GB2077832A - Mine roof support with advancing mechanism - Google Patents

Abstract

This invention covers a roof support that slides on skids 1 and can be drawn forwardly by a ram 16. The connection of the ram 16 to the roof support is by means of a lever 10, pivotally connected by its front end to the roof support and sloping downwardly to its trailing end that rests on the mine floor. Actuation of the ram 16 will tend, through the effect of the lever, to raise the front end of the support to facilitate its negotiation of bumps on the mine floor. <IMAGE>

Description

SPECIFICATION Improvements in or relating to mine roof supports This invention relates to mine roof supports.

A well known form of mine roof support comprises a canopy carried by a rectangular array of hydraulically extensible pillars extending upwardly from a base. The base commonly provides a pair of skids, and to slide the support on its skids towards a newly cut face it is well known to use a hydraulic ram extending between the support and an anchor point located forwardly of the support. The anchor point is usually a conveyor extending longitudinally of the working face, between the face and a row of similar aligned supports.

Now as the support slides forwardly, there will be a tendency for the front ends of the skids to shear off the surface of the mine floor causing debris to be bulldozed-up in front of the support.

By use of the present invention, this tendency can be mitigated.

According to the present invention, there is provided a mine roof support provided with a hydraulic ram connected at one end to the mine roof support and being such that, with the ram extended and the other end of the ram fixed forwardly of the support, contraction of the ram will be effective to move the support towards the location at which the other end is fixed, the connection between the ram and the support being effected through a 'lever device extending longitudinally of the support and to which the ram is pivotally connected between its ends, the rear end of the lever device being in ground engagement and the front end being pivotally connected to the support above the level at which the ram is connected to the lever device.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 represents the longitudinal axial section of a mine roof support, and Figure 2 represents a plan view of the roof support represented in Figure 1.

The mine roof support that is illustrated comprises a pair of longitudinally extending skids 1 from each of which there extends upwardly a pair of hydraulically extendible props 2, the props 2 forming a rectangularly disposed support for the canopy 3. The front ends of the skids 1 curve upwardly to facilitate the forward sliding of the skids.

As is apparent from Figure 2, the skids 2 are spaced apart laterally. A yoke 8 is connected transversely between them, just ahead of the forward props 2, to provide an anchor, for a purpose that will be described later. Longitudinally between them there extends a lever indicated generally at 10, comprising two flat, similar parallel, relay bars 11. Each relay bar 11 is of "swan's neck" form and comprises a straight rear portion 1 a that inclines gently upwards and a further shorter, portion 1 b that inclines more sharply upwards. The relay bars 11 are joined together at the rear of their lower edges by a pressure pad 12. The pressure pad 12 curves upwardly at its rear, whiist the front portion slopes upwardly with the rear portions of the relay bars 11, leaving only a narrow arc in contact with the ground.Near the front of their upper edges, the relay bars 11 are connected together by a brace 14. A rib 1 5 extends longitudinally along the bottom of the brace 14 and projects forwardly thereof, the forward end of the rib 1 5 lies within a fork 8a extending rearwardly of the yoke 8 and is pivotally connected to it by a pin 9.

The outer end of the rod 1 6a of a double acting hydraulic ram 1 6 is connected to the relay bars 11 just forwardly of the pressure pad 1 2, there being a gap between the connection and the leading end of the pressure pad 12. The connection lies a little above a line passing through the leading end of the contact between the ground of the pivot pad 12 and the axis of the pin 9.

The outlet end of the cylinder 1 6b is provided with a link 17 through which connection with a coal face conveyor, of which a part is indicated at 1 8 may be effected through the double swivel coupling 19. The ram 16 just clears the ground and is sufficiently strong to, on operation, effect movement of the roof support.

In use, the roof support that has been deseribed is one of a row of similar supports disposed side-by-side along the length of a conveyor 1 8 that runs parallel to a working mine face on the side of the conveyor remote from the supports. The link 1 7 of each support is connected to the conveyor 1 8 through the coupling 1 9.

Now whilst the face is being cut, the roof supports, lie closely adjacent the conveyor 1 8.

When the face has been cut, then the rams 1 6 of the adjacent roof supports are extended in sequence to move the conveyor 1 8 towards the new face. The conveyor 1 8 in its new position then acts as an anchor for the movement of each roof support towards the conveyor 1 8. To effect movement, the ram 1 6 is contracted. The support will slide forward on the skids 1. The pressure pad 12 will also slide on the ground and an elect of the force applied by the ram 1 6 above and forwardly of the pressure pad 1 2 will be to tilt the lever 10 upwardly, with the pressure pad 1 2 acting as the fulcrum.The rise of the forward end of the lever 10 will, through its connection at the pin 9, also raise the leading end of the skids 1 so as to reduce any tendency of the front ends of the skids 1 to shear off any of the mine floor over which they pass. The skids 1 will, too, pass more easily over any bumps that there may be in their path. Should the pressure pad 12 scape debris from the mine floor, this will pass back over the pressure pad 11 , through the gap between the pad 12 and the end of the ram 16.

In operation of the ram 16, the "differential push" system is used. To extend the ram 16, to push the conveyor 1 8 towards the new face, pressure is applied to the full face of the piston head and the annular space on the other side of the piston head. To contract the ram, and pull the roof support towards the conveyor, fluid is applied only to the annular space. In this way, the force exerted in moving the support is greater than the force exerted in moving the conveyor In other embodiments of the invention, other hydraulic rams operated differently may be used.

As will be seen in the drawings, the canopy 3 projects forward far enough to cover the ram 16 and link 1 7 so that these are protected by the canopy from falling debris. Moreover, the ram 1 6 lies wholly forwardly of the rearmost location at which it is fixed. This location lies within the normal limits of the roof support, so obviating any need, in order to protect the rear of the ram from falling debris, to make special screening provision that would extend the length of the support.

In modifications of what has been described, means may be included to limit the possible vertical angle through which the lever 10 may tilt.

For instance, to prevent the lever 10 from dropping too far, a chain connected at its ends to the two skids 1 may pass beneath the lever, hanging clear of the lever unless the lever has reached the lowermost position to which it is to be allowed to drop. To prevent the lever from rising too far, a buffer may be fixed to a pillar extending upwardly from one of the skids, the buffer projecting laterally from the pillar to provide an abutment with which the lever 10 makes contact when it has reached the uppermost position to which it is to be allowed to rise.

It is envisaged that in modifications of what has been described, a so-called "lemniscate" linkage may be connected between the skids 1 and the canopy 3 to minimise lateral thrust on the props 2 during the raising and lowering of the canopy 3.

Claims (7)

1. A mine roof support provided with a hydraulic ram connected at one end to the mine roof support and being such that, with the ram extended and the other end of the ram fixed forwardly of the support, contraction of the ram will be effective to move the support towards the location at which the other end is fixed, the connection between the ram and the support being effected through a lever device extending longitudinally of the support and to which the ram is pivotally connected between its ends, the rear end of the lever device being in ground engagement and the front end being pivotally connected to the support above the level at which the ram is connected to the lever device.

2. Apparatus as claimed in claim 1 in which the lever device provides a rear portion that slopes upwardly from the rear and, forwardly of the rear portion, a further portion that is inclined more steeply than the rear portion to the pivotal connection between the lever device and the support, the ram being connected to the rear portion of the lever device.

3. Apparatus as claimed in either of the preceding claims in which the rear end of the lever device includes a transversely extending presure pad, and the connection between the ram and the lever device lies forwardly of the pad and is separated from it by a gap.

4. Apparatus as claimed in any of the preceding claims in which the connection between the ram and the lever device lies above a line passing through the axis of the connection between the lever device and the support and the forward end of the engagement of the lever device with the ground.

5. Apparatus as claimed in any of the previous claims in which the support is one of several forming an aligned row and each associated with a conveyor extending along the row, each ram with which a support is provided is connected at its end remote from the support to the conveyor, the ram is a double-acting ram, and the means by which fluid is supplied to the ram is such that when fluid is supplied to the full base area of the piston head, fluid at the same pressure is applied to the other side of the piston head.

6. Apparatus as claimed in any of the preceding claims in which the, or each, support is provided with only one hydraulic ram, and the ram extends centrally of the support.

7. A mine roof support substantially as described with reference to, and as illustrated by, the accompanying drawings.