Abstract: A hydraulic system for operating a rear gate of a baler implement includes a hydraulic cylinder having a housing that defines an interior, and a piston that is moveably disposed within the interior of the housing. The housing includes a first fluid port and a second fluid port, each disposed in fluid communication with a first fluid volume of the hydraulic cylinder. A flow rate control valve is moveable between a first position for directing fluid to or from the first fluid port at a first flow rate, and a second position for directing fluid to or from the second fluid port at a second flow rate. The second flow rate is different than the first flow rate.

Abstract: A hydraulic assembly includes a barrel having a head port disposed proximate an end of the barrel, a piston assembly disposed within the barrel and movable relative thereto, the piston assembly including a bore terminating at a back wall, the bore defining a longitudinal axis, and a plunger at least partially received within the bore and translatable along the longitudinal axis. The plunger includes a main body having an end facing the head port, a shoulder extending radially-outwardly from the main body, and a passageway extending through the main body. A spring is disposed in a first region defined between the shoulder and the back wall, the spring configured to exert a biasing force on the shoulder.

Abstract: A compressed gas motor and methods comprise a working plunger and a control plunger arranged in the internal space between the working plunger and a closed rear side such as to be mobile in linear direction. The control plunger, in a first position, covers a gas outlet opening and does not cover the gas inlet opening and, in a second position, covers the gas inlet opening and does not cover the gas outlet opening. The control plunger is supported as in a bearing such as to be mobile with respect to the working plunger, and a catch element is arranged on said working plunger and/or control plunger and pulls the control plunger in the direction of the working plunger, at a first distance, when the working plunger moves away from the control plunger, as well as a lavage system comprising said compressed gas motor.

Abstract: A compressed-gas motor has a cylindrical inner chamber closed gas-tight at a first base surface, and a piston arranged so as to be movable along the cylinder axis in the cylindrical inner chamber. A first opening feeds a compressed gas into the inner chamber, and a second opening discharges a gas from inside the inner chamber. The openings are arranged in the cylinder casing of the cylindrical inner chamber, wherein the first opening is arranged between the second opening and the closed first base surface. The first opening is closable by a first piston part and the second opening by a second piston part. The compressed-gas motor has a resetting device which exerts a force on the piston in the direction of the first base surface of the cylindrical inner chamber if the second piston part does not completely close the second opening.

Abstract: A lifting mechanism is disclosed which is operated hydraulically and is configured to be mounted or used on a mobile working machine. The lifting mechanism or its hydraulics have a relieving pressure limiting valve which can be regulated as a function of the ground profile. For this purpose, a directly or indirectly measuring sensor arrangement is provided. Furthermore, a method is disclosed which serves for regulating a relieving pressure of a lifting mechanism of a mobile working machine. The method has the following steps (i) detection of the ground profile via a sensor arrangement, and (ii) limitation of the relieving pressure of a relieving line by setting an opening pressure of an electronically activatable proportional relieving pressure limiting valve via a control unit as a function of signals from the sensor arrangement.

Abstract: Arrangement for damping of a piston movement in a compressed air cylinder (10; 20), which arrangement includes a compressed air cylinder (10; 20), a valve device, a compressed air device, and a control unit. The control unit controls valve devices such that the movement of the piston is damped before the piston reaches the casing of the compressed air cylinder. A method for control of the arrangement is disclosed.

Abstract: An arrangement in which a valve assembly is provided between the supply air inlet and the magnetic valve that is activated by a position threshold sensor that can be activated by the actuator element and/or a pressure threshold sensor registering the actuating pressure on the magnetic valve and connects the magnetic valve directly to the supply air to increase the availability of the actuator device when the position threshold sensor detects the attaining of a specified operation position of the actuator element or the pressure threshold sensor detects the failure to attain a specified minimum pressure.

Abstract: A device for the operation of a valve (5) to the combustion chamber (6) of a combustion engine, wherein the combustion engine comprises a cylinder, a piston (3) displacably arranged in the cylinder (2), and a combustion chamber (6) delimited by the cylinder (2) and the piston (3), and said valve (5), and wherein the device comprises a valve actuator (7) that comprises an actuator chamber (8), an actuator piston (9) displacably arranged in the latter and arranged to drive the valve (5), and a communication channel (11) through which a pressure fluid is conducted into the combustion chamber (8) for the driving of the actuator piston (9) and, thereby, the valve (5) in a direction in which the valve (5) is opened. The communication channel (11) extends from the combustion chamber (6) to the actuator chamber (8), and said pressure fluid comprises fluid pressurized by the pressure in the combustion chamber (6).

Abstract: An electromagnetic operation-type automatic pressure-adjusting valve outputting an air pressure corresponding to an amount of electric power is connected in an air flow path connecting a pressure chamber of a single-acting main cylinder and an air source. A controller is configured to obtain a relationship between a position of a piston and an air pressure from a relationship between the position of the piston of the main cylinder and a spring force of a return spring, and a relationship between the air pressure supplied to the pressure chamber and an acting force applied to the piston by the air pressure. When a target position of a movement of the piston is inputted to the controller, the controller is operated to move the piston toward the target position and to stop the piston at the position by means of controlling the amount of electric power for the automatic pressure-adjusting valve so that an air pressure corresponding to the target position is outputted.

Abstract: A hydraulic cylinder for use with a machine is disclosed. The hydraulic cylinder including a tube having a first end and a second end and a cap assembly connected to the first end of the tube to close off the first end. The hydraulic cylinder also includes a piston assembly having a piston rod and being movably disposed within the tube to move between the first end and the second end. The hydraulic cylinder further includes a valve plunger connected to the cap assembly and having a first axial bore and a plurality of radially oriented passages. The plurality of radially oriented passages being configured to sequentially restrict fluid flow through the first axial bore as the piston assembly approaches the first end of the tube.

Abstract: It is a question of a pneumatic drive system comprising at least one pneumatic drive (2) possessing a drive housing (4) and an output drive unit (6) able to be shifted in relation to it by the action of compressed air, the output drive unit (6) including an output drive piston (8), which in the drive housing (4) separates two working chambers (12 and 13) from one another, one or both of such chambers being connected with a pneumatic control line (17 and 18), such line having control valve means (22 and 23) able to be switched over between an air economy position and an open position (24) making available a flow cross section which is larger than that of the air economy position, such control valve means being provided with actuating means (32) able to be activated in a manner dependent on the position of the output drive unit (6), such actuating means being able to cause a switching over of the control valve means (22 and 23) into the air economy position, when the output drive unit (6), owing to the compress

Abstract: Hydraulic actuator as an element of a system for controlling an engine valve is presented. The actuator includes a fluidic actuation chamber, defined by an actuation piston that increases chamber volume as the actuation piston is urged away from a neutral. Chamber includes a high pressure fluid inlet and a fluid outlet. A fluidic actuator control chamber, defined by a control piston connected to the actuation piston that increases chamber volume as the actuation piston is urged away from neutral. A control fluid outlet is connected to a fluid control spool valve. The fluid outlet of the actuation chamber is fluidly connected to an inlet of the control valve. There is a valve actuation plunger operably connected to the actuation piston, and a drain outlet to maintain a fluidic backpressure to the actuator control chamber.

Abstract: A pneumatic actuator system is provided which includes one or more piston-cylinder type actuators (14) intended for crust breaking operations at electrolytic alumina reduction baths. Each actuator (14) includes a working piston (21), and a piston rod (22) carrying a crust breaking working implement (17). A control circuit having a directional valve (24) is arranged to operate the actuator piston (21) in alternative directions. The control circuit includes air feed flow restrictions (26, 27), end position sensors (28, 29) and air feed shut-off valves (30, 31) for minimizing the pressure air volume needed for accomplishing complete working strokes of the actuator piston (21) at varying crust layer thickness.

Abstract: An actuating device for a friction clutch arranged in the drive train of a motor vehicle. The actuating device has a positioning servo arrangement with a pressure-medium power cylinder arrangement which acts on a disengagement bearing arrangement. There is provision, for assigning to a pressure-medium subsystem, made up of the pressure-medium power cylinder arrangement and a control valve of the positioning servo arrangement, a pressure compensating orifice which, at least when the positioning servo arrangement is in a holding state, permits a defined pressure-medium pressure compensating flow, in order to influence at least one positioning behavior of the positioning servo arrangement.

Abstract: A control apparatus for an industrial vehicle is disclosed. The vehicle has a rear axle that is swingable during straight travel of the vehicle and can be fixed during turning of the vehicle. A damper looks or unlocks the rear axle. A controller has a memory that stores a first value and a second value of an angular velocity rate that represents an angular velocity per unit time. The controller activates or deactivates the damper. The controller activates the damper to lock the rear axle when the angular velocity rate is greater than the first value. The controller deactivates the damper to unlock the rear axle when the angular velocity rate is kept smaller than the second value for a predetermined time period after the angular velocity rate has become smaller than the second value.

Abstract: A circuit is provided for the circulation of solvent to and from a valve having a movable component and a housing for movably housing the movable component. The movable component has a first orientation with respect to the housing in which it permits the flow of a valved fluid from the valve through a first port provided on the valve and a second orientation with respect to the housing in which it permits the flow of the valved fluid from the valve through a second port provided on the valve. The circuit includes a first passageway provided between the movable component and the housing. A third port is provided on the housing for the introduction of the solvent into the housing and a fourth port is provided on the housing for removal of the solvent from the housing. The first passageway couples the fourth port to the third port. The solvent is a solvent for the valved fluid. A reservoir is provided for the solvent, along with conduits for coupling the third and fourth ports to the reservoir.

Abstract: A pneumatic or hydraulic cylinder assembly (10) includes a cylinder (10), a piston (12) axially slidable within the cylinder (10), and structural elements are disposed within the cylinder (10) to issue a piston (12) position signal in response to the piston reaching a predetermined position.

Abstract: For enabling a boom to be smoothly raised during the triple combined operation of boom-up, arm-crowd and bucket-crowd in a hydraulic circuit system for a hydraulic excavator, in a first valve group of a hydraulic valve apparatus (12), a variable throttle valve (70) is installed in a feeder passage (32) of a bucket directional control valve (21) downstream of a load check valve (32a), and a secondary pressure C as a boom-up operation command is introduced through a line (71) to a pilot control sector (70a) of the variable throttle valve (70) which sector operates in the throttling direction, so that when the secondary pressure C is 0 or small, the variable throttle valve (70) is fully opened and, as the secondary pressure C increases, an opening area of the variable throttle valve (70) is reduced to restrict the flow rate of a hydraulic fluid supplied through the bucket directional control valve (21).

Abstract: A hydraulic cylinder snubbing arrangement includes a pilot operated control valve having a predetermined snubbing position at which flow exhausted from a hydraulic cylinder actuating chamber must pass through a plurality of flow restricting orifices in a valve spool when the hydraulic cylinder is retracted to a predetermined position. The valve spool is shifted to the snubbing position automatically by reducing the fluid pressure in a pilot chamber at the end of the valve spool to a predetermined level so that a snubber spring device resiliently moves the spool from a lower or float position. By forcing the fluid to pass through the restricted flow path created by the orifices, the gravity induced velocity of the hydraulic cylinder is greatly reduced as the hydraulic cylinder approaches its end of stroke position.

Abstract: A pile driver arrangement including a reciprocal impact member connected to a piston rod which is also connected to a reciprocal piston located in a hydraulic cylinder having a lower rod end and an upper blind end. A hydraulic fluid tank and a pump for supplying hydraulic fluid from the tank to the lower rod end of the hydraulic cylinder to lift the piston and the impact member. A first hydraulic fluid conduit connecting the upper blind end of the hydraulic cylinder and the lower end of the hydraulic cylinder and a check valve to prevent the flow of hydraulic fluid from the lower end to the upper end of the hydraulic cylinder. A second hydraulic fluid conduit connecting the pump and the lower end of the hydraulic cylinder and a control valve in the second conduit for controlling the flow of hydraulic fluid from the pump to the lower end of the hydraulic cylinder.

Abstract: A pile driver arrangement including a reciprocal impact member connected to a piston rod which is also connected to a reciprocal piston located in a hydraulic cylinder having a lower rod end and an upper blind end. A hydraulic fluid tank and a pump for supplying hydraulic fluid from the tank to the lower rod end of the hydraulic cylinder to lift the piston and the impact member. A first hydraulic fluid conduit connecting the upper blind end of the hydraulic cylinder and the lower end of the hydraulic cylinder and a check valve to prevent the flow of hydraulic fluid from the lower end to the upper end of the hydraulic cylinder. A second hydraulic fluid conduit connecting the pump and the lower end of the hydraulic cylinder and a control valve in the second conduit for controlling the flow of hydraulic fluid from the pump to the lower end of the hydraulic cylinder.

Abstract: A pressurized fluid actuation system as provided for a surgical instrument. The system includes a double-acting fluid pressure actuator with an extension chamber and a retraction chamber separated by a piston for engaging a component of the instrument. An operating lever is pivotally mounted to the piston. The operating lever is also pivotally connected to a servo valve that has a valve spool. The valve is connected to a source of pressurized fluid and has first and second return ports for venting the fluid. The actuator extension and retraction chambers are connected with the valve for each communicating with the pressurized fluid source and with one of the return ports in response to the position of the valve spool. The system includes a feedback line communicating between the extension chamber and the valve to apply a force to the valve spool in one direction when the extension chamber is pressurized.

Abstract: A position-controlled actuator including a double acting pneumatic actuator, a selector valve which causes function of the actuator, a comparator which controls the action of the selector valve in response to a comparison between an input signal and a signal indicative of the position of the actuator, and a feedback link which provides the comparator with a signal indicative of the position of the actuator. The actuator would have oscillation damping seals such as seals of VITON brand fluorocarbon rubber.

Abstract: Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

Abstract: A drive for a steam servo valve (2), including a control valve arrangement for regulating the actuating pressure of a servo drive (1), whereby the drive can always be actuated reliably and quickly even with comparatively high oil pressure. This is achieved by the control valve arrangement having at least two regulatable control valves (17, 21) which are pressure-actuated via at least one pilot regulating valve (proportional pressure valve 29, 34).

Abstract: A directional control valve for a penumatic cylinder in which a piston of the cylinder can be lowered and elevated in a high speed with a minimum air consumption and the lowering/rising speed of the piston can be controlled before it reaches the upper/lower end portions to prevent bounding of the piston.

Abstract: A variable frequency control for a hydraulic percussion actuator includes a piston bore and a valve bore. A piston is axially disposed within the piston bore, while a valve is axially disposed within the valve bore. A first piston biasing member biases the piston in a first direction while a second piston biasing member, which overcomes the bias of the first piston biasing member to move the piston in a second direction. A first valve biasing pin biases the valve in a third direction while a second valve biasing pin overcomes the bias of the first valve biasing pin to move the valve in a fourth direction. A hydraulic valve actuator displaces the second valve biasing pin when the piston is extended in the second direction, and a piston actuator activates the second piston biasing pin when the valve is extended in the fourth direction. A valve response member controls the time required for the valve to be displaced in said fourth direction upon actuation of said valve actuating member.

Abstract: This invention relates to a pneumatic valve assembly for controlling a compressed air stream in response to a non-contacting actuation. It is desired to provide such a valve assembly which is adapted to control high working pressures without an intermediate amplifier. This is accomplished in that a pivoted one-armed or double-armed lever is provided with a permanent magnet on one side or on each of both sides of its pivotal axis and via a ferromagnetic or magnetic actuating member which is moved into the proximity of the permanent magnet or magnets and via a plunger causes a pilot orifice to be opened or closed, which orifice is adapted to be flown through by a pilot air stream for actuating a pilot piston for moving a valve piston to positions in which the valve is opened or closed.

Abstract: A speed-reducing valve assembly is provided in an air passage through which compressed air is discharged when a pneumatic actuator is decelerated. The speed-reducing valve assembly comprises a three-way valve actuated by a signal generated when the actuator has reached the point where deceleration is started, a relief valve through which the compressed air in the passage is let out when the air pressure has reached the preset level, and a check valve that allows only the admission of compressed air into the same passage. The signal-actuated three-way valve brings the air passage of the actuator into communication with the passage in which the relief valve and check valve are provided. When the signal generated when the actuator has reached the deceleration starting point is fed to the speed-reducing valve assembly, the exhaust passage of the actuator communicates with the relief valve and check valve.

Abstract: An impact tool for striking a tool such as a chisel includes a piston mounted in a cylinder. Upper, middle and lower chambers are formed therebetween. Pressure oil is fed into and discharged from the middle and lower chambers to reciprocate the piston in the cylinder under oil pressure. During a downward stroke of the piston, the oil pressure in the lower chamber is kept low. But just before it strikes a tool, the oil pressure in the lower chamber is adapted to increase so as to prevent what is called cavitation or prevent air bubbles mixed in the pressure oil in the lower chamber from growing suddenly owing to a sharp drop in the oil pressure which is caused by the rebound of the piston after striking the tool.

Abstract: A hydraulic operating apparatus in which a differential piston is used as a drive unit, and in which the differential piston is driven by applying a high pressure fluid on a large piston face side through a hydraulic pressure control device for controlling the hydraulic pressure, and a high pressure fluid always being applied on the small piston face side. The hydraulic operating apparatus is constructed such that a high pressure fluid is applied concurrently on both piston faces when the differential piston stops at its receded position, and a thrust generated due to the difference between the forces applied on the both piston faces is held in check by a holding device acting on the differential piston or its extension. The differential piston is moved forward upon the removal of the holding force of the holding device, and the piston is moved backward upon the removal of the high pressure fluid on the large piston face side.

Abstract: Method and apparatus of controlling and positioning a fluid actuator by supplying pressurized fluid to right and left actuating chambers of the actuator through an on-off control valves. To drive and position the actuator rapidly and accurately, the actuator can be driven at a higher speed by an initial driving force until it reaches near the desired position and continuously moved at a low speed by gradually increasing the fluid pressure to be supplied to the right and left actuating chambers of the actuator. The initial driving force in the high-speed range becomes maximum when the pressure is applied to one of the right and left actuating chambers while at the same time the other actuating chamber is exhausted. In the low-speed range and near the target position, the one actuating chamber is continuously supplied with the pressure while at the same time the other actuating chamber is gradually closed.

Abstract: Apparatus for confirming the clamping conditions of a clamping device which is used to clamp workpieces of different sizes. Signals corresponding to the kind of workpiece being clamped are derived from the flow rate of pressurized fluid used to drive the actuator of the clamping device. These signals are used to confirm the clamping conditions and also the kind, and the presence or absence, of the workpiece.

Abstract: A control device for a drive unit, preferably the drive unit of a power vehicle, is provided having a hydrostatic transmission where the adjusting device of the latter and the adjusting device of the internal combustion engine are controlled by means of a servo piston loaded by control pressure, whereby the internal combustion engine is prevented during reversing from being adjusted to an increased power output through a circuit before the adjusting device of the hydrostatic transmission has passed through the zero-stroke position, and where the circuit has two shut off valves whose outlets are connected with a line, which are connected to the spring-side pressure chamber of the operating cylinder of the internal combustion engine through a multiway valve.

Abstract: An improved mechanism is provided for controlling the relative pivoting movement of two members about a main pivot axis as effected by two hydraulic motors. Each hydraulic motor is a double-acting piston-cylinder type that is fully extended when its respective line of action intersects the main pivot axis. Each hydraulic motor has an end port at each end. Two spaced-apart intermediate ports are provided within the piston stroke length of each motor. Pilot-actuated top dead center-selector valves are provided for reversing the flow to one of the hydraulic motors in response to a pressure differential between an end port and an intermediate port of the other of the hydraulic motors. Decelerator selector valves are provided to normally direct the return flow from the hydraulic motors so as to bypass a hydraulic cushioning circuit.

Abstract: An impact-type surface seismic source utilizing a closed air system includes a heavy pistons supported above an earth contacting base plate partially within a hollow upstanding cylindrical housing, having a closed top and an open bottom. The housing side walls are provided with ports which communicate with a source of high pressure air. Preparatory to a firing operation, the piston blocks these ports, but upon a firing signal the piston is released and falls under gravity permitting high pressure air to enter the bore of the housing through the ports, thus driving the piston downwardly to strike the base plate. As the piston is retrieved and nears its original position, blocking the side ports, it mechanically actuates a valve so as to vent any air trapped above the piston within the housing bore. The vent remains open until the piston again falls.

Abstract: A fluid operated positioning apparatus includes a multi-position valve operated in response to differential pressure in a fluid control circuit. The control circuit includes two adjustable throttles in series, the junction between the throttles being connected to a control device at one end of the valve. Particular relationships for the throttles are disclosed. Other embodiments include additional throttles for improved control with low pressures.

Abstract: An apparatus for controlling the movement of a movable element as a working circuit (10) with a directional control valve (3) equipped to control devices (11, 12) which can be pressure activated in two directions. A control circuit (29) which can be connected to a fluid source (19) is used to activate the directional control valve for which the control circuit is connected to the two control devices and has an adjustable first choke (24) connected to one of the two control devices (12), a second choke (22) which is similarly adjustable and connectable to the same control device, and third and fourth adjustable chokes (27, 28) which are connectable to the other of the two control devices (11). The first and third chokes are connectable further to a storage tank (7) and the second and fourth chokes are further connectable to a pressure source. A proportioning pressure valve (45) can be connected to the other of the two control devices (11). The first and third chokes are connected to a pilot valve (38).

Abstract: An apparatus for positioning an adjustable member as a function of a command signal and a control condition, especially for the positioning of a hoisting mechanism on a tractor or the like, comprises an operating circuit and a control circuit. The operating circuit has a bidirectional positionable valve with a valve side and first and second control devices for regulating flow of pressure medium from a supply tank to the adjustable member. The control circuit connects a control pressure medium source to the control devices at first and second junctions and includes adjustable throttles and a flow-regulating valve. A first adjustable throttle is connected between the supply tank and the first junction. The second adjustable throttle is connected between the control pressure medium source and the first junction and in series with the first adjustable throttle.

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 device for the positioning of an adjustment element dependent upon a desired level and the actual level, particularly for the adjustment of a hoist gear train of a tractor, a combine or the like, has an operating circuit 10, which has a multi-way valve 3 pressure-operated in two directions, and a control circuit 29 for the operation of the multi-way valve, connected to a pressure source 19, which is connected to two control devices 11, 12 of the multi-way valve. Circuit 29 has two adjustable series-connected throttles 22, 24, connected to one of the two control devices. The first throttle 24 is also connected to a tank 7 and the second throttle 22 is also connected to pressure source 19. Both throttles have the same maximum flow-through cross section, and are adjustable in the same manner. Third and fourth throttles 27, 28 are provided, one being between the pressure source and control device 11, and the other between the control device and tank 7.

Abstract: A tool for driving fasteners includes a casing defining a nose portion and a handle portion within which is a reservoir for pressurized fluid. A driver is mounted in the nose portion that is reciprocated by a piston attached thereto and an assembly for returning the piston to a static position after a driving stroke is also included. The return assembly includes a chamber in fluid communication through an inlet with pressurized air and with an outlet that is in communication with a location beneath the return piston. A diaphragm is mounted within the chamber and is biased by pressurized fluid into sealing engagement with the inlet and the outlet. Another metered inlet is also included in the chamber that is in fluid communication with the source of pressurized fluid and controls the sealing action of the diaphragm. The chamber for the return assembly is also in fluid communication with a second chamber within which is mounted a differential area piston.

Abstract: A hydraulic driving device of a circuit breaker which opens and closes a system in response to two signals is principally constructed of a cylinder, a piston, and a main control valve for controlling the motion of the piston. A spool adapted to slide within the main control valve has its motion controlled by four pressure faces. The first pressure face is normally subjected to a high oil pressure. The second pressure face receives a low oil pressure upon application of the first signal, and a high oil pressure upon release thereof. The third pressure face receives a high oil pressure upon application of the second signal, and a low oil pressure upon release thereof. A high or low oil pressure acts on the fourth pressure face in correspondence with the piston motion. The magnitudes of the forces on the respective pressure faces of the spool are set in a predetermined relationship.

Abstract: A pneumatically buffered drive system is provided which quickly moves a movable member, such as a press safety curtain or press bolster, a predetermined length in three sequential speed stages to prevent maximum acceleration from occurring at the end of the predetermined length. The movable member is coupled to a differential pressure piston which is initially pressurized on only one side of the piston to initiate movement. After traversing approximately half the predetermined length both sides of the piston are pressurized to decelerate the piston during the member movement for approximately the next third of the predetermined length. The remaining length is traversed with the decelerating pressure being vented to positively finish the motion along the predetermined path. In vertical moving members having significant mass such as press safety curtains, a higher pressure is used to decelerate the piston than the pressure used to drive the piston.

Abstract: A fluid cylinder assembly includes a cylinder and a piston slidably disposed in the cylinder, the cylinder having a cylinder bore closed at both ends by end caps. One of the end caps is provided therein with a flow control valve assembly for controlling the fluid flow from the cylinder bore during a working stroke of the fluid cylinder assembly. The flow control valve assembly comprises a poppet valve having a pair of poppets on a valve rod and a spool valve movable in response to the operation of the poppet valve. The poppet valve is shiftable by a solenoid alternately energized and de-energized by an electric control circuit which is closed just before contact of a cutter on the piston rod with a workpiece.

Abstract: The invention relates to a hydraulic steering apparatus comprising a continuously operating pump, an operating motor for controlling the parts to be steered, a control device which is adjustable by the steering wheel and which, in its neutral position, connects the pump to a tank through a short-circuiting path. The control device has two operating positions in which the pump is connected to one side or the other of the operating motor and connects the other side of the operating motor to the tank. The control device has a control element connected to a steering wheel and a following element connected to a metering motor and these elements are relatively displaceable to a limited extent. Apparatus is provided to prevent the steering parts moved by the operating motor from stroking mechanical abutments.