Abstract: A rod seal system having a pair of rod seals that form a buffer area between a high pressure area containing working gas and a low pressure area of a heat engine, such as a Stirling cycle engine. A pump that becomes passively charged with working gas at relatively low pressure and which releases working gas at relatively high pressure when actuated is used to force working gas from the buffer area to the high pressure area through a conduit. The working gas may be hydrogen gas and the pump may be a metal hydride pump that is thermally actuated. The low pressure area may contain air and lubricant at atmospheric pressure. A system for separating the lubricant collecting within the buffer area and reintroducing the lubricant into the low pressure area can also be incorporated into the rod seal system.

Abstract: The high-pressure fuel supply device for an internal combustion engine for pressurizing fuel to a high pressure and supplying the pressurized fuel to the internal combustion engine.

Abstract: A chuck drive system, especially for a rotating clamping device of a machine tool, includes a rotating chuck cylinder, a stationary frame positioned adjacent the chuck cylinder, and a piston which subdivides the cylinder into two pressure chambers and is formed with a piston rod having one end rotatably supported in the stationary frame. Fluid under pressure is supplied to the pressure chambers, whereby check valves are positioned in the passageways to the pressure chambers to maintain the fluid pressure in the pressure chambers. In order to monitor the fluid pressure in the pressure chambers, a pressure monitoring unit is provided which includes pressure sensors that are respectively assigned to the pressure chambers for determining the fluid pressure in the pressure chambers separately and independently from one another.

Abstract: An actuator, particularly for the operation of a vehicle clutch in which an annular piston (10) slides between cylinder walls (11, 12) to define an annular working chamber (20). A sealing means (15) seals the piston to the cylinder walls and an overflow chamber (26, 27) retains any fluid which leaks past the sealing means from the working chamber. A return means (28) is also provided for returning fluid from the overflow chamber when the piston is not undertaking a working stroke.

Abstract: A high-pressure and a method for high-pressure treatment of substances. The high-pressure press comprises a high-pressure cylinder consisting of a number of concentrically arranged cylinder elements (1, 2, 3). The cylinder elements (1, 2, 3) are radially prestressed to a predetermined prestress and surround a high-pressure chamber (6) for accommodating a pressurized medium. A thin safety liner (3), which is intended to be placed in the high-pressure cylinder until a fracture arises on the safety liner (3), is arranged in the interior of the high-pressure cylinder. Further, means (14, 15) are provided to conduct at least part of the pressurized medium from the high-pressure chamber (6) when a fracture arises on the safety liner (3). The means (14, 15) comprise at least one channel (14) running essentially along the outer envelope surface of the safety liner (3). The method comprises using the high-pressure press without liner replacement until a fracture has occurred on the thin safety liner.

Abstract: A fuel injection pump includes a casing; a drive shaft rotatably mounted in the casing and extending from a drive receiving end which is located outside of the casing to a point inside the casing; and first and second spaced apart seals each for preventing the flow of fluid between the casing and the drive shaft at the location of the seal. A chamber is formed between the drive shaft and the casing, the chamber being bounded at opposite ends thereof by the seals, and a vent passage extends from the chamber to a point on the surface of the casing to vent the chamber. The vent passage includes a portion defined by the clearance space between a screw threaded opening and a screw threadedly engaged with the opening. The screw is preferably a screw which secures the casing to the engine supplied by the pump.

Abstract: A fluid pressure operated clutch release bearing for a diaphragm clutch of a motor vehicle includes a fixed part which comprises a cylindrical annular external body and an internal tube. The body and tube together define an annular cavity, into which pressurised fluid is fed for controlling the release bearing by actuation of a tubular piston, which slides axially in the cavity and which has a front end portion that carries an actuating element which acts on the clutch diaphragm. This front end portion also carries a finned sealing ring which cooperates with the outer peripheral surface of the tube, so as to restrict leakage of fluid through the annular space which is defined between the outer surface of the tube and the internal bore of the piston; and the piston has at least one evacuation orifice which connects the annular space to a zone in which leaked fluid can be recovered.

Abstract: An oil mist eliminator filter used with a dynamic oil control mechanism consisting of a vacuum-inducing jet-pump to vacuum oil leaking from about an oil seal, an oil seal located around the drive piston on the press slide, a drain port located about the housing in which the drive piston reciprocates. The oil mist eliminator filter, downstream of the jet pump, separates the oil from the air with 99.97% efficiency allowing the cleaned air to escape freely to atmosphere without causing pressurization of the press reservoir and leaks at the press reservoir, and allowing the oil to constantly recirculate back to the press reservoir thus permitting use of the oil control system without the need to shut the oil control system off to drain accumulated leakage oil.

Abstract: An intensifier type of fluid actuator includes a body including a first manifold connected by a first tube to a second manifold to define an intensifier chamber, a third manifold connected by a second tube to the second manifold to define a reservoir chamber, and a fourth manifold connected by a third tube to the third manifold to define a work chamber. A reservoir piston is disposed within the reservoir chamber and has an outer surface in sealing and sliding engagement with the second tube. The reservoir piston includes an inner surface defined by a central opening formed therethrough which extends from a first end of the reservoir piston adjacent to the second manifold to a second end of the reservoir piston adjacent to the third manifold. A passageway is formed in the reservoir piston which extends from the inner surface to the outer surface, thereof.

Abstract: The invention relates to a hydraulic drive apparatus having a cylinder. Said cylinder comprises a piston movably mounted in a working chamber, a piston rod which is guided towards the outside through a cylinder head and a wear resistant primary seal and a leakage free secondary seal. Both said seals act between the cylinder head and the piston rod, with the primary seal being closer to the working chamber than the secondary seal. Further, a leakage oil conduit is provided between the primary seal and the secondary seal. Such a hydraulic drive apparatus is to be improved such that the cylinder will hold or maintain a load in a certain position even if the pump is switched off for a long period of time. This is achieved by providing that the leakage oil conduit can be subjected to the load holding pressure by switching a valve.

Abstract: A dynamic oil control mechanism for a press including a vacuum inducing ejector or jet-pump to vacuum oil leaking from about an oil seal. The oil seal is located around the drive piston on the press slide to prevent oil migration from the press crown to the die area or slide of the press. A drain port is located about the housing in which the drive piston reciprocates. The ejector maintains a low pressure area within the drain port to pull oil leaking from the seal into the drain port and away from the drive piston. The vacuumed oil is then transferred to an oil reservoir.

Abstract: A hydraulic cylinder bearing gland for seals hydraulic cylinder chamber having an a piston rod extending externally therefrom and includes a cylindrical sleeve with an inner bearing surface having an axial length greater than the outer diameter of the piston rod. The inner bearing surface also has a spiral, helical groove machined therein permitting fluid flow from the cylinder chamber along the length of the inner bearing surface of the bearing gland. A primary seal allows low volume flow of hydraulic fluid therethrough to prevent outside contamination from entering the cylinder chamber, while a secondary seal preventing fluid from exiting the cylinder. A port and annular groove between the primary and secondary seals return the flow of hydraulic fluid to a reservoir.

Abstract: A pump that is in essence leak-proof and prevents the escape to ambient atmosphere of environmentally hazardous fluent materials is comprised of an outlet block defining a pump chamber having a fluid inlet and a fluid outlet, a piston having one end reciprocable within the pump chamber and sealed to the outlet block, a piston rod connected to the other end of the piston for reciprocating the piston, a dynamic block secured to the outlet block and defining a sealed dynamic chamber within which the other end of the piston reciprocates, and an outlet from the dynamic chamber in continuous closed-circuit communication with a recirculating system for preventing escape into the environment of any fluent material that may leak past the piston seal. The pump also includes an articulated seal for sealing the piston rod to the dynamic chamber to maintain the sealed integrity of the chamber while at the same time accommodating reciprocation of the piston rod.

Abstract: A fluid-powered actuator (42) has a body (11) which includes an end wall (16) provided with a through-opening (21). A piston rod (44) has an inner portion (44A) arranged on one side of the end wall within a pressurizable working chamber (24) of the actuator, has a penetrant portion (44B) passing through the end wall opening, and has an outer portion (44C) arranged on the other side of the end wall. The rod is configured such that the transverse cross-sectional area of the penetrant portion is greater than the transverse cross-sectional area of the outer portion so as to define an annular surface (46) which faces away from the actuator chamber. The improvement provides a seal assembly (43) for containing fluid leaking from the actuator chamber.

Abstract: A hydro-pneumatic pressure transformer with a storage piston fixed between storage oil and compressed air, which furthermore is centrally penetrated by a plunger piston, wherein, for the separation of oil from water, relief grooves are provided on the jacket face as well as in the wall of the central bore, which are connected with each other and are pressure-relieved via a ventilating bore leading to the exterior.

Abstract: A reciprocating mechanism includes two cylinders oppositely extended outwards from a housings a piston slidably engaged in each of the cylinders, a cap fixed to the free end of each of the cylinders, a pair of gears rotatably supported in the housing, a pair of pinions engaged between the gears, and a pair of racks engaged with the gears respectively and secured to the pistons respectively. The pinions and the axles are rotated by the gears and the racks when the pistons move toward each other and move away from each other.

Abstract: A diaphragm valve for high pressure use has a metal diaphragm which is actuated into and out of direct engagement with a valve seat by an air operator acting through a force multiplying lever assembly. The valve seat is confined by rigid interior and exterior sleeves while the sealing surface is contoured to have a concave configuration corresponding to the contour of the diaphragm in its deflected position. The air operator is provided with a stroke adjustment mechanism that is locked in adjusted position by a member that is generally accessible only when the operator is disconnected from the valve.

Abstract: A hydraulic telescoping ram of the type suitable to tip dump trucks and the like, which permits the use of outer aggressive seals and a bore sealing device by providing a conduit which hydraulically connects the upper end of each cylinder of the telescopic ram with an oil reservoir. This makes it possible to use seals which are not aggressive and which can run on surfaces of somewhat less than top quality, on the internal bottom faces of the rams so as to allow the passage of a small quantity of oil into a gap formed within the ram and cylinder and between the aggressive and non-aggressive seals. The oil which passes the non-aggressive seal is returned to the oil reservoir when the ram is extended.

Abstract: The present invention is drawn to an isolation system for separating two diverse fluid mediums from each other and, more particularly, an isolation system for prohibiting leakage of the diverse mediums around the peripheral surface of a piston movably mounted within a chamber. The present invention further relates to an improved multi-piston air-oil pressure intensifier employing the improved isolation system for separating and preventing leakage of the air and oil mediums during operation of the pressure intensifier.

Abstract: An apparatus for transferring electrically conductive coating materials such as water-based paint from a source to an electrostatically charged dispenser includes first and second shuttle devices and two large reservoir, piston pumps each having structure for preventing contamination of the coating material and pressure build-up at their piston heads. The first shuttle device is movable between a neutral position wherein it is electrically isolated from a filling station connected to the coating material source, and a transfer position wherein coating material is transmitted to one of the piston pumps through a coupling device which connects the filling station and first shuttle.

Abstract: Fluid is detected within a protective encasement of an hydraulic cylinder of an elevator by applying a low pressure to the interior of the encasement and sensing for the presence of fluid as a result of the application of the low pressure. If fluid is detected, a greater pressure is applied within the protective encasement to eliminate the detected fluid. The protective encasement, which may be pressurized, has a pressure input port, an evacuation port, and an evacuation tube which attaches to the fluid evacuation port and extends to a region within the encasement below the bottom of the cylinder.

Abstract: Actuator (14) drives inlet vanes (22) selectively to three positions, using high (58) and low (56) pressure fuel as the driving medium. Each of the three position is externally adjustable (94, 92, 68). An overboard leak path (86) is provided at the most often sliding seal.

Abstract: Described herein is an internal mixer of the type including a mixing chamber rotatably accommodating mixing rotors therein, a hopper frame erected on the mixing chamber, a charge hopper provided on one lateral side of the hopper frame for charging a mixing material therethrough, and a floating weight provided in the hopper frame for upward and downward movements therein, the floating weight being held in an upper lifted position when charging a mixing material into the mixing chamber and then lowered into a pressing position in a mixing stage to apply pressure on the charged material in the mixing chamber, wherein the floating weight is dimensioned to have an axial length sufficient for closing an inlet opening formed in the side wall of the hopper frame in communication with the charge hopper, when in the lower pressing position, and lift means for lifting the floating weight up and down in the hopper frame is provided separately from a pressing means with a function of pressing the floating weight resilient

Abstract: In normal operation, a control or regulating device controls vehicle rear wheel steering in accordance with freely-selectable specifications. If a malfunction of the control or regulating device is detected, the latter becomes inoperative immediately. A piston-cylinder unit drivingly connected to the front wheel steering and a piston-cylinder unit drivingly connected to the rear wheel steering are simultaneously positively coupled to one another, with the result that the rear wheel steering is actuated positively via the front wheel steering.

Abstract: In a cryogenic refrigerator, a displacer 12 and its drive piston 28 are guided by a displacer guide 32 seated within an expander body 16. An expander cap 40 enclosing a spring volume 38 extends within the expander body 16 and abuts the displacer guide 32. An indium seal 50 is positioned in the chamfer at the intersection of the cap, body and guide.

Abstract: Hydraulic fluid is replenished in a pulsator chamber of a fluid driven pulsator pump by having the power plunger in an upstanding bore with spaced seals. The power plunger is withdrawn upon each stroke vertically upward. As it is withdrawn past seals, any gas within the pulsator chamber may be purged or bled into an annular space and there out into a reservoir and scrubbing chamber. Additional hydraulic fluid will flow into the pulsator chamber. Upon the down stroke of the plunger an exact amount of volume will be displaced within the pulsator chamber. Adjustment of the product pumped on each stroke is by sacrificing a measured amount of the pulsator liquid into a sacrifice chamber. The amount of liquid which flows into the sacrifice chamber upon each down stroke and out of the chamber on each upstroke is adjusted by adjusting the movement of a floating piston by a micrometer rod.

Abstract: Method and apparatus for recovering leaked fluid or directing fluid flow or propagation through utilization of negative pressure pulses occurring in a pressurized fluid system. The invention has particular application in double acting hydraulic fluid motors where leakage of hydraulic fluid past the output shaft seal may be efficiently collected and redirected into the pressurized hydraulic fluid system through utilization of negative pressure pulses that are developed periodically by fluid direction changes during operation of the hydraulic fluid motor.

Abstract: A rod seal for a linear hydraulic or pneumatic actuator cylinder includes a seal ring that has a bore that closely matches the diameter of the rods, proximal and distal cylindrical portions and a central annular flange. A seat in the actuator cylinder distal end assembly has proximal and distal cylindrical portions and a central void to receive the rod seal ring proximal and distal portions and central flange respectively. A radial clearance is provided so that the rod seal ring can travel radially, at least for a limited distance, while the rod passes axially through it. Static elastomeric ring seals are provided in the proximal, distal and central portions, and define pressure balancing regions. The rod seal assembly can be constructed at low cost, yet achieve a high degree of sealing with low axial friction characteristics.

Abstract: An improved seal arrangement is used in a cushion assembly of a press. The seal arrangement includes a high pressure piston seal assembly which is connected with a piston and is disposed in sealing engagement with a cylinder of the cushion assembly. The high pressure piston seal assembly blocks fluid flow between upper and lower variable volume chambers of the cushion assembly. A high pressure cylinder seal assembly is disposed in sealing engagement with a piston rod and the cylinder to block fluid flow from the upper variable volume chamber along the piston rod. An outer low pressure seal assembly is also provided between the piston rod and cylinder to block contaminants from entering the cylinder from the surrounding environment. A low pressure leak down chamber is provided between the high pressure cylinder seal assembly and the low pressure seal assembly.

Abstract: Hydraulic fluid leakage collection apparatus that includes an annular collection chamber that is carried in a cylindrical member within which a piston member is movable. A seal and wiper are carried by the clamp cylinder of an injection molding machine to seal the space between the clamp piston and the clamp cylinder and also to wipe from the surface of the clamp piston accumulated hydraulic fluid. Positioned adjacent the wiper ring is a drain passageway that is adapted to receive the hydraulic leakage fluid that is wiped by the wiper ring from the piston. A conduit extends from the drain passageway to an air operated vacuum pump to draw the leakage hydraulic fluid from the drain passageway. A container is positioned in the conduit between the drain passageway and the vacuum pump to collect the hydraulic leakage fluid that is collected.

Abstract: A plunger pump comprises a cylinder (1); a plunger (2) reciprocating within said cylinder; a sucking chamber (1a) formed upon a top of said plunger; a sucking pipe (4) and a discharge pipe (5) communicated with said sucking chamber; and slidable means (1b) formed upon an inner wall of said cylinder in the proximity of an open end thereof. The sucking chamber and the slidable means are intercepted from each other by an intercepting fluid stream formed therebetween, thereby any contaminants occurring from the slidable means are prevented from being penetrated into the sucking chamber, and discharged outside the plunger pump together with the intercepting fluid stream.

Abstract: A hydraulic power drive unit for connection to the hydraulic system of an agricultural tractor is provided with a pressure release valve to protect the unit seal from damage if connected the wrong way round, and a bleed pipe which bursts to relieve pressure if the pressure release valve fails to operate.

Abstract: A hydraulic cylinder apparatus is used by connecting an external pressure source with extension and contraction-side liquid chambers defined by a cylinder, a piston sliding in the cylinder and a piston rod integral with the piston. The apparatus includes seal members provided with the extension and contraction-side liquid chambers and formed to enable liquid to leak through clearances between the seal members and the parts disposed opposite to the seal members. Liquid leaked from the extension and contraction-side liquid chambers is received by a receiving chamber which is formed so as to change its volume with the movement of the piston rod.

Abstract: A housing of a reciprocating gas compressor comprises a partition member separating an upper suction chamber through which gas passes and a lower crankcase chamber in which a crankshaft rotates and which has an oil sump at the bottom. The partition member is imperforate except for sealed openings through which cylinder sleeves and hydraulic fluid lines extend between the chambers. A conduit located on the housing exterior and connected between the chambers performs three functions, namely: enables gas flow in either direction to effect pressure equalization; enables oil to flow by gravity from low points in the upper chamber into the sump; and enables oil mist in the gas flow through the conduit to coalesce on the inner walls of the conduit and flow by gravity into the sump.

Abstract: A stroke variable device comprising a large diameter cylinder and a small diameter cylinder which are interconnected to each other. A large diameter piston and a small diameter piston are slidably inserted into the large diameter cylinder and the small diameter cylinder, respectively, and a cylinder chamber is formed between the inner end of the large diameter piston and the inner end of the small diameter piston. A first seal member is arranged to surround the projecting outer end of the large diameter piston, and a second seal member is arranged to surround the projecting outer end of the small diameter piston. One end of the first seal member is fixed to the projecting outer end of the large diameter piston, and the other end thereof is fixed to the housing of the device to form a first hermetically sealed chamber therein.

Abstract: A work cylinder having an internally-disposed, automatically-operated drain valve disposed in one or both ends of a housing having a cylinder bore formed therein. A reciprocally-movable piston divides the bore into first and second pressure chambers. A drain chamber formed in one or both ends has a movable plunger member disposed therein. A first passageway allows fluid from the pressure chamber to act on one surface of the plunger. A pilot valve is partially formed on a bottom portion of the plunger and opens when fluid pressure is exhausted from the adjacent pressure chamber. A bias spring acts on the plunger to prevent closing of the drain valve upon initial pressurization of the adjacent chamber. This initial pressurization assists in purging additional moisture from the chamber until a threshold level is exceeded to close the drain valve.

Abstract: An improved pump is provided for pumping non-lubricating fluids at extremely high pressure while reducing galling and wear on components such as pistons and cylinders. The reduction in component wear and galling is achieved by modifying the piston-cylinder combination to provide a pressure area and a centering area that is axially displaced from the pressure area of the piston-cylinder combination. The pressure area of the piston-cylinder combination is modified by reducing the diameter of the piston or increasing the inside diameter of the cylinder or both to provide a 0.1 percent to 2.5 percent increase in clearance at the pressure end of the piston-cylinder combination than is provided at a centering area. The advantages of the invention are further enhanced by employing a release area disposed intermediate the pressure area and the centering area of the piston-cylinder combination.

Abstract: A hydraulic jack assembly for a hydraulic elevator including a jack having a cylinder, cylinder head and plunger, and a footer for mounting the jack which includes a box beam having a bottom, side webs and lateral flanges. The cylinder extends through the bottom of the box beam and is fixed to the bottom and lateral flanges. End plates are fixed inwardly from the ends of the box beam to define an overflow oil reservoir which surrounds the jack below the cylinder head for collecting oil which may leak from the cylinder head.

Abstract: This invention relates to integrated electro-hydraulic actuators for use aboard aircraft or elsewhere. A balanced, double-acting hydraulic ram or motor (12) is connected between a support (16) and a member to be moved relative to the support. The ram includes first and second changeable volume hydraulic chambers (30, 32). A reversible hydraulic pump (38) is connected by a pair of conduits (44, 46) to the ram chambers (30, 32). The pump (38) displaces hydraulic fluid from one chamber to another for the purpose of causing a pressure differential between them. A hydraulic accumulator (60) provides leakage makeup fluid to the actuator, and further provides a quiescent pressure to the actuator when it is in a substantially nonoperative condition. A conduit (62) may connect the accumulator (60) to the ram (12). A laminar leakage flow path within the actuator permits hydraulic connection of the accumulator (60) to the ram (12) without use of valves.

Abstract: A brake booster includes a valve member which is operable to communicate fluid pressure to a pressure chamber for generating a power assist during braking. The brake booster provides an auxiliary chamber to trap fluid pressure leakage past the valve member. An input member is operable during braking to initially vent the auxiliary chamber and thereafter to control operation of the valve member.

Abstract: A Scotch yoke mechanism for actuating opposed-piston gas compressor is disclosed. The mechanism comprises a crank pin eccentrically extending from an end of a main drive shaft, a slider rotatably surrounding the crank pin, and a yoke defining a pair of opposed parallel sliding surfaces for confining the motion of the slider only to the sliding motion along the surfaces, said yoke further defining a pair of outwardly extending connecting rods for connecting oppositely disposed pistons on either side of the york, whereby the orbital motion about the axis of the main drive shaft causes the slider to reciprocate the yoke and thus oppositely disposed pistons.

Abstract: The mechanism incorporates at least one assistance unit consisting of a fixed piston (44) supported by a hollow rod (43) and of a cylinder (32) housed in a bore (30) of the rack (11), the chambers (60, 61) being supplied through separate passages (62, 63) extending through the hollow rod (43). The mechanism, advantageously of the type with central output and with a double circuit, incorporates a double circuit distribution valve mechanism (20) for supplying selectively the pairs of chambers (60, 61) on each side of the pinion (12) of the rack (11).

Abstract: A seal assembly is arranged to contain leakage of hydraulic fluid passing between a wall opening and a penetrant rod portion passing through the opening. The seal assembly includes a sliding-seal member mounted on a portion of the rod for sliding movement toward and away from an abutment surface and a non-sliding flexible-seal member arranged between the body and the sliding-seal member. The body, flexible-seal member, sliding-seal member and rod define a sealed chamber into which such fluid will leak. The chamber communicates with a fluid reservoir through a oneway check valve. The sliding-seal and flexible-seal members are arranged in parallel with one another. In one embodiment, a spring urges the sliding-seal member to move toward an abutment surface provided on the rod. In another embodiment, movement of the sliding-seal member relative to the body is limited by facing abutment steps.

Abstract: A pressure relieved piston rod seal for piston-cylinder having tandem seals around the piston rod which are subject to failure when the pressure between the seals is greater than the pressure in the cylinder chamber. The piston rod seal of this invention solves this problem by providing a unidirectional seal between the end or low pressure rod seal and the cylinder chamber which relieves the pressure between the seals while sealing the chamber. The unidirectional seal includes a fluid passage which permits fluid flow into the cylinder chamber when the pressure between the seals is greater than the pressure in the cylinder chamber and seals the cylinder bore when the pressure in the chamber is greater than the pressure between the seals.

Abstract: In a hydraulic rock drill there is a hydraulic so called recoil damper that damps the reflected shock waves that propagates from the rock backwardly through the drill stem. The damper comprises a support piston (68) slidably in a cylinder so that a pressure chamber (20) is formed in which the support piston has a piston area. Narrow clearances (75,76) between the support (68) and its cylinder form leak passages and these leak passages are coupled in series with an orifice restrictor (84) to a sump. The pressure peaks in the pressure chamber do not reach sealing rings located at the outer portions of the clearances.

Abstract: The present invention relates to a plunger or floating piston pump which is particularly adapted for use as a small-size metering pump in performing chemical analyses. In a pump head casing there is disposed a plunger guide bushing made of a ceramic material in which a plunger made of sapphire is slidably guided permanently with extreme accuracy in relation to the bore in an annular seal, said annular seal itself cooperating with said plunger in such a way that there is no clearance between the plunger and said plunger guide bushing. In a modification of the invention, said displacement chamber is formed in a pump head liner which is mounted in said pump head casing. The pump head liner is made of a chemically inert material, preferably of a ceramic material.

Abstract: This invention relates to a pump arrangement (54) for use in a linear fluid operated device having a reciprocating piston (14) separating a first active fluid chamber (30) and a second chamber (32) which eliminates the problem associated with fluid leakage buildup developing in the second chamber. The pump arrangement (54) is connected to the reciprocating piston (14) and pumps leakage fluid present in the second chamber (32) from the second chamber (32) and into the first chamber (30) in response to a force of a preselected minimum magnitude being applied to the pump arrangement (54). Thus, the problems of inefficient linear fluid operated device operation, reduced piston stroke length, external fluid leakage, and erratic piston travel speed are eliminated. The pump arrangement (54) is particularly suited for use in a single acting linear hydraulic jack (12) such as used on a material handling vehicle.

Abstract: A power cylinder of a hydraulic percussion implement, in whose bore a ram with an enlarged piston head is vertically reciprocable to strike a tool at the lower end of the bore, has a control chamber above the piston head alternately communicating with the high-pressure side and the low-pressure side of a source of hydraulic fluid, an annular recess in the bore being permanently or intermittently connected to high pressure acting upon the underside of the piston head. An annular drainage chamber formed by the bore at a lower level, disposed above an oil seal, collects liquid leaking down from that recess and returns it to the source. A pneumatic buffer lies in or communicates with that drainage chamber for absorbing hydraulic shocks generated when the ram strikes the tool.

Abstract: There is provided a hoist as for an ocean floor dredging operation, which is capable of providing hydraulic heavy lifting capacity, for raising or lowering the dredging means between a surface ship and the ocean floor, and further can routinely provide the ship heave compensation when lifting capacity is not required, for example during dredging operation, or if the raising or lowering of pipe during pipe deployment and retrieval operations is discontinued for any other reasons, such as extremely high seas. The pneumohydraulic system comprises a piston slidably sealably movable within a cylinder and dividing the cylinder into upper and lower portions; a pneumohydraulic accumulator for providing hydraulic fluid to each of the cylinder portions and the necessary valve means to open and close the necessary connections for filling and evacuating one of the cylinder portions with hydraulic fluid without rendering hydraulically inoperative the second portion of the cylinder.

Abstract: In an hydraulic rock drill there is an hydraulic so called recoil damper that damps the reflected shock waves that propagates from the rock backwardly through the drill stem. The damper comprises a support piston (68) slidably in a cylinder so that a pressure chamber (20) is formed in which the support piston has a piston area. Narrow clearances (75,76) between the support (68) and its cylinder form leak passages and these leak passages are coupled in series with an orifice restrictor (84) to sump. The pressure peaks in the pressure chamber do not reach sealing rings located at the outer portions of the clearances.