US2985418A - Extensible hydraulic supports - Google Patents

Extensible hydraulic supports Download PDF

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Publication number
US2985418A
US2985418A US843977A US84397759A US2985418A US 2985418 A US2985418 A US 2985418A US 843977 A US843977 A US 843977A US 84397759 A US84397759 A US 84397759A US 2985418 A US2985418 A US 2985418A
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United States
Prior art keywords
hydraulic
ram
conduit
head piece
tube
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
US843977A
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English (en)
Inventor
Tebb Bernard
Perry Clarence Herbert
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.)
Mastabar Mining Equipment Co Ltd
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Mastabar Mining Equipment Co Ltd
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 Mastabar Mining Equipment Co Ltd filed Critical Mastabar Mining Equipment Co Ltd
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Publication of US2985418A publication Critical patent/US2985418A/en
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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

Definitions

  • This invention concerns extensible hydraulic supports of the type, such as hydraulic pit props, which comprise an outer tubular member, an inner tubular member provided or formed at its lower end with a piston or ram working in a pressure chamber presented by said outer member, and hydraulic release and yield valves adapted respectively to enable said support to be collapsed from an extended condition and to enable said support fractionally and repeatedly to yield on the application thereto of a load in excess of a predetermined maximum load, said collapsing and yielding operations taking place by said valves allowing hydraulic medium from the pressure chamber to exhaust to a reservoir usually constituted by. the interior of the inner tubular member above the piston thereof.
  • hydraulic pit props which comprise an outer tubular member, an inner tubular member provided or formed at its lower end with a piston or ram working in a pressure chamber presented by said outer member, and hydraulic release and yield valves adapted respectively to enable said support to be collapsed from an extended condition and to enable said support fractionally and repeatedly to yield on the application thereto of a load in excess of a predetermined maximum load,
  • valve mechanisms In hydraulic supports of this type, it is desirable for maintenance purposes to have the valve mechanisms at the outer or uppermost end of the ram tube, Where they can be easily replaced if necessary, and one convenient way of arranging said valves is in a head piece located within and sealing the ram tube, and serving also as a location for extension tubes which may have to be employed e.g. at a coal face, on account of varying roof to floor height.
  • valves therein to communicate with the pressure chamber by way of a hydraulic conduit or tube passing down the ram tube and secured at one end to said head and at the other end to the ram or piston, the necessary connections between the head, the hydraulic conduit and the ram being effected by welding, brazing or screwing, or a combination of all three.
  • hydraulic supports in operation are subjected to substantial degrees of loading, for example, in a typical hydraulic pit prop, the normal loading applied to the inner or ram tube is of the order of 20/25 tons, and under such conditions compression of the ram tube takes place, to the extent of some 0.001 inch per ton of applied load. Consequently, due to this compression, the jointing of the hydraulic conduit or tube to the head and ram of the ram tube frequently develops faults.
  • the hydraulic conduit connected between the ram and the head piece of the inner tubular member is fixedly arranged at one end only, and the other end of said conduit is arranged to permit relative displacement to occur between said other end and either the ram or the head piece, as the case may be.
  • the relative displacement is Permitted by way of a slidable connection between the end concerned of said hydraulic conduit and the ram or the head piece, to whichever it is connected, although a flexible connection such as a flexible tube between the two may alternatively be employed.
  • the hydraulic conduit is preferably fixedly seice cured at its lower end to the ram and at its upper end engages slidingly with a short tube or probe fixed to and extending from the head piece of the inner tubular member of the support, a suitable seal being provided circumferentially'between said hydraulic conduit and said short tube or probe.
  • the head piece since the hydraulic conduit is fixedly jointed at one end only, the head piece may readily be removed from the ram tube (i.e. the inner tubular member) for servicing or replacement of the valves therein, and, even more important, the compression load experienced by the ram tube is not applied to the said joints.
  • outer tubular member 10 In the drawing on outer tubular member 10 is telescopically engaged by the inner tubular member 12 provided at its lower end with a ram or piston 14.
  • the interior 16 of the inner tubular member or ram tube 12 constitutes a reservoir for hydraulic medium
  • the space 18 of the outer tubular member 10, below the piston 14, constitutes a working chamber to which hydraulic medium under pressure is transferred from reservoir 16 as described below.
  • the upper face of the prop piston 14 has secured thereto, a cylinder 20 within which is reciprocable a pump piston '22 displaceable by a connecting rod 24 extending axially through the reservoir 16 so as to be reciprocated by a crank 26 having a driving member 28 extending through the wall of the ram tube 12 for manual operation externally thereof.
  • the prop piston 14 is provided with pump intake and delivery passages and valves (not shown) for enabling hydraulic medium to be transferred from the reservoir 16 to the pressure chamber 18.
  • the upper end of the ram tube 12 is closed by a head piece 30 which also serves as a convenient means for locating a replaceable extension piece 32 adapted to bear against the roof of a mine working and having its length chosen to accord with the prevailing roof to floor height.
  • the pit prop is provided with hydraulic medium relief and release valves 34 and 36 respectively adapted to allow momentarily relief of the pressure obtaining in pressure chamber 18 and to allow said pressure to collapse completely, in both instances by allowing transfer of the hydraulic medium from the chamber 18 through passages 38 and 40 of the prop piston or ram 14, a hydraulic conduit 42, and into passages '44 and 46 in the head piece 30 and respectively communicating with the rehef valve 34 and the release valve 36.
  • the communication of the passage 44 with the relief valve 34 will be seen to be by way of a filter 35 for the hydraulic medium.
  • the relief valve 34 may be of any convenient construction adapted for the purpose, and, as shown, is preferably incorporated in a removable capsule, whilst the release valve 36 is shown in the drawing as being a ball valve member adapted for unseating by a plunger 48 displaceable by a pivotal lever 50 which in turn is adapted to be rocked if an outward pull is exerted on a movable abutment 52 incorporated in the pump actuating member 28.
  • the hydraulic conduit 42 is fixedly jointed at one end to the head piece 30 and at the other end to the prop piston 14, and when compression of the inner tubular member 12 takes place in consequence upon the high load applied thereto, it has been found that faults frequently develop in such fixed joints and/ or in the hydraulic conduit 42.
  • the invention therefore provides that onlythe lower end of the hydraulic conduit 42 is fixedly jointed to the prop piston 14 so as to communicate with the passages 38 and 40, whilst the upper end of the hydraulic conduit 42 isrbell-mouthed or otherwise suitably formed or enlarged to slidingly receive a hollow probe 54- depending from the head piece 30, said probe 54 communicating With the passages 44 and 46 of the head piece 30.
  • the probe 54 may be secured or jointed to the head piece 30 in any convenient conventional manner, as by welding, brazing or screwing, and is provided with an oil seal 56 to prevent any leakage of pressurized oil from the conduit 42 when the prop is under pressure.
  • the oil seal 56 may be an O-ring or any other suitable conventional type seal.
  • the head piece 30 may readily be removed from the inner tubular member 12 of the pit prop when maintenance of the valves 34 or 36 is required, but even when the ram tube 12 is subjected to physical compression under loaded conditions, the compression load is relieved from the joint of the probe 54 with head piece 30 and from the joint of the hydraulic conduit 42 with the piston 14 due to the ability of the conduit 42 of the probe 54 to slide relative to one another.
  • the only stresses then required to be taken into account are the usual bursting stress on the conduit 42 due to the pressure of hydraulic medium therein, and the end load exerted by said pressure on the probe 54. This end load, however, is relatively small, and is more than balanced by the load on the prop tending to seat the head piece 30 on the ram tube.
  • a hydraulic support of the type comprising an outer tubular member provided at its lower end with a closure member, an inner tubular member provided at its lower end with a closure member in the form of a ram engaged within said outer member, the space in said outer member below said ram constituting a pressure chamber, and the interior of said inner member above said ram constituting a reservoir for hydraulic medium, a second closure member in the form of a head piece sealing the upper end of said inner member, a hydraulic medium release valve, a hydraulic yield valve, said valves both being arranged in said second closure member, and a hydraulic conduit extending between said two closure members to enable said valves to communicate with said pressure chamber, the improvement wherein said hydraulic conduit is fixedly secured by one of its ends to only one of said closure members, and the other end of said conduit terminates short of the other one of said closure members, a hollow probe extending from said other closure member to engage slidably in sealing relation in said other end of said conduit and a sealing ring of circular cross section surrounding a free end region of said probe to

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  • 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)
  • Actuator (AREA)
  • Forklifts And Lifting Vehicles (AREA)
US843977A 1958-10-29 1959-10-02 Extensible hydraulic supports Expired - Lifetime US2985418A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB34603/58A GB862033A (en) 1958-10-29 1958-10-29 Improvements in or relating to extensible hydraulic supports

Publications (1)

Publication Number Publication Date
US2985418A true US2985418A (en) 1961-05-23

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ID=10367701

Family Applications (1)

Application Number Title Priority Date Filing Date
US843977A Expired - Lifetime US2985418A (en) 1958-10-29 1959-10-02 Extensible hydraulic supports

Country Status (4)

Country Link
US (1) US2985418A (fr)
BE (1) BE584049A (fr)
FR (1) FR1237069A (fr)
GB (1) GB862033A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3133720A (en) * 1962-03-27 1964-05-19 Commercial Shearing Yieldable pit posts
US4142449A (en) * 1976-02-03 1979-03-06 Thyssen Industrie Ag Hydraulic mine prop

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US371919A (en) * 1887-10-25 belden
US1886621A (en) * 1928-05-09 1932-11-08 William L Bagwill Cracking still and process
US2477533A (en) * 1946-10-19 1949-07-26 William A Whiting Pipe joint
US2621631A (en) * 1948-01-12 1952-12-16 Dowty Equipment Ltd Telescopic hydraulic mine roof support
US2693223A (en) * 1952-02-21 1954-11-02 Goodrich Co B F Method of making flexible hollow connections

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US371919A (en) * 1887-10-25 belden
US1886621A (en) * 1928-05-09 1932-11-08 William L Bagwill Cracking still and process
US2477533A (en) * 1946-10-19 1949-07-26 William A Whiting Pipe joint
US2621631A (en) * 1948-01-12 1952-12-16 Dowty Equipment Ltd Telescopic hydraulic mine roof support
US2693223A (en) * 1952-02-21 1954-11-02 Goodrich Co B F Method of making flexible hollow connections

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3133720A (en) * 1962-03-27 1964-05-19 Commercial Shearing Yieldable pit posts
US4142449A (en) * 1976-02-03 1979-03-06 Thyssen Industrie Ag Hydraulic mine prop

Also Published As

Publication number Publication date
GB862033A (en) 1961-03-01
BE584049A (fr) 1960-02-15
FR1237069A (fr) 1960-07-22

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