US3296942A - Deceleration control for piston of conventional hydraulic cylinder - Google Patents

Deceleration control for piston of conventional hydraulic cylinder Download PDF

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US3296942A
US3296942A US437667A US43766765A US3296942A US 3296942 A US3296942 A US 3296942A US 437667 A US437667 A US 437667A US 43766765 A US43766765 A US 43766765A US 3296942 A US3296942 A US 3296942A
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piston
cylinder
deceleration
fluid
ring
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US437667A
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Vaughn A Nelson
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Dresser Industries Inc
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International Harverster Corp
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Assigned to DRESSER INDUSTRIES, INC., A CORP. OF DEL. reassignment DRESSER INDUSTRIES, INC., A CORP. OF DEL. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL HARVESTER COMPANY
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F15B15/224—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke having a piston which closes off fluid outlets in the cylinder bore by its own movement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F15B15/222—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke having a piston with a piston extension or piston recess which throttles the main fluid outlet as the piston approaches its end position

Definitions

  • This invention relates to a deceleration control for a conventional hydraulic cylinder of the type generally used in hydraulic brake or other hydraulic systems and employing a reciprocating piston in which it is desirable to avoid too rapid deceleration of the piston including shock at the end of the piston stroke.
  • An object of my invention is to provide simple, self-operating means for gradually reducing the speed of the piston of such a system as it approaches either end of its stroke according to a predetermined pattern, thereby enhancing durability of parts, and smoothness and efliciency of operation.
  • Another object of the invention is to provide means associated with the piston for controlling the discharge of fluid from the cylinder as the piston approaches the end of its stroke.
  • a further object of the invention is to provide means associated with the piston and operating in response to the discharge of fluid from the cylinder as the piston approaches the end of its stroke to limit such discharge thereby to control deceleration of the piston.
  • An additional object of the invention is to provide such means adjacent each end of a reciprocating piston thereby to control deceleration of the piston as it approaches each end of its stroke.
  • I provide a radially displaceable ring which, being carried by the piston, is brought opposite an outlet port of the cylinder as the piston approaches the end of its stroke.
  • the hydraulic fluid passing out of the outlet port entrains and radially displaces, or lifts, the ring into a port blocking position so that the ring functions as a valve to restrict the flow of fluid and thus to retard further advance of the piston.
  • FIG. 1 shows diagrammatically a vertical section longitudinally of the axis of a conventional hydraulic cylinder with piston embodying one form of the invention, the piston being in mid-position A, an operated position of the piston B being indicated in broken lines.
  • FIG. 2 is a vertical section along the line 2-2 of FIG. 1.
  • FIGS. 3, 4 and 5 illustrate modifications of a portion of the invention.
  • the conventional hydraulic cylinder 11 is provided with a reciprocable piston 12 and openings or ports 13, 14 connected with suitable fluid conduits of a conventional hydraulic brake system. Adjacent each face 15, 16 of the piston a ring 17, 18 is arranged in a radially and axially displaceable relation, said ring being supported and retained in such relation by a retaining member 19, 19 disposed co-axially with and secured to the adjacent face of the piston.
  • piston 12 is provided with a central opening 12a for receiving a reduced portion 20 of a coaxial piston rod 21.
  • Rod 21 has a threaded projection 22 extending outwardly of the piston.
  • the retaining members 19, 19 have a central opening 23 for receiving the reduced portion 20 of rod 21; one of said members 19 being mounted intermediately of ice piston face 16 and a shoulder 24 of rod 21 and the other member 19 being mounted on threaded projection 22, the several palts being secured in position by means of nut 25 threaded thereon.
  • Retaining members 19, 19 are generally lazy-U or cupshape with peripheral outstanding flanges 26 and so arranged that wheh secured in position as shown in association with the adjacent surfaces 15, 16 of the piston 12, they provide a circumferential seat or race 27 for supporting rings 17, 18 in a radially and axially displaceable relation.
  • ring 19 at the left end of piston 12 in FIG. 1 is inset slightly in the adjacent face 15 of the piston as indicated at 15a.
  • rings 17, 18 have a median circumferential groove or trough 17a, 18a of generally V-shape. Modifications of the groove or trough arrangement of FIG. 1 shown in FIGS. 3, 4 and 5, include grooves of various dimensions, numbers and arrangements, the purpose of which will be explained as the operation of the invention is described.
  • the piston 12 being in mid-position A, the rings17, 18 which are of steel or other suitable materials as are the cylinder and piston, and of somewhat smaller diameter than the latter, are in lower position A, the inner surface 17b of the upper portion of the ring abutting the seat 27 and the outer surface of the lower portion abutting the adjacent inner surface 11a of the cylinder.
  • restriction of port 13 has the effect of building up resistance to the movement of piston 12 in the completion of its stroke, causing deceleration of the piston, and thereby reducing shock and enhancing smoothness in operation of the system.
  • ring 37 is provided with a plurality of spaced grooves 37a arranged to afford more gradual deceleration than ring 17 having a single groove 17a.
  • Different effects would be produced by the arrangements of FIGS. 4 and 5 with grooves 47a and 57a.
  • the modulation of deceleration effected by means of the invention would be related quantitatively and in timing to the dimensions of the ring and port, and the number, size and arrangement of the grooves in relation to the associated ring and port. Depending on the width of the ring, its diameter and its projection ahead of the leading face of the piston, satisfactory deceleration may be achieved without any groove in rings 17 and 18.
  • a hydraulic system comprising a conventional hydraulic cylinder having a reciprocating piston therein and a plurality of ports respectively arranged in predetermined spaced relation with opposite ends of said cylinder and in communication with the system, whereby upon operation of the piston in the direction of one of said ports fluid in the cylinder will be discharged through said port
  • apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a radially and axially displaceable ring provided with a groove extending circumferentially thereof and reducing the restrictive surface of the,ring and adapted in response to said discharge of fluid to move into a position substantially restricting said one port and reducing the discharge of fluid therethrough progressively as the piston advances thereby to modulate deceleration of the piston in the completion of its stroke according to a predetermined pattern.
  • a hydraulic system comprising a conventional hydraulic cylinder having a reciprocating piston therein and a plurality of ports respectively arranged in predetermined spaced relation with opposite ends of said cylinder and in communication with the system, whereby upon operation of the piston in the direction of one of said ports fluid in the cylinder will be discharged through said port
  • apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a radially and axially displaceable ring provided with a plurality of grooves extending circumferentially thereof in predetermined spaced relation with one another and adapted in response to said discharge of fluid to move into a position '4 substantially restricting said one port and reducing the discharge of fluid therethrough progressively as the piston advances thereof to modulate deceleration of the piston in the completion of its stroke according to a predetermined pattern of deceleration of said piston.
  • apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a ring and a cup-shaped retainer having a peripheral outstanding retaining flange thereon and having said retainer disposed in abutting relation with a face of the piston and constrained for movement therewith and arranged to supportably guide and retain said ring about an exterior surface of the retainer in a radial and axially displaceable relation that permits limited radial and axial movement of the ring relative to the retainer, and having said ring adapted in response to said discharge of fluid to restrict the said one of said ports and reduce discharge of fluid therethrough whereby to control deceleration of said piston in the completion of its stroke.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)

Description

Jan. 10, 1967 v. A. NELSON DECELERATION CONTROL FOR PISTON OF CONVENTIONAL HYDRAULIC CYLINDER Filed March 8, 1965 WW: wwj NA lmiil ll Q5: N Np United States Patent 3,296,942 DECELERATION CONTROL FOR lPiSTON 0F CONVENTIONAL HYDRAULIC CYLINDER Vaughn A. Nelson, Downers Grove, 111., assignor to international Harvester Company, Chicago, 111., a corporation of Delaware Filed Mar. 8, 1965, Ser. No. 437,667 3 Claims. (Cl. 91-409) This invention relates to a deceleration control for a conventional hydraulic cylinder of the type generally used in hydraulic brake or other hydraulic systems and employing a reciprocating piston in which it is desirable to avoid too rapid deceleration of the piston including shock at the end of the piston stroke.
Various devices and expedients have been provided for this purpose, including externally controlled, electronic and other more or less complex forms. An object of my invention is to provide simple, self-operating means for gradually reducing the speed of the piston of such a system as it approaches either end of its stroke according to a predetermined pattern, thereby enhancing durability of parts, and smoothness and efliciency of operation.
Another object of the invention is to provide means associated with the piston for controlling the discharge of fluid from the cylinder as the piston approaches the end of its stroke.
A further object of the invention is to provide means associated with the piston and operating in response to the discharge of fluid from the cylinder as the piston approaches the end of its stroke to limit such discharge thereby to control deceleration of the piston.
An additional object of the invention is to provide such means adjacent each end of a reciprocating piston thereby to control deceleration of the piston as it approaches each end of its stroke.
According to my invention, I provide a radially displaceable ring which, being carried by the piston, is brought opposite an outlet port of the cylinder as the piston approaches the end of its stroke. The hydraulic fluid passing out of the outlet port entrains and radially displaces, or lifts, the ring into a port blocking position so that the ring functions as a valve to restrict the flow of fluid and thus to retard further advance of the piston.
Other features and advantages of the invention will become apparent as the description of it proceeds in conjunction with the accompanying drawing in which:
FIG. 1 shows diagrammatically a vertical section longitudinally of the axis of a conventional hydraulic cylinder with piston embodying one form of the invention, the piston being in mid-position A, an operated position of the piston B being indicated in broken lines.
FIG. 2 is a vertical section along the line 2-2 of FIG. 1.
FIGS. 3, 4 and 5 illustrate modifications of a portion of the invention.
Referring to the drawings the conventional hydraulic cylinder 11 is provided with a reciprocable piston 12 and openings or ports 13, 14 connected with suitable fluid conduits of a conventional hydraulic brake system. Adjacent each face 15, 16 of the piston a ring 17, 18 is arranged in a radially and axially displaceable relation, said ring being supported and retained in such relation by a retaining member 19, 19 disposed co-axially with and secured to the adjacent face of the piston.
In the arrangement shown piston 12 is provided with a central opening 12a for receiving a reduced portion 20 of a coaxial piston rod 21. Rod 21 has a threaded projection 22 extending outwardly of the piston.
The retaining members 19, 19 have a central opening 23 for receiving the reduced portion 20 of rod 21; one of said members 19 being mounted intermediately of ice piston face 16 and a shoulder 24 of rod 21 and the other member 19 being mounted on threaded projection 22, the several palts being secured in position by means of nut 25 threaded thereon.
Retaining members 19, 19 are generally lazy-U or cupshape with peripheral outstanding flanges 26 and so arranged that wheh secured in position as shown in association with the adjacent surfaces 15, 16 of the piston 12, they provide a circumferential seat or race 27 for supporting rings 17, 18 in a radially and axially displaceable relation.
For reasons unrelated to the invention and which need not be explained, ring 19 at the left end of piston 12 in FIG. 1 is inset slightly in the adjacent face 15 of the piston as indicated at 15a.
As shown in FIG. 1, for a purpose to be explained, rings 17, 18 have a median circumferential groove or trough 17a, 18a of generally V-shape. Modifications of the groove or trough arrangement of FIG. 1 shown in FIGS. 3, 4 and 5, include grooves of various dimensions, numbers and arrangements, the purpose of which will be explained as the operation of the invention is described.
It will be noted that the piston 12 being in mid-position A, the rings17, 18 which are of steel or other suitable materials as are the cylinder and piston, and of somewhat smaller diameter than the latter, are in lower position A, the inner surface 17b of the upper portion of the ring abutting the seat 27 and the outer surface of the lower portion abutting the adjacent inner surface 11a of the cylinder.
The conventional hydraulic cylinder 11 being equipped and supplied with fluid (oil) for reciprocation of the piston 12 in the usual manner, operation of the invention will be readily understood.
Pressure being applied to move the piston 12 to the left in FIG. 1 to the position B indicated in broken lines, resulting flow of the oil to the left of the piston outwardly through port 13 Will create suction radially displacing the forward ring 17, causing it to move to upper position B. Its outer surface 17c then abuts the adjacent inner surface 11b of the cylinder 11, restricting the port 13 and leaving a substantially reduced outlet for oil under pressure including that afforded by groove 17a. In contrast, ring 18 at the opposite end of piston 12, not being subject to radial displacement from updraft of outward flow of oil, remains in lower position as at A.
It will be readily understood that restriction of port 13, retarding the outward flow of oil, has the effect of building up resistance to the movement of piston 12 in the completion of its stroke, causing deceleration of the piston, and thereby reducing shock and enhancing smoothness in operation of the system.
Corresponding results will follow upon operation of piston 12 in the opposite direction.
It will be apparent that quantitative variation in the retardation or deceleration of the piston 12 in the completion of its stroke in either direction will accompany variation in the number, dimensions and arrangement of grooves in the rings 17, 18, in relation to the ports 13, 14. Illustrations appear in FIGS. 3, 4 and 5.
In FIG. 3, for example, ring 37 is provided with a plurality of spaced grooves 37a arranged to afford more gradual deceleration than ring 17 having a single groove 17a. Different effects would be produced by the arrangements of FIGS. 4 and 5 with grooves 47a and 57a.
In all cases the modulation of deceleration effected by means of the invention would be related quantitatively and in timing to the dimensions of the ring and port, and the number, size and arrangement of the grooves in relation to the associated ring and port. Depending on the width of the ring, its diameter and its projection ahead of the leading face of the piston, satisfactory deceleration may be achieved without any groove in rings 17 and 18.
Modifications of the structure described in respect of size, form and arrangement of parts may be made without departing from the spirit and scope of the invention, as will be readily understood.
I claim:
1. In a hydraulic system comprising a conventional hydraulic cylinder having a reciprocating piston therein and a plurality of ports respectively arranged in predetermined spaced relation with opposite ends of said cylinder and in communication with the system, whereby upon operation of the piston in the direction of one of said ports fluid in the cylinder will be discharged through said port, apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a radially and axially displaceable ring provided with a groove extending circumferentially thereof and reducing the restrictive surface of the,ring and adapted in response to said discharge of fluid to move into a position substantially restricting said one port and reducing the discharge of fluid therethrough progressively as the piston advances thereby to modulate deceleration of the piston in the completion of its stroke according to a predetermined pattern.
2. In a hydraulic system comprising a conventional hydraulic cylinder having a reciprocating piston therein and a plurality of ports respectively arranged in predetermined spaced relation with opposite ends of said cylinder and in communication with the system, whereby upon operation of the piston in the direction of one of said ports fluid in the cylinder will be discharged through said port, apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a radially and axially displaceable ring provided with a plurality of grooves extending circumferentially thereof in predetermined spaced relation with one another and adapted in response to said discharge of fluid to move into a position '4 substantially restricting said one port and reducing the discharge of fluid therethrough progressively as the piston advances thereof to modulate deceleration of the piston in the completion of its stroke according to a predetermined pattern of deceleration of said piston.
3. In a hydraulic system comprising a conventional hydraulic cylinder having a reciprocating piston therein and a plurality of ports respectively arranged in predetermined spaced relation with opposite ends of said cylinder and in communication with the system, whereby upon operation of the piston in the direction of one of said ports fluid in the cylinder will be discharged through said port, apparatus for controlling deceleration of the piston as it approaches the end of its stroke including a ring and a cup-shaped retainer having a peripheral outstanding retaining flange thereon and having said retainer disposed in abutting relation with a face of the piston and constrained for movement therewith and arranged to supportably guide and retain said ring about an exterior surface of the retainer in a radial and axially displaceable relation that permits limited radial and axial movement of the ring relative to the retainer, and having said ring adapted in response to said discharge of fluid to restrict the said one of said ports and reduce discharge of fluid therethrough whereby to control deceleration of said piston in the completion of its stroke.
References Cited by the Examiner UNITED STATES PATENTS 1,953,674 4/1934 Dean 9l409 2,755,775 7/1956 Flick 91-26 2,935,047 5/1960 Ortman 91396 MARTIN P. SCHWADRON, Primary Examiner.
P. T. COBRIN, Assistant Examiner.

Claims (1)

1. IN A HYDRAULIC SYSTEM COMPRISING A CONVENTIONAL HYDRAULIC CYLINDER HAVING A RECIPROCATING PISTON THEREIN AND A PLURALITY OF PORTS RESPECTIVELY ARRANGED IN PREDETERMINED SPACED RELATION WITH OPPOSITE ENDS OF SAID CYLINDER AND IN COMMUNICATION WITH THE SYSTEM, WHEREBY UPON OPERATION OF THE PISTON IN THE DIRECTION OF ONE OF SAID PORTS FLUID IN THE CYLINDER WILL BE DISCHARGED THROUGH SAID PORT, APPARATUS FOR CONTROLLING DECELERATION OF THE PISTON AS IT APPROACHES THE END OF IT STROKE INCLUDING A RADIALLY AND AXIALLY DISPLACEABLE RING PROVIDED WITH A GROOVE EXTENDING CIRCUMFERENTIALLY THEREOF AND REDUCING THE RESTRICTIVE SURFACE OF THE RING AND ADAPTED IN RESPONSE TO SAID DISCHARGE OF FLUID TO MOVE INTO A POSITION SUBSTANTIALLY RESTRICTING SAID ONE PORT AND REDUCING THE DISCHARGE OF FLUID THERETHROUGH PROGRESSIVELY AS THE PISTON ADVANCES THEREBY TO MODULATE DECELERATION OF THE PISTON IN THE COMPLETION OF ITS STROKE ACCORDING TO A PREDETERMINED PATTERN.
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405605A (en) * 1966-06-14 1968-10-15 Milburn M. Ross Hydraulic pump jack means
US3559538A (en) * 1968-12-23 1971-02-02 Borg Warner Actuator
US3592106A (en) * 1969-06-25 1971-07-13 Cascade Corp Ram with cushioned piston stroke
FR2168944A1 (en) * 1972-01-27 1973-09-07 Alsthom Cgee
US3776100A (en) * 1972-05-01 1973-12-04 Int Harvester Co Cushion device
US3802319A (en) * 1971-12-27 1974-04-09 Caterpillar Tractor Co Cushioning device for hydraulic cylinders
FR2212500A1 (en) * 1972-12-29 1974-07-26 Ibm
US3969990A (en) * 1972-12-29 1976-07-20 International Business Machines Corporation Self-snubbing miniature piston assembly
US4207800A (en) * 1978-11-02 1980-06-17 Homuth Kenneth C Single directional sealing piston ring
US4253538A (en) * 1978-05-01 1981-03-03 Texas Instruments Incorporated Broadband seismic energy source
US5193433A (en) * 1989-05-24 1993-03-16 Ab Mecman Piston sealing and dampening device
EP1050686A3 (en) * 1999-05-05 2002-01-02 Lucas Industries Limited Piston and cylinder assembly and flow restrictor device therefor
WO2004055391A1 (en) * 2002-12-13 2004-07-01 Trw Automotive Gmbh Hydraulic cylinder
DE102007054224A1 (en) * 2006-11-29 2008-06-05 Smc K.K. Fluid pressure cylinder for use as transport device to transport different workpieces, has ring bodies made of metallic material and movable together with piston, and receiving openings partially receiving bodies during movement of piston
US20130032027A1 (en) * 2011-08-04 2013-02-07 Smc Kabushiki Kaisha Fluid pressure cylinder

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1953674A (en) * 1930-11-01 1934-04-03 Francis W Dean Unireturn flow steam cylinder
US2755775A (en) * 1954-12-27 1956-07-24 Flick Reedy Corp Floating cushion for a piston and cylinder device
US2935047A (en) * 1957-08-02 1960-05-03 Ortman Miller Machine Co Inc Cushioned cylinder construction

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1953674A (en) * 1930-11-01 1934-04-03 Francis W Dean Unireturn flow steam cylinder
US2755775A (en) * 1954-12-27 1956-07-24 Flick Reedy Corp Floating cushion for a piston and cylinder device
US2935047A (en) * 1957-08-02 1960-05-03 Ortman Miller Machine Co Inc Cushioned cylinder construction

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405605A (en) * 1966-06-14 1968-10-15 Milburn M. Ross Hydraulic pump jack means
US3559538A (en) * 1968-12-23 1971-02-02 Borg Warner Actuator
US3592106A (en) * 1969-06-25 1971-07-13 Cascade Corp Ram with cushioned piston stroke
US3802319A (en) * 1971-12-27 1974-04-09 Caterpillar Tractor Co Cushioning device for hydraulic cylinders
FR2168944A1 (en) * 1972-01-27 1973-09-07 Alsthom Cgee
US3776100A (en) * 1972-05-01 1973-12-04 Int Harvester Co Cushion device
FR2212500A1 (en) * 1972-12-29 1974-07-26 Ibm
US3969990A (en) * 1972-12-29 1976-07-20 International Business Machines Corporation Self-snubbing miniature piston assembly
US4253538A (en) * 1978-05-01 1981-03-03 Texas Instruments Incorporated Broadband seismic energy source
US4207800A (en) * 1978-11-02 1980-06-17 Homuth Kenneth C Single directional sealing piston ring
US5193433A (en) * 1989-05-24 1993-03-16 Ab Mecman Piston sealing and dampening device
EP1050686A3 (en) * 1999-05-05 2002-01-02 Lucas Industries Limited Piston and cylinder assembly and flow restrictor device therefor
WO2004055391A1 (en) * 2002-12-13 2004-07-01 Trw Automotive Gmbh Hydraulic cylinder
US20050226750A1 (en) * 2002-12-13 2005-10-13 Trw Automotive Gmbh Hydraulic cylinder
US7171888B2 (en) 2002-12-13 2007-02-06 Trw Automotive Gmbh Hydraulic cylinder
DE102007054224A1 (en) * 2006-11-29 2008-06-05 Smc K.K. Fluid pressure cylinder for use as transport device to transport different workpieces, has ring bodies made of metallic material and movable together with piston, and receiving openings partially receiving bodies during movement of piston
US20080173169A1 (en) * 2006-11-29 2008-07-24 Smc Kabushiki Kaisha Fluid Pressure Cylinder
US7798052B2 (en) 2006-11-29 2010-09-21 Smc Kabushiki Kaisha Fluid pressure cylinder
US20130032027A1 (en) * 2011-08-04 2013-02-07 Smc Kabushiki Kaisha Fluid pressure cylinder
US9038527B2 (en) * 2011-08-04 2015-05-26 Smc Kabushiki Kaisha Fluid pressure cylinder

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