US3241801A - Hydraulic prop - Google Patents

Hydraulic prop Download PDF

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Publication number
US3241801A
US3241801A US414541A US41454164A US3241801A US 3241801 A US3241801 A US 3241801A US 414541 A US414541 A US 414541A US 41454164 A US41454164 A US 41454164A US 3241801 A US3241801 A US 3241801A
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United States
Prior art keywords
tube
prop
piston
stage
cylinder
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Expired - Lifetime
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US414541A
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English (en)
Inventor
Wilkenloh Wilhelm
Jager Erich
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Rheinstahl Wanheim GmbH
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Rheinstahl Wanheim GmbH
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Priority claimed from DER36680A external-priority patent/DE1231194B/de
Application filed by Rheinstahl Wanheim GmbH filed Critical Rheinstahl Wanheim GmbH
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Publication of US3241801A publication Critical patent/US3241801A/en
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D23/00—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor
    • E21D23/006—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor provided with essential hydraulic devices
    • E21D23/0069—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor provided with essential hydraulic devices without essential advancing shifting devices
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
    • E21D15/14—Telescopic props
    • E21D15/44—Hydraulic, pneumatic, or hydraulic-pneumatic props
    • 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
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/16—Characterised by the construction of the motor unit of the straight-cylinder type of the telescopic type

Definitions

  • HYDRAULIC PROP Filed NOV. 50, 1964 United States Patent O M 3,241,801 HYDRAULC PR01 Wilhelm Willrenloh, Duisburg-Wanheim, and Erich lager, Duisburg-Neudorf, Germany, assignors to Rheinstahl Wanheim G.m.h.H., Duisburg-Wanheim, Germany Filed Nov. 3), 1964, Ser. No. 414,541 Claims priority, appiication Germany, Nov. 29, 1963, R 36,68)
  • the present invention relates to extensible and contractible hydraulic props. More particularly, the invention relates to an improved multiastage hydraulic prop which may be utilized as a separate pit prop or as one of a series of pit props in a walking mine roof support to prevent cave-in of underground excavations.
  • Another object of the invention is to provide a hydraulic prop of the just outlined characteristics wherein each stage may be shifted with reference to the other stage or stages to thereby lengthen the prop in response to admission of hydraulic fiuid to a single pressure chamber of the Yprop and wherein a single relief valve suffices to protect the prop from undue stresses.
  • a further object of the invention is to provide a hydraulic pit prop which may be assembled with similar props to form the roof supporting structure of a walking mine roof support, which may be manipulated by remote control, which may be constructed in any desired size, and which may comprise two or more relatively movable stages to insure that its length may be varied within a desired range.
  • An additional object of the instant invention is to provide a pit prop whose resistance to construction (shortening) remains unchanged regardless of the momentary length thereof and which consists of a small number of simple, rugged and easily connectible or disassemblable parts.
  • a further object of the present invention is to provide a very simple, rugged and reliable two-stage pit prop.
  • a concomitant object Iof the invention is to provide a pit prop which may be readily installed in many types of existing mine roof supports and which is equally useful as an independent roof-supporting or propping unit.
  • Still another object of the invention is to provide a hydraulic multi-stage prop which is capable of resisting exceptionally high compressive stresses such as will arise when the prop is utilized to prevent cave-in in underground excavations.
  • a further object of the invention is to provide a pit prop which may be extended to its full length within a short period of time and which may be rapidly contracted to be separable from a mine roof when the operator desires to transfer the prop to a different position -or to ad- Vance the walking mine r-oof support toward the mine face.
  • an extensible and contractible hydraulic prop which comprises a first tube, at least one first starge including a second tube having a portion reciprocably and sealingly telescoped into the first tube, and a second stage including a third tube having a portion reciprocably and sealingly telescoped into the second tube.
  • the prop is provided with a single pressure chamber and the second stage comprises a piston which is located at one end of the pressure chamber.
  • Each stage comprises a plurality of effective surfaces which are acted upon by the hydraulic fluid when the length of the prop is being changed in response to admission 3,241,801 Patented Mar.
  • the prop will operate properly with a single relief valve and the combined cross-sectional area of effective surfaces in the rst stage preferably approximates or equals the combined cross-sectional area of effective sur-faces in the second stage to insure that the prop offers an unchanging resistance to contraction regardless of the momentary axial position of tubes in the rst and second stages.
  • the hydraulic fluid which is admitted into the pressure chamber acts upon the piston in a sense to expel the third tube from the second tube.
  • an extensible and contractible hydraulic prop which comprises an outer tube 1.
  • the tube 1 is stationary and comprises a lower end which is closed by a sole plate 1a.
  • This sole plate may engage the oor of an underground excavation when the prop is used to prevent cave-in of the mine roof or when the prop forms part of a so-called walking or travelling mine roof support.
  • the sole plate 1a is preferably welded to the lower end of the outer tube 1 and the upper end of this tube is open so that it may receive a second tube 2 which forms part of the first stage of the prop and whose lower end is provided with an annular portion 1t] which constitutes a plunger and is slidably telescoped into the outer tube 1.
  • the plunger 10 is provided with a U-packing 11 which is in sealing engagement with the internal surface of the outer tube 1.
  • the second stage of the prop comprises a third tube 3 whose lower end is provided with an annular portion 12 forming a plunger provided with a U-packing 13 which is slidable along the internal sur-face of the second tube 2.
  • the third pipe 3 extends through and beyond the open upper end of the second pipe 2.
  • the upper end portion 3a of the pipe 3 carries a roof-engaging shield 3b which is preferably articulately secured to the end portion 3a and comes in direct engagement with the mine roof when the .prop of the present invention is used as a pit prop. If the prop forms part of a walking mine roof support, the shield 3b is preferably coupled to the shields of the other props which form part of the same mine roof support.
  • the open upper ends of the tubes 1 and 2 are provided with sealing sleeves 4, 4 whereby the sleeve 4 surrounds a median portion of the tube 2 and the sleeve 4' surrounds a median portion of the tube 3.
  • Each of these sleeves carries a slide ring 5 which engages the peripheral surface of the respective tube to prevent entry of foreign matter into the prop.
  • the connection between the sleeve 4 and the open upper end of the outer tube 1 comprises at least one horizontal coupling pin 4a which is recessed into the peripheral surface of the tube 1 and is accessible through a cutout 4b provided in the sleeve 4.
  • the connection Ibetween the sleeve 4 and the open upper end of the tube 2 is of identical construction.
  • the tube 3 comprises a header 6 which is welded to and is located at a level below the upper end portion 3a.
  • This header is provided with a first inlet 7 which serves to admit a hydraulic fluid in the direction indicated by ⁇ an arrow 7a, such fluid serving to contract the prop by causing retraction of the tube 3 into the tube 2.
  • a second inlet 8 of the header 6 serves to admit hydraulic fluid in a direction indicated by arrow 8a for the purpose of extendingy the prop, Le., for expelling the tube 2 from the tube 1 and for expelling the tube 3 from the tube 2.
  • the header 6 is welded to a downwardly extending tubular piston rod 9 which projects into the interior of the tube 2 and carries at its lower end a piston 14.
  • This piston is provided with a U-packing which is slidable in a vertical cylinder 16.
  • the cylinder 16 is received with clearance in the lower portion of the tube 3 and extends into the tube 2.
  • the upper end of the cylinder 16 is provided with an annular piston 17 which surrounds the piston rod 9 and accommodates an internal sealing ring 18 which seals the upper end of a retraction chamber 23 extending between the pistons 14, 17 and surrounding the lower-portion of the piston rod 9.
  • the piston 14 and the sole plate 1a define between themselves a pressure chamber 23a which is surrounded by the lower portion of the cylinder 16.
  • the inlet 7 communicates with the retraction chamber 23 through the interior of the piston rod 9 and through one or more radial ports 9a provided at the lower end of the piston rod just above the piston 14.
  • the pressure chamber 23a communicates with the inlet 8 through the interior of the third tube 3, through an annular clearance 20 between the tube 3 and cylinder 16, through an annular compartment 20a between the tube 2 and cylinder 16, through an annular clearance 21 between the cylinder 16 and plunger 10, and through one or more radial ports 22 provided in the lower end face of the cylinder 16. It will be noted that the lower end of the cylinder 16 is open.
  • the motion transmitting connection between the lower end of the cylinder 16 and the second tube 2 comprises a pair of annular collars 19, 19a provided on the cylinder above and below the plunger 10.
  • the tube 2 When the fluid is admitted to the undersurface of the plunger 10, the tube 2 will begin to move upwardly and an annular shoulder 10a of the plunger 10 will entrain the upper collar 19 so that the tube 2 and cylinder 16 move as a unit.
  • the plunger 10 entrains the collar 19a.
  • the prop is provided with a valve unit V having a suitable fiuid supply pump P by which fluid Linder pressure is admitted to the chamber 23a to thereby lengthen the prop, having furthermore a suitable relief valve 8b to limit the pressure, which ⁇ can be built up in the chamber 23a to thereby protect the prop from undue stresses, and having a suitable release valve 8c which may be, for instance, manually operated to release the pressure in the chamber 23a so that the prop may be contracted and transferred to the next position in the underground mining room.
  • the valve unit V may be arranged in or at the header 6 as actually shown in the drawing. However, when the prop forms part of a walking mine roof support, the valve unit V may be mounted at -a distance from the prop so that several props may be controlled by a common valve unit.
  • the operator firstly operates the above-mentioned release valve 8c by moving its actuating member 8e to the brokenline position 8e so that the passage 8 communicates with an outlet Sd through which the hydraulic fluid may be expelled from the chambers or compartments 2t), 20a, 21 and 23a via the passage 8. Then the operator will admit hydraulic fiuid through the inlet 7 (arrow 7a) so that the fiuid fiows through the interior of the piston rod 9 and through the ports 9a to enter the retraction chamber 23. Such fiuid acts against the surfaces 14a, 17a of the pistons 14, 17 and causes the tube 3 to descend. When its actuating member 8e is moved to the position 8e, the valve 8c seals the passage 8 from the pump P and from the outlet 3d.
  • the cross-sectional areas of effective surfaces in the two stages of the prop are selected in such a way that, when the prop is being extended, the third tube 3 begins to rise in the first step and the tube 2 begins to rise as soon as the tube 3 reaches the upper end of its stroke. However, when the shield 3b is subjected to stresses which tend to shorten the prop, the second tube 2 will descend first While the third tube 3 remains in fully extended position.
  • Such dimensioning of effective surfaces in the two stages of the prop is of advantage because the prop may be shortened by the full length of the stroke of the tube 3 regardless of the axial position of the tube 2 with reference to the tube 1.
  • the shield 3b may be separated from the mine roof regardless of the axial position of the tube 2 so that the prop may be shifted to a different position or that the walking mine roof support may be advanced toward the mine face.
  • the combined effective surface F3 of the second stage (tube 3) is composed of three surfaces including a first surface F3 (this is the annular surface at the underside of the annular plunger 12 at the lower end of the tube 3), a second surface F3 (this is the annular surface at the underside of t'ne header 6) and a third surface F3'" (this is the surface at the underside of the lower piston 14).
  • the underside F3 of the piston 14 forms part of the effective surface F3 of the third stage whereby the total cross-sectional area of the surface F3 at least approximates but preferably equals the cross-sectional area of the interior of theouter tube 1, i.e., the area of the surface F3 equals or approximates the area within a circle whose diameter corresponds to the internal diameter of the tube 1.
  • the combined effective surface F2 of the first stage (tube 2) equals the surface F2 (this is the annular surface at the upper side of the piston 17) minus the surface F2 (this is the annular surface at the underside of the plunger 10 provided at the lower end of the second tube 2).
  • the cross-sectional area of the surface F2 will exceed very little (for example, by a few cm2) the cross-sectional area of the surface F2.
  • the operator admits hydraulic fluid through the inlet 8 (arrow 8a).
  • the fiuid acts against the effective surface 'F3 by acting against the surfaces Fa, F3", F3m whereby the tube 3 begins to move upwardly and the piston 14 expels fluid from the retraction chamber 23.
  • Such fiuid returns through the ports 9a to escape via inlet 7.
  • the tube 2 remains stationary because the area of the surface F2" is greater than the area of the surface F2', i.e., the cylinder 16 is pressed into abutment with the sole plate 1a.
  • a very important advantage of the improved prop is that its stages offer a substantially unchanging :resistance to contraction regardless of the momentary length of the prop. In other words, the resistance which the prop 4offers to contraction is the same when the tube 2 and/ or 3 is partly or fully extended.
  • a single relief valve will sufiice to control the escape of fluid in response to contraction of the prop and a single pressure chamber suffices to extend the prop to its full length.
  • the ports 9a in the piston rod 9 and the inlet 7 in the header 6 may be closed so that the chamber 23 is sealed from the atmosphere.
  • the charnber Z3 is filled with air and such air undergoes compression in response to admission of hydraulic fluid into the chamber 23a, i.e., in response to upward movement of the piston 14 in a sense to reduce the volume of the retraction chamber 23.
  • the thus entrapped air forms a cushion and stores energy which is released when the release valve 8c is operated to connect the outlet 8d with the cylinder chamber 23a via passages 8, so that the hydraulic fluid may be expelled from the cylinder chamber 23a.
  • this valve 3c has been opened, the expanding air in the chamber 23 rapidly retracts the tube 3 into the tube 2 or the tube 1 to shorten the prop.
  • the prop need not be provided with means for retracting the first stage (tube 2) because the tube 2 will be retracted in the first step whenever the magnitude of stresses acting on the shield 3b is such that the length of the prop rnust be reduced.
  • the second stage tube 3
  • the effective surface F3 of the second stage is enlarged by the surface F3" of the lower piston 14 which contributes considerably to the resistance which the prop offers to contraction without necessitating the provision of large-diameter tubes.
  • the piston 14 forms part of the means for shortening the prop, the effective surface F3 is enlarged without necessitating the provision of additional parts for such enlargement.
  • An extensible multi-stage hydraulic prop comprising a first tube; at least one first stage including a second tube having a portion reciprocably telescoped into said first tube; and a second stage including a third tube having a portion reciprocably telescoped into said second tube, said prop defining a single pressure chamber and said second stage comprising a piston located at one end of said chamber, each of said stages having an effective surface which is acted upon by fluid when the prop is being extended in response to admission of hydraulic fluid into said chamber, the cross-sectional area of each effective surface being substantially the same so that the prop offers a substantially constant resistance to stresses which tend to contract the same and the cross-sectional area of the effective surface in said second stage at least approximating the cross-sectional area of the internal space of said first tube.
  • said second stage further comprises a cylinder received in said third pipe and slidably receiving said piston, means connecting the cylinder for reciprocatory movement with said second tube, and a second piston secured to said cylinder and defining with said first named piston a retraction chamber arranged to receive pressure fiuid when said third tube is to be retracted into said second tube.
  • said second stage further comprises a piston rod connected with said first named piston and received in said third tube, and a header connecting said piston rod to said third tube, said header having an inlet for admitting hydraulic fluid into said pressure chamber.
  • An extensible and contractible hydraulic prop comprising a first tube having an open end and a closed end; a second tube extending through said open end and having an annular end portion reciprocably telescoped into said first tube, said second tube having an open end; a third tube extending through the open end of said second tube and comprising an annular end portion reciprocably telescoped into said second tube; a cylinder received in said third tube and coupled to said second tube; a piston rod connected with said third tube and extending into said cylinder; a first piston connected with said piston rod and reciprocably telescoped into said cylinder so as to define in said cylinder a pressure chamber which extends to said closed end; a second piston provided on said cylinder and slidably surrounding said piston rod so as to define with said first piston a retraction chamber which is separated from said pressure chamber by said first piston; first inlet means for admitting a hydraulic fluid into said pressure chamber via said third tube and around said cylinder; and means for regulating the fiow of fluid into and from said retraction chamber.
  • An extensible and contractible hydraulic prop comprising an outer tube having an open end and a closed end; a second tube extending through said open end and having an annular plunger reciprocably telescoped into said outer tube, said second tube having an open end which is distant from said closed end; a third tube extending through the open end of said second tube and having an annular plunger reciprocably telescoped into said second tube, each of said plungers having an annular surface facing said closed end; an open-ended cylinder received with clearance in the plunger of said third tube and adjacent to said closed end when the prop is contracted; motion transmitting means for coupling said cylinder to said second tube; a first piston provided on said cylinder and spaced from said closed end, said piston having an annular surface facing away from said closed end; a tubular piston rod reciprocably received in said first piston; a second piston secured to said piston rod intermediate said first piston and said closed end so as to divide the interior of said cylinder into a retraction charnber extending between said pistons and a pressure chamber extending between said second piston
  • An extensible and contractible hydraulic pit prop adapted to be installed between the floor and the roof of an underground excavation, comprising an outer tube having an open end and a closed end provided with a floorengaging sole plate; a second tube extending through said open end and having an annular plunger reciprocably telescoped into said outer tube, said second tube having an open end which is distant from said closed end; a third tube extending through the open end of said second tube and having an annular plunger reciprocably telescoped into said second tube, each of said plungers having an annular surface facing said closed end and said third tube comprising an upper end portion provided with a roofengaging member; an open-ended cylinder received with clearance in the plunger of said third tube and adjacent to said closed end when the prop is contracted; motion transmitting means for coupling said cylinder to said second tube; a first piston provided on said cylinder and spaced from said closed end, said piston having an annular surface facing away from said closed end; a tubular piston rod reciprocably received in said first piston; a second piston secured to said piston rod intermediate said

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Actuator (AREA)
  • Lining And Supports For Tunnels (AREA)
  • Fluid-Damping Devices (AREA)
US414541A 1963-11-29 1964-11-30 Hydraulic prop Expired - Lifetime US3241801A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DER36680A DE1231194B (de) 1963-11-29 1963-11-29 Mehrstufiger hydraulischer Grubenstempel
DER41253A DE1237040B (de) 1963-11-29 1965-08-06 Mehrstufiger hydraulischer Grubenstempel

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US3241801A true US3241801A (en) 1966-03-22

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Application Number Title Priority Date Filing Date
US414541A Expired - Lifetime US3241801A (en) 1963-11-29 1964-11-30 Hydraulic prop
US571369A Expired - Lifetime US3426649A (en) 1963-11-29 1966-08-08 Multistage hydraulic mine prop

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Application Number Title Priority Date Filing Date
US571369A Expired - Lifetime US3426649A (en) 1963-11-29 1966-08-08 Multistage hydraulic mine prop

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US (2) US3241801A (sl)
JP (1) JPS5117651B1 (sl)
BE (1) BE655844A (sl)
DE (1) DE1237040B (sl)
GB (2) GB1065559A (sl)
NL (1) NL6413598A (sl)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3301519A (en) * 1964-10-20 1967-01-31 Gewerk Eisenhuette Westfalia Double telescoping hydraulic prop
JPS4863172A (sl) * 1971-12-03 1973-09-03
DE2941168A1 (de) * 1979-10-11 1981-04-23 Thyssen Industrie Ag, 4300 Essen Hydraulisch betaetigbares schubkolbengetriebe, vornehmlich zur verwendung im bergbau
JPS5666503A (en) * 1979-09-10 1981-06-05 Gen Electric Speed reduction and buffer device for hydraulic linear drive
US4756496A (en) * 1984-06-01 1988-07-12 Stabilus Gmbh Continuously adjustable levelling column
US6209440B1 (en) 1996-11-20 2001-04-03 Dbt Deutsche-Bergbau Technik Gmbh Hydraulic double telescopic prop
CN106969002A (zh) * 2017-04-10 2017-07-21 湖北工业大学 两级双作用液压油缸
CN111058882A (zh) * 2019-12-12 2020-04-24 天地科技股份有限公司 一种防冲击超前液压支架的顶梁

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US3592108A (en) * 1969-02-07 1971-07-13 Borje Oscar Rosaen Fluid cylinder
GB1280899A (en) * 1969-06-21 1972-07-05 Gewerk Eisenhuette Westfalia Improvements in hydraulic props
PL80403B3 (sl) * 1969-11-21 1975-08-30
US3858485A (en) * 1971-01-27 1975-01-07 Borje O Rosaen Fluid cylinder
JPS5512006Y2 (sl) * 1972-03-02 1980-03-15
US3791628A (en) * 1972-07-26 1974-02-12 Ocean Science & Eng Motion compensated crown block system
FR2253160B1 (sl) * 1973-12-03 1977-06-24 Poclain Sa
US4076465A (en) * 1974-01-18 1978-02-28 Pauliukonis Richard S Volumetric proportioning diluter
US3986438A (en) * 1975-09-08 1976-10-19 Deere & Company Hydraulic cylinder with integral feedback cylinder
DE2719848C2 (de) * 1977-05-04 1985-09-26 Montanhydraulik Gmbh & Co Kg, 4755 Holzwickede Mehrstufiger hydraulischer Teleskopzylinder
ZA804072B (en) * 1979-08-07 1981-06-24 Dobson Park Ind Telescoping jack
DE3213468A1 (de) * 1982-04-10 1983-10-13 Ecker Maschinenbau GmbH, 6680 Neunkirchen Hydraulischer grubenstempel
DE3318641A1 (de) * 1982-12-22 1984-06-28 Gewerkschaft Eisenhütte Westfalia, 4670 Lünen Einrichtung zur steuerung der schiebekappenzylinder hydraulischer schreitausbaueinheiten
US4516468A (en) * 1983-01-10 1985-05-14 Hydraulic Technology Corporation Double acting telescopic cylinder construction
DE3622424A1 (de) * 1986-07-03 1988-01-14 Montan Hydraulik Gmbh & Co Kg Zweistufiger teleskopzylinder
US5953967A (en) * 1996-05-28 1999-09-21 Junkers; John Fluid-operated cylinder-piston unit, and a tool provided therewith
GB2357806A (en) * 1999-12-02 2001-07-04 Trevor John Honour Load bearing props
CN102454658B (zh) * 2010-10-25 2014-12-10 徐州重型机械有限公司 臂架系统及其伸缩油缸
CN107387491B (zh) * 2016-05-16 2018-11-30 卡特彼勒（郑州）有限公司 双作用液压机构、多级伸缩液压机构及液压支架

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US2364741A (en) * 1942-11-26 1944-12-12 St Paul Hydraulic Hoist Compan Telescopic jack structure
FR1343862A (fr) * 1962-11-03 1963-11-22 Pousseur-ravanceur, étançon, distributeur d'étançon et système de distribution de soutènement marchant

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US2151057A (en) * 1936-10-07 1939-03-21 Suth Jack Well drilling machine
US2517153A (en) * 1946-08-16 1950-08-01 Gar Wood Ind Inc Telescopic power down hoist
US2487920A (en) * 1948-05-25 1949-11-15 John A Celenza Hydraulic ram
US2933070A (en) * 1958-08-12 1960-04-19 Rheinstahl Siegener Eisenbahnb Double-acting hydraulic jack
GB905379A (en) * 1960-03-23 1962-09-05 Dowty Mining Equipment Ltd Improvements relating to hydraulic mine roof supporting devices
DE1153705B (de) * 1960-10-01 1963-09-05 Rheinstahl Gmbh Wanheim Hydraulischer Grubenstempel
DE1138007B (de) * 1960-12-16 1962-10-18 Bosch Gmbh Robert Mehrteiliger Grubenstempel
US3190324A (en) * 1962-07-27 1965-06-22 Nordberg Manufacturing Co Fluid piston and cylinder assembly for use in railway tie cutters and the like

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2364741A (en) * 1942-11-26 1944-12-12 St Paul Hydraulic Hoist Compan Telescopic jack structure
FR1343862A (fr) * 1962-11-03 1963-11-22 Pousseur-ravanceur, étançon, distributeur d'étançon et système de distribution de soutènement marchant

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3301519A (en) * 1964-10-20 1967-01-31 Gewerk Eisenhuette Westfalia Double telescoping hydraulic prop
JPS4863172A (sl) * 1971-12-03 1973-09-03
JPS5666503A (en) * 1979-09-10 1981-06-05 Gen Electric Speed reduction and buffer device for hydraulic linear drive
JPS5939604B2 (ja) * 1979-09-10 1984-09-25 ゼネラル・エレクトリック・カンパニイ 液圧直線駆動用減速緩衝装置
DE2941168A1 (de) * 1979-10-11 1981-04-23 Thyssen Industrie Ag, 4300 Essen Hydraulisch betaetigbares schubkolbengetriebe, vornehmlich zur verwendung im bergbau
US4756496A (en) * 1984-06-01 1988-07-12 Stabilus Gmbh Continuously adjustable levelling column
US6209440B1 (en) 1996-11-20 2001-04-03 Dbt Deutsche-Bergbau Technik Gmbh Hydraulic double telescopic prop
CN106969002A (zh) * 2017-04-10 2017-07-21 湖北工业大学 两级双作用液压油缸
CN111058882A (zh) * 2019-12-12 2020-04-24 天地科技股份有限公司 一种防冲击超前液压支架的顶梁

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Publication number Publication date
DE1237040B (de) 1967-03-23
GB1065559A (en) 1967-04-19
US3426649A (en) 1969-02-11
GB1126940A (en) 1968-09-11
NL6413598A (sl) 1965-05-31
JPS5117651B1 (sl) 1976-06-03
BE655844A (sl) 1965-03-16

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