Abstract: A hydraulic fluid pressure amplifier system includes a boost cylinder assembly, an energy storage device in fluid communication with the boost cylinder assembly, and a working cylinder assembly. The boost cylinder assembly is configured to selectively receive a plunger member into a boost cylinder, wherein movement of the plunger member received in the boost cylinder compresses a charge fluid within a blind side volume of the boost cylinder from a first fluid pressure to an amplified fluid pressure greater than the first pressure. The working cylinder assembly is selectively operable responsive to receiving a source hydraulic fluid having a nominal fluid pressure less than the amplified fluid pressure for effecting the movement of the plunger member into the boost cylinder. The energy storage device is operable to selectively receive and store a portion of the charge fluid compressed to the amplified fluid pressure.

Abstract: A brake release mechanism for a spring brake actuator includes a brake release bolt having a threaded portion, a running engaging the threaded portion, the running nut being adapted to axially travel along the threaded portion in order to move a spring brake actuator piston against a force of an actuator power spring, an indicator device comprising an indicator pin being at least partially accommodated in a receiving space of the release bolt, wherein the indicator device further comprises a pin actuator for axially moving the pin relative to the receiving space. It is proposed according to the invention that the pin actuator comprises an indicator cap being attached to the pin, the indicator cap comprising a basic body and at least one spacing element being attached to the basic body, the spacing element being configured to abut against the running nut.

Abstract: A hydraulic fluid pressure amplifier system includes a boost cylinder assembly, an energy storage device in fluid communication with the boost cylinder assembly, and a working cylinder assembly. The boost cylinder assembly includes a boost cylinder and a boost cylinder piston movable relative to the boost cylinder between a retracted position and an extended position, wherein movement of the boost cylinder piston from the retraced position to the extended position compresses a hydraulic fluid in a blind side volume of the boost cylinder from a nominal fluid pressure to an amplified high fluid pressure greater than the nominal fluid pressure. The energy storage device receives the hydraulic fluid compressed from the nominal fluid pressure to the amplified high fluid pressure. The working cylinder assembly is operatively connected with the boost cylinder assembly and is selectively operable for effecting the movement of the boost cylinder piston.

Abstract: A fluidic valve may include an inlet, a control port, an additional control port, an outlet, a fluid channel configured to convey fluid from the inlet to the outlet, and a piston that includes (1) a restricting gate transmission element configured to block, when the piston is in a first position, the fluid channel and unblock, when the piston is in a second position, the fluid channel, (2) a controlling gate transmission element configured to interface with a control pressure from the control port that forces the piston towards the first position when applied to the controlling gate transmission element, and (3) an additional controlling gate transmission element configured to interface with an additional control pressure from the additional control port that forces the piston towards the second position when applied to the additional controlling gate transmission element. Various other related devices, systems, and methods are also disclosed.

Abstract: The disclosed invention introduces an efficient lifting mechanism for reciprocating vertically a load system, the load consisting of the aggregate weights of a cargo payload in conjunction with “dead weights” of moving parts of the lifting apparatus. The disclosed invention uses a hydro-pneumatic linear actuator to lift the load and a pressurized accumulator, acting as a force intensifier. The pressurized accumulator, acting as a self-contained stored energy source, provides to the actuator adequate power to lift the “dead weights” plus part of the cargo payload. An external power source provides to the actuator adequate power to lift the remainder of the cargo payload. The disclosed invention saves significant amounts of power and energy in applications in which the “dead weights” are sizable compared to the cargo load. The disclosed invention provides also exceptional means for accurate motion control of the cargo payload.

Abstract: The invention concerns a telescopic hydraulic cylinder, comprising an inner cylindrical tube and an outer cylindrical tube located concentrically about the inner cylindrical tube, and a guide ring for guiding the inner and outer cylindrical tubes, the guide ring has a cylindrical support surface with a centre line and a guide surface and is mounted in a cylindrical groove. The guide surface slides along the inner surface of the outer cylindrical tube or the outer surface of the inner cylindrical tube. In accordance with the invention the guide surface has a curved surface with a curve radius and a tangent and the tangent to the curved surface and the centre line form an inclination angle; wherein the inclination angle is between zero and five degrees and the curve radius is larger than the radius of the guide ring in the plane perpendicular to the centre line.

Abstract: A cushion arrangement for smoothing stage changes in an hydraulic cylinder and including at least one compression chamber of variable volume with a movable and/or deformable chamber wall element displaceable by at least one of the pistons when approaching the transition zone between first and second stages of displacement. The compression chamber is operatively connected to a gas volume to be compressed upon displacement of the chamber wall element.

Abstract: A hydraulic actuator has an armored section having concentric cylinders and an unarmored section having a cylinder with a frangible piston and a frangible upper gland nut. The hydraulic actuator may have leakage vents adapted to prevent leakage between hydraulic systems used to power the cylinders. The hydraulic actuator also may have a gland seal for sealing an end of the cylinder of the unarmored section and a sensing port adapted for allowing detection of fluid leaking due to damage of the gland seal.

Abstract: A digital hydraulic system including a hydraulic source, a housing and a transtatic bridge. The transtatic bridge being substantially contained within the housing. The transtatic bridge being in fluid communication with the hydraulic source. The transtatic bridge communicating a force to or from a shaft or a fluid.

Abstract: A die drive unit has a cylinder mechanism which hydraulically drives a piston member and an additional drive mechanism which drives the piston member by means of a drive source other than a hydraulic one. A first oil chamber is formed on one side of the piston member. A second oil chamber and a third oil chamber are formed on the other side of the piston member. The first oil chamber and the second oil chamber are connected to each other by an oil passage. The piston pressure receiving area of the first oil chamber is equal to the sum of those of the second and third oil chambers.

Abstract: A compact 180° opposed piston pump/compressor minimizes axial spacing between its pistons on the drive shaft and thereby reduces the shaking couple and noise from reciprocation. Each piston has its own eccentric element press-fit into the connecting rods so as not to occupy space between the pistons. The shaking couple can be further reduced for pistons of different masses by selecting the mass of the cup retainers to compensate for the difference in overall piston masses. The pump also includes an improved cylinder sealing arrangement having a circumferential groove in an angled surface at the end of the cylinder. The pump also has a special cover and seal for closing the open neck of the pump crankcase and an improved multi-lobed valve stop. The pump further uses tubular transfer members for transferring intake and/or exhaust air into the crankcase and/or between valve heads.

Abstract: This invention relates to a linear path slide (10) with a slide (26) which is arranged slidingly movable in a housing (12) along a sliding guide (20) and safe against torsion and with a hydraulic driving gear (40) integrated into the slide (26) for a shifting movement of the slide (26), whereby a working piston of the hydraulic driving gear (40) is configured with at least two stages, whereby each stage of the working piston forms a partial hydraulic driving gear (40′, 40″) of the hydraulic driving gear (40) so that higher actuation forces can thus be realized.

Abstract: A bidirectional self-contained end-of stroke snubbing device (20) includes a housing (21), a rod (22) movable relative to the housing, a single fluid-filled variable-volume chamber (23) communicating with a fluid sump (24) through an orifice (65), and a lost-motion mechanism for selectively reducing the volume of the chamber proximate either end of the stroke of the rod-like member. The mechanism will force fluid from the chamber through the orifice to decelerate and cushion movement of the rod-like member relative to the housing proximate either end of its stroke.

Abstract: The pressing method includes the first step of displacing a sub-piston provided within a sub-cylinder from its initial position to press working fluid such that the working fluid is introduced via a check valve into a main cylinder to displace a main piston provided therein, and the second step of causing the sub-piston to return to the initial position such that the working fluid is supplied to the sub-cylinder. The first and second steps are repeated successively until the working fluid in the main cylinder attains a prescribed pressure level. With this method, variation in the way of pressing an object is alleviated, contamination due to the working fluid is prevented, and downsizing of the pressing mechanism is enabled.

Abstract: This engine is substantially free from any vibration and noise, small in friction loss, improved in mechanical efficiency to a considerable extent, compact and lightweight, and applicable to a reciprocating piston engine. The engine comprises: curved cylinders each assuming a circular shape in cross section; curved pistons (1, 1a) each fitting and reciprocating within the cylinder; a rotor (2) carrying the pistons (1, 1a) to keep them in balance and to have them be rockable about the center of the rotor (2), wherein the rotor (2) is provided with connecting rods (6, 6a) to impart half a rocking power of the rotor (2) to each of crank shafts (10, 10a) each of which converts the half of the rocking power to a piece of torque on its axis of rotation; a gear mechanism for receiving the pieces of torque to combine them into an output power; and, an output shaft connected with the gear mechanism for receiving and out-putting the output power.

Abstract: An actuator assembly that has a constant net pressure area telescoping piston. The actuator assembly has a cylindrical housing; nesting, telescoping pistons; a central plug; an outer cap; and a vent. The cylindrical housing has an interior surface and a base that terminates at an open end. The nesting, telescoping pistons are located in the housing and can extend past the housing open end. The telescoping pistons have an outer piston slidably sealed against the housing and an inner piston that is slidably sealed against the outer piston. The outer piston has a first end proximal to the housing base, and a second end distal to the housing base. The inner piston has an open end proximal to the housing base, and a closed end distal to the housing base. The central plug extends from the base and into the telescoping pistons. The central plug is in pressurized communication with the inner piston and is engagable with a pressurized fluid source. The outer cap has a first and a second member.

Abstract: A press assembly includes a hydraulic cylinder assembly having first and second chambers and respective piston and rod assemblies therein. The rod of the second assembly is arranged to enter the first chamber and thereby raise the pressure therein. Initially, fluid flows into the first chamber, forcing the first rod to exert a force on a work object. When a predetermined pressure is reached within the cylinder, fluid is introduced to the second chamber, and causes the second rod to move into the first chamber, which raises or boosts the pressure in the first chamber.

Abstract: A hydraulic motor has three interconnected power pistons. The pistons include passageways therebetween that allow a working fluid to be conserved upon reciprocating piston motion. Valves control the pressure state of working fluid within working chambers, which in turn will cause the three piston assembly to oscillate within the working chambers. The hydraulic motor is combined with a pressure source and an energy converter to form a hydraulic-pneumatic power plant. The energy converter converts pressurized working fluid from a single port into pressurized fluid passed through a first port and reduced pressure fluid passed through a second port. The pressure source is preferably pneumatic, which provides the necessary store of energy, or push, to initiate motion within the hydraulic motor.

Abstract: An hydraulic servo device for a friction brake in a planetary transmission for motor vehicles contains a cylinder with stepped interior wall, a stationary dividing wall that has a hole and divides the interior of the cylinder into two regions, one piston in each of the two regions formed by the dividing wall, and a hollow piston rod that passes through the hole of the dividing wall and connects the two pistons. The wall of the cylinder has passages, through which a pressure medium enters or exits the cylinder, in each one of the regions formed by the dividing wall. The pistons in each of the regions of the cylinder divides each of the regions into an application-pressure chamber and a release-pressure chamber, forming four chambers in the order of an application-pressure chamber, a release-pressure chamber, an application-pressure chamber, and a release-pressure chamber. The hollow piston rod has openings which allow the pressure medium to enter or exit the piston rod and the application-pressure chambers.

Abstract: A first cylinder of a smaller diameter and a second cylinder of a larger diameter are connected in a coaxially intercommunicating state. A first piston of a smaller diameter which is hermetically slidable within the first cylinder is mounted on a rod which is commonly passed through the two cylinders in such a way as to permit the first piston to move also in the second cylinder. Received in the second cylinder is a second piston which is hermetically slidable only in the second cylinder and which is adapted to be integrally coupled with the first piston during movements within the second cylinder.

Abstract: A brake booster mounting including a support to which the booster is securable by means of at least one mounting bolt, and a captive nut located on a side of the support opposite to that to which the booster is to be attached and which is engageable by the bolt so as to effect attachment of the booster to the support. The captive nut is held against separation from the support and is also held against rotation by a retainer so that connection of the bolt to the nut can be effected from the side of the support to which the booster is to be attached. A pilot section on one end of the bolt locates within the captive nut so as to thereby automatically position the nut to be cooperable with a threaded portion of the bolt. The bolt also serves to hold separable parts of the booster housing against separation, and is rotatable relative to those parts to permit the booster to be attached to or detached from the support.

Abstract: A low-impact drive unit operates by air under pressure. It includes aligned working and pressure chambers. The working chamber contains a working piston and a working piston rod extending from an end of the chamber. The pressure chamber contains a rear outer piston having a cylindrical recess and a central bore. An inner piston is located in the cylindrical recess and has a main piston rod extending through the bore, a bore in a separator separating the chambers, and is affixed to the working piston, so as to move together. The main rod has a longitudinal passage which supplies air from the pressure chamber to the back of the working piston under certain conditions. After the working piston rod contacts a workpiece, force of air pressure on all three pistons act on the working piston rod. An air return passage is provided to return the various components to their initial position after the working operation is complete.

Abstract: The vacuum servomotor comprises a main casing (12) divided sealingly on the inside into first and second chambers (10, 20) by a flexible membrane (9) bearing on a rigid disk (7) integral with an activating piston (3). The first chamber (10) is subjected to a low pressure, while the second chamber (20) is subjected either to this low pressure or to a higher pressure. An auxiliary casing (25) is integral with the rigid disk (7) and projects into the first chamber (10), an auxiliary piston (27) sealingly dividing the auxiliarly casing (25) on the inside into third and fourth chambers (30, 40), the third chamber (30) being closed by the rigid disk (7), the auxiliary piston (27) being mounted stationary relative to the main casing (12).

Abstract: The invention is directed to an arrangement for actuating a braking device for bringing a motor-driven work tool of a work apparatus to standstill. The braking device is actuated by a brake lever and the brake lever is connected to a pivotably journalled throttle lever via a first actuator. The throttle lever controls the carburetor of the engine driving the work apparatus via a second actuator. In order to bring the work tool rapidly to standstill in idle, the second actuator is attached to a drag lever which is pivotable relative to the throttle lever. After passing through an idle movement path, the throtle lever takes the drag lever along via a follower in a pivot direction.

Abstract: A gas cylinder valve for high pressure gas cylinders includes a pneumatic actuator with tandem pistons which are operated by normal industry "house" pneumatic pressures to overcome the large closing bias force generated by a set of disc springs so that the valve opening spring can lift the valve stem from its seat. A floating pressure plate which seats against an annular internal shoulder in the actuator housing prevents pneumatic pressure applied to the upper piston from acting on the back of the lower piston. Pneumatic pressure from a common source is applied to both pistons through an axial hole in a piston rod integral with one piston and bearing against the other piston. The actuator is easily assembled by merely inserting the lower piston, the pressure plate, the upper piston and the disc springs into the open end of a cup-shaped housing, and securing them in place with a preload on the springs by screwing on a housing cover.

Abstract: This invention relates to a fail-safe or auto-return actuator cylinder employing the air spring effect provided by compressed air trapped in an air-spring compartment; which air spring effect replaces the conventional mechanical coil spring employed in conventional fail safe or auto-return air cylinders. The air spring chamber integrally built into the cylinder body is connected to the compressed air supply tube through a check valve that provides the self-charging and self-recharging feature for the air-spring chamber and, consequently, the air-spring chamber remains fully charged with compressed air even when there is a compressed air leak from the air-spring chamber. The air-spring compartment stays charged or becomes automatically recharged even when there is a leak from the air-spring compartment as long as there is compressed air to actuate the cylinder.

Abstract: The invention provides a piston and cylinder unit whose piston rod is sealed by a supporting and sealing arrangement arranged in an end cap of the unit. This supporting and sealing arrangement comprises a sealing portion made integrally with a stripper portion and joined therewith to form a sleeve-like sealing member surrounding the piston rod having the said portions at its ends. A lubricant-permeable supporting bushing encompassing the piston rod is mounted in the sealing member between the sealing and stripper portions and receives lubricant from lubricant reservoirs in the part of the sealing member between the stripper and sealing portions.

Abstract: The casing of the jack is divided into two cylinders by a cross partition, with a first piston which moves in one of the cylinders and a second piston, forming two parts, linked by a rod which crosses the partition to its first part which moves in the first cylinder-shaped piston and its second part which moves in the second cylinder of the jack. The fluid is conveyed selectively either to the cylinder formed by the first piston or to the second cylinder which communicates with the first cylinder through holes drilled in the partition.

Abstract: The Compressor is small, compact and lightweight in that it is formed of the barest essentials. It has a pair of in-line cylinders, with pistons reciprocatable therein, and the crankshaft, having only one crank, is drivingly coupled to one of the pistons. The other piston is fastened to the crank-driven piston, in spaced-apart disposition, for a common reciprocation of the two. One of the cylinders serves as the crankcase.

Abstract: A self-lubricating die cylinder assembly is provided containing a cylinder, piston, expansion reservoir and working chamber. A lubricating oil recirculation means is provided to transport oil between the working chamber and the expansion reservoir during each of the piston strokes. A flow restrictor is provided to create a pressure differential between the two chambers during movement of the piston thus creating a jet mixture of compressible working fluid and lubricating oil spraying onto the walls of the cylinder.

Abstract: In an actuator (102), a piston head portion (108) reciprocates in a large diameter section of a cylinder casing (102), dividing such section into first and second variable volume chambers (112, 116). An end portion (104) projects outwardly of the cylinder casing (102) and includes a mounting (162) at its end. The opposite end portion (106) extends into a third variable volume chamber (120). A piston head portion (82) reciprocates in a piston section (72) of a volumetric compensator (14). One end portion of piston (80) is slidably received within first variable volume chamber (90). The opposite end portion (86) of the piston (80) extends through a central opening in a diverter wall (88) between the piston section (72) and a gas charge section (78). Pressurized gas within the gas charge section (78) acts on the second end (86) of the piston (80), forcing hydraulic fluid in chamber (90) to chamber (120 ) of actuator (102).

Abstract: The actuator (12) comprises three main parts, an outer casing (20), a movable piston (28) and a fixed piston (36). A stepped outer portion (50, 52, 54) of the movable piston (28) cooperates with a stepped cavity (40, 42, 44) in the casing (20) to define a plurality of concentric, variable diameter fluid chambers (1, 2, 3) bounded at their ends by radial surfaces on the movable piston (20) and within the casing cavity. The movable piston (20) and the fixed piston (36) define a plurality of axially spaced apart variable diameter fluid chambers (1', 2', 3') which are bound on their ends by radial surfaces on the fixed piston (36) and radial surfaces within the cavity formed in the movable piston (20). One set of the chambers (1, 2, 3) is connected to supply pressure (P.sub.S) and the second set of chambers (1', 2', 3') is connected to return pressure (P.sub.R). Seal receiving grooves are formed in outer surface portions of the fixed and movable pistons (28, 36). Seal rings (S.sub.

Abstract: A hydraulic servo device with a built-in accumulator, comprising a servo piston fit in a servo cylinder and connected via a stem to a band brake, an accumulator piston having a large diameter outer diameter portion and a small diameter outer diameter portion fit in the servo cylinder at two inner diameter portions thereof having different diameters and an inner diameter portion fit around a small diameter outer diameter portion of the servo piston, and an accumulator piston spring biasing the accumulator piston toward the servo piston.

Abstract: The invention relates to a hydraulic actuator for the control of valves such as the kind found in ships. The actuator has a piston which is actuated in a valve opening direction with a hydraulic pressure medium and may be actuated in the return direction by a gas-compression type spring. Certain emergency situations require an immediate closing of a valve or group of valves controlled by the piston acting through a spindle. Emergency closing apparatus includes an abutment on the piston which forms an annular chamber when the piston abuts the end wall of the piston cylinder. The housing has an emergency passage means in fluid communication with the annular chamber when the piston abuts the end wall to effect an emergency moving of the piston in a valve closing direction when a pressure medium is admitted into the emergency passage.

Abstract: In a cylinder apparatus for a rack and pinion type power steering mechanism of a motor vehicle or the like, including two pressure chambers defined in a power cylinder, there is provided means for making the effective pressure-applied areas of the two pressure chambers substantially equal to each other, whereby steering operation can be performed with accuracy and ease.

Abstract: A control valve and a multiple control system therefor for controlling a plurality of remotely positioned hydraulically actuated underwater devices. The control valve includes first and second equal size pilot pistons acted upon by first and second pilot ports, respectively, for moving the valve to either an open or closed position, and third and fourth unequal size pilot pistons acted upon by third and fourth pilot ports for moving the valve to either an open or closed position. The control valve may be operated in an electro-hydraulic control mode by the use of electrically actuated valves controlling the supply of fluid to the first and second ports. In addition, the control valve can be operated in a hydraulic mode by hydraulically controlling the supply of fluid to the third and fourth pilot ports.

Abstract: In a belt type stepless shifter, movable flanges of pulleys are driven by hydraulic cylinders, and each of the cylinders is provided with a plurality of pressure carrying surfaces disposed in the axial direction, thereby a great amount of torque can be transmitted at low hydraulic pressure or at a small outer diameter. The belt type stepless shifter is adapted for use in a transmission apparatus of vehicles.

Abstract: A hydraulically operated actuator employs multiple metal-to-metal static seals to isolate the hydraulic fluid and to isolate the actuator from surrounding contaminating (ambient) fluids. A housing contains at least two linearly spaced apart chambers. A piston reciprocates from a retracted position to an extended position (power stroke) and from the extended position to the retracted position (return stroke) in one of the chambers (hydraulic chamber). The hydraulic chamber is separated by the piston into two sections, one of which contains high pressure hydraulic fluid and the other of which contains low pressure hydraulic fluid. A first static metal seal ring unit is designed to seal first at the completion of the power stroke of the piston to isolate the low pressure hydraulic fluid section from external contaminating fluids which may be at a higher pressure.

Abstract: A compact valve actuator for operating a valve of the butterfly type or the like. The actuator comprises a pair of joined pistons which respond by simultaneous reciprocation to introduction of operating fluid such as air into the actuator. Means such as a linkage for connecting the actuator to a valve is provided, such means being connected to the pistons interiorly thereof for minimizing the actuator size for a given required stroke. One of the pistons at a bearing surface thereof, rides on a guide means received interiorly of the piston thereby further enhancing the compactness of the actuator. The surface of the guide means is pressurized with the operating fluid applied to that one piston whereby risk of operating fluid leakage across that piston at the bearing surface thereof is substantially eliminated.

Abstract: A vent accumulator for a hydraulic integrator of the type having at least three pistons arranged in end-to-end relationship within an elongated housing. Each piston is adapted to move under hydraulic pressure in a direction away from one longitudinal end of the housing towards the opposite longitudinal end. Each of the pistons, except for the last piston adjacent the opposite end of the housing, is provided with a piston rod operatively connected to the piston next adjacent towards one end of the housing. Each piston is defined as having a first side directed towards one end of the housing and a second side directed towards the opposite end of the housing. Each of the pistons, except for the last two pistons in line, is provided with means for receiving hydraulic fluid under pressure from a load cell on its first side and an air vent communicates on it second side.

Abstract: The use of the air-spring in automatically retracting (or extending) an air cylinder after it was extended (or retracted) by the air pressure supplied from the compressed air line is disclosed.

Abstract: A hydraulically actuated gate valve having a hermetically sealed piston head adapted to receive a remotely operable actuator for overriding the valve to open the gate.

Abstract: A telescoping hydraulic cylinder apparatus for elevator application, wherein telescoping cylinders and a piston rod extend or retract simultaneously, having a compensator pump for automatically replenishing fluid lost due to leakage from the upper cylinders of the apparatus.

Abstract: A two-stage double acting telescopic hydraulic cylinder includes two fluid ports formed in the external cylinder, one port for receiving fluid to distend both cylinder stages and the other port for receiving fluid to retract both cylinder stages. The cylinders are used in combination with car carrying trailers.

Abstract: Disclosed is a pneumatic launch apparatus which employs separable telescoping tubes. The open ends of the tubes are provided with valves which automatically close upon separation of the tubes to trap operating gas in the tubes at the moment of separation.

Abstract: In a piston and cylinder assembly the cylinder comprises at least one annular cylinder block received in a complementary bore of a housing. A means for axially retaining the cylinder block in place relative to the housing includes a pair of slidably engaging part spherical surfaces one of which is carried by a radially displaceable member to adjust for misalignment between the cylinder block and an associated retaining component and to thereby alleviate axially offset pressure which might otherwise be applied to the cylinder block.

Abstract: A heavy-duty disc brake assembly and pneumatic actuating assembly therefor. The pneumatic actuating assembly may include a pair of annular pistons operatively connected for simultaneous movement thereof, apparatus being provided for supplying air under pressure to the working faces thereof, or a single piston spring biased to braking position with apparatus for supplying air under pressure to either face thereof. The disc brake assembly includes a plurality of relatively movable rotor and stator discs, and preferably a closed cooling system with circulatory loop is provided.

Abstract: An extendible and contractible shaft comprises a number of shaft members on a common longitudinal axis, each except the outermost member being telescoped within the one next adjacent. Each telescoped member has a piston slidably sealed to the inner wall of the next adjacent outer member to form a series of tandem arranged sealed pistons. Fluid passageways are provided between adjacent shaft members so that fluid supplied under pressure to an inlet port of the device flows through the passageways to all the piston heads, thereby extending the telescoped shaft members and at the same time driving fluid out from under each piston through fluid passageways to an exit port of the device. When the pressurized fluid flow is reversed to send pressurized fluid to the undersides of the pistons, thereby driving fluid above the piston heads out through the first mentioned port, there would normally be incurred substantial shock as each piston head strikes its stop in the retraction operation.

Abstract: An actuating device comprises a cylinder of hollow cylindrical form a plurality of pistons respectively of different operational strokes slidably fitted within the cylinder and undergoing sliding displacements in a mutually unitary manner in regions where their strokes overlap and in a separate manner in regions where their strokes differ under driving force due to a working fluid supplied into and discharged from the cylinder interior through ports provided in the cylinder, a working fluid system for supplying the working fluid and having at least one changeover valve for controlling the working fluid supply into and discharge from the cylinder, the piston of longest stroke among the pistons being a driving piston, and a driven shaft coupled to the driving piston thereby to be driven by the sliding displacement thereof. The driving piston undergoes sliding displacement in a noncontinuous manner in multiple stages, whereby the driven shaft is driven in multiple stages.

Abstract: This invention relates to a telescopic jack constituted by a main cylinder, a first piston sliding in said main cylinder, a first piston rod fast with the first piston which passes in tight manner through a first bottom of the cylinder, a second piston which may be disposed in a bore of the first rod and is mounted to slide with respect to the first piston, and by a second piston rod which is fast with the second piston.The second piston rod passes through the second bottom of the cylinder whilst the piston is separable from the rod.One application of the invention is the production of an inexpensive telescopic jack.