GB2196371A

GB2196371A - Constant pressure mine roof support canopy extension

Info

Publication number: GB2196371A
Application number: GB08624745A
Authority: GB
Inventors: Roy Park
Original assignee: Gullick Dobson Ltd
Current assignee: Gullick Dobson Ltd
Priority date: 1986-10-15
Filing date: 1986-10-15
Publication date: 1988-04-27
Anticipated expiration: 2006-10-15
Also published as: GB8624745D0; GB2196371B; ZA877637B; DE3734642A1; DE3734642C2

Description

GB2196371A 1 SPECIFICATION member has a free end arranged to engage with

the mine roof to apply a load thereto, a Mine roof supports pivot point, and a force application point at which force can be applied from the mine roof The invention relates to mine roof supports. 70 support to tilt the extensible roof engaging In the application of the modern under- member, the distance of the free end and the ground mining technique known as longwall pivot point from the force application point mining, there is provided a row of self ad- being fixed.

vancing mine roof supports, which are se- The pivot point may comprise a fulcrum ly- quentially advanced up to the newly exposed 75 ing between the free end and the force appli mine face after the passage of a mining macation point.

chine between the mine roof supports and the A hydraulic ram may be positioned at the mine face, the passage of the machine remov- force application point, the ram acting be ing a strip of coal or other mineral. Thus the tween the extensible roof engaging member corresponding newly exposed mine roof is un- 80 and another part of the mine roof support.

supported until such time as the mine roof The ram may be slidable over the other part supports can be advanced. There may be a of the mine roof support when the extensible delay in advance of at least some of the mine roof engaging member extends.

roof supports, either because of obstruction of The extensible roof engaging member may the mine roof supports by the machine or by 85 be provided with force application means the conveyor on which the machine traverses operable irrespective of the degree of exten the mine face. sion of the extensible roof engaging member When mining in an area having an unstable from the roof engaging member, resulting in a or friable roof, it is not prudent to leave the constant lift of the extensible bar tip relative roof unsupported even for a short period of 90 thereto.

time. It is therefore known to provide mine The constant lift may be provided relating to roof supports with forepoling bars or exten- a track or like guide means embodied in the sion bars which can be extended and set to roof engaging member.

the mine roof immediately after the passage The track may be parallel to the roof engag- of the mining machine, before the mine roof 95 ing surface of the roof engaging member supports themselves are advanced. The forethroughout its length.

poling bars or extension bars can be left ex- Alternatively the track may have an inclined tended and set until such time as the associ- part at the end thereof. A hydraulic jack or ated mine roof support can be advanced, capsule may be used as the force application whereupon the forepoling bars or extension 100 means.

bars are simultaneously retracted. The hydraulic feed for the hudraulic jack or The distance and height of the tip of a fore- capsule will be preferably through the piston poling bar in its extended position, relative to rod of a further hydraulic jack arranged to the roof engaging member from which it ex- bring about the extension of the extensible tends, may vary, relative to the method of 105 roof engaging member.

mining and the type and attitude of the mining To ensure that a constant load requirement machine as it passes the mine roof support, is attained, the force application means is pre resulting in the tip of the forepoling bar being ferably spaced at a constant distance from a higher or lower than the roof engaging mem- fulcrum part of the extensible roof engaging ber in its set position. 110 member, there also being a constant distance Forepoling bars have taken many differing between the fulcrum part and the tip of the designs, ranging from manually set bars as extensible member to provide a lever system described in our earlier U.K. Patent Specificawhich results in a constant tip loading.

tion No. 977503, to a more complex hydraulic The hydraulic circuit feeding the force appli- system as described in U.K. Patent Specifica- 115 cation means may be provided with a relief tion No. 1329125. Whilst these two earlier valve to prevent excess loading of the extensi designs are adequate under certain mining ble roof engaging member.

conditions, they do not meet all the para- The extensible member may be extended meters required to cope with all conditions relative to the roof engaging member by hy encountered in current mining practice. 120 draulic jack means, which may be mounted According to the present invention there is within or without the roof engaging structure.

provided a mine roof support having a main Retraction of the extensible member may be roof engaging member, the main roof engag- by use of the hydraulic extension jack, which ing member being provided with an extensible may be double-acting.

roof engaging member, the extensible roof en- 125 Alternatively, the extensible member may be gaging member being operable to apply a conretracted by the advancing of the roof support stant load to the mine roof, irrespective of its towards a mine face, in which case the exten degree of extension from the main roof en- sible member remains static with respect to gaging member, the mine face and the main roof engaging Preferably the extensible roof engaging 130 member is advanced over the static member, 2 GB2 196371A 2 the tip of which will be abutting the mineral build-up within the superstructure 10 which face during such retraction sequence. might otherwise jam the extensible bar 11.

By way of example, a specific embodiment In use the extensible bar 11 is fully re- of the invention will now be described, with tracted using the ram 13, the capsule 12 be reference to the accompanying drawings, in 70 ing inoperative. The mine roof support is posi which: tioned in a conventional manner with the lead- Figure 1 is a side view, partially in cross- ing edge of the superstructure 10 abutting the section, showing the upper part of an embodi- mineral face. As soon as a cutting machine ment of mine roof support according to the (not shown) passes along the mine face, cut invention, with an extensible member ex- 75 ting away a strip of mineral and leaving an tended and a hydraulic- capsule partially operarea of unsupported mine roof, the ram 15 is ated; extended by whatever amount is necessary to Figure 2 is a view similar to Figure 1 but bring the tip 25 into abutment with the newly showing the hydraulic capsule fully operated; exposed and forwardly advanced mine face.

and 80 The capsule 12 is extended to tilt the bar 11 Figure 3 is a view similar to Figure 1 but and apply upward pressure to the mine roof.

with the hydraulic capsule inoperative. It will be seen from a comparison of Figures 1 In the Figures the item 10 is the main roof to 3 that the degree of tilting of the member engaging superstructure of a mine roof sup- 11 is dependent upon the position of the ful port, the lower part of the support not being 85 crum 22 with respect to the channel wall 19, shown. and the degree of extension of the capsule Slidable within the superstructure 10 is an 12.

extensible bar 11. The sides of the bar 11 are Because of the fixed relationship between respectively guided by a pair of channel mem- the tip 25, the fulcrum 22, and the capsule bers arranged at the sides of the superstruc- 90 12, the force that is applied by the tip 25 to ture 10 with the mouths of the channels the mine roof, for a given force supplied by facing each other. The upper wall of one the capsule 12, is always constant. Thus this channel is shown at 18 and the lower wall of embodiment of mine roof support can always the channel is shown at 19. The walls of the apply to the mine roof exactly the degree of channels are generally parallel to the upper 95 pressure which is required to support a given face of the superstructure 10 but at their lead- roof. With the known forepoling bar arrange ing ends they sweep upwardly as shown at ments, the force that is applied varies depen and 21. dent upon the degree of extension of the fore- The extensible bar 11 has a fulcrum point poling bar.

22 which slides along the channel face 19. 100 Furthermore the disposition of the channel Extension of the extensible bar 11 is con- members 18, 19 being parallel to the upper trolled by a hydraulic jack 13 which is pivosurface of the structure 10 ensures a constant tally mounted on the superstructure 10 at 14. lift of the tip of the extensible bar except The jack 13 has a piston rod- 15 pivotally when approaching maximum extension when attached to the extension bar 11 at 16. 105 the channel guides sweep upwards giving a In order to tilt the bar 11 to force its tip 25 greater lift to offset any natural deflection as- against a mine roof, a very short hydraulic sociated with the loading of a cantilever and jack, generally referred to as a hydraulic cap- the required tip lift which will be at its great su[e, is provided at 12. The capsule is pivo- est when fully extended.

tally connected to the rear end of the bar 11 110 The invention is not restricted to the details and has a pivotal contact plate 23. This con- of the foregoing embodiments.

tact plate 23 can slide along the upper chan

Claims

nel wall 18 and because of its pivotal nature it CLAIMS is self-aligning

with the channel wall 18 re- 1. A mine roof support comprising a main gardless of the orientation of the capsule 12 115 roof engaging member, the main roof engag itself. ing member being provided with an extensible The piston rod 15 is hollow, having fluid roof engaging member, the extensible roof en- channels therein, for feeding fluid to and from gaging member being operable to apply a con the hydraulic capsule 12. stant load to the mine roof, irrespective of its It will be seen that the fulcrum 22 and cap- 120 degree of extension from the main roof en- sule 12 are each arranged at a constant dis- gaging member.

tance from the tip 25 of the extensible bar.
2. A mine roof support as claimed in Claim Conventional main roof supporting jacks are 1, in which the extensible roof engaging mem- affixed to the superstructure 10 at 26 and 27, ber has a free end arranged to engage with for urging the roof supporting structure 10 125 the mine roof to apply a load thereto, a pivot against a mine roof. point, and a force application point at which The superstructure 10 is open underneath at force can be applied from the mine roof sup- 28, so that any loose mining_material which port to tilt the extensible roof engaging mem enters the area between the channels can ber, the distance of the free end and the pivot flush away freely downwardly, to avoid any 130 point from the force application point being
3 GB2196371A 3 fixed. 16. A mine roof support as claimed in Claim 3. A mine roof support as claimed in Claim 14 or Claim 15 in which the hydraulic jack 2, in which the pivot point comprises a ful- means is operable to retract the extensible crum lying between the free end and the force member.

application point. 70 17. A mine roof support constructed and
4. A mine roof support as claimed in Claim arranged substantially as herein described with 2 or Claim 3, in which a hydraulic ram is reference to the accompany drawings.

positioned at the force application point, the ram acting between the extensible roof engag- Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from ing member and another part of the mine roof The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

support. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.
5. A mine roof support as claimed in Claim 4, in which the ram is slidable over the other part of the mine roof support when the exten sible roof engaging member extends.
6. A mine roof support as claimed in any one of the preceding claims, in which the ex tensible roof engaging member is provided with force application means operable irre spective of the degree of extension of the extensible roof engaging member from the roof engaging member, resulting in a constant lift of the extensible bar tip relative thereto.
7. A mine roof support as claimed in Claim 6, in which the constant lift is provided relat ing to a track or like guide means embodied in the roof engaging member.
8. A mine roof support as claimed in Claim 7, in which the track is parallel to the roof engaging surface of the roof engaging member throughout its length.
9. A mine roof support as claimed in Claim 7, in which the track has an inclined part at the end thereof.
10. A mine roof support as claimed in any one of the preceding claims having force ap plication means in the form of a hydraulic jack or capsule.
11. A mine roof support as claimed in Claim 10, in which the hydraulic feed for the hydrau lic jack or capsule is through the piston rod of a further hydraulic jack arranged to bring about the extension of the extensible roof en gaging member.
12. A mine roof support as claimed in Claim 1, in which in order to ensure that a constant load requirement is attained, force application means is spaced at a constant distance from a fulcrum part of the extensible roof engaging member, there also being a constant distance between the fulcrum part and the tip of the extensible member to provide a lever system which results in a constant tip loading.
13. A mine roof support as claimed in Claim 1, in which a hydraulic circuit feeding force application means is provided with a relief valve to prevent excess loading of the extensi ble roof engaging member.
14. A mine roof support as claimed in Claim 1, in which the extensible member is extenda ble relative to the roof engaging member by hydraulic jack means.
15. A mine roof support as claimed in Claim 14, in which the hydraulic jack means is mounted within the roof engaging structure.