US3777619A - Hydraulic pit prop - Google Patents

Hydraulic pit prop Download PDF

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Publication number
US3777619A
US3777619A US00292339A US3777619DA US3777619A US 3777619 A US3777619 A US 3777619A US 00292339 A US00292339 A US 00292339A US 3777619D A US3777619D A US 3777619DA US 3777619 A US3777619 A US 3777619A
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US
United States
Prior art keywords
piston
prop
guide tube
outer guide
valve
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
US00292339A
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English (en)
Inventor
H Bull
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.)
Hemscheidt Hermann Maschinenfabrik GmbH and Co
Original Assignee
Hemscheidt Hermann Maschinenfabrik GmbH and Co
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.)
Filing date
Publication date
Application filed by Hemscheidt Hermann Maschinenfabrik GmbH and Co filed Critical Hemscheidt Hermann Maschinenfabrik GmbH and Co
Application granted granted Critical
Publication of US3777619A publication Critical patent/US3777619A/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
    • E21D15/50—Component parts or details of props
    • E21D15/51—Component parts or details of props specially adapted to hydraulic, pneumatic, or hydraulic-pneumatic props, e.g. arrangements of relief valves
    • E21D15/512—Arrangement of valves

Definitions

  • ABSTRACT An hydraulic prop having a relatively movable piston and cylinder which are surrounded by an outer guide tube provided with a closed end which is normally spaced away from an opposing end of the piston by spring means but which moves telescopically in relation to the piston if excess loads are applied to the prop, such relative movement between the piston and the outer guide tube causing the latter to actuate and move a plunger which, in turn, acts on a valve member in the piston so that liquid under pressure in a pressure chamber of the piston can flow out rapidly past the valve member and thus quickly relieve the prop of transitory excess loads such as those caused by rock falls or a partial collapse of the seam being worked.
  • Hydraulic pit props or chocks are generally protected from excessive loads imposed on them by rock pressure by at least one valve which may, if desired, be located in a control device disposed outside the prop.
  • These valves are so set that, when the pressure on the prop exceeds a predetermined value, a tapered surface on a movable valve member which is normally biased by a mechanical spring into a closed position is raised for a short period of time away from a seat for the valve member, the spring force being overcome by the excess pressure. Liquid under pressure then flows out of a pressure chamber in the prop so as to allow the latter to yield. The valve remains in its open condition until pressure equilibrium is attained, whereupon the valve closes under the biasing force of its spring.
  • the crosssection of the valve opening is made relatively small so as to keep the pressure per unit area at the sealing surfaces of the prop within a permissible range.
  • the abrupt increase in pressure in the prop results directly from the crosssection of the valve opening not being large enough to allow a sufficient quantity of liquid to be discharged rapidly from the pressure chamber in order to obtain a condition of pressure equilibrium. Quite apart from the fact that this may have dangerous consequences for mining personnel, there is also the danger that the prop will be destroyed through this abrupt increase in pressure.
  • the aim of the present invention accordingly, is to so construct an hydraulic prop, and, in particular, the hydraulic means for protecting it against excess pressures, that, on the occurrence of an abrupt and substantial increase in pressure in the prop such as results from a rock fall or partial collapse of the scam, the crosssection of openings and passages for the flow of liquid will be sufficiently large to enable liquid under pressure to be discharged rapidly from the pressure chamber to relieve the prop of excess pressure.
  • the invention is directedto an hydraulic prop comprising a cylinder, a tubular piston arranged partially in the cylinder for axial sliding movement relatively thereto, a pressure chamber in the piston for liquid under pressure, a valve opening of large size in the piston for the rapid passage therethrough of liquid under pressure from the pressure chamber, a valve member arranged to close the valve opening, an outer guide tube, closed at one end and open at the other end, surrounding the cylinder and the piston, an endsurface on the piston spaced away from and opposing the closed end of the outer guide tube, spring means disposed between the closed end of the outer guide tube and a part of the piston to maintain said spacing between the said end surface of the piston and the closed end of the outer guide tube under normal loads on the prop, an axially movable plunger in the piston, an end surface on the plunger opposing the valve member, and at least one large liquid-discharge opening in the piston on the downstream side of the valve opening therein, the outer guide tube and the piston being axially movable relatively to each other against
  • the plunger thus pushes the valve member open so that large quantities of liquid under pressure can flow rapidly out of the pressure chamber through the wide valve opening, thereby ensuring that a further increase in pressure in the prop will not occur.
  • the valve is once again closed, preferably by a valve spring and by the liquid under pressure remaining in the pressure chamber of the prop. The prop can now again carry its full load.
  • the prop comprises a cylinder 1 and a tubular piston 2 which are surrounded by an outer guide tube 3 having a closed upper end 3a and an open lower end 3b.
  • the closed upper end of the tube 3 opposes the upper end 3a of the piston 2, while the lower part of the tube 3 surrounds the cylinder l concentrically with the provision of an annular clearance 16 between them.
  • annular space 4 which is not sealed off and which lies radially outwardly of a pressure chamber 5 in the piston 2. Liquid under pressure is fed into the said pressure chamber 5 of the prop through. a duct 6 and a pipeline 17 from a control device 18 which lies outside the prop.
  • This control device 18 accommodates a pressurerelief valve 19 loaded by a spring 20, which serves to protect the prop against excessive pressures or loads.
  • a pressurerelief valve 19 loaded by a spring 20, which serves to protect the prop against excessive pressures or loads.
  • the opening of the valve 19 allows liquid under pressure to be discharged from the pressure chamber 5 of the prop through a discharge opening 21 into a return duct or pipe 22 which is free of pressure and which contains the pressure-relief valve 19.
  • the outer guide tube 3 is supported at its closed upper end 3a by sets of superposed. frustoconical washer-type springs 7 from a shoulder 8 on the upper portion of the piston 2 of the prop. Under normal circumstances of use, the number of springs 7 provided, as well as their combined strength, will ensure that a gap 9 is formed between the upper end 2a of the piston 2 and the opposing surface of the outer guide tube 3. The size of the gap 9 can therefore be varied by telescoping movements between the piston 2 and the outer guide tube 3. The number and strength of the springs 7 are so selected that the spring force exerted by them exceeds by a predetermined amount the magnitude of the load at which the pressure-relief valve 19 is set to open or yield.
  • valve member 12 has a large surface area in comparison with the size of the prop and is located in the upper portion of the piston 2.
  • the conical surface of the valve member 12 bears against a valve seat 13 which is formed as a frusto-conical surface on a shoulder projecting from the inner wall of the piston 2.
  • valve member 12 When the lower end 11a of the plunger 11 presses against the valve member 12, the latter is moved off its seat 13 so as to allow the flow of liquid under pressure from the pressure chamber of the prop into the outer annular space 4 through the outlet openings 14 which are of large diameter. From the space 4, the liquid can flow to th outside of the prop through the clearance 16 or through a slot 23 in the outer guide tube 3 for the duct 6.
  • An hydraulic prop comprising a cylinder, a tubular piston arrange partially in the cylinder for axial sliding movement relatively thereto, a pressure chamber in the piston for liquid under pressure, a valve opening of large size in the piston for the rapid passage therethrough of liquid under pressure from the pressure chamber, a valve member arranged to close the valve opening, an outer guide tube, closed at one end and open at the other end, surrounding the cylinder and the piston, an end surface on the piston spaced away from and opposing the closed end of the outer guide tube, spring means disposed between the closed end of the outer guide tube and a part of the piston to maintain said spacing between the said end surface of the piston and the closed end of the outer guide tube under normal loads on the prop, an axially-movable plunger in the piston, an end surface on the plunger opposing the valve member, and at least one large liquid-discharge opening in the piston on the downstream side of the valve opening therein, the outer guide tube and the piston being axially movable relatively to each other against the action of the spring means on the application of excess
  • valve member is biased into sealing contact with the valve seat by a valve spring and the pressure of liquid in the pressure chamber, the valve seat being formed on a shoulder projecting from the inner wall of the piston.
  • tubular piston is provided with at least two liquid discharge openings leading to a space, outside the piston, which is in communication with the outside of the prop.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Safety Valves (AREA)
US00292339A 1971-10-04 1972-09-26 Hydraulic pit prop Expired - Lifetime US3777619A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2149451A DE2149451C2 (de) 1971-10-04 1971-10-04 Gebirgsschlagventilanordnung fuer einen hydraulischen Grubenstempel

Publications (1)

Publication Number Publication Date
US3777619A true US3777619A (en) 1973-12-11

Family

ID=5821410

Family Applications (1)

Application Number Title Priority Date Filing Date
US00292339A Expired - Lifetime US3777619A (en) 1971-10-04 1972-09-26 Hydraulic pit prop

Country Status (5)

Country Link
US (1) US3777619A (cs)
CA (1) CA963453A (cs)
DE (1) DE2149451C2 (cs)
PL (1) PL77333B1 (cs)
ZA (1) ZA726547B (cs)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6609646B2 (en) 2001-02-08 2003-08-26 Black & Decker Inc. Magazine assembly for fastening tool
US6648202B2 (en) 2001-02-08 2003-11-18 Black & Decker Inc. Pneumatic fastening tool
US6679413B2 (en) 2001-02-08 2004-01-20 Black & Decker Inc. Magazine assembly for fastening tool

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2603978C3 (de) * 1976-02-03 1982-10-14 Thyssen Industrie Ag, 4300 Essen Gebirgsschlagventilanordnung in einem hydraulischen Grubenstempel
DE3340888C1 (de) * 1983-11-11 1985-02-07 Hermann Hemscheidt Maschinenfabrik Gmbh & Co, 5600 Wuppertal Hydraulischer Stempel mit Gebirgsschlagventil für ein Schreitausbaugestell
WO1991000416A1 (fr) * 1989-06-27 1991-01-10 Institut Gornogo Dela Sibirskogo Otdelenia Akademii Nauk Sssr Support hydraulique
DE4035874A1 (de) * 1990-06-29 1992-01-02 Voss Richard Grubenausbau Ausbaustempel mit in dem stempelkopf integriertem druckbegrenzungsventil

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3046947A (en) * 1959-08-21 1962-07-31 Acrow Eng Ltd Hydraulic props
US3321372A (en) * 1964-01-17 1967-05-23 Soc Anglo Belge Vulcain Sa Nuclear reactor control mechanism

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3046947A (en) * 1959-08-21 1962-07-31 Acrow Eng Ltd Hydraulic props
US3321372A (en) * 1964-01-17 1967-05-23 Soc Anglo Belge Vulcain Sa Nuclear reactor control mechanism

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6609646B2 (en) 2001-02-08 2003-08-26 Black & Decker Inc. Magazine assembly for fastening tool
US6648202B2 (en) 2001-02-08 2003-11-18 Black & Decker Inc. Pneumatic fastening tool
US6679413B2 (en) 2001-02-08 2004-01-20 Black & Decker Inc. Magazine assembly for fastening tool
US20040020966A1 (en) * 2001-02-08 2004-02-05 Miller Keven E. Magazine assembly for fastening tool
US6772931B2 (en) 2001-02-08 2004-08-10 Black & Decker Inc. Magazine assembly for fastening tool
US20050092806A1 (en) * 2001-02-08 2005-05-05 Miller Keven E. Method for operating the engine of fastening tool
US6938812B2 (en) 2001-02-08 2005-09-06 Black & Decker Inc. Magazine assembly for fastening tool
US7185712B2 (en) 2001-02-08 2007-03-06 Black & Decker Inc. Fastening tool apparatus and method for operating the engine of fastening tool
US20070079978A1 (en) * 2001-02-08 2007-04-12 Miller Keven E Method for operating the engine of fastening tool
US7527106B2 (en) 2001-02-08 2009-05-05 Black & Decker Inc. Method for operating the engine of fastening tool

Also Published As

Publication number Publication date
PL77333B1 (cs) 1975-04-30
CA963453A (en) 1975-02-25
DE2149451C2 (de) 1974-09-19
ZA726547B (en) 1973-06-27
DE2149451B1 (de) 1972-10-05

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