GB2208404A

GB2208404A - Roof supports with pivotal, lockable toe

Info

Publication number: GB2208404A
Application number: GB8815630A
Authority: GB
Inventors: John Hirst Walker; Edmund Douglas Bradley; David Chandler
Original assignee: Dowty Mining Equipment Ltd
Current assignee: Dowty Mining Equipment Ltd
Priority date: 1987-07-04
Filing date: 1988-06-30
Publication date: 1989-03-30
Anticipated expiration: 2008-06-30
Also published as: GB8815630D0; GB8715774D0; DE3822618A1; GB2208404B

Description

16 t 1 ROOF SUPPORTS This invention relates to roof supports for use in

mines and in particular a floor engaging structure for use with a roof support.

Known types of roof support are provided with a floor engaging structure which comprise one or more members i.e. a single piece platen or a multipiece pontoon base. Each of these members are manufactured as a single piece, i.e. they are longitudinally stiff.

In particular mining conditions i.e. conditions in which a loose floor is encountered, it can prove to be very difficult to advance this type of roof support so as to enable continued working of the face.

m Ihe normal method of advancing the support or supports in a mining operation involves dragging the support across the floor. This means that the toe portion of the support digs into the loose material and in turn, causes a bow wave effect in the region adjacent to the toe portion leading to a ridgelbank of material building up. The ridge/bank of material impedes the advance of the 2208404 2 support, leading to the problems mentioned earlier.

The present invention is concerned with eliminating, or at least reducing to a minimum, this problem.

In accordance with the present invention a roof support includes:

a floor engaging structure having a main portion and a toe portion; a canopy; and roof supporting means mounted thereon to act between the canopy and the main portion wherein the toe portion is pivotally connected to the main portion and means is provided to lock the toe portion relative to the main portion in a roof supporting mode.

The toe portion of the floor engaging structure can therefore be pivoted, or allowed to pivot, with relation to the mine floor so as to prevent i 1 1P 3 digging in of the toe portion with respect to the loose material on the mine floor as the support is advanced. in practice when the roof support is advanced, provided that the toe portion has not secured-in, a fixed position, under the forces exerted thereon and find its own natural position. in this natural position the toe portion will be inclined with respect to the mine floor. In the inclined position the toe portion is prevented from digging into the mine floor, by the relative remoteness thereof imparted by the inclination and, in fact the floor engaging surface (undersurface) of the toe portion will act in a ski like mariner so as to allow enable the roof support to glide over the loose material of the mine floor.

been pivoted to, and the toe portion will move The pivotal movement of the toe portion is, preferably, limited so as to prevent the toe portion from being forced into a vertical position, in which the desired ski like motion will not occur. The limitation in the pivotal movement means that in mine floor conditions where difficulties i. e. large obstructions are encountered during the advance of the support the toe portion will still produce the desired ski 4 like motion, and movement of the support will not be significantly impeded.

The toe portion may be pivoted by any suitable means, for example hydraulic ram, to a fixed predetermined position. However, preferably the toe portion is allowed to pivot freely between a first horizontal position and a second inclined position.

In this preferred arrangement the forces causing the pivotal movement are supplied by the interaction of the support with the loose material the mine floor during advance of the support.

The unpivoted end of the toe portion has a front surface which is preferably, inclined to the mine floor when the toe portion is in the locked position. This enhances the ability of the toe portion to pivot during advance particularly, the initial movement of the support and enables the toe portion to ride/glide over the loose material in the start up of movement.

Further, for many years in the industry it has been appreciated that a two stage inclination at the front end of the support enables easier T 1 - 1 movement of the support in loose floor mines. The most efficient angle relationship for this being dependent on the particular support and floor conditions encountered.

With a roof support in accordance with invention the present invention the toe portion presents a two stage inclination under motion to the mine floor. The angle between the two stages of inclination is set, however, the angle between the floor and toe portion is still allowed to reach an equilibrium position during advance of the support.

The advantages incorporated by using the two stage inclination are, therefore, fully recognised and utilised in a roof support in accordance with the present invention.

In order to assist in the pivotal movement cf the toe portion the floor engaging surface is preferably provided with a chamfered edge which helps to clear away the material which has built up in the vicinity of the pivotal connection on return of the toe portion to the locked horizontal position.

6 The present invention may be used with roof supports which utilise all types of floor engaging structure i.e. platen or pontoon bases. However, with certain types of floor engaging structures it may prove necessary to provide a plurality of locking means across the width of support.

Further, for practical reasons it would be advantageous to use only one locking means per pivotal toe portion of the support.

Any suitable locking means may be used to lock the toe portion into position. However, the locking means has to be able to resist the forces applied to the toe portion as the roof support is engaged to, and supports, the mine roof. These forces can be very considerable, therefore the pivot of the toe portion with the mairl portion has to be buil so that failure in this region will not occur.

As is well appreciated in the industry roof supports are built to incorporate certain safety features which take account of the balance of forces acting on the roof support during supporting operation. in view of this the pivot of the toe portion with the main portion is, t 7 preferably, positioned forward of the roof supporting means and therefore the resultant tipping force balance point.

Preferably, the locking means operates on a wedged action principle. That is, a wedge that is driven, or pulled, between two fixed surfaces so as to prevent movement therebetween. In this case, a pad or bar on an arm member of the toe portion and a suitable body mounted on the main portion may be used.

The wedge arrangement is, preferably, an arcuate wedge system, having cooperating arcuate surfaces. The advantages of this type of wedge arrangement are discussed in our U.K. patent 21- 4 3,27 1 B. The wedge is, preferably, driven into a locking position by means of an hydraulic ram. The hydraulic ram may be mounted in any suitable position in the roof support with pivotal joints being used to enable force to be transmitted to enable the locking means to be applied. Preferably, the hydraulic ram is pivotally mounted in the toe portion.

8 The invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 shows a side view of a roof support in accordance with the present invention; Figure 2 shows a side view of the toe portion and part of the main portion of the roof support shown in Fig. 1.

Referring to the drawings the roof support 1 comprises:

a canopy 2; a floor engaging structure 3 having a main portion 4 and a toe portion 5 pivoted with respect thereto about a pivot 6; roof supporting means in the form of four hydraulic legs 7 (only two of which are shown) mounted so as to act between the main portion 4 and the canopy 2; a shield 8 pivoted from the canopy 2; 7' 9 a toe portion locking means; and a lemniscate arm arrangement.

The lemniscate arm arrangement having four arms 9 (only two of which are shown), each of which is pivotally mounted at one end to the main portion 4 and at the other end to the shield 8.

Now referring to Fig. 2, the toe portion 5 of roof support is provided with a bar member.10, mounted so as to extend between side plates 11 The toe portion locking means comprises:

a hydraulic ram 12 mounted in the toe portion on a pivot 13; an arcuate block 15 mounted in the main portion 4; and an arcuate wedge 14 attached to the ram 12 by means of a pivot 16.

The arcuate block 15 and arcuate wedge 14 have interacting surfaces 15a and 14a which are shaped so that they co-operate with each other to enhance the wedging/locking action.

The arcuate wedge 14 is attached to the hydraulic ram 114 by means of a pivot connection 16 between the wedge 14 and an arm 17 of the hydraulic ram.

When the toe portion is in the locked position, shown in hard lines in Fig. 2, the wedge 14 abuts against the bar member 10 and edge 18 of the toe portion 5 abuts against edge 19 of the main portion. In this way all pivotal movement of the toe portion 5 with respect to the main portion 4 is prevented. Therefore when the hydraulic legs 7 impart the necessary supporting load to the mine roof the transmitted force from the reaction with the mine floor will not bring about pivotal movement of the toe portion.

Now when the wedge 14 is withdrawn to the position, shown in Fig. 2 in chain link lines, the wedge 14 no longer abuts the bar member 10. There is, therefore, nothing which now prevents the toe portion from pivoting in a direction A. This withdrawal of the wedge 4 from abutment with bar member 10 will normally not occur whilst the roof support is in a roof engaging mode.

2 1 1 11 As the roof support is dragged into a new working position, the loose material on the mine floor causes the toe portion 5 to pivot in the direction A. The toe portion 5 is forced clear of the loose material, and glides over the material. Further, the material is forced under the toe portion 5 and acts to lift the roof support 1 over the material and enables the roof support 1 glide on the material, so that movement thereof is not impeded.

The toe portion 5 will pivot about pivot 6 and thereby be inclined to the horizontal. The degree of this inclination, as shown in chain link lines in Fig. 2, is limited by the action of the bar member 10 with the wedge 14. In the position shown in chain link lines in Fig. 2, the bar member 10 abuts the wedge 14 in order to prevent further pivotal movement of the toe portion 5.

The action of the pivot 16 between the wedge 14 and the arm 17 and pivot 13, enables the hydraulic ram 12 to impart the necessary force to the locking means to cause the toe portion 5 to be locked in the horizontal position.

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Claims

A roof support which includes:

a floor engaging structure having a main portion and a toe portion; a canopy; and a roof supporting means mounted thereon to act between the canopy and the main portion wherein the toe portion is pivotally connected to the main portion and means is provided to lock the toe portion relative to the main portion in a roof supporting mode.
2. A roof support as claimed in claim 1 wherein the pivotal movement of the toe portion is limited so as to prevent the toe portion from being forced into a vertical position.
3. A roof support as claimed in claim 1 or 2, wherein the toe portion is allowed to pivot freely between a first horizontal position and a second inclined position.

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4. A roof support as claimed in any one of claims 1 to 3, in which the unpivoted end of the toe portion has a front surface which is inclined to the mine floor when the toe portion is in the locked position.
5. A roof support as claimed in any one of claims 1 to 4, in which the floor engaging surface of the toe portion is provided with a chamfered edge which helps to clear away the material which has built up in the vicinity of the pivotal connection on return of the toe portion to the locked horizontal position.
6. A roof support as claimed in any one of claims 1 to 5, in which the floor engaging structure comprises a platen type floor engaging structure.
7. A roof support as claimed in any one of claims 1 to 5, in which the floor engaging structure comprises two substantially parallel pontoons.
8. A roof support as claimed in any one of the preceding claims, in which only one locking means per pivotally connected toe portion is provided.

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9. A roof support as claimed in any one of the preceding claims, wherein the locking means is a wedged locking means.
10. A roof support as claimed in claim 9, in which the wedged locking means is an arcuate surface wedged locking means.
11. A roof support as claimed in claim 9 or 10, in which the wedged locking means is operated by means of an hydraulic ram.
12. A roof support as claimed in claim 11 in which the hydraulic ram is pivotally mounted in the toe portion.
13. A roof- support substantially as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Patent Office. State House. 66'71 High Holborr,. London WClR 4TP F'urther copies may be obtained from The Patent Office, Sales Branch, St Mazy Cray. Orpington, Kent BR5 3RD Printed by Multiplex techniques ltd, St Mary Cray. Kent Con 1'87