Working Member Or Part Carried Thereby Uncovers Inlet Port Patents (Class 91/25)
  • Patent number: 7624574
    Abstract: A piston apparatus which configures an air bearing by introducing a compressed working media into an inside of a piston, and ejecting the working media from plural holes arranged on a circumferential portion of the piston into a clearance between the piston and the cylinder, which prevents a back-flow of the working media in the piston to a working space, and which readily secures reliability and longevity is provided.
    Type: Grant
    Filed: December 27, 2005
    Date of Patent: December 1, 2009
    Assignee: Toyota Jidosha Kabushiki Kaisha
    Inventors: Daisaku Sawada, Hiroshi Yaguchi, Shinichi Mitani
  • Patent number: 6293175
    Abstract: A web cut-off device including a frame defining a piston chamber, a piston movable in the piston chamber, a cutter blade attached to the piston such that upon movement of the piston in a first direction, the cutter blade is adapted to engage and cut a web, at least one pressure chamber and lower connecting ducts for connecting the pressure chamber(s) to a lower part of the piston chamber. The ducts opening directly into opposed side walls defining the piston chamber such that the piston operates as a valve between the piston chamber and the pressure chamber(s).
    Type: Grant
    Filed: June 7, 1999
    Date of Patent: September 25, 2001
    Assignee: Valmet Corporation
    Inventors: Petri Enwald, Aaron Mannio, Pekka Ruha, Kalevi Vesterinen
  • Patent number: 5778754
    Abstract: A valve assembly (10) for controlling a pneumatic brake booster comprises a valve housing (16) with a first and a second valve seat (18, 20) as well as with a valve body (26) adapted to be applied to both valve seats (18, 20). In one position of an operating member (24) the valve body (26) is lifted off the first valve seat (18) only, while in another position of the operating member (24) it is lifted off the second valve seat (20). Radially outside the valve housing (16) an annular third valve seat (64) and a control sleeve (60) surrounding the valve housing are arranged, which as an additional valve body can be axially moved by means of the operating member (24) relative to the valve housing (16).
    Type: Grant
    Filed: March 26, 1997
    Date of Patent: July 14, 1998
    Assignee: Lucas Industries public limited company
    Inventor: Manfred Kaub
  • Patent number: 5228380
    Abstract: A linear drive comprising a drive member adapted to be reciprocated axially in a housing between two end positions. Opposite to the former there is a wall on at least one axial side. There are means to reduce the impact in the end position, such means having an annular lip. The lip is arranged on the drive member or on the wall and respectively faces the wall or the housing. The lip defines a damping space which is open on an impact side. If the drive member approaches one end position thereof, the damping space is occluded and reduced in volume so that some trapped fluid will escape via a relief opening so that there is a braked part of the stroke. Using simple means it is therefore possible to provide an extremely efficient fluid damping at the end position.
    Type: Grant
    Filed: August 28, 1992
    Date of Patent: July 20, 1993
    Assignee: Festo KG
    Inventors: Kurt Stoll, Eugen Schlotzer, Herbert Kongeter
  • Patent number: 4858937
    Abstract: The sealing apparatus is designed to automatically maintain the pressure of a buffer fluid above that of the sealed fluid. The apparatus consists of a cylinder (1) which has a movable piston (4, 5) therein. The piston (4, 5) is coupled to a valve shaft (8) and a first chamber (Z) in communication with sealed fluid is disposed on one side of the piston and a second chamber (Y) is on the other side of the piston for continuous communication with the buffer fluid. Recharging means in the form of a valve (12) and third chamber (X) which contains buffer fluid is a pressure greater than (Y) are associated with the second chamber (Y) so that in response to failure of seals the buffer fluid pressure drops in chamber (Y) and the pistons (4, 5) rise so that shaft mounted valve (12) is disengaged from valve seat (14) allowing high pressure buffer fluid to be transferred from chamber X to chamber Y.
    Type: Grant
    Filed: June 8, 1987
    Date of Patent: August 22, 1989
    Inventors: Anthony C. Fairlie-Clarke, Charles O. Etheridge
  • Patent number: 4843951
    Abstract: A servocylinder (1, 3, 4) with an electric piston end position transmitter is suggested. It is constructed as a piezoelectric converter (17 and 18). By means of applying voltage to the piezoelectric converter (17 and 18) the latter becomes a regulating element which overcomes a force holding the piston (2) in its stroke end position and removes the piston (2) from its position in which the feed line (7 and 8) of the pressure medium is sealed.
    Type: Grant
    Filed: October 6, 1987
    Date of Patent: July 4, 1989
    Assignee: Robert Bosch GmbH
    Inventors: Gerhard Bruggen, Manfred Gaugler, Dieter Karr, Josef Winkler
  • Patent number: 4823588
    Abstract: The present invention is a hydraulic hand-tool which includes an elongate piston having at least two sections of different transverse cross-sectional areas, a housing including a hollow front end portion having an interior surface defining a plurality of sections with different inner diameters corresponding in size, position and number to accommodate the sections of the piston in a manner which permits the piston to slide in a reciprocating manner within the hollow forward end of the housing and to define a main chamber and at least one auxiliary chamber for receiving hydraulic fluid as the piston slides in a forward direction; an hydraulic fluid conduit having a primary line with an end opening directly into the main chamber and at least one supplemental line communicating with at least one of the auxiliary chambers after the piston slides in a forward direction a predetermined distance; an hydraulic fluid or reservoir adapted to supply hydraulic fluid to another end of the primary line; and a pump in commun
    Type: Grant
    Filed: November 6, 1987
    Date of Patent: April 25, 1989
    Assignee: Societe D'Etudes Et De Methode D'Applications
    Inventors: Marcel Bussereau, Alain Courtois, Jean-Pierre Huet
  • Patent number: 4807514
    Abstract: A differential hydraulic jack with a damping system for the control of electric circuit-breakers is provided with a floating ring which produces a damping action at the end of travel and is also provided with a damping extension stud which forms part of the jack piston and penetrates into the damping ring. No provision is made on the jack piston for any packing ring forming a seal with the jack cylinder. The damping ring carries two projecting lips constituting a double valve which forms a leak-tight seal with the bottom face of the jack piston and the internal face of the cylinder end. At the end of the travel of the piston, the damping ring forms a double sealing valve for shutting-off the supply/drain orifice of the jack.
    Type: Grant
    Filed: April 4, 1988
    Date of Patent: February 28, 1989
    Inventor: Claude A. Gartzmuller
  • Patent number: 4785712
    Abstract: A hydraulic operating apparatus in which a differential piston is used as a drive unit, and in which the differential piston is driven by applying a high pressure fluid on a large piston face side through a hydraulic pressure control device for controlling the hydraulic pressure, and a high pressure fluid always being applied on the small piston face side. The hydraulic operating apparatus is constructed such that a high pressure fluid is applied concurrently on both piston faces when the differential piston stops at its receded position, and a thrust generated due to the difference between the forces applied on the both piston faces is held in check by a holding device acting on the differential piston or its extension. The differential piston is moved forward upon the removal of the holding force of the holding device, and the piston is moved backward upon the removal of the high pressure fluid on the large piston face side.
    Type: Grant
    Filed: May 27, 1986
    Date of Patent: November 22, 1988
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Toshiaki Yoshizumi, Tsutomu Sugiyama
  • Patent number: 4766802
    Abstract: Small-sized engine operated by an expanding gaseous fluid, which comprises a cylinder (18), a piston (20) and an inlet valve (38), the upper parts of the cylinder (18) and the piston (20) cooperating momentarily with a perforated (29) resilient membrane (28) circumferentially secured to the cylinder (18) and performing the functions of a pneumatic seal temporarily.
    Type: Grant
    Filed: March 27, 1987
    Date of Patent: August 30, 1988
    Inventors: Alessandro Caenazzo, Silvana Pasqualotto
  • Patent number: 4730540
    Abstract: The cylinder for a two cycle engine includes at least a port opened and closed by a piston in the cylinder the port being divided into a plurality of port portions by a rib extending longitudinally of the cylinder. The inner surface of the cylinder is formed with elongated concave recesses at the respective ends of the rib extending in the direction of extension thereof for regulating the pressing force per unit area of honing process. Each of the concave recesses has preferably substantially the same width as the width of the rib and the sum of the lengths of the concave recesses is preferably substantially the same as the length of the port.
    Type: Grant
    Filed: June 27, 1986
    Date of Patent: March 15, 1988
    Assignee: Kawasaki Jukogyo Kabushiki Kaisha
    Inventor: Sosuke Kinouchi
  • Patent number: 4569271
    Abstract: An hydraulic booster has a housing provided with a bore, an inlet connected to a source of pressure fluid, and an outlet connected to a reservoir for fluid, a boost piston being advanced in the bore in response to pressurization of a boost chamber, the boost chamber being pressurized under the control of a valve mechanism operative in response to a load applied to an input member. Two connections are provided between the source and the boost chamber, both connections being closed when the booster is inoperative, and when the booster is operated the first connection is opened following initial movement of the input member, and the second connection is opened following initial movement of the boost piston in response to pressurization of the boost chamber. Thus the booster is in a closed center mode when inoperative, but operates in an open center mode. The connections are preferably controlled by valves. The input load may be applied in tension or compression.
    Type: Grant
    Filed: June 6, 1983
    Date of Patent: February 11, 1986
    Assignee: Lucas Industries Public Limited Company
    Inventor: Desmond H. J. Reynolds
  • Patent number: 4563938
    Abstract: A cylinder (15) is reciprocable in the housing (11) of a hydraulic percussive tool and a piston hammer (16) is reciprocable in the cylinder. The force between the cylinder and the housing is constant during the cycle of reciprocation and as a result the housing (11) is practically not vibrating at all. The piston hammer (16) and the cylinder (15) are coupled together to move conjointly during a part of each forward stroke of the hammer piston, which ensures the timing of the reciprocation of the hammer piston 16 and the cylinder (15).
    Type: Grant
    Filed: July 23, 1984
    Date of Patent: January 14, 1986
    Assignee: Atlas Copco Aktiebolag
    Inventor: Stig R. Henriksson
  • Patent number: 4480525
    Abstract: A control device for working cycles of a self-propelled pneumatic boring device with a non-rotatable axially displaceable impact piston controllable by control edges of a control sleeve supported axially non-displaceably but rotatably and at its front end forming a control head with the control edges. The control head engaging in a cylindrical recess at a rear end of the impact piston cooperates with a radial main control opening formed in the impact piston in the vicinity of the recess. The control edges form two different pairs of the control edges, offset peripherally as well as axially such that respectively in one rotated position of the control sleeve only one of the pairs is aligned for cooperation with the main control opening. The impact piston is formed with at least one additional control opening which cooperates with the other pair and has a flow cross-section considerably smaller than that of the main control opening.
    Type: Grant
    Filed: January 27, 1982
    Date of Patent: November 6, 1984
    Inventor: Gustav Jenne
  • Patent number: 4467699
    Abstract: A valveless, pneumatic motor including a cylinder within which a hammer piston reciprocates and a buffer ring fixedly secured within the cylinder. A source of motive fluid under pressure cooperates with the buffer ring which through supply porting provides pressurized motive fluid alternately to opposed faces of the piston head. Intake ports are formed within the piston stem and adapted to cooperate intermittently with the buffer ring supply porting to provide motive fluid to the piston interior wherein an axial bore transmits the fluid along the stem toward the piston head and discharge porting delivers the motive fluid to the forward face of the piston head thereby urging the piston rearwardly. A reduced diameter portion of the piston stem then comes into communication with the buffer ring supply porting and permits the motive fluid to impinge directly on the rearward face of the piston head without passage through the piston to urge the piston forwardly.
    Type: Grant
    Filed: November 4, 1981
    Date of Patent: August 28, 1984
    Assignee: Joy Manufacturing Company
    Inventor: Louis H. LeBlanc
  • Patent number: 4434704
    Abstract: An apparatus for converting pressure into motion includes a housing having a plurality of ports formed therein. Movably disposed within the housing is a piston having a first plurality of apertures communicating with a first chamber and a second plurality of apertures communicating with a second chamber therein. The piston is positioned within the housing so that the apertures can register with consecutive ones of the ports as the piston is moved in either of two directions within the housing. The movable member is moved by a pressurizing substance applied to a selectable one of the ports through an appropriate valve circuit. The valve circuit is operated by excitation signals from a control member. By operating the valve circuit in an appropriate sequence, the pressurizing substance is sequentially applied to consecutive ones of the ports to move the piston longitudinally through the housing.
    Type: Grant
    Filed: April 14, 1980
    Date of Patent: March 6, 1984
    Assignee: Halliburton Company
    Inventor: Jim B. Surjaatmadja
  • Patent number: 4399968
    Abstract: An actuator for ejecting a store from an aircraft, with a pre-selected force vs stroke profile, is disclosed. The actuator comprises a cylinder and a fixed tubular member coupled to a source of fluid under pressure having a first array of orifices for flowing fluid into the cylinder. A piston assembly is provided, which is adapted to engage and eject the store. The iston assembly is slidably mounted within the cylinder and telescopically movable over the fixed tubular member from a first position, wherein the piston assembly covers a portion of the first array of orifices, to a second position, wherein the first array of orifices is uncovered. Typically, the pressure level of the source of fluid varies, generally as a function of the flow into the cylinder during the stroke of the piston assembly.
    Type: Grant
    Filed: May 16, 1980
    Date of Patent: August 23, 1983
    Assignee: Rockwell International Corporation
    Inventors: William H. Stock, Bernard C. Holland, Jr.
  • Patent number: 4362475
    Abstract: A compressor having an inlet valve which includes a valve housing and a control tube having a portion adapted to be in communication with a source of fluid. A piston is normally spring biased away from a valve element which is adapted to be alternately placed in sealing contact with a valve seat and withdrawn from such contact. The piston and valve element are movably mounted on the exterior of the control tube. Orifices in the control tube are adapted to control movement of the piston against the bias of the spring and also to provide a modulating influence as well as additional pressure balancing characteristics. The valve is also adapted to function as a bypass valve, a check valve and a blowdown function.
    Type: Grant
    Filed: March 16, 1981
    Date of Patent: December 7, 1982
    Assignee: Joy Manufacturing Company
    Inventor: William R. Seitz
  • Patent number: 4359930
    Abstract: A variable speed multi-cylinder assembly is provided with expandable bushing seals to block leakage of fluid from higher speed stages to lower speed stages.
    Type: Grant
    Filed: May 4, 1981
    Date of Patent: November 23, 1982
    Assignee: Western Gear Corporation
    Inventors: Robert M. Brown, John H. Short
  • Patent number: 4323002
    Abstract: A hydraulically actuable piston and cylinder unit comprising a hollow piston rod, slidably housing, at least partially, an elongate extension piece having a circular outer periphery, means to connect mechanically, the extension piece to the piston rod at the outer end of the latter remote from the piston head, at least one fluid passageway communicating between the annulus side of the piston head and the hollow interior of the piston rod, and a fluid seal carried by the extension piece and sealing against the internal periphery of the hollow piston rod, the arrangement being such that the seal always lies between the passageway and the outer end of the hollow piston rod.
    Type: Grant
    Filed: May 16, 1980
    Date of Patent: April 6, 1982
    Assignee: Fletcher Sutcliffe Wild Limited
    Inventor: Malcolm Wake
  • Patent number: 4323001
    Abstract: A bracing jack comprising a cylinder and a jack bar slidable in the cylinder from a bar extended position to a bar retracted position, the jack having an internal locking mechanism including a hydraulic and a mechanical actuator for unlocking under load.
    Type: Grant
    Filed: August 21, 1978
    Date of Patent: April 6, 1982
    Assignee: Messier-Hispano-Bugatti
    Inventors: Jean Masclet, Jacques Veaux
  • Patent number: 4266465
    Abstract: Fluid-actuated percussion mechanism includes a housing with an internal cylindrical space receiving a reciprocating piston dividing the space into a working stroke chamber and an idle stroke chamber. The mechanism further includes distributing means mounted in the housing and communicating the chambers and the source of the working fluid. The housing also accommodates a work-performing member adapted to receive impacts from the piston. The distribution means includes at the inlet of at least one of the chambers a valve made in the form of a resilient element. The surface of the distribution means has made therein valve seats of which the number corresponds to that of inlets for supplying the working fluid into the chamber.
    Type: Grant
    Filed: July 2, 1979
    Date of Patent: May 12, 1981
    Inventors: Viktor A. Gaun, Anatoly V. Belousov, Vadim D. Petukhov, Gennady I. Suxov, Nikolai A. Belyaev, Vitaly K. Alyabiev, Klimenty E. Rassomakhin
  • Patent number: 4194435
    Abstract: The fluid-actuated percussion mechanism includes a housing with an internal ylindrical space wherein a reciprocating piston, which divides the space into a working stroke chamber and an idle stroke chamber, is received. The mechanism further includes fluid distributing means and a distribution unit mounted in the housing for placing the chambers and a source of the working fluid in communication. The housing also accommodates a work-performing member adapted to receive impacts from the piston. The distribution unit includes at the inlet of at least one of the chambers a valve made in the form of a resilient annular element. The surface of the distribution unit has valve seats made in it, the number of which corresponds to that of the inlets for supplying the working fluid into the chambers. The resilient valve element is taut about the surface of the distribution unit in opposition to the inlets and encircles the periphery of the unit.
    Type: Grant
    Filed: June 30, 1977
    Date of Patent: March 25, 1980
    Assignee: Institut Gornogo Dela Sibirskogo Otdelenia Akademii Nauk SSSR
    Inventors: Viktor A. Gaun, Anatoly V. Belousov, Vadim D. Petukhov, Gennady I. Suxov, Nikolai A. Belyaev, Vitaly K. Alyabiev, Klimenty E. Rassomakhin
  • Patent number: 4173171
    Abstract: At the beginning of a working stroke of a compressed air loaded working piston disposed reciprocally in a pneumatic operated ramming tool said piston is initially set in motion under the action of minor amounts of compressed air until its top becomes immersed into stored compressed air and the working piston is then exposed to the full force of said stored compressed air to perform its working stroke. This working process permits to use a substantially simpler ramming apparatus.
    Type: Grant
    Filed: June 17, 1977
    Date of Patent: November 6, 1979
    Assignee: Firma Dieter Haubold Industrielle Nagelgerate
    Inventor: Wilfried Lange
  • Patent number: 4154146
    Abstract: A fluid motor or vacuum break for use with the carburetor of an internal combustion engine in which an output plunger of the motor moves in two stages and at different rates in each of the stages through means of an auxiliary housing supported within the main housing. Upon admission of vacuum pressure to the primary housing and output plunger moves in a first stage at the end of which vacuum pressure is admitted to the auxiliary housing causing it to collapse and move the plunger in a second stage.
    Type: Grant
    Filed: September 21, 1977
    Date of Patent: May 15, 1979
    Assignee: Schmelzer Corporation
    Inventor: Benjamin C. Benjamin
  • Patent number: 4151784
    Abstract: A shock absorber of the kind having an infinitely adjustable damping characteristic comprises a main cylinder containing a piston fixed to a piston rod which extends from the main cylinder and liquid within the cylinder acting on the piston. The main cylinder has openings for the flow from it of the liquid upon movement of the piston in the cylinder and an adjustment device is provided for restricting these openings to provide the adjustment of the damping characteristic. The openings are situated in the peripheral wall of the main cylinder and are axially spaced apart from each other in positions in which they are successively passed over and closed by the piston as the piston approaches the end of its stroke at one end of the main cylinder in a damping movement. Thus the flow of liquid from the main cylinder is progressively further throttled by closure of the openings as the piston approaches the end of its movement.
    Type: Grant
    Filed: September 13, 1977
    Date of Patent: May 1, 1979
    Inventor: Hubert Fussangel
  • Patent number: 4109894
    Abstract: A pilot valve device adapted to be brought to an open position in response to a mechanical signal so as to cause a compressed fluid to actuate an operating valve. The pilot valve device comprises a main valve located in a pilot valve chamber, and a daughter valve located in a daughter valve chamber formed in the main valve. When a mechanical signal is applied to the daughter valve and brings the same to an open position, a compressed fluid contained in the pilot valve chamber is introduced into a main valve actuating chamber, with the result that the main valve is brought to an open position to permit the compressed fluid to flow into an operating valve actuating chamber.
    Type: Grant
    Filed: June 4, 1976
    Date of Patent: August 29, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Haruo Honda, Hiroshi Itoh
  • Patent number: 4103863
    Abstract: A valve actuator for an expanding gate valve having a gate and a segment thereon. The actuator includes a piston connected to a gate stem and mounted within a cylinder with a pressurized gas on the upper side of the piston and liquid on the lower side of the piston. The gate valve moves from an open position to a closed position across the flow passage at a rapid rate and decelerates adjacent the end of its downward movement upon a metering of the liquid in the cylinder. The expanding gate valve expands laterally into fluid-tight sealing relation at the end of the downward stroke after moving across the flow passage. The bonnet is mounted internally of the valve body and a pressure seal is positioned between the bonnet and the valve body to permit operation of the valve actuator and gate valve even after failure of the pressure seal.
    Type: Grant
    Filed: October 4, 1976
    Date of Patent: August 1, 1978
    Assignee: ACF Industries, Incorporated
    Inventors: Robert C. Houlgrave, Larry J. Talafuse
  • Patent number: 4070946
    Abstract: The actuator piston has a generally cylindrical central projection about the exterior of which a similarly formed rolling diaphragm is closely fitted. The piston rod can turn freely, to avoid any twisting of the piston and diaphragm, and can also be axially withdrawn from its engagement with the piston. Return spring means extends into the diaphragm enclosed part of the piston.
    Type: Grant
    Filed: May 3, 1976
    Date of Patent: January 31, 1978
    Assignee: Design & Manufacturing Corporation
    Inventors: Roger H. Sandvik, Richard G. Huebscher
  • Patent number: 4056040
    Abstract: A shock absorber of the kind having an infinitely adjustable damping characteristic comprises a cylinder containing a piston fixed to a piston rod which extends from the cylinder and liquid within the cylinder acting on the piston. The cylinder has openings for the flow from it of the liquid upon movement of the piston in the cylinder and means are provided for restricting these openings to provide the adjustment of the damping characteristic. The openings are situated in the peripheral wall of the cylinder and are axially spaced apart from each other in positions in which they are successively passed over and closed by the piston as the piston approaches the end of its stroke at one end of the cylinder in a damping movement. Thus the flow of liquid from the cylinder is progressively further throttled by closure of the openings as the piston approaches the end of its movement.
    Type: Grant
    Filed: April 16, 1975
    Date of Patent: November 1, 1977
    Inventor: Hubert Fussangel
  • Patent number: 4026192
    Abstract: A motor driven by a pressurized fluid medium for operating an impact tool in a linear direction adapted for metal stamping and high velocity milling comprising a housing and a piston unit. The latter comprises a drive piston, a piston rod and a tool. In addition, the motor includes a kinetic energy absorbing device comprising a hydraulic fluid chamber and a retard piston which is rigidly connected to said piston unit and arranged to reciprocate in said fluid chamber. The retard piston retards the piston unit at the end of the strokes only and is freely passed by hydraulic fluid during the working stroke. Cup-shaped means are provided to restrict said by-pass flow of hydraulic fluid at the end of the strokes and thereby protect the motor from excessive stresses during no-load conditions.
    Type: Grant
    Filed: May 17, 1974
    Date of Patent: May 31, 1977
    Assignee: Atlas Copco Aktiebolag
    Inventors: Carl Anders Noren, Bertil Waldemar Sundin
  • Patent number: 4009639
    Abstract: A hydraulic swing motor which is provided so as to assure an improved cushioning effect near the end of its stroke and ultimately to make possible a reduction in the cushion stroke sector or an increase in the effective stroke, with fluid inlet and outlet passages at the casing being connected to chambers partitioned with a first vane fixed to the shaft side and a second vane fixed to the casing side and which are closed by means of the said first vane when the relative motion of the first and the second vanes nears its end, and with throttle valves to control the fluid discharge rate and relief valves to release the discharge fluid when its pressure rises beyond a certain limit in a section which remains open throughout the whole stroke.
    Type: Grant
    Filed: November 28, 1975
    Date of Patent: March 1, 1977
    Assignee: Kayabakogyo-Kabushiki-Kaisha
    Inventor: Toshihiko Sabashi
  • Patent number: 3973468
    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.
    Type: Grant
    Filed: August 2, 1974
    Date of Patent: August 10, 1976
    Inventor: Wayne B. Russell, Jr.