GB2088458A

GB2088458A - Mine roof support

Info

Publication number: GB2088458A
Application number: GB8134996A
Authority: GB
Original assignee: Dowty Mining Equipment Ltd
Current assignee: Dowty Mining Equipment Ltd
Priority date: 1980-11-28
Filing date: 1981-11-20
Publication date: 1982-06-09
Also published as: GB2088458B

Abstract

A shield-type mine roof support with a lemniscate linkage and suitable for use in a method of mining known as sub-level caving has a normally- closed opening 11 in the shield 3 which, when open, allows material to fall into the space under the shield below the opening. According to the invention, the part of the floor beam 1 which forms part of the lemniscate linkage is of such a length that material falling through the opening 11, when the support is set against a roof, substantially falls through part of the space above that part of the floor beam. <IMAGE>

Description

SPECIFICATION Mine roof support This invention relates to mine roof supports.

A known mine roof support, suitable for use in a special way of mining coal, referred to as sublevel caving, comprises a floor beam, a roof-engageable member, a downwardly-extending and rearwardly-extending shield pivotally connected to the roof engageable member and pivotally associated with the floor beam, and hydraulicallyoperated prop means by which the roofengageable member can be urged into engagement with the roof of a mine.

The shield and the floor beam are pivotallyassocated by a first pair of parallel links and by a second pair of parallel links. These links, the part of the floor beam between one pair of links and the other pair of links, and the part of the shield between one pair of links and the other pair of links provide a four-bar linkage. The four-bar linkage, with the part of the shield extending between the pivot points for the upper pair of links and the pivot point of the shield to the roof engageable member, provide a linkage of a special kind, usually referred to as a lemniscate linkage.It is special in that the disposition of the pivotal points of the links with the floor beam and with the shield is such that when the roof-engageable member is moved away from a towards the floor beam, the path of movement of the pivot point of the shield to the roof-engageable member is approximately a straight line perpendicular to the floor beam.

In the shield there is an opening which is normally closed by a door but which, when the door is opened at an appropriate moment, is large enough to permit material which has fallen onto the shield from the roof above the shield (e.g. by caving of a roof or, if necessary, by shot-firing) to pass through the opening into the space below that opening.

Such a mine roof support is hereinafter referred to as "a mine roof support of the kind described." Customarily, the material falling through the opening in the shield of a mine roof support of the kind described is removed by a suitable means such as, for example, a scraper-chain conveyor, supported on the floor beams, below the openings, of a plurality of such mine roof supports ranged, one beside another, along a coal face being cut by a cutting machine.

When a mine roof support of the kind described is set against a roof, to support a roof, the scraperchain conveyor will be near to one of the pair of links of the lemniscate linkage. Before the mine roof support can be advanced towards a newly-cut coal face, over a distance having a relationship with the web of coal being cut by a coal-cutting machine, it is necessary first to advance towards the newly-cut coal face, by a similar amount, the part of the scraper chain conveyor associated with it. This is done by moving the part of the scraperchain conveyor over the floor beam towards the leading edge of the floor beam.

In that known mine roof supports of the kind described, the space below the opening in the shield, when the roof support is set against a roof, to support the roof, is above that part of the floor beam which does not form a part of the four-bar linkage. As a consequence of this and of the need to advance a scraper-chain conveyor over the floor beam, by a desired amount, prior to advance of the mine roof support, by a desired amount, towards a newly-cut coal face, the length of the floor beam and the length of the shield are considerable.

An object of the invention is to provide an improved mine roof support of the kind described which is particularly suitable for sub-level caving.

According to the invention, there is provided a mine roof support of the kind described in which that part of the floor beam which forms a part of the four-bar linkage is of such a length that material falling through an opening in the shield, when the support is set against a roof, substantially falls through part of the space above that part of the floor beam.

As material falling through the opening falls towards that part of the floor beam it may be received upon, and be carried away by, a conveyor, part of which is mounted on that part of the floor beam. The space defined by the four bars of the four-bar linkage may be large enough not only to provide for the presence of the conveyor but also to provide for the movement of the conveyor, with respect to the support, for a distance having a relationship with the width of a web of coal being cut by a cutting machine.

The opening in the shield may, preferably, be in that part of the shield which, in effect, forms one bar of the four-bar linkage. It may, however, be in the other part of the shield.

In a mine roof support in accordance with this invention the distance between the one pair of parallel links and the other pair of parallel links is much greater than the distance between them in the mine roof support hitherto known.

As a consequence, there is significant reduction in the size and the cost of such a support because the length of the floor beam and the length of the shield are both shorter than the equivalent parts of a hitherto-known mine roof support of the the kind described.

An exemplary mine roof support of the kind described in accordance with one embodiment of the invention is illustrated in the accompanying drawings, of which Figure 1 is an elevational view of the support when set against a roof, and Figure 2 is an elevational view of the support when not set against a roof.

Referring to the drawings, the mine roof support has a floor beam 1, a roof-engageable member 2, a downwardly-extending and rearwardly-extending shield 3 pivotally-connected at 4, to the roof-engageable member 2 and pivotally-associated with the floor beam 1. That pivotal association is provided by a pair of parallel links 5 (only one of which is visible in the drawings) and a pair of parallel links (only one of which is visible in the drawings and which may, if desired, be connected to form a box-like torsion link). Each link is pivotally-connected at one end portion to the floor beam 1 and at the other end to the shield 3.

A pair of parallel hydraulic props 7 (only one of which is visible in the drawings) are connected between the floor beam 1 and the roofengageable member 2. A further pair of parallel hydraulic props 8 (only one of which is visible in the drawings) are connected between the floor beam 1 and the shield 3.

The pivot points by which the links are connected to the floor beam 1 and the shield 3 are such that, as the props are extended to urge the roof-engageable member into engagement with a roof and contracted to disengage the member from such engagement, the links, the part of the floor beam between the pivotal connections (which includes the upstanding portions 9, only one of which is visible in the drawings), and the part of the shield between the connections (that is to say, the part on the right-hand side of the dotted line 10) provide a four-bar linkage and, with the remainder of the shield, provide a lemniscate linkage so that the pivot point of the shield to the roof-engageable member moves approximately in a straight line at right-angles to the floor member.

An opening 11 in the shield 3 is normally closed by a door 12. The door 12 is openable by any suitable means, e.g. a hydraulic jack (not shown), which causes the door to slide upwardly towards the roof-engageable member 2. The opening 11 is in that part of the shield 3 which is on the right-hand side of the dotted line 10 and which acts as one of the bars of the four-bar lemniscate linkage.

Caved material on the shield 3 can be moved towards the opening 11 by an agitator arm 1 3 which can be moved by a hydraulic jack, say, (not shown) from an inoperative position against the shield to an operative position (see Figure 1) in which it extends above the shield.

The part of the floor beam which forms a part of the four-bar linkage is of such length that material falling through the opening 11 of the shield 3, when the support is set against the roof and the door 12 is open, substantially falls through part of the space above that part of the floor beam towards that part of the floor beam.

In use, a scraper-chain conveyor 14, for removing material falling through the opening 11 when the door 12 is open, may pass through the space defined by the four bars of the linkage being supported on the floor beam. That space affords room for the conveyor to be moved over the floor beam 1 to a position near to the pair of links 5 by means of a jack connected between the conveyor and the roof support. This permits the support to be advanced by a desired amount towards a newly-cut coal-face which is cut by a machine 15, the cut material from which is carried away by another conveyor 1 6.

The floor beam may comprise one or more parts, and the roof-engageable member may comprise one or more parts.

Claims

1. A mine roof support of the kind described in which that part of the floor beam which forms a part of the four-bar linkage is of such a length that material falling through an opening in the shield, when the support is set against a roof, substantially falls through part of the space above that part of the floor beam.

2. A mine roof support of the kind described substantially as hereinbefore described with reference to the accompanying drawings.