstract: An arrangement for hydraulic actuation of a movable component on vehicles, particularly a vehicle top, trunk lid, a cover or the like, includes at least one double-action working cylinder (1) whose working chambers are connected to a pressure source (5) via a pressure line (4) or whose working chambers are at least temporarily connectable thereto through a switching valve (11).

Abstract: A hydraulic elevator system of an inverter control method directly controlling a flow amount of a pressed oil discharged from a hydraulic pump by a speed control of a motor driving the hydraulic pump, which can improve energy efficiency and stability. The hydraulic elevator system includes a reverse check valve connected between a hydraulic cylinder operated by the pressed oil to lift/lower an elevator car and a hydraulic pump driven to discharge the pressed oil, opened to pass the pressed oil by the pressure of the discharged pressed oil in a driving of the hydraulic pump, and closed to prevent the pressed oil from being reversed by using a pilot pressed oil of the hydraulic cylinder as a power source in a stopping of the hydraulic pump; and a pilot hydraulic cylinder operated by the pilot pressed oil from the hydraulic cylinder in order to apply an additional close force to the reverse check valve in the lifting/lowering or emergency stopping of the elevator car.

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

Abstract: Main piston servo-actuation system, with hydromechanic self-contained failure detection device, working with hydraulic fluid supplied by a pump, including two servovalves (1 and 2) which are identical in design, controlling a piston (3) mechanically linked to a position transducer (4) according to the electrical demand (6, 7) supplied by the feedback position control loops (8 and 9) for the servovalves (1 and 2) to the torque motors (12 and 13) of the servovalves. These loops (8 and 9) receive the same piston position request, and they are given feedback at the same time with the same position signal fed by the position transducer (4). The system is furthermore compensated by two pressure selection valves (14 and 15) and by its own interconnection servo lines.

Abstract: An automatic and sequencing pneumatic actuation assembly is provided for use in an ejection system capable of unlocking and forcibly ejecting stores from racks mounted on an aircraft or similar weapon carrier. The actuation assembly including a primary valve and release ram for reciprocating movement along a common longitudinal axis between closed and open positions. A solenoid control valve initiates movement of the primary valve by creating a pressure imbalance across the primary valve. Pressurized gas is caused to vent to an environment having a pressure lower than the pressurized gas, allowing the primary valve to move the release ram into engagement with a mechanism capable of unlocking the hooks before moving ejector pistons to forcibly eject the unlocked stores. A bias member is provided for automatically returning the primary valve to the closed position after the stores have been released.

Abstract: A cartridge valve assembly (19) including a sleeve valve (49) fixed within a valve housing (17), and a spool valve (47) moveable both axially and rotatably within the sleeve valve. Rotation of an input (35,39) causes rotation of a cam member (43) and the spool valve, and the engagement of the cam member (43) with a cam surface (57) results in axial movement of the spool valve within the sleeve valve. The spool and sleeve valves define a neutral axial and rotational position (FIG. 5), and rotation from neutral in a first direction (FIG. 6) communicates fluid from an inlet port (21) to a first actuator port (25), and rotation from neutral in a second direction (FIG. 7) communicates fluid from the inlet port to a second actuator port (27). In either case, the axial movement of the spool valve (47), relative to the sleeve valve (49) is the same. The spool valve defines a load holding land (97) which, in the neutral position (FIG.

Abstract: A hydraulically controllable valve for double-acting consumers that in the lowering mode drains off a flow of load volume from connection B to connection A in throttled fashion. To that end, the valve has a valve seat (5), which communicates with a sealing face (4) of a main piston (3). A pilot piston (8) is guided concentrically in the main piston (3) and communicates with a sealing face (7) to a pilot valve seat (6) in the main piston; the main piston (3) and the pilot piston (8) are held on the valve seat (5) and pilot valve seat (6), respectively, by the load pressure and/or by spring force. On the pressure-relieved side, the pilot piston (8) has a piston shank (9), guided in a seat bore, with a continuously decreasing throttling action and in particular throttle grooves (10), which form a throttle restriction.

Abstract: A valve mechanism for use in a hydrostatic transmission including a closed porting system for hydraulic fluid and a sump is provided. The valve mechanism includes a valve body mounted to the hydrostatic transmission whereby the valve body is open to the closed porting system at one end thereof and open to the sump at the other end thereof. The valve body has a first open position whereby hydraulic fluid is pulled into the closed system from the sump when the pressure of the fluid in the closed system is below a first pressure, a second open position whereby hydraulic fluid exists the closed system to the sump when the pressure of the fluid is at a second pressure higher than the first pressure, and a closed position when the pressure of the hydraulic fluid in the closed system is at a third pressure higher than the second pressure.

Abstract: A screwdriving spindle assembly comprising a spindle shaft provided with a holding device and secured to a gear wheel rotated by a drive assembly which comprises a pressurized fluid actuating cylinder having a piston rod secured to a transmission system, and a member for adjusting pressure disposed on a line for feeding fluid to the cylinder in the screw-tightening direction.

Abstract: A fluid-operated brake actuator having a check valve in the spring chamber to equalize the pressure on opposite sides of an operating movable diaphragm. The check valve being double redundant and tamper resistant and comprising a tubular body having a first one-way valve disposed and one end of the tubular body and a second one-way valve disposed at an opposite end of the tubular body. A support plate is mounted to the tubular body to support the second valve and prevents the easy removal of the check valve from the brake actuator.

Abstract: A pneumatic actuation assembly for use in an ejection system capable of unlocking and forcibly ejecting stores from racks mounted on an aircraft or similar weapon carrier. The actuation assembly including a primary valve and release ram attached to one-another for joint, reciprocating movement along a common longitudinal axis between closed and open positions. A solenoid control valve initiates movement of the primary valve by creating a pressure imbalance across the primary valve member. Pressurized gas is caused to vent to the atmosphere, allowing the primary valve member to move the attached release ram into engagement with a mechanism capable of unlocking the hooks before moving thrust pistons to forcibly eject the unlocked stores.

Abstract: A valve mechanism for use in a hydrostatic transmission including a closed porting system for hydraulic fluid and a sump is provided. The valve mechanism includes a valve body mounted to the hydrostatic transmission whereby the valve body is open to the closed porting system at one end thereof and open to the sump at the other end thereof. The valve body has a first open position whereby hydraulic fluid is pulled into the closed system from the sump when the pressure of the fluid in the closed system is below a first pressure, a second open position whereby hydraulic fluid exists the closed system to the sump when the pressure of the fluid is at a second pressure higher than the first pressure, and a closed position when the pressure of the hydraulic fluid in the closed system is at a third pressure higher than the second pressure.

Abstract: A controlling motor for moving a stem along an axis has a hydraulic actuator with a cylinder in which a piston that is frictionally linked to the stem is slidingly and sealingly mounted, as well as a compression spring that is frictionally linked to the stem and acts against the actuator. The controlling motor has a trigger with an inflow area into which hydraulic fluid may be introduced, a pressure area that communicates with the inflow area through a diaphragm and is connected to the actuator, and a drainage area from which the hydraulic fluid may be evacuated without pressure, as well as a switching element that links the pressure area to the drainage area when a positive pressure differential occurs between the pressure area and the inflow area, and that otherwise shuts off the drainage area. The stem may be pushed out of the cylinder by the compression spring and may be drawn into the cylinder when hydraulic fluid is applied to the inflow area.

Abstract: A control system for a press having a clutch and a brake includes a clutch control valve and a brake control valve. The clutch control valve operates the clutch by supplying pressurized air to the clutch. The brake control valve operates the brake by supplying pressurized hydraulic fluid to the brake. The brake control valve is activated by pressurized fluid from the clutch control valve in order to insure simultaneous release of the brake with engagement of the clutch as well as simultaneous application of the brake with disengagement of the clutch.