GB2214963A

GB2214963A - Mine roof support

Info

Publication number: GB2214963A
Application number: GB8803351A
Authority: GB
Inventors: John Halton; David Woodcock
Original assignee: Gullick Dobson Ltd
Current assignee: Gullick Dobson Ltd
Priority date: 1988-02-13
Filing date: 1988-02-13
Publication date: 1989-09-13
Anticipated expiration: 2008-02-13
Also published as: GB8803351D0; GB2214963B

Abstract

A mine roof support has two parallel floor engaging members 10 and 11, the rear ends of which are held together, to resist the greater part of spacial displacement forces, by a force resistant means 14, attached to each floor engaging member by at least one pair of force transmitting pivotal links 15, 16. Although the arrangement provides resistance to the greater part of spacial displacement forces, the lower rear part of the support is substantially unobstructed, assisting the free flow of waste material through the support. Preferably, one of the pairs of links, for example the rear pair 15, 16 have a greater cross-sectional resistance to torsion and bending forces than the second pair of links 17 and 18. <IMAGE>

Description

MINE ROOF SUPPORTS The invent Ion relates to mine roof supports.

Mlne roof supports for use in the longwall method of mining are often required to accommodate varlous differing mining conditions, such as different seam heights, soft or hard floors, friable roofs, and the like. It is essentlal for any given mine roof support to have features which suit the combination of specific parameters which will be encountered by that mine roof support in use.

For example, a support for use with soft floors must be designed to ride over loose materlal, or provide for the free flow of such loose material through the base structure of the mine roof support. If this Is not achieved successfully, material will build up In the path of the support and could, in time, after a low number of mining cycles, Inhibit the advance of the roof support.

Most modern supports have a pivotal linkage at the rear of the support, generally of the type known as a lemniscate linkage, having four parallel pivotal axes usually located at the corners of an Irregular quadrilateral. The purpose of this linkage is to control the foremost part of the mine roof engaging structure of the support, relative to the base structure, during vertical travel of the mine roof engaging structure.

A well known design of mine roof support has a base unit which comprlses two parallel spaced-apart floor engaging members Joined together at their rear ends by a rear lower shield, for example in the form of a torsion box extending across the full width of the support. This torsion box resists forces tending to displace vertically the rear ends of the floor engaging members. Another method of resisting such displacement forces Is to arrange a single torslon resistant link, forming part of a lemniscate type linkage, between the floor engaging members, pivotally attached thereto, thus acting as both a spacer member and a bridging member.

Both these known methods of preventing displacement at the rear of the floor engaging members have the disadvantage that they restrict the free flow of loose material between the floor engaging members and towards the rear or waste end of the mine roof support, when the support is advanced.

It may be possible, on medium to high seam roof supports, to make the lower edge of a torsion box construction in a bridge I ike manner to assist in providing the free flow of material through the support.

However this assistance Is generally only provided while the torsion box Is working in the upper quadrant of its pivotal movement. On lower seams however, where the torsion box may be pivoting in the lower quadrant of Its movement, the torslon box may, In Its lowest working position, present an almost horizontally extending structure full In the path of the material flow, resulting In a build up of loose material wlthin the bounds of the roof support structure.

It should be understood that during the roof support operating cycle, the roof engaging structure, located directly above the floor engaging structure, has to be lowered such that the roof support may be advanced In a non load bearing conditlon, and this of course reduces the space between the roof engaging structure and the floor engaging structure.

To maintain the hydraulic system of such roof supports, It has been found that It Is advantageous to locate all the control valves and other hydraulic components In fIxed relationship to the roof engaging structure, whereby they remaln relatively clean and free from damage. Consequently, space must be available to accommodate the hydraulic system as the roof engaging structure Is lowered, and this Is not possible when working a low seam If the floor engaging structure is packed with loose material which has been unable to pass through the support.

The Invention Is therefore directed towards providing a degree of control to the rear ends of the floor engaging members without substantially obstructing the flow of loose material through the support.

Accordingly, the invention provides a mine roof support having two parallel floor engaging members, the rear ends of which are held together, to resist the greater part of spaclal displacement forces, by linkage means pivotally attached to torsion resistant means.

Preferably the linkage means comprise lemniscate linkage means.

The torsion resistant means preferably comprises an InclIned shield member connected to a roof engaging canopy of the support.

The parallel floor engaging members may be held together in spaclal relationship at their forward ends, by rigid connection means, which prevents one member lifting relative to the other or the splaying thereof during the support advance.

Alternatively, dependent upon the mining conditions, the forward ends of the parallel floor engaging members may be held together In spaclal relationship by flexible or pivotal means having fixed centres.

The linkage means may comprise at least one pivotal link attached at or towards the rear end of each of the floor engaging members, the two pivotal links providing transmission means for any displacement forces normal to the mine floor, to the torsion resistant means to which the other end of each link is pivotally attached.

A further pair of links may be provided, pivotally interconnecting each floor engaging member with the torsion resistant means to provide, in combination with the first pair of links, means to control the longitudinal relatlonship between the floor engaging members and the canopy.

The floor engaging members and the canopy may have means to urge them apart comprising at least one hydraulic Jack mounted on each floor engaging member.

The pivotal connection of the second pair of links with the floor engaging members may be alongside said hydraulic Jacks, or may lie forwardly of said hydraulic Jacks.

Two further hydraulic Jacks may be provided, one for each floor engaging member, located forwardly of the sald second pair of links.

Where the forward ends of the floor engaging members are held together by rigid connection means, the hydraulic Jacks preferably lie rearwardly of said rigid connection means.

Where each floor engaging member Is provided with two hydraulic Jacks, the hydraulic Jacks may have divergent axes leading from the floor engaging member to the canopy.

A hydraulic Jack attached to one of the floor engaging members may converge towards a hydraulic Jack of the other floor engaging member In the direction from the floor engaging member to the canopy.

The first pair of links may have a greater cross sectional resistance to torsional and bending forces than the second pair of links.

The second pair of links may be located alongside one pair of hydraulic Jacks, towards the outer sides of the mine roof support structure.

A pivotal or flexible bridging member may be provided between the floor engaging members for mounting a hydraulic Jack for use in advancing the mine roof support.

The ratio of floor engaging length to seam height for stability purposes may be broadly maintained with respect to a prior art mine roof support, thus resulting In a mine roof support which has a shorter floor engaging structure than might be conventionally adopted for utilitarian purposes.

By way of example, a specific embodiment of the Invention will now be descrlbed with reference to the single accompanying figure, which is a perspective view of an embodiment of mine roof support according to the Invent Ion, partly broken away for purposes of clarity.

The mine roof support shown In the figure has a base structure In the form of two, parallel spaced-apart floor engaging skids 10 and 11.

The only direct Interconnect Ion between the skids 10 and 11 is in the form of a rigid bridge 12 arranged at the forward end of the skids. The bridge is cut away at 13 to allow free flow of material between the skids, when the support is moving forwardly.

In prior art supports, there is also some form of rear direct Interconnection between the skids, to restrain torslonal and other loads applied to the rear of the support. One form of known interconnection comprises a torsion box structure extending between the skids.

Another known form of interconnection comprises a substantlal central link pivotally connected to each of the skids. Both of these structures provide a substantlal barrier to the free flow of material, particularly in low seams.

In this embodiment of the Invention however, the rear ends of the skids are only connected together Indirectly, by means of an incllned rear shield structure 14, to which the skids are pivotally connected by a first pair of rear links 15 and 16 and a second pair of forward links 17 and 18.

To complete the support, the shield 14 is pivotally connected at 19 and 20 to a roof engaging canopy, which has been removed In the drawing to show more clearly the hydraulic Jacks which urge the base structure and the canopy apart In use.

There is a first pair of rear Jacks 21 and 22 whose lower ends are positioned between the lower pivotal connections 23 and 24 of the palrs of links. The upper ends of these Jacks 21 and 22 are positioned closer together than their lower ends, so that the Jacks converge In the upward directlon, to facilltate pivotal movement of the links 17 and 18 past the Jacks.

The forward pair of Jacks 25 and 26 are positioned between the Jacks 21 and 22 and the front bridge 12. Jack 26 diverges from Jack 22 in the upward direction, and Jack 25 diverges from Jack 21 In the upward direction.

The area In front of the Jacks 25 and 26, and above the skids 10 and 11, provides a walkway through which mine operatives may walk or crawl, protected by the roof engaging canopy.

The rear shield 14 has substantial bearing plates 27 and 28 and lighter bearlng 29 and 30. The floor engaging members respectively have outer bearing plates 31 and 32 and Inner bearlng plates 33 and 34.

Each of the links 15 and 16 comprises a substantial box cross sectlon structure which Is pivotally connected between the bearing plates of the associated skid and a pair of the bearing plates of the shield 14. Each of the links 17 and 18 comprises a lighter structure Interconnecting an outer bearlng plate of the associated skid and an outer bearing plate of the shleld structure 14.

The pivot pins for each of the pivotal connectlons of the linkage are provided wlth working clearances which provide a degree of float in the pivotal connections. However, once the float has been taken up, any further displacement forces applied to the rear ends of the skids are effectively resisted by a combination of the links and the rear shield structure 14. There is therefore no need to provide a direct interconnection between the rear ends of the skids, either in the form of a rigid bridge or other connection. Thus loose material has the greatest chance of belng able to pass freely between the skids.This In turn reduces the risk that there will be a substantial build up of material at the rear of the support, which could not only impede the advance of the support, but could also prevent hydraulic control gear from being safely accommodated as the roof engaging canopy Is lowered.

The Invent ion Is not restricted to the particular configuration shown in the drawing. For example, the pivot points 23 may be alongside, or even slightly rearward of the lower ends of the hydraulic Jacks 21 and 22.

The contents of all papers and documents filed concurrently with this specification are incorporated herein by reference.

All of the features disclosed in this speclficatlon (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined In any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

The invention Is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed In this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A mine roof support having two parallel spaced apart load bearing floor engaging members, the rear ends of which are held together, to resist the greater part of spaclal displacement forces, by a force resistant member attached to each floor engaging member by at least one pair of force transmitting pivotal links.

2. A mine roof support as claimed In Claim 1, in which the links comprise lemniscate links.

3. A mine roof support as claimed in Claim 1 or Claim 2, in which the force resistant means comprises an inclined shield member connected to a roof engaging canopy of the support.

4. A mine roof support as claimed in any one of the preceding ClaIms, in which the parallel floor engaging members are held together In spacial relationship at their forward ends, by rigid connection means, which prevents one member lifting relative to the other or the splaying thereof during the support advance.

5. A mine roof support as claimed in any one of Clalms 1 to 3, In which, dependent upon the mining conditions, the forward ends of the parallel floor engaging members are held together in spatial relationship by flexible or pivotal means having fixed centres.

6. A mine roof support as claimed in any one of the preceding Claims, in which there is at least one pivotal ilnk attached at or towards the rear end of each of the floor engaging members, the two pivotal links providing transmission means for any displacement forces normal to the mine floor, to the force resistant means to which the other end of each link is pivotally attached.

7. A mine roof support as claimed In Claim 6, in which a further pair of links Is provided, pivotally Interconnecting each floor engaging member with the force resistant means to provide, in combination with the first pair of links, means to control the longitudinal relationship between the floor engaging members and the canopy.

8. A mine roof support as claimed in Claim 7, in which the floor engaging members and the canopy have means to urge them apart comprising at least one hydraulic Jack mounted on each floor engaging member.

9. A mine roof support as claimed in Claim 8, in which the pivotal connection of the second pair of links with the floor engaging members is alongside sald hydraulic Jacks, or lies forwardly of said hydraulic Jacks.

10. A mine roof support as claimed in Claim 9, in which two further hydraulic Jacks are provIded, one for each floor engaging member, located forwardly of the said second pair of links.

11. A mine roof support as claimed in any one of the preceding Claims, In which each floor engaging member is provided with two hydraulic Jacks, the hydraulic Jacks having divergent axes leading from the floor engaging member to a canopy.

12. A mine roof support as claimed in an one of the preceding Claims, in which a hydraulic Jack attached to one of the floor engaging members converges towards a hydraulic Jack of the other floor engaging member in the direction from the floor engaging member to a canopy.

13. A mine roof support as claimed in any one of the preceding Claims, In which a first pair of links each has a greater cross sectional resistance to torsional and bending forces than a second pair of links.

14. A mine roof support as claimed in any one of the preceding Claims having two pairs of links, the second pair being located outside a pair of hydraulic Jacks, towards the outer sides of the mine roof support structure.

15. A mine roof support as claimed in any one of the preceding Claims, in which a pivotal or flexible bridging member is provided between the floor engaging members for mounting a hydraulic Jack for use in advancing the mine roof support.

16. A mine roof support constructed and arranged substantially as hereln described, with reference to the accompanying drawings.