Abstract: A communication area of a left pressure reception chamber, a pressure reception chamber, a right pressure reception chamber and another pressure reception chamber for moving a spool to first and second positions with a first pump port and a second pump port is made large at the beginning of a stroke, small at the intermediate of the stroke and medium at the end of the stroke so as to return the spool from the first and second positions to the neutral position in a short time while preventing cavitation from occurring. While the volume of the pressure reception chamber located opposite to the moving direction of the spool is prevented from changing, the spool is moved slowly in the above-described opposite direction. Thus, the spool is prevented from making an over-stroke and also prevented from having a hunching even if a return pressure oil has a large change in pressure.

Abstract: An oil-pressure cylinder in a crushing device is connected to a crushing jaw via a pivot shaft so that the crushing jaw can open and close. The extension of oil-pressure cylinder causes the crushing jaw to close and crush the object to be crushed. Oil-pressure cylinder has a piston with a greater pressure-receiving area on the head side than on the rod side. An acceleration valve serves to switch the extension/retraction operations of the oil-pressure cylinder. During a rod unloaded interval, beginning when the crushing jaw starts to close and ending when the crushing jaw comes into contact with the object to be crushed, the acceleration valve makes communication between a head-side port and a rod-side port in the cylinder continuous, while the oil path from the rod side to a tank is blocked. The oil from the rod side is made to flow to the head side.

Abstract: In a load holding valve L, comprising a check valve R and a pressure limiting valve D in a housing chamber which is common to said two valves, a seat insert 13 has provided therein a valve seat 19 for a closure member 4 of the pressure-limiting valve D and a sealing surface 15 for a check-valve closure member 16, and an opening piston 9, which is coupled to the closure member 4, is provided in a pilot chamber 10, an effective area of said closure member 4 being, in a direction opposite to the direction of spring loading, adapted to be acted upon by the pressure to be limited, the opening piston 9 is formed integrally with the closure member 4 and is provided with a pressure surface in the pilot chamber 10 which is slightly smaller than the cross-sectional area of the valve seat 19, and the valve seat 19 defines in combination with control passages K formed in the closure member 4 a stroke-dependent quantity control device M.

Abstract: Thick matter and solids are conveyed together and substantially continuously through a conveyor pipeline. The thick matter is forced by a conveyor piston driven by a piston pump from a feed container into a conveyer cylinder. A forward face of the piston has a cutting crown with a cutting edge cooperating with an annular cutting ring to cut off solids projecting beyond an inlet in the conveyer pipeline.

Abstract: A valve assembly includes a check valve element in the output chamber. The check valve element opens to permit forward flow of fluid under pressure in the output chamber from a source toward a load. The check valve element closes to block back flow of fluid under pressure in the output chamber from the load toward the source. The back flow of fluid under pressure exerts a closing force upon the check valve element from within the output chamber. A counter force generating element is located within the output chamber and coupled to the valve element. The counter force generating element applies a counter force to the check valve element, which urges the valve element toward the opened condition. The counter force is, by purpose, less than the closing force, so the check valve element remains closed.

Abstract: A double-acting electropneumatic positioner for controlling an actuator, the actuator having a first and second chamber, comprises a single-acting electropneumatic positioner which provides an output pneumatic pressure to the first chamber of the actuator. A pressure inverter, coupled to the single-acting electropneumatic positioner, inverts the output pneumatic pressure. The inverted output pneumatic pressure is then coupled to the second chamber of the actuator.

Abstract: In order to achieve repeatable, consistent operation of a counterbalance valve, a poppet valve element within the valve has a radial bore therein in communication with a control fluid port and an axial bore therein which receives a rod that is anchored to a poppet valve cage that surrounds the poppet valve element. The poppet valve element is urged by a spring into engagement with a valve seat and pilot pressure is applied in opposition to the spring. By virtue of this arrangement, control fluid pressure is applied via the rod directly to the valve body in which the poppet valve element and cage are mounted. By changing the diameter of the rod and axial bore through the poppet valve element which receives the rod, the relief set pressure can easily be changed.

Abstract: A hydraulic control for a dividing machine tool, in particular a shear or cutting press, in which a damping device is provided in order to counteract a sudden downward movement of the working piston upon the cutting through of a workpiece during an operating stroke.

Abstract: Cylinder drift resulting from internal leakage of a recycling circuit, which recycles oil returned from the arm cylinder of a hydraulic shovel to the hydraulic supplying end, is reduced by an hydraulic circuit which includes a recycle valve attached directly to a control valve. When working fluid is returned from a rod chamber of arm cylinder into the control valve, the recycle valve recycles a part of the working fluid through a recycle selector valve to the hydraulic supplying end. A pilot operated check valve is disposed in the oil channel that connects the rod chamber and recycle selector valve together. When extending arm cylinder of the hydraulic shovel, pilot pressure from control valve shifts a pilot selector valve in such a direction as to open pilot operated check valve. When control valve is at the neutral position, pilot selector valve is shifted back to the return position and closes pilot operated check valve so that return oil of arm cylinder is prevented from working on recycle selector valve.

Abstract: A control valve is provided for use in a hydraulic steering system of an agricultural vehicle of the type having a steering valve of the reactive type for controlling the supply of hydraulic fluid to hydraulic cylinders having opposed working chambers serving to move the steerable vehicle wheels in opposite directions. The control valve is connectable between the steering valve and the hydraulic cylinders and has a first setting in which fluid flow in both directions between the steering valve and the working chambers of the hydraulic steering cylinders is possible at all times and a second setting in which return flow of hydraulic fluid from any one working chamber of the hydraulic cylinders to the steering valve is only possible when a positive pressure is present at the outlet of the steering valve connected by the control valve to the opposed working chamber of the hydraulic cylinders.

Abstract: The hydraulic control system disclosed herein employs a pair of combination poppet/spool valves to control the operation of a hydraulic cylinder driven from a bidirectional pump. Flow introduced through the source port of one valve lifts the poppet of the other valve on its way to one side of the cylinder which in turn opens a throttling port to modulate return flow from the other side of the cylinder.

Abstract: A return fluid regeneration device for construction vehicles is provided. The regeneration device includes an orifice disposed on a return-side internal line of a directional control valve of an actuator. A regeneration line is arranged between the return-side internal line and a return line extending to a return tank and is further selectively connected to the return-side internal line during a weight operation of the actuator. A regeneration branch line is branched from the return-side internal line and is connected to a supply-side internal line of the valve, thus selectively feeding the return fluid from the return-side internal line to the supply-side internal line and thereby regenerating the return fluid. First and second check valve are also provided on the regeneration line and branch line, respectively. The regeneration device regulates the moving speed of the actuator while simultaneously preventing the generation of high pressure in a fluid supply line.

Abstract: An hydraulic system has an hydraulic cylinder connected to a reversible pump by a first fluid line. A check valve assembly is connected in the first line and in a second line extending from the pump to a tank. The check valve assembly has a ball that seats on a conical valve seat to enable flow of fluid from the pump to the cylinder but to prevent flow in the opposite direction. A shuttle member in the check valve assembly is displaced by fluid pressure in the second line when the pump is reversed to unseat the ball and allow flow from the cylinder in the opposite direction via the pump to the tank.

Abstract: The hydraulic counterbalance valve has a valve body with an inlet port, a cylinder port and a pilot port. The valve body has an interior chamber extending through the valve body which forms a check seat where the interior chamber narrows. The interior chamber is in communication with each port by a number of passages. A check valve is disposed in a first passageway between the interior chamber and the inlet port. A bypass passage exists to circumvent the check valve and provide communication between the interior chamber and the inlet port. A control spool is movably disposed in the interior chamber. The control spool has a pilot end, a sealing means, metered groove and a pilot check. The pilot check of the control spool forms a pilot check seal with the check seat of the interior chamber. A spool spring is disposed in the interior chamber and biases the control spool pilot check to seat against the pilot check seat of the interior chamber.

Abstract: The disclosure relates to a new valve and a hydraulic system incorporating such valve. A mode-selection assembly on the valve is adjustable between an open-loop position for system purging and a closed-loop position for normal system operation. A sealing member moves with the spool and with the mode-selection assembly in the open-loop position, the sealing member may be urged against a stationary abutment member in the valve. Such cooperative sealing member/abutment member contact blocks the closed-loop flow path and causes fluid to be "rerouted" to tank rather than back to the pump. The system is thereby temporarily converted to open-loop configuration for purging and is restored to closed-loop configuration by moving the mode-selection assembly to the closed-loop position. The new valve is particularly useful in hydraulic steering circuits for boats.

Abstract: A pneumatic cylinder, especially for a spot-welding machine, has a sleeve valve mounted on the piston rod. The sleeve valve provides a venting valve for dumping pressure from a return chamber at the end of the forward stroke, and a progressive restrictor to close off a forward chamber and provide cushioning at the end of the return stroke.

Abstract: A control valve having a regeneration function, including a hollow valve body, a plurality of spaced ports provided at the valve body, the ports including a pump port, an actuator port, a regeneration port and a tank port, a hollow main spool movably disposed in the valve body, a regeneration spool movably disposed in the main spool and adapted to be moved by a flow of fluid delivered from a pump through the pump port, a fluid passage provided at the main spool and adapted to communicate the actuator port and the tank port together, the fluid passage being opened or closed by the movement of the regeneration spool, whereby as the regeneration spool is moved by the fluid flow delivered from the pump, a part, to be fed to the tank port, of a flow of fluid emerging from the actuator port is increased, while a part to be fed to the regeneration port is correspondingly decreased.

Abstract: A hydraulic control system for excavators includes a variable displacement pump for producing a variable volume of pressurized working fluid, a hydraulic swing motor rotatably driven by the working fluid and a flow control valve operable to control flow of the working fluid with respect to the swing motor. The first flow control valve comprises a valve body and a valve spool slidably fitted into the valve body for selective shifting movement between a first operative position, a second operative position and a neutral position.

Abstract: A hydraulic fluid-loss control valve for preventing uncontrolled load movement in the event of a fluid loss such as from the bursting of a hose and further for allowing an operator to move the load in a controlled way despite the fluid loss. The control valve is situated between a conventional main spool valve and a piston/cylinder hydraulic actuator which powers the load. The control valve has a spool sliding reciprocally in a bore. Grooves and lands on the spool combine with passages in the control valve body to provide alternate fluid paths between a pump and the actuator and between the actuator and a reservoir. Fluid can flow from a controlled chamber of the actuator only when the spool is in a position which provides a fluid path. A passage within the spool provides fluid communication between an input fluid flow and a chamber at one end of the spool. A second passage within the spool provides fluid communication between an actuator chamber and a chamber at the other end of the spool.

Abstract: Disclosed is a stiffness enhanced electrohydrostatic actuator for aircraft flight controls which eliminates the requirement for a central hydraulic system. The actuator replicates the blocked port condition of the central hydraulic system to provide static and dynamic stiffness by the use of valves having a first sleeve and spool and a second sleeve and spool disposed on either side of a valve seat with the first spool biased towards the valve seat.

Abstract: A hydromechanical differentiating system for actuator dynamic stiffness enhancement and dynamic load damping. A free floating spool valve receives a pressure signal and moves in opposite directions away from a null position. When the valve moves in response to an increase in the pressure signal it compresses fluid in a chamber connected at the opposite end of the cylinder in which the spool moves and simultaneously connects a source of fluid under pressure to the chamber causing the valve to return to its null position. Conversely, if the pressure signal decreases, the spool valve allows the fluid in the chamber to expand moving the valve away from the chamber and simultaneously connecting system return to the chamber to decrease the fluid pressure in the chamber and cause the valve to return to its null position.

Abstract: An auxiliary mechanical position locking device is coupled to the hydraulic system that motivates a double acting piston for positional control of surgical tables. The combination of hydraulic coupling and mechanical locking maintains positional stability of the surgical table and insures against sudden or precipitous movements.

Abstract: A lock valve apparatus and a hydraulic system incorporating a lock valve apparatus including a lock valve body with a bore, a first port, a second port, a third port and a fourth port. There is a spool valve with a valve spool reciprocatingly received in the bore. The spool valve, a first one-way valve and a second one-way valve normally prevent fluid flowing between the ports. The first one-way valve and passageways in the valve permit a fluid flow from the first port to the third port when the first port is pressurized. The second one-way valve and passageways in the spool valve body permit a fluid flow from the second port to the fourth port when the second port is pressurized. The spool valve is shifted to align passageways, including a first annular passageway, between the spool and the bore to permit a return flow of fluid from the fourth port to the second port when the first port is pressurized. The first annular passageway receives pressurized fluid from the fourth port.

Abstract: A holding valve for use in a hydraulic operating system of a machine which is adapted to perform both lifting and digging functions is disclosed. The holding valve includes a conventional poppet assembly for modulating the rate at which hydraulic fluid flows from a hydraulic cylinder when the machine is used for lifting functions. The poppet assembly regulates the speed at which a heavy load can be lowered. The holding valve further includes a pilot actuated piston assembly which is operated only when the machine is used for digging functions. When so actuated, the piston assembly engages the poppet assembly and moves it to a fully opened position. In this fully opened position, the poppet assembly is prevented from modulating the flow rate of hydraulic fluid therethrough, effectively removing the holding valve from the hydraulic circuit. Consequently, hydraulic fluid can flow to and from the digging device without interference from the holding valve.

Abstract: A relief valve for the hydraulic fuse minimizes the chance of a device such as a hydraulically powered lift device from collapsing upon a break in a hydraulic input line to a cylinder powering the lift. The relief valve comprises a valve seat biased in a first direction by a relatively heavy spring and a hydraulic fuse biased away from the valve seat by a relatively light, second spring. Upon a break occurring in the hydraulic input line, back pressure urges the fuse to seat against the valve seat, thus closing the valve. Upon applying additional hydraulic pressure in the direction of the fuse, the valve seat disengages from the fuse, allowing hydraulic fluid to flow through the relief valve and thus allowing a piston in the hydraulic cylinder to retract so as to permit lowering of the lift device.

Abstract: A vehicle convertible top is moved by hydraulic cylinders between extreme raised and lowered positions. The cylinder ends are connected to ports in a reversible hydraulic pump in one end of an elongated housing, which has a reservoir in the other end, separated by a pump cap. The pump cap houses two fluid circuits connecting the pump to the ends of the cylinders. Each circuit has an end of cycle hydraulic locking device comprising a normally-closed valve and a valve actuator. The circuit valves are alternately opened by pump pressure to pressurize one end of the cylinders to alternately raise and lower the top. The opened valve closes when the pump ceases operation, preventing fluid backflow through the one circuit to the pump. This hydraulically locks the top in extreme raised and lowered positions to facilitate top latching and tonneau installation.

Abstract: A lock valve for marine hydraulic steering systems includes a valve body with a spool valve reciprocatingly received in a bore therein. A first port and a second port of the valve are connected to a manual pump. A third port and fourth port are connected to a double acting hydraulic cylinder connected to a rudder or steerable motor. There are valves within the lock valve which normally prevent fluid flowing between the ports so the steering system remains in a fixed position when the helm is released. Fluid can flow from the first port to the third port when the first port is pressurized. A return flow of fluid from the fourth port to the second port is permitted only when the first port is pressurized. When the second port is pressurized, fluid can flow the second port to the fourth port. A return flow of fluid from the third port to the first port is permitted only when the second port is pressurized.

Abstract: A counterbalance valve has a first port connected to a hydraulic cylinder and a second port connected to a four-way controller, such as a four-way control valve. Disposed between the ports is a poppet biased to a closed position. The poppet opens to allow operating hydraulic fluid to drain from the hydraulic cylinder and also opens if excessive pressure builds up in the hydraulic cylinder due to thermal conditions. When an operator decides to move the piston within the hydraulic cylinder, hydraulic fluid must be drained from the cylinder. This is accomplished by moving the poppet from a blocking position to an open position with pressurized pilot fluid. On occasion, confusion caused by operator error can cause a build-up of valve backpressure from the four-way control valve, which prevents the poppet from moving upon applying pilot pressure thereto. The resulting excess pressure in the hydraulic cylinder can rupture the hydraulic cylinder.

Abstract: A vehicle convertible top has hydraulic cylinders for moving the top between extreme raised and lowered positions. The cylinders each have a pair of fluid translating ports each connected to ports in an elongated housing. A reversible hydraulic pump is in one end of the housing, while a reservoir is in the other end, separated by a pump cap. The pump cap houses two fluid circuits each connected to a housing port and each including an end of cycle hydraulic locking device which comprises a normally-closed valve and a valve actuator in each circuit. In one direction of pump operation, one of the valves is opened by pressure fluid in the one circuit to enable the outflow of the pressure fluid to the cylinders. The other valve is forced open by its actuator, in response to pressure in the one circuit, to enable the return flow of fluid to the pump through the other circuit. The one valve closes when the pump ceases operation, preventing fluid backflow through the one circuit to the pump.

Abstract: In a control device (S) for a hydraulic motor (V) which is adapted to be ed upon at both sides, there are provided working conduits (4, 5) which are alternately connectable via a directional control valve (C) to a pressure source (P) and a tank (T), a load holding valve (H) which is hydraulically openable in a controlled way and is arranged in at least one working conduit (4), as well as a control pressure conduit (13) which is connected to the opening side (16) of said load holding valve (H), with pressure variations arising during the controlled opening of the load holding valve, and the amplitudes of the pressure variations being adapted to be dampened in the control pressure conduit (13) at least via a damping throttle (D).

Abstract: In a hydraulic control device (S) comprising a double-acting hydraulic consumer (V) which is actuable by pressure via two working conduits (4, 5) and secured in at least one working direction by a load holding valve (H) which is hydraulically openable and closable in a controlled way, further comprising a control pressure conduit (12) which is connected to a control connection of the load holding valve and selectively actuable, as well as a damping throttle (13) arranged in control pressure conduit (12), there is provided a valve (15, 15', 15", 15'", 15.sup.IV) which during the controlled closing movement of load holding valve (H, 6) is automatically responsive to a delay of the controlled closing movement which is caused by the instantaneous viscosity of the pressure medium and/or a too tight setting of damping throttle (13) and is critical as to the after-running of hydraulic consumer (V) under a load (F), with the valve switching in such a case to passage and bypassing damping throttle (13).

Abstract: A circuit for limiting a static and/or dynamic pressure load in a hydraulically actuated use device which is controlled in a closed control circuit by means of a directional control valve and a mechanically or hydraulically releasable blocking device. Aa pressure control valve is arranged between the use device and the pressure relief valve and being adapted to discharge a hydraulic fluid from the use device to a tank when a predetermined hydraulic pressure in the use device is exceeded. The output port of the pressure relief valve is connected to a hydraulic control line is adapted to hydraulically connect the pressure relief valve to a control side of the control valve.

Abstract: In a position independent locking of a hydraulic cylinder/piston mechanism, a pressure limiting member is provided in the supply pipe for the hydraulic medium, with the pressure limiting member being open during the hydraulic displacement of the piston and is closed during lack of hydraulic pressure. The pressure limiting member opens starting from a specific pressurization of the hydraulic medium as a result of a force generated by means of the piston and is located in a related working chamber.

Abstract: A pressure holding valve for pressure-fluid-actuated leveling systems in vehicles, having at least one seat valve with a valve opening, a valve seat and a valve member in which the valve member is opened by a control piston acted upon by pressure fluid. In order to achieve an absolutely pressure-tight seat valve with a long service life, an elastomer seal which seals off from the valve member is disposed on the valve seat, and pressure equalizing means are provided such that upon an impingement of pressure on the control piston in an opening direction of the seat valve, pressure build up upstream of the valve member is such that only a slight pressure difference arises at the seal at the onset of opening. In addition, the valve member is embodied such that upon displacement in a closing direction of the seat valve, the valve member substantially closes the valve opening in advance of the valve member becoming seated upon the seal.

Abstract: The control circuit of a double-acting hydraulic jack (10), consisting of a piston (12) connected to an output rod (18) and separating a cylinder into two chambers (14, 16), comprises a source of fluid under pressure (20, 26), a distribution system (28, 28', 52, 52') alternately putting one of the chambers, or control chamber, in communication with the source of fluid under pressure (20, 26) and the other chamber, or controlled chamber, in communication with a reservoir of fluid under low pressure (25), in order to control the movement of the piston (12) of the jack (10). The jack comprises an auxiliary circuit (50, 120, 122) for preventing communication between the controlled chamber and the reservoir (25), interrupting communication between the control chamber and the source of fluid under pressure (20, 26) and allowing communication between the controlled and control chambers when the pressure of the fluid in the controlled chamber exceeds a predetermined value.

Abstract: A proportional valve comprises two electrically actuated proportional throttle valves, each having an outlet connected to a non-return valve, to each of which a seat valve is connected, each seat valve being pilot-controlled by one of the proportional throttle valves; the electric actuation of the proportional throttle valves proportionally controls and regulates the functions of a hydraulic cylinder. The two throttle valves and the two seat valves are mounted on a housing block which has a planar face at which are connections to a pressure line, a tank line and working lines.

Abstract: In the case of a hydraulic control device for an oscillating load moving system comprising a double-acting hydroconsumer (V), which is adapted to be selectively connected to a pressure source (P) or to a reservoir (T) via two separate main lines (9, 10) and a control valve (C), and further comprising a load supporting valve (H), which is arranged in at least one main line (10) between the control valve (C) and the hydroconsumer (V) and which is adapted to be opened from the other main line (9) via a pilot line (16), a damping device (X), which consists of a bypass line (23) and an interference throttle aperture (D2), is connected to the pilot line (16) of the load supporting valve (H). The pilot line (16) has provided therein a throttle aperture (D1) which is smaller than the interference throttle aperture (D2).

Abstract: An automatically sequenced hydraulic cylinder mechanism, including a hydraulic cylinder having a piston rod which is attached to a working member. The hydraulic system includes a pump which supplies hydraulic fluid to opposite sides of the cylinder. Due to the differential in surface area on opposite sides of the piston, the piston is moved in a direction to extend the piston rod. When the piston bottoms out in its stroke of travel, the pressure in the system is increased and the increased pressure will operate a three-position valve to decrease the pressure in one end of the cylinder and automatically retract the piston rod. The cylinder is thus automatically sequenced to extend the piston rod and retract the piston rod without the use of auxiliary switched or sensors.

Abstract: The power steering mechanism for vehicles, in particular motor boats, has a control wheel that is drive-connected to a control via cable that is attached thereto and a lever system connected thereto. The core of the cable is mechanically connected to the lever system whereas the sheath of the cable is attached to the displaceable control member of the control valve. The control valve controls a hydraulic operating cylinder whose power piston also acts on the lever system of the control. To simplify and reduce the size of the arrangement, the operating cylinder and the control valve are built directly together in axial direction, and the core of the cable penetrates the control member of the control valve and is connected to the power piston of the operating cylinder and in this manner is also connected to the lever system of the control.

Abstract: A counterbalance valve including a spool (62) divided into two spool pieces (63, 64) at its axial center, return springs (71, 72) for urging the spool pieces inwardly along the axial direction toward their innermost positions, a first passage (90) for introducing an inside pressure in a supply and exhaust passage (48) to an outermost end of the spool piece (63), a second passage (91) for introducing an inside pressure in the supply and exhaust passage (49) to an outermost end of the spool piece (64), a pressure selecting member (88) for selecting higher inside pressure among the inside pressures in the supply and exhaust passages (48, 49) and for introducing the selected pressure via a choke (87) to a pressure chamber (73) formed between the spool pieces (63, 64), and a communicating passage (95) formed for communicating the supply and exhaust passages (48, 49) with each other when both the spool pieces (63, 64) are moved outwardly in the axial direction from the innermost positions due to fluid in the pressu

Abstract: An apparatus includes a feed cylinder having a first end port and a second end port. A feed cylinder is located within the feed cylinder and is movable in a drive direction in response to fluid pressure applied to the first end port, and is movable in a return direction in response to fluid pressure applied to the second end port. A feed pump selectively displaces fluid between the first and the second end ports. A variable overcenter device controls fluid pressure offset, independent of the feed pump, between the first end port and the second end port. An adjustment device automatically adjusts the variable overcenter device during travel of the feed cylinder in the drive direction to a value corresponding to an amount of force required to displace the feed cylinder in the return direction.

Abstract: A buffer valve for a cylinder control unit includes a cylinder having first and second plungers each axially slidable in the cylinder with an intermediate piston disposed between the plungers and slidable in the cylinder with springs urging the plungers in the direction of the intermediately located piston; separate chambers are provided in the cylinder between the piston and the first and second plungers and second chambers are provided on the side of the plungers facing away from the piston; passages are provided in the first and second plungers for communicating between the first and second chambers on opposite sides of each plunger; a bypass passage connecting the first chambers for each plunger is provided with a check valve for allowing flow in only one direction from the first chamber of the first plunger to the first chamber of the second plunger so that when one of the plungers closes off communication between the bypass passage and the cylinder control unit, the check valve will prevent flow from th

Abstract: A fluid distributor for sequentially distributing pressurized fluid from at least one inlet port to a plurality of distribution ports and exhausting fluid from said distribution ports to at least one exhaust port, said distributor having a valve actuated by pressure of fluid supplied at said inlet port and arranged to close said exhaust port when said fluid pressure drops below a predetermined minimum. The distributor is suitable for use in conjunction with an inflatable human body support.

Abstract: A device for the control of a double-acting hydraulic jack (10) comprises in a main circuit, a distributor assembly (28, 28', 34, 34') electrically controlled and commanding the putting of each of the two chambers (14, 16) of the jack selectively in relation with a source of fluid under high pressure (20, 26) or with a reservoir of fluid at low pressure (24), and an auxiliary circuit controlled by a mechanism (76) sensitive to the position of the piston (12) of the jack (10). The auxiliary circuit comprises a slide distributor (50) which ensures the return of the piston (12) of the jack (10) into a rest position in the event of a failure of the electrical control mechanism by governing the distributor assembly (34, 34') of the main circuit.

Abstract: A counterbalance valve for use in drive oil hydraulic circuitry of an oil hydraulic motor is constructed so that an oil hydraulic motor can slow down without shock, while cavitation is prevented, thus coming to rest in a short period time. A spool (26) is retained by springs in a neutral position. Pressurized oil in a left pressure receiving chamber (28) moves the spool (26) to a first position in which the port (23) on the second pump side is connected to the port (25) on the second motor side, whereas pressurized oil in a right pressure receiving chamber (29) moves the spool (26) to a second position in which the port (22) on the first pump side is connected to the port (24) on the first motor pump side. Throttle apertures (37, 38, 39) are arranged between the left pressure receiving chamber (28) and the port (22) on the first pump side, and throttle apertures (37, 38, 39) are also arranged between the right pressure receiving chamber (29) and the port (23) on the second pump side.

Abstract: A hydraulic platform lift for use on trucks and truck trailers has two hydraulic cylinders, one on each side of a door. The cylinders are phasing cylinders in that one cylinder is larger than the other cylinder by a specific ratio. The cross-sectional area of the fluid in the rod end of the larger cylinder minus the area of the rod is equal to the cross-sectional area of the smaller cylinder. A connecting line interconnects the rod end of the large cylinder with the cap end of the small cylinder. Hydraulic fluid can be directed by a controller into the cap end of the large cylinder or the rod end of the small cylinder. For upward movement, hydraulic fluid is forced into the rod end of the small cylinder. This in turn forces hydraulic fluid through the connecting line into the rod end of the large cylinder, thereby raising both pistons.

Abstract: A locking valve for selectively locking fluid pressure in a fluid cylinder in the event of failure of the source of fluid pressure to the cylinder and including an integral fluid flow control valve, the locking valve also including a fluid pressure seal between the fluid supply port and the pilot port of the locking valve to prevent back pressure on the pilot pressure operated valve components.

Abstract: A counterbalance valve with a relief function, disposed in a pair of supply and exhaust lines communicating a directional control valve with a fluid actuator for adjusting a flow area at an exhaust side of the supply and exhaust lines in response to a pressure at a supply side of the supply and exhaust lines, which includes two divided spools, corresponding to the supply and exhaust lines, respectively, as a spool of the counterbalance valve, a device for moving one of the divided spools at the supply side of the supply and exhaust lines in such a direction that the flow area increases in response to an increased pressure at the exhaust side of the supply and exhaust lines, when the pressure increases beyond a predetermined pressure due to a pumping function of the fluid actuator, and a communicating passage for communicating the exhaust side of the supply and exhaust lines with a supply side of the supply and exhaust lines when the moving device is actuated so that the fluid at the increased pressure at the

Abstract: The invention concerns a spindle drive for a veneer lathe. In view of reducing the mobile masses of the drive gear equipment making the lathe better adaptable to different log lengths, the opposite spindles in the lathe are provided with drive motors of their own. In the preferred embodiment, the rotor of the motor is mounted directly on the spindle and the stator is mounted on a frame unit displaceable on guides. The motor may be an electric motor provided with speed regulation, or it may be a hydraulic motor.

Abstract: A lock valve for marine hydraulic steering systems includes a valve body with a spool valve reciprocatingly received in a bore therein. A first port and a second port of the valve are connected to a manual pump. A third port and fourth port are connected to a double acting hydraulic cylinder connected to a rudder or steerable motor. There are valves within the lock valve which normally prevent fluid flowing between the ports so the steering system remains in a fixed position when the helm is released. Fluid can flow from the first port to the third port when the first port is pressurized. A return flow of fluid from the fourth port to the second port is permitted only when the first port is pressurized. When the second port is pressurized, fluid can flow the second port to the fourth port. A return flow of fluid from the third port to the first port is permitted only when the second port is pressurized.