GB2082661A - Improvements in or relating to mining equipment - Google Patents

Abstract

A mine roof support, for example of the self-advancing type, has advancing means (18) comprising a pressure- fluid operated ram comprising a piston and cylinder (20). The piston rod 24 is connected to a part of the roof support and the cylinder (20) is adapted for connection to an anchorage, or vice versa. The anchorage may be the face- conveyor structure (16). A member (32), is adjustable axially relative to the cylinder (20) to reduce the effective stroke of the ram (18). Means (36, 38, 48) is provided for securing the member (32) relative to the cylinder. <IMAGE>

Description

SPECIFICATION Improvements in or relating to mining equipment The invention relates to mining equipment, particularly mine roof supports, and is applicable especially, but not exclusively, to self-advancing mine roof supports.

Such roof supports usually have a pressure fluid advancing ram with its piston connected to the support and its cylinder adapted for connection to an anchorage, or vice versa. Operation of the advancing ram produces relative movement between the support and the anchorage to advance one or the other towards the mineral face being worked. Such roof supports are used in, for example, longwall mining systems.

In longwall mining systems, a conveyor extends parallel to the mineral face being worked and carries away the mined material which has been removed from the face by a cutter travelling along the conveyor. The roof supports are arranged in a row behind the conveyor and each has a roof-engaging canopy which extends in cantilever fashion over the conveyor. Each support is coupled to the conveyor, commonly by a connecting or relay bar.

After each pass of the cutter, the conveyor is pushed towards the newly-exposed mineral face by operating the advancing rams while the roof supports are still firmly anchoraged between roof and floor. When the conveyor is in the desired positions, ready for the next cut to be made, each roof support is lowered individually and advanced towards the conveyor by operating its advancing ram in the appropriate direction. During this operation the conveyor serves as an anchorage, being held firmly by the roof supports on each side of the one being advanced.

For various reasons it may be necessary to alter the thickness of coal removed - usually referred to as the "web depth". This entails substituting a face cutter of a different width. Each advance step of the roof supports and conveyor should, of course, be equal to the web depth, so it is also necessary to adapt the advancing means to provide a corresponding length of advance step.

An object of the present invention, therefore, is to provide mine roof support advancing means which can be readily adapted to change the length of each advance step.

According to the present invention there is provided a mine roof support having advancing means comprising a pressure-fluid operated ram comprising a piston and cylinder, the piston being connected to the roof support and the cylinder being adapted for connection to an anchorage, or vice versa, a member adjustable axially relative to the cylinder to reduce the effective stroke of the ram, and means for securing the member relative to the cylinder or piston.

The member may comprise a sleeve, slidably located around that end of the cylinder from which the piston rod projects. Securementofthesleeveto the cylinder may then conveniently be by means of pins, bolts or the like inserted into registering ones of a number of holes in the sleeve and cylinder, respectively.

The adjustable member may be slotted longitudinally to slidably accommodate a lug projecting radialliy from the cylinder. Flanges may be provided along the edges of the slot. The securement holes may then be provided in the flanges, spaced apart according to the required difference between effective strokes of the ram, a corresponding hole or holes being provided in the lug so as to be registrable with different ones of the holes in the flanges.

The ram may serve to actuate, at one end of a stroke, a valve to initiate raising of the props of the roof support. Stroke termination, at least during retraction, may be by abutment of a clevis or other part on or of the piston rod against the end of the cylinder or adjustable member.

The actuator for the valve may comprise an abutment e.g. a striker bar, mounted upon the adjustable member at a selected one of a plurality of positions depending upon the effective stroke setting. Alternatively the abutment might be fixed non-adjustably to the cylinder upon a spigot which projects through a suitable slot in the adjustable member.

In one preferred embodiment the piston rod is coupled to the base member of the roof support and the sleeve member coupled, usually by a connecting or relay bar, to the conveyor or other anchorage.

An embodiment of the invention will now be described, by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a side elevation of part of a roof support with its advancing ram set for a long effective stroke; Figure 2 is a view corresponding to Figure 1, but with the advancing ram set for a short effective stroke; and Figure 3 is a perspective view of an advancing ram disassembled - modified slightly as compared with that of Figure 1.

Referring first to Figures 1 and 2, a roof support 10 comprises props 12 projecting upwardly from a base member 14. The upper parts of the props 12, the roof-engaging canopy they support, canopy links, and so on, being of conventional construction, are omitted, as are the flights and drive chain of a mineral face conveyor 16 to which the roof support 10 is coupled.

The coupling between the roof support 10 and conveyor 16 is by way of a pressure-fluid operated advancing ram 18, comprising a cylinder 20 and a piston (not shown) carried by a hollow piston rod 24.

The end of the piston rod 24 remote from the cylinder 20 carries a pressure-fluid connection block 25 having two ports 26 (only one shown) for applying pressure fluid to opposite sides of the piston via coaxial passages in the hollow piston rod 24. Suitable seals 27 are provided at the end of the piston rod 24 to segregate the ports 26 and their associated passages. A clevis 28 is secured to the end of the connection block 25. A lug 29, coupled pivotally to the base member 14, is also coupled pivotally to the clevis 28 by a pin 30, the couplings permitting pivotal movement of the advancing ram in the vertical and horizontal planes during its extension or retraction.

A cylindrical sleeve 32 surrounds the cylinder 20 and is slidably supported for axial movement relative to the cylinder by an enlarged end portion 31 of the cylinder 20. A clearance space 33 is provided between the remaining part of the cylinder 20 and the sleeve 32. At one end the sleeve 32 has an annular end plate 34 through which the piston rod 24 will project. At one side, the sleeve 32 has an axial slot 35, extending from its other end for a distance at least equal to the difference between the different effective stroke lengths required for the advancing ram. As shown in Figure 3, two narrow flanges, 36 and 38, extend along the upper and lower edges, respectively, of the slot 35 and project radially therefrom. Each flange has two spaced holes 40,42 which align with those of the other flange.The holes 40,42 are spaced apart by a distance dequal to the difference between the longer and shorter effective strokes of the ram 18, typically 40 inches and 30 inches, respectively. A lug 44 having a through hole, 46, projects radially from the cylinder 20 into the slot 35 and is slidable between the flanges 36 and 38.

The hole 46 can be brought into register with either of spaced holes 40,42 and secured by inserting a pin or bolt 48 through the registering holes and attaching a nut 49 thereto. Securement of the lug 44 to the foremost hole 40 sets the ram for its longer effective working stroke, and to the rearmost hole 42 sets the ram to its shorter effective working stroke.

A pair of flanges 50 depend from adjacent the piston rod end of sleeve 32 to form a clevis. One end 52 of a connecting or relay bar 54 is coupled between the flanges 50 by a bolt 56, which extends through aligned holes in the flanges 50 and the end of the bar 54, such that the bar 54 may pivot in the vertical plane.

At its other end 58, the connecting or relay bar 54 is coupled to the base of the mineral face conveyor structure 16 by a sliding clevis comprising a pair of flanges 59 with elongate holes 60 between which the relay bar end 58 is coupled by a pin 61. The mineral face conveyor structure 16 extends along the mineral face M and carries away the mine material.

Referring again to Figures 1 and 2, a striker valve 62 is shown secured to the base member 14 at a position adjacent the rearmost end of the cylinder 20. An operating arm 64 for the valve 62 depends from a pivot 66 towards sleeve 32. An abutment in the form of a striker bar 68 is mounted upon the sleeve 32. The arrangement is such that the arm 64 projects into the path which will be travelled by the striker bar 68 during extension of the ram.

In both Figures 1 and 2, the ram is shown in the retracted state. To advance the roof support 10 towards the conveyor structure 16 the ram is extended, by application of pressure fluid by control means (not shown) causing the cylinder 20 and sleeve 32 to travel rearwardly. When the striker bar 68 engages the striker arm 64, the striker valve is actuated at the end of the advancing stroke of the ram and initiates the raising of the props 12to engage the canopy (not shown) against the roof. To advance the conveyor, the ram is retracted until the block 25 abuts the end 34 of sleeve 32.

With the ram set for its longer effective working stroke, the striker bar 68 is positioned adjacent the forward end of the sleeve 32, as shown in Figure 1.

To set the shorter effective working stroke, the pin 48 is removed from hole 40, the sleeve 32 is slid along the cylinder 20 until the lug 44 registers with the other hole 42, and the pin 48 is replaced.

The striker bar 68 is also repositioned. As can be seen by comparing Figures 1 and 2,fortheshortr stroke the striker bar 68 is moved rearwardly by the stroke difference "d" i.e. 10 inches. To facilitate suwoh repositioning, the striker bar 68 may be carried by a pin and suitable sockets provided in the sleeve at the positions required for the bar.

Alternatively the striker bar 68 may be secured directly to the cylinder 20, at its enlarged portion 31 so that its position is adjusted at the same time as the effective stroke. Then the bar 68 might be mounted upon a spigot protruding through a longitudinal slot in the sleeve 32. The length of the slot should of course be sufficient to allow displacement of the striker bar 68 by the stroke difference "d".

It should be noted that whilst described specifically as applied to a self-advancing conveyor-coupled roof support, the invention is applicable to advancing means for other types of roof support, for example so-called "walking" roof supports in which the advancing ram is coupled between two relatively movable parts of the support itself.

Various modifications of the specific embodiment are envisaged within the scope of the present invention.

For example, the ram cylinder could be connected to the roof support and its piston adapted for connection to the anchorage, for example the conveyor.

It is also envisaged that the striker bar, where provided, could be integral with the pin for securing the sleeve, the striker valve being suitably repositioned. An advantage of this is the reduced likelihood of loss or incorrect positioning during the changeover.

Embodiments of the invention advantageously enable simple and quick changing of the effective stroke of the roof support advancing means - so quick that an entire set of roof supports can be adapted to the different web depth in the time taken to change the cutter drum.

Afurther advantage is that the adjustment is made without uncoupling the ram from the support or, the conveyor, or removing any pressure fluid lines.

Yet another advantage is that embodiments of the invention allow for operation of the striker valve regardless of effective stroke length, which is not so where the striker valve is located in the end of the cylinder of the advancing ram.

Claims (9)

1. A mine roof support having advancing means comprising a pressure-fluid operated ram comprising a piston and cylinder, the piston being connected to the roof support and the cylinder being adapted for connection to an anchorage, or vice versa, a member adjustable axially relative to the cylinder to reduce the effective stroke of the ram, and means for securing the member relative to the cylinder or piston.

2. A mine roof support as claimed in claim 1, wherein the member serves to actuate a valve for controlling supply of pressure-fluid to the props of the roof support.

3. A mine roof support as claimed in claim 2, wherein the member comprises an abutment arranged to operate the valve at the end of the stroke of the ram.

4. A mine roof support as claimed in claim 3 wherein the abutment is, or is integral with, the means for securing the member relative to the cylinder.

5. A mine roof support as claimed in any preceding claim, wherein the member comprises a sleeve around at least the end portion of the cylinder and adapted to be secured in at least one position wherein it extends beyond that end of the cylinder from which the piston rod projects.

6. A mine roof support as claimed in claim 3, wherein either one of the member and cylinder has a plurality of axially spaced holes which register with a hole in the other at different positions of their relative axial adjustment, whereby a pin or bolt passing through the registering holes serves to secure the member and cylinder against relative movement therebetween.

7. A mine roof support as claimed in claim 6, wherein the member has an axial slot of a length at least equal to the required differences in effective working strokes and a lug projects from the cylinder through the slot, and is securable relative thereto.

8. A mine roof support as claimed in claim 7, wherein radially extending flanges are provided along the edges, respectively, of the slot to slidingly accommodate the lug, said axially spaced holes being provided in the flanges and said hole being provided in the lug.

9. A mine roof support substantially as described herein with reference to, and as shown in, the accompanying drawings.