US2723100A - Releasable supports for roofs in underground mines - Google Patents
Releasable supports for roofs in underground mines Download PDFInfo
- Publication number
- US2723100A US2723100A US234966A US23496651A US2723100A US 2723100 A US2723100 A US 2723100A US 234966 A US234966 A US 234966A US 23496651 A US23496651 A US 23496651A US 2723100 A US2723100 A US 2723100A
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- US
- United States
- Prior art keywords
- wedge
- support
- surface portions
- members
- chocks
- 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
Links
- 239000003245 coal Substances 0.000 description 7
- 238000012856 packing Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 101100285518 Drosophila melanogaster how gene Proteins 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
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
- E21D15/60—Devices for withdrawing props or chocks
Definitions
- each post having an upper inclined face associated with it and a tapered member permanently fastened to it and being capable of displacement on said inclined face to change the effective height of the post; in this construction the displacement is effected from a chain or the like by which the support is towed, and stops are employed for limiting movements of the tapered members such that the eflective maximum and minimum heights which each post may assume is predetermined.
- stops are employed for limiting movements of the tapered members such that the eflective maximum and minimum heights which each post may assume is predetermined.
- An object of the invention is to avoid the necessity for said separate wood beams and packing pieces by providing a self contained support. It is desired that, during the progressive cutting of coal from the working face, the newly formed roof should be supported as soon as practicable, and a further object of the invention therefore is to provide an improved roof support which is self contained and-is particularly suitable for use in confined spaces.
- the invention provides a roof support for coal mines and the like comprising a body structure, a top beam permanently connected to the structure and disposed substantially horizontally at the upper end thereof, and relatively movable parts by which the top beam may be raised and lowered.
- the top beam is movable up and down initially through a predetermined distance and subsequently through a variable distance, conveniently by relatively movable parts having co-operating inclined faces.
- the structure is comparatively narrow consisting of two posts connected by a bridge and having the top beam extending along the bridge, and relatively movable parts having co-operating inclined faces are pro vided at or near each end of the top beam, and the beam is connected to the structure by means which permits raising or lowering of the respective ends to different extents.
- said parts consist of, the body structure, main movable tapered members co-operating with the structure and having a predetermined movement for obtaining the predetermined adjustment (for example in the manner and by the means described in the specification of our patent application Serial No. 205,046) and additional movable tapered members conveniently co-operan ing with said main movable tapered members and with the top beam, for obtaining the variable adjustment.
- the top beam is conveniently a channel member and the Said additional member extend transversely through the channel members and are provided with stepped surfaces for locating them in different positions of adjustment.
- the top beam is permanently connected and is adjustable for height, the support is self contained and packing pieces are unnecessary. Furthermore a support as above, when having only two posts and therefore being of comparatively narrow nature, is particularly suitable for use in confined spaces. This latter support may be disposed'for example parallel to, or at right angles to, the coal face. If desired, in a support according to the invention, the top beam may extend for an appreciable distance beyond the support in cantilever manner so as to support the roof where uprights cannot be satisfactorily fitted.
- Figure 1 is a side view of a support according to the invention.
- Figure 2 is an end view of Figure l partly in section.
- a roof support is provided particularly for use in coal mines and comprising a pair of spaced uprights (one of which is indicated at 1) said uprights being connected at their upper ends by a bridge 2.
- This bridge 2 has upper inclined surfaces 3, 4 on which bears tapered wedge or chock members, one of which is shown at 5.
- the uprightsf l are H sectioned girders and the bridge 2 is composed of a pair of plate members suitably welded to opposite sides of the uprights 1.
- Each wedge or chock member 5 conveniently constructed by a pair of side plates 5a, 5b connected by a pin 6 and spaced by a member 26; each of these side plates 5a, 5b has an inclined undersurface, bearing on the appropriate inclined faces 3, 4 of the bridge plate with each end overlying the respective uprights.
- This top beam is preferably of channel shape and consists of a corrugated upper number 8 to which there is fastened, by welding, downwardly depending spaced walls 9 and 10. These walls 9 and 10 fit on opposite sides of the bridge 2 and the channelmember is conveniently retained connected to the bridge 2 by a pin .11 forming trunnions, and a slot 12 in each wall 9, 10.
- each wedge 13 has its lower edge stepped i. e. formed with horizontal spaced surfaces 16 and interthan the upper edge of the wall 5bzto allow for the taper of the wedge 13; conveniently said upper-edges of the walls 5a and 5b are horizontal to register with horizontal surfaces of the wedge and the said wedge 13 preferably has a hole 18 at its apex for a chain or the like.
- the wedge or chock members 5 In use it is desired for the wedge or chock members 5 to be moved from the inner and raised operative position, automatically, as the support is moved away from its roof supporting position and conveniently for this purpose the support is modified in accordance with the specification of our patent application Serial No. 205,046 and to which reference is directed for full details.
- a Briefy, or tapered members 5 to the support and said means are displaceable (between stops to limit 7 the movement) through the medium of operating means and a chain or the like; said chain or the like is adapted to pull the supto their inoperative positions whereat Patented Nov. 8, 1955 means are provided permanently connecting the wedge,
- roof supporting apparatus for coal mines and the like comprising, in combination, an elongated base plate adaptedto serve as a runner; an elongated supporting structure fixed to said base plate, extending along the length thereof and upwardly therefrom and being provided with oppositely inclined top surface portions extending inwardly and upwardly toward each other from opposite ends of said supporting structure, respectively; a pair of chocks respectively located on said oppositely inclined top surface portions of said supporting structure for, sliding movement therealong, each of said chocks having opposite side walls engaging said supporting structure and having top substantially horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length of said supporting structure, being located over the same, and having opposite side walls between which said chocks are located, said side walls being formed with two pairs of opposite elongated cutouts respectively extending upwardly from said chocks and overlapping the same; and apair of wedge members respectively extending through said pairs of' cutouts in a direction transverse to the length of said beam and supporting structure and each having
- Roof supporting apparatus for coal mines and the like comprising, in combination, an elongated base plate adapted to serve as a runner; an elongated supporting structure fixed to said, base plate, extending along the lengththereof and upwardly therefrom and being provided with oppositely inclined top surface portions extending inwardly and upwardly toward each other from opposite ends ofsaid supporting structure, respectively; a pair of' chocks respectively located on said oppositely inclined" top surface portions of said supporting structure forsliding movement therealong, each of said chockshaving-opposite sidewalls engaging said supporting structureand having top substantially horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length of said supporting structure, being located over the same, and having opposite sidewalls between which said chocks are located, said side walls being formed with two pairs of opposite elongated cutouts respectively extending upwardly from. said chocks and overlapping the same, saidbeam having between said side wallsa trans r e. all.
- Roof supporting apparatusv for coal mines and the like comprising, in combination, an. elongated base plate adapted to serve as a runner; an, elongated supportingstructure fixed to said base plate, extending along the length. thereof and: upwardly therefrom and: being provided with oppositely inclined top surface portions ex tending inwardly and upwardly. toward. each other from opposite, ends of said supporting structure, respectively;v a pair of chocks respectively located on, said: opposite-. ly inclined top surface portions of said supporting stru,c. ture for sliding movement therealong, each of said. chocks having opposite side;v walls engaging said supporting structure and having top; substantially. horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length. of said supporting structure, beinglocated: over.
- said checks are located, said side walls being. formed: with two pairs of opposite elongated, cutouts respectively extending upwardly from said. chocks andi overlapping the same, and said beam being formedint at. least. one of said side walls thereof with anelongated. slot extending downwardly towards said supporting struc-. ture and overlapping the same; a pair'of wedge mem-.
- each chock said fiat surface portions of each wedge member being interconnected by a. bottom surfafie pop tion thereof which is inclined to said flat surface per v tions; and a pin fixed to said supporting structureand, extending through. said slot to interconnect, said b ea rnv and supporting structure while freeing said. beam, for; for movement toward and away from said supporting structure.
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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)
- Conveying And Assembling Of Building Elements In Situ (AREA)
Description
Nov. 8, 1955 N. J. MUSCHAMP ET AL RELEASABLE SUPPORTS FOR ROOFS IN UNDERGROUND MINES Filed July 3, 1951 United States Patent .This invention isfor improvements in or relating to releasable supports for roofs in underground mines, and is particularly concerned with supports of the type incorporating relatively movable. parts with inclined surfaces by which the elfective height of the supports may be changed from an inoperative non-supporting height to' an operative supporting height. Examples of this type of support-are described in the specification of our co-pending patent application Serial No. 205,046, now abandoned, which discloses a support having one or more posts, each post having an upper inclined face associated with it and a tapered member permanently fastened to it and being capable of displacement on said inclined face to change the effective height of the post; in this construction the displacement is effected from a chain or the like by which the support is towed, and stops are employed for limiting movements of the tapered members such that the eflective maximum and minimum heights which each post may assume is predetermined. Generally, with this type of support, separate top beams of wood are provided, and because the roof is usually uneven, packing pieces often have to be employed.
An object of the invention is to avoid the necessity for said separate wood beams and packing pieces by providing a self contained support. It is desired that, during the progressive cutting of coal from the working face, the newly formed roof should be supported as soon as practicable, and a further object of the invention therefore is to provide an improved roof support which is self contained and-is particularly suitable for use in confined spaces.
The invention provides a roof support for coal mines and the like comprising a body structure, a top beam permanently connected to the structure and disposed substantially horizontally at the upper end thereof, and relatively movable parts by which the top beam may be raised and lowered. Preferably the top beam is movable up and down initially through a predetermined distance and subsequently through a variable distance, conveniently by relatively movable parts having co-operating inclined faces. Preferably the structure is comparatively narrow consisting of two posts connected by a bridge and having the top beam extending along the bridge, and relatively movable parts having co-operating inclined faces are pro vided at or near each end of the top beam, and the beam is connected to the structure by means which permits raising or lowering of the respective ends to different extents. Conveniently said parts consist of, the body structure, main movable tapered members co-operating with the structure and having a predetermined movement for obtaining the predetermined adjustment (for example in the manner and by the means described in the specification of our patent application Serial No. 205,046) and additional movable tapered members conveniently co-operan ing with said main movable tapered members and with the top beam, for obtaining the variable adjustment. The top beam is conveniently a channel member and the Said additional member extend transversely through the channel members and are provided with stepped surfaces for locating them in different positions of adjustment.
Because in a support according to the invention the top beam is permanently connected and is adjustable for height, the support is self contained and packing pieces are unnecessary. Furthermore a support as above, when having only two posts and therefore being of comparatively narrow nature, is particularly suitable for use in confined spaces. This latter support may be disposed'for example parallel to, or at right angles to, the coal face. If desired, in a support according to the invention, the top beam may extend for an appreciable distance beyond the support in cantilever manner so as to support the roof where uprights cannot be satisfactorily fitted.
The above and other features of the invention are disclosed in detailed description given byway of example of the particular embodiments illustrated in the accom panying drawings in which:
Figure 1 is a side view of a support according to the invention, and
Figure 2 is an end view of Figure l partly in section.
Referring now to the drawings, a roof support is provided particularly for use in coal mines and comprising a pair of spaced uprights (one of which is indicated at 1) said uprights being connected at their upper ends by a bridge 2. This bridge 2 has upper inclined surfaces 3, 4 on which bears tapered wedge or chock members, one of which is shown at 5. Preferably the uprightsf l are H sectioned girders and the bridge 2 is composed of a pair of plate members suitably welded to opposite sides of the uprights 1. Each wedge or chock member 5 conveniently constructed by a pair of side plates 5a, 5b connected by a pin 6 and spaced by a member 26; each of these side plates 5a, 5b has an inclined undersurface, bearing on the appropriate inclined faces 3, 4 of the bridge plate with each end overlying the respective uprights. This top beam is preferably of channel shape and consists of a corrugated upper number 8 to which there is fastened, by welding, downwardly depending spaced walls 9 and 10. These walls 9 and 10 fit on opposite sides of the bridge 2 and the channelmember is conveniently retained connected to the bridge 2 by a pin .11 forming trunnions, and a slot 12 in each wall 9, 10. There is also provided a pair of wedges, one of which is shown at 13 extending transversely of the channel member .7 and bearing at its lower edges on the upper edge of said walls 5a, 5b of the wedge or chock 5; its upper inclined edge co-operates with a correspondingly inclined surface 14 formed by a filling member 15 in the base of the channel 'member 7. Preferably as shown, each wedge 13 has its lower edge stepped i. e. formed with horizontal spaced surfaces 16 and interthan the upper edge of the wall 5bzto allow for the taper of the wedge 13; conveniently said upper-edges of the walls 5a and 5b are horizontal to register with horizontal surfaces of the wedge and the said wedge 13 preferably has a hole 18 at its apex for a chain or the like.
In use it is desired for the wedge or chock members 5 to be moved from the inner and raised operative position, automatically, as the support is moved away from its roof supporting position and conveniently for this purpose the support is modified in accordance with the specification of our patent application Serial No. 205,046 and to which reference is directed for full details. A Briefy, or tapered members 5 to the support and said means are displaceable (between stops to limit 7 the movement) through the medium of operating means and a chain or the like; said chain or the like is adapted to pull the supto their inoperative positions whereat Patented Nov. 8, 1955 means are provided permanently connecting the wedge,
. 3.. beam 8 is lowered. When the support is being erected the wedges are raised by handand the stepped wedges 13 are hammered in to tighten the top beam 8 up to the roof,
onewedgebeing drivenfurther inthan the other if necesface for example between said cantilever supports. If'
and when desired the said chains or the like may be conveniently guided for examplevby right. angle tubular members having flaredsends such thatthe operation of the wedge or chock members iseffected by a pulling actionv on the chain or the like in a direction at right angles to the general plane of the support.
We claim:
1. Roof supporting apparatus for coal mines and the like comprising, in combination, an elongated base plate adaptedto serve as a runner; an elongated supporting structure fixed to said base plate, extending along the length thereof and upwardly therefrom and being provided with oppositely inclined top surface portions extending inwardly and upwardly toward each other from opposite ends of said supporting structure, respectively; a pair of chocks respectively located on said oppositely inclined top surface portions of said supporting structure for, sliding movement therealong, each of said chocks having opposite side walls engaging said supporting structure and having top substantially horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length of said supporting structure, being located over the same, and having opposite side walls between which said chocks are located, said side walls being formed with two pairs of opposite elongated cutouts respectively extending upwardly from said chocks and overlapping the same; and apair of wedge members respectively extending through said pairs of' cutouts in a direction transverse to the length of said beam and supporting structure and each having a top surface engaging said beam, said wedge members respectively having bottom surfaces engaging said chocks, and each of'said bottom surfaces of said Wedge members having a pair of spaced'substantially horizontal fiat surface-portions located at different elevations and respectively engaging saidtop surface portions of said side walls of each chock, said flat surface portions of each wedge member'being interconnected by a bottom surface portion thereof whichis inclined to said'fiat surface portions.
2: Roof supporting apparatus for coal mines and the like comprising, in combination, an elongated base plate adapted to serve as a runner; an elongated supporting structure fixed to said, base plate, extending along the lengththereof and upwardly therefrom and being provided with oppositely inclined top surface portions extending inwardly and upwardly toward each other from opposite ends ofsaid supporting structure, respectively; a pair of' chocks respectively located on said oppositely inclined" top surface portions of said supporting structure forsliding movement therealong, each of said chockshaving-opposite sidewalls engaging said supporting structureand having top substantially horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length of said supporting structure, being located over the same, and having opposite sidewalls between which said chocks are located, said side walls being formed with two pairs of opposite elongated cutouts respectively extending upwardly from. said chocks and overlapping the same, saidbeam having between said side wallsa trans r e. all. EQL iQn. provided. with. a. bottom. 1
4. face which is inclined to said top, horizontal surface portions of saidchocks; and a pair of wedge members respectively extending through said pairs of cutouts in a direction transverse to the length of said beam and supporting structure and each having a top surface of the same inclination as and engaging said:- bottom surface of said transverse wall portion of said beam, said wedge members respectively having bottom surfaces engaging said chocks, and each of said bottom surfaces of said wedge members having a pair of spaced substantially horizontal flat surface portions located. at diiferent elevations and respectively engaging said top su face portions of said side walls of each chock, said fi t surface portions of. each. wedge member being intei; connected by a bottom. surface portion thereof whic is inclined to said fiat. surface portions.
3. Roof supporting apparatusv for coal mines and the like comprising, in combination, an. elongated base plate adapted to serve as a runner; an, elongated supportingstructure fixed to said base plate, extending along the length. thereof and: upwardly therefrom and: being provided with oppositely inclined top surface portions ex tending inwardly and upwardly. toward. each other from opposite, ends of said supporting structure, respectively;v a pair of chocks respectively located on, said: opposite-. ly inclined top surface portions of said supporting stru,c. ture for sliding movement therealong, each of said. chocks having opposite side;v walls engaging said supporting structure and having top; substantially. horizontal flat surface portions located at different elevations; an elongated channel-shaped beam extending along the length. of said supporting structure, beinglocated: over.
the same, and havingopposite-side walls. between which,
said checks are located, said side walls being. formed: with two pairs of opposite elongated, cutouts respectively extending upwardly from said. chocks andi overlapping the same, and said beam being formedint at. least. one of said side walls thereof with anelongated. slot extending downwardly towards said supporting struc-. ture and overlapping the same; a pair'of wedge mem-.
bersrespectively extending through said pairs, of, cutouts: in a direction. transverse to the length of said'beam and? supporting. structure and each having a top surface; en,-
gaging said beam, said wedge members respectively,-hay.-..
ing bottom surfaces engaging said chocks, andeach of said bottom surfaces of said wedge members having a pair of spaced substantially horizontal fiat surface portions located at different elevations and respectively en,- gaging said top surface portions. of said, side walls of; each chock, said fiat surface portions of each wedge member being interconnected by a. bottom surfafie pop tion thereof which is inclined to said flat surface per v tions; and a pin fixed to said supporting structureand, extending through. said slot to interconnect, said b ea rnv and supporting structure while freeing said. beam, for; for movement toward and away from said supporting structure.
References Cited in the file of this patent UNITED STATES PATENTS 212,230 Johnston Feb. 11, 1879 1,046,517 Weber Dec. 10, 1912 1,450,329 Morgan Apr. 3, 1923. 2,036,490 Neilson et'al. Apr. 7, 1936 2,256,620 Markham Sept. 23, 194 1 FOREIGN PATENTS 20,472 Great Britain Feb. 24, 1910 419,939 Great Britain Nov. 22, 1934;
425,120 Great Britain Mar. 5, 19352v 455,942 Great Britain Oct. 30, 1936'.
507,045 Great Britain June 8', 1939 572,537 Germany Feb. 19, 1931 923-,079, France Feb. 10', 1947"
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2723100X | 1951-04-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2723100A true US2723100A (en) | 1955-11-08 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US234966A Expired - Lifetime US2723100A (en) | 1951-04-13 | 1951-07-03 | Releasable supports for roofs in underground mines |
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US (1) | US2723100A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3883106A (en) * | 1973-05-14 | 1975-05-13 | Dominion Bridge Co Ltd | Telescoping post |
US4113219A (en) * | 1977-06-03 | 1978-09-12 | Donn Products, Inc. | Adjustable pedestal for elevated floors |
US5442882A (en) * | 1994-04-20 | 1995-08-22 | Repasky; John | Universal slope compensator for use in constructing a flat surface |
CN102828759A (en) * | 2012-08-31 | 2012-12-19 | 山东新煤机械装备股份有限公司 | Moving and support dismantling method for working faces of breaking roofs of mines |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US212230A (en) * | 1879-02-11 | Improvement in wedges for splitting logs | ||
GB191020472A (en) * | 1910-09-02 | 1911-02-16 | William Fairburn-Hart | Improvements in and relating to Glazing Roofs, Skylights and the like. |
US1046517A (en) * | 1911-02-04 | 1912-12-10 | Jeffrey Mfg Co | Mine-post. |
US1450329A (en) * | 1916-01-05 | 1923-04-03 | Edmund C Morgan | Mine-roof-supporting method and apparatus |
DE572537C (en) * | 1933-03-17 | Dipl Berging Dr Ing Adolf Lohm | Vorpfaendeeisen | |
GB419939A (en) * | 1933-04-22 | 1934-11-22 | Peter Kay | Improved means for releasing or collapsing mine chocks and the like |
GB425120A (en) * | 1933-09-05 | 1935-03-05 | Matthew Smith Moore | Improvements in or relating to pit props |
US2036490A (en) * | 1934-05-29 | 1936-04-07 | Stewarts & Lloyds Ltd | Support for mines and the like |
GB455942A (en) * | 1935-09-07 | 1936-10-30 | John William Thompson | Improvements in and relating to collapsible props for supporting the roofs of mine galleries and for similar purposes |
GB507045A (en) * | 1938-11-08 | 1939-06-08 | Naylor Brothers Ltd | Improvements in chocks for use in mines |
US2256620A (en) * | 1940-07-30 | 1941-09-23 | Charles M Markham | Adjustable shore |
FR923079A (en) * | 1946-03-01 | 1947-06-26 | Const Metalliques & Forges De | Improvement in metal props |
-
1951
- 1951-07-03 US US234966A patent/US2723100A/en not_active Expired - Lifetime
Patent Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US212230A (en) * | 1879-02-11 | Improvement in wedges for splitting logs | ||
DE572537C (en) * | 1933-03-17 | Dipl Berging Dr Ing Adolf Lohm | Vorpfaendeeisen | |
GB191020472A (en) * | 1910-09-02 | 1911-02-16 | William Fairburn-Hart | Improvements in and relating to Glazing Roofs, Skylights and the like. |
US1046517A (en) * | 1911-02-04 | 1912-12-10 | Jeffrey Mfg Co | Mine-post. |
US1450329A (en) * | 1916-01-05 | 1923-04-03 | Edmund C Morgan | Mine-roof-supporting method and apparatus |
GB419939A (en) * | 1933-04-22 | 1934-11-22 | Peter Kay | Improved means for releasing or collapsing mine chocks and the like |
GB425120A (en) * | 1933-09-05 | 1935-03-05 | Matthew Smith Moore | Improvements in or relating to pit props |
US2036490A (en) * | 1934-05-29 | 1936-04-07 | Stewarts & Lloyds Ltd | Support for mines and the like |
GB455942A (en) * | 1935-09-07 | 1936-10-30 | John William Thompson | Improvements in and relating to collapsible props for supporting the roofs of mine galleries and for similar purposes |
GB507045A (en) * | 1938-11-08 | 1939-06-08 | Naylor Brothers Ltd | Improvements in chocks for use in mines |
US2256620A (en) * | 1940-07-30 | 1941-09-23 | Charles M Markham | Adjustable shore |
FR923079A (en) * | 1946-03-01 | 1947-06-26 | Const Metalliques & Forges De | Improvement in metal props |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3883106A (en) * | 1973-05-14 | 1975-05-13 | Dominion Bridge Co Ltd | Telescoping post |
US4113219A (en) * | 1977-06-03 | 1978-09-12 | Donn Products, Inc. | Adjustable pedestal for elevated floors |
US5442882A (en) * | 1994-04-20 | 1995-08-22 | Repasky; John | Universal slope compensator for use in constructing a flat surface |
CN102828759A (en) * | 2012-08-31 | 2012-12-19 | 山东新煤机械装备股份有限公司 | Moving and support dismantling method for working faces of breaking roofs of mines |
CN102828759B (en) * | 2012-08-31 | 2014-11-26 | 山东新煤机械装备股份有限公司 | Moving and support dismantling method for working faces of breaking roofs of mines |
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