US3301519A - Double telescoping hydraulic prop - Google Patents

Double telescoping hydraulic prop Download PDF

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Publication number
US3301519A
US3301519A US496822A US49682265A US3301519A US 3301519 A US3301519 A US 3301519A US 496822 A US496822 A US 496822A US 49682265 A US49682265 A US 49682265A US 3301519 A US3301519 A US 3301519A
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US
United States
Prior art keywords
piston
stage
prop
hydraulic fluid
hydraulic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US496822A
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English (en)
Inventor
Dommann Gunther
Hoffmann Erich
Floter Manfred
Warns Egon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gewerkschaft Eisenhutte Westfalia GmbH
Original Assignee
Gewerkschaft Eisenhutte Westfalia GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Gewerkschaft Eisenhutte Westfalia GmbH filed Critical Gewerkschaft Eisenhutte Westfalia GmbH
Application granted granted Critical
Publication of US3301519A publication Critical patent/US3301519A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J13/00—Covers or similar closure members for pressure vessels in general
    • F16J13/02—Detachable closure members; Means for tightening closures

Definitions

  • Double telescoping hydraulic props are well known. They are used extensively in mining operations to hold up the mine tunnel roof. In general these devices provide a cylinder housing two telescoping pistons arranged in such manner that both pistons are activated and moved from a single source by a single hydraulic fluid.
  • the inside piston has a smaller working face surface area than does its surrounding outside piston.
  • the outside piston may be hereinafter referred to as the first stage and the inside piston may be hereinafter referred to as the second stage.
  • the single hydraulic fluid is capable of acting on both the first and second stages :at the same time. Since the first stage has a larger working surface, it will tend to be projected in preference to the second or inside stage.
  • Double telescoping hydraulic props are generally constructed in such a manner as to permit the first or outer stage to be hydraulically extended to a maximum point predetermined by means of a stop or shoulder extending inwardly from the top of the encasing cylinder a distance suflicient to engage a shoulder or flange which extends outwardly from the base of the first stage. When these two shoulders engage, the first stage is prevented from further extension without fracture of at least one of these two shoulders.
  • the top of the first stage has an inwardly extending shoulder to engage and mate with an outwardly extending shoulder of the base of the second stage for the same purpose.
  • a space is defined by the combination of the inside cylinder wall, the outside of the first stage piston, the first stage base shoulder and the cylinder top shoulder; similarly a space is defined by the combination of the inside wall of the first stage piston, the outside wall of the second stage piston, the second stage base shoulder and the first stage top shoulder.
  • Such spaces are known to the prior art and have been used to retract the pistons under positive hydraulic pressure as desired.
  • the hydraulic fluid pressure was relieved or released thus causing the piston assembly to retract from the roof and permit the total device to be moved.
  • the first stage piston was the first to retract with the relation between the first and second stage pistons remaining substantially constant until the first stage has been fully retracted.
  • the piston assembly is not fully retracted since it is to be used very shortly and very near to the place where it was previously used.
  • hydraulic fluid pressure is again exerted on the double pistons and the outer stage is the first to extend until as before the cylinder and first stage shoulders engage.
  • the new location of use offers a floor to roof dimension less than that of the old or prior location of use, the first stage will not extend fully to the shoulder engagement since the top of the second stage will have met the roof and will have become set through the additional hydraulic fluid pressure.
  • this invention comprises a multiple telescoping hydraulic activated prop so arranged that the largest, and each succeeding smaller stage except the smallest, is physically prevented from extending to its maximum prior to its next smallest stage having extended to its maximum until the top of the smallest stage engages and contacts the roof to be supported by the prop and then providing the setting force to hold the top of the smallest stage against the roof by action of the hydraulic fluid pressure upon the largest stage piston.
  • FIG. 1 is a front elevation partially in section, with parts broken away, of a device according to this invention
  • FIG. 2 is a front elevation of a slightly modified device according to this invention.
  • FIGS. 3 and 3a are similar to FIG. 2 showing further modified forms of this invention.
  • FIG. 4 is similar to FIG. 1 showing the hydraulic fluid circulation system of a device according to this invention.
  • FIG. is a full front elevation partially in section of the device shown in FIG. 4.
  • a double telescoping hydraulic prop having a cylinder 1 encasing a first stage piston 5 and a second stage piston 11).
  • the first stage piston base 15 and the base of the cylinder 33 together with the inside walls of the cylinder define a space 25 into which hydraulic fluid can be pumped through an orifice 31.
  • a similar space 30 into which hydraulic fluid can be pumped to act upon a second stage piston is defined by the inside walls of the first stage piston 5, the top of the first stage piston base and the base 14 of the second stage piston 10. Hydraulic fluid will be admitted into this space 30 through a valve 26 in the first stage piston base .15.
  • the hydraulic fluid Upon release of hydraulic pressure, the hydraulic fluid will drain out of space 25 first thus causing the first and second stages to retract as a single unit. Upon complete retraction of this unit, the hydraulic fluid from the space 30 would then drain permitting the second stage to retract with reference to the first stage.
  • the first stage 5 can be prevented from extending to its maximum by providing a chain 3 or other extension device from a flange 4 on the first stage 5 to a flange or other extension 2 on the cylinder.
  • a modification of this is shown in FIG. 2 where the chains 3 are attached to the cylinder 1 by means of springs 6 so as to prevent or at least reduce the tendency for the chains 3 to snap under the tension caused by the hydraulic pressure.
  • FIGS. 3 and 3a a different arrangement is shown to accomplish the same purpose of preventing the first stage from extending to its maximum before extending the second stage.
  • the flange 4 has a guard jacket 7 attached thereto.
  • the bottom of the guard jacket 7 has a brake collar 8 thereon which is adjustable in its braking effect by means of lever 9 which may be a tensioning device, a set screw or the like.
  • lever 9 which may be a tensioning device, a set screw or the like.
  • the guard jacket 7 has been replaced by lead screws 11 which are adjustable to position the distance from the brake collar to the flange 4.
  • the first stage piston is prevented from extending to its maximum prior to the extension of the second stage piston.
  • the stopping device is either released, in the case of the chain 3 of FIG. 1 or the spring 6 of FIG. 2, or it may be overridden, as in the case of the brake collar 8 of FIGS. 3 and 3a.
  • the hydraulic fluid pressure is then free to act upon the first stage causing it to extend slightly further and thereby exerting the setting force necessary to support the roof.
  • stops 13 can be provided on the cylinder to retard or prevent the downward sliding of the brake collar upon retraction of the first stage piston.
  • annular chamber .17 is formed between the cylinder 1, the first stage piston 2 and the shoulders 16 and 19.
  • This chamber or space can be utilized to aid in retraction or as a holding device as shown in FIG. 4.
  • the chamber 17 is shut off from the return line by means of an over pressure (pressure release) valve 18.
  • a three way valve 21 is inserted into the line 20 leading from the chamber 17 which connects to the hydraulic system feed or return line 23 and to a drain line 22. In the position shown, the valve 21 permits the chamber 17 to exhaust only through the valve 18 (assuming valve 24 is closed) thereby maintaining the pressure in the chamber 17 at a value equal to the setting of the valve 18.
  • the chamber 17 may be drained, thereby permitting retraction of the first stage piston 5 by turning the valve 21 clockwise.
  • the first stage piston 5 is also prevented from extending further due to the pressure in the chamber 17.
  • the second stage piston 10 is now permitted to extend by means of hydraulic pressure despite the fact that the first stage piston 5 has not extended to its maximum.
  • the valve 21 can be turned 90 clockwise and the hydraulic fluid pressure permitted to extend the first stage piston 5 thus applying the required setting force.
  • Retraction of the first stage pistons can also be accomplished as shown in FIG. 4 by opening of the valve 24.
  • the setting force for the prop can be predetermined by use of a pressure release valve 32 which is set to open at a certain pressure. After the two pistons have been extended to support the roof 12 (shown in FIG. 3a), pressure from the roof is transmitted back through the pistons to the hYdI'ZiILlllC system through the valve 32.
  • the pistons are extended as heretofore mentioned by filling the chamber 25 first until the first stage piston has been extended as far as desired.
  • the hydraulic fluid pressure then opens the check valve 26 by overcoming the pressure of the spring 28.
  • the chamber 30 is then filled thereby extending the second stage piston 10 until it contacts the roof.
  • the pressure in the chambers 25 and 30 equalizes permitting the valve 26 to close whereby the setting force is applied solely to the first stage piston 5 since the roof acting upon the second stage piston 10 maintains the valve 26 closed.
  • the pressure in chamber 30 maintains the valve 26 closed while both pistons retract as a unit through draining of the chamber 25.
  • the base of the cylinder 33 is provided with an elevation 29 and the valve 26 with an extension 27 so that as the base 15 of the first stage piston 5 comes to rest upon the elevation 29, its weight forces the valve 26 open permitting the chamber 30 to drain and retracting the second stage piston 10.
  • the first stage piston When the device is under pressure from above but still under hydraulic fluid pressure, the first stage piston will retract into the cylinder and cause the valve 26 to open whereby chamber 30 comes into communication with the pressure relief valve 32. Since the pressure in chamber 311 is less than the pressure in chamber 25, the valve 32 will permit the hydraulic system to increase the pressure into chamber 25. This will extend the first stage piston 5 and close the valve 26. During this the second stage piston 10 has retracted somewhat. With the valve 26 closed, the pressure on the second stage piston 10 will retract the entire piston assembly thus causing the valve 26 to open and so on repeating until the second stage piston is fully retracted. This cycling retraction mechanism maintains a quite smooth descent by extraordinarily simple means.
  • a multiple telescoping hydraulic prop having a single hydraulic fluid system to all telescoping pistons thereof wherein said prop contains means to restrain said largest piston from fully extending to its maximum prior to a smaller piston contacting a surface to be supported by said prop; and check valve means :between two successive pistons operative to permit flow of hydraulic fluid therethrough from said hydraulic system into supporting relation with the smaller of said successive pistons and operative to permit flow of said hydraulic fluid from supporting relation with respect to said smaller piston to a source of said hydraulic fluid only when said larger piston is unsupported by hydraulic fluid.
  • a prop as claimed in claim 1 having a larger first stage and a smaller second stage piston; said first stage piston being restrained from extending toits maximum until said second stage piston contacts said surface.
  • a double telescoping hydnaulic prop comprising a cylinder having walls, a base and inwardly projecting shoulders at the top thereof; .a first stage piston ha'ving walls, a base, outwardly projecting shoulders at the base of said walls and inwardly projecting shoulders at the top thereof inside said cylinder; and a second stage piston having walls, a base and outwardly projecting shoulders at the base of said walls inside said first stage piston; said first stage piston base, said cylinder base and said cylinder wa lls defining a first chamber; said first stage piston base, said first stage piston walls and said second stage piston base forming a second chamber; a valve in said first stage piston base adapted to provide communication between said first and said second chambers; means to communicate said first chamber with a supply of hydraulic fluid; and means to restrain said first stage piston from extending to its maxi-mum prior to said second stage piston contacting a surface to be supported by said prop.
  • valve between said first and second chambers is a check valve characterized by the ability thereof to maintain said second chamber sealed until said first stage piston is substantially completely retracted.
  • a prop as claimed in claim 9 wherein said restraining means is adjustable to permit extension of said first stage piston any predetermined amount less than to its maximum.
  • valve means is operable externally from said prop.
  • Method of supporting a member by means of a multiple telescoping hydraulic prop wherein said prop has a single hydraulic fluid system to all telescoping pistons thereof wherein said prop contains means to restrain said largest piston from fully extending to its maximum prior to 'a smaller piston contacting a surface to be supported by said prop; and check valve means between two successive pistons operative to permit flow of hydraulic fluid therethrough from said hydraulic system into supporting relation with the smaller of said successive pistons and operative to permit flow of said hydraulic fluid from supporting relation with respect to said smaller piston to a source of said hydraulic fluid only when said larger piston is unsupported by hydraulic fluid, which method comprises exerting hydraulic pressure upon the largest piston to extend such until said restraining means prevents further extension; exerting hydraulic pressure on each successively smaller piston in turn until the extension of each is restrained; exerting hydraulic pressure upon the smallest piston until it contacts the member being supported; and exerting additional hydraulic pressure upon the assembly to set the assembly against the member.
  • a valve means communicates between a first reservoir serving to exert hydraulic pressure on a larger piston .and a second reservoir serving to exert hydraulic pressure on a next smaller piston; said valve means being within the base of said larger piston and containing a shaft operable to open said valve which extends beyond said base; said valve being opened by said larger piston base approaching its fully withdrawn position and said shaft making contact with the member against which said fully withdrawn larger piston rests.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Structural Engineering (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Actuator (AREA)
  • Food-Manufacturing Devices (AREA)
  • Earth Drilling (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
US496822A 1964-10-20 1965-10-18 Double telescoping hydraulic prop Expired - Lifetime US3301519A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEG41819A DE1226972B (de) 1964-10-20 1964-10-20 Hydraulischer Doppel-Teleskopstempel
DEG0043012 1965-03-05

Publications (1)

Publication Number Publication Date
US3301519A true US3301519A (en) 1967-01-31

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ID=27210640

Family Applications (1)

Application Number Title Priority Date Filing Date
US496822A Expired - Lifetime US3301519A (en) 1964-10-20 1965-10-18 Double telescoping hydraulic prop

Country Status (6)

Country Link
US (1) US3301519A (cs)
BE (1) BE671064A (cs)
DE (1) DE1226972B (cs)
FR (1) FR1459137A (cs)
GB (1) GB1124096A (cs)
NL (1) NL6513272A (cs)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5219429A (en) * 1992-08-10 1993-06-15 Shelton Bill E Hydra-lift system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS481663U (cs) * 1971-06-01 1973-01-10
DE2924380A1 (de) * 1979-06-16 1981-01-08 Gewerk Eisenhuette Westfalia Hubbegrenzungsvorrichtung fuer schubkolbengetriebe, insbesondere fuer schreitund rueckzylinder fuer das ruecken eines foerderers und/oder eines schreitausbaus in bergbau-untertagebetrieben
ZA804072B (en) * 1979-08-07 1981-06-24 Dobson Park Ind Telescoping jack

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1928533A (en) * 1933-01-20 1933-09-26 Milford T Goss Jack
US3145964A (en) * 1962-05-12 1964-08-25 Groetschel Karl Maria Hydraulic mine prop
GB972317A (en) * 1961-02-18 1964-10-14 Hoesch Bergbautechnik Gmbh Improvements in or relating to telescopic pit props
US3241801A (en) * 1963-11-29 1966-03-22 Rheinstahl Gmbh Wanheim Hydraulic prop

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1063101B (de) * 1956-02-20 1959-08-13 Gutehoffnungshuette Sterkrade Hydraulischer Grubenstempel
DE1123640B (de) * 1957-12-23 1962-02-15 Kloeckner Werke Ag Doppelt ausfahrbarer hydraulischer Grubenstempel
BE607500A (cs) * 1960-09-02
DE1149678B (de) * 1960-09-15 1963-06-06 Rheinstahl Gmbh Wanheim Mehrstufiger hydraulischer Grubenstempel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1928533A (en) * 1933-01-20 1933-09-26 Milford T Goss Jack
GB972317A (en) * 1961-02-18 1964-10-14 Hoesch Bergbautechnik Gmbh Improvements in or relating to telescopic pit props
US3145964A (en) * 1962-05-12 1964-08-25 Groetschel Karl Maria Hydraulic mine prop
US3241801A (en) * 1963-11-29 1966-03-22 Rheinstahl Gmbh Wanheim Hydraulic prop

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5219429A (en) * 1992-08-10 1993-06-15 Shelton Bill E Hydra-lift system

Also Published As

Publication number Publication date
GB1124096A (en) 1968-08-21
FR1459137A (fr) 1966-11-18
NL6513272A (cs) 1966-04-21
DE1226972B (de) 1966-10-20
BE671064A (cs) 1966-04-19

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