US3395616A

US3395616A - Self-advancing mine roof supports

Info

Publication number: US3395616A
Application number: US600984A
Authority: US
Inventors: Lubojatsky Walter
Original assignee: Gullick Ltd
Current assignee: Gullick Ltd
Priority date: 1965-12-22
Filing date: 1966-12-12
Publication date: 1968-08-06
Anticipated expiration: 1985-08-06
Also published as: AT274711B; FR1505297A; GB1108710A

Description

Aug. 6, 1968 w. LUBOJATSKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS INVENTOR: v

WALTER LuoBrYArs/w ,q-ews. *Y

Aug- 6, 1968 w. LUBoJATsKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS Filed Dec. l2, 1966 5 Sheets-Sheet 2 7 16 21 17 73a P213 t WALTER LUBJ'ATS/(Y BY Q O Q fris INVENTORI Aug# 6, 1968 w. LuBoJATsKY 3,395,616

SELF-ADVANCING MINE ROOF SUPPORTS Filed Dec. 12, 196e 5 sheets-Sheet s INVENTOR:

WALTER LU BOJATSKV 3,395,616 SELF-ADVANCNG MINE RGF SUPPORTS Waiter' Luhojatslry, Recklinghausen, Germany, assignor to Gullick Limited, Wigan, England, a British company Filed Dec. l2, 1966, Ser. No. 600,984 Claims priority, application Germany, Dec. 22, 1965, B 85,095 Claims. (Cl. 91-412) This invention is for improvements in or relating to self-advancing mine roof supports of the kind in which the advance of the support is effected by a pressure-fluidoperated device hereinafter referred to as a hydraulic ram.

In one known self-advancing mine roof support of this kind the advancing ram has a cylinder secured to the support and a piston rod adapted to be attached to a coal face conveyor. After the passage of the mineral cutting machine the hydraulic ram is extended so as to push over the conveyor towards the newly exposed mineral face. The ram is then retracted so that the support, after it has been temporarily released from between floor and roof, is advanced up to the conveyor. The hydraulic leg or legs of the support are then extended to secure the support between floor and roof.

An alternative form of support of the self-advancing kind comprises two support elements connected together by an advancing7 ram. These support elements are released from between floor and roof and advanced alternately, one support element, when secured between iioor and roof, serving as an abutment for the advance of the other support element.

It has been found advantageous, particularly in certain geological conditions, that the support should maintain some, although a low pressure against the roof during its advance. For this purpose it has already been proposed to provide the hydraulic legs or props of the support with a bleed valve set so as to bleed-off sufficient pressure to allow the support to advance whilst at the same time maintaining the required pressure against the roof. Such an arrangement has the disadvantage that should the support meet an obstruction during its advance an excessive amount of pressure-fluid is discharged through the bleed valve and the support subsequently fails to maintain the required pressure against the roof.

It has also been proposed, whilst maintaining some pressure against the roof as the support is advanced, to discharge pressure-fluid from the hydraulic cylinders of the legs or props if there is an excessive increase in pressure on the pulling side of the hydraulic advancing ram such as will occur if the advancing movement of the support is impeded. Here again, there is a possibility of too much pressure-fluid being discharged with the result that the support fails to maintain the required pressure against the roof during its advance.

It has also been proposed to maintain a pressure-fluid supply to the hydraulic cylinders of the props or legs during advance of the support so that the roof-engaging structure of the support is held with the required pressure against the roof. This arrangement has the disadvantage that it requires a separate Huid-pressure source and fluidpressure main along the face to provide the particular pressure required in the hydraulic legs or props during advance of the support.

An object of the present invention is to provide a selfadvancing mine roof support capable of maintaining a required pressure against the roof during its advance and notwithstanding that its advance may be impeded temporarily by irregularities in the roof or floor and which does not require a separate pressure source and pressureuid supply main along the face.

According to the present invention there is provided a self-advancing mine roof support comprising a base, hy-

3,395,616 Patented Aug. 6, 1968 draulically extensible leg means on said base, a roof-engaging structure mounted on said leg means and adapted to be applied thereby to the roof, a hydraulic ram means operative to advance the support and means for -connecting the leg means to the hydraulic circuit of the ram means so that the leg'means, during advance of the support, is subjected to fluid-pressure, to maintain the roofengaging structure against the roof, dependent on the resistance to advance of the support. Thus, when there is an increase in the resistance to advance of the support the pressure of the support against the roof is relieved and when there is a decrease in resistance to advance the pressure is restored.

In one preferred arrangement the leg means, during advance of the support, is subjected to fluid-pressure, to maintain the roof-engaging structure against the roof, dependent on the advancing speed of the support.

The advancing speed of the support depends on the resistance which the support encounters during its advance and pressure in the cylinder of the advancing ram is a measure of such resistance provided the cross-section of the pressure-fluid supply lines is proportionately smaller than the cross-section of the ram cylinder. The fluid-pressure to which the leg means is subjected during advance of the ram may, therefore, be controlled by means responsive to the pressure in the cylinder of the advancing ram. This is one preferred arrangement for the purpose of the present invention.

Alternatively, the fluid-pressure to which the leg means is subjected during advance of the ram may be controlled by a force measuring device between the advancing ram and one of its abutments, e.g. the fa-ce conveyor. For instance, if the connection between the piston rod of the advancing ram and the conveyor includes a force measuring device, such device will respond to the resistance to movement of the support and its response can be used to adjust valve means controlling the supply of pressure-fluid required to maintain the roof-engaging structure of the support against the roof during advance of the support.

In another preferred arrangement according to the invention the hydraulic leg means is supplied with pressurefluid from one side of a double-acting advancing ram of the support whilst pressure-fluid is being supplied to the other side of said ram for the advancement of the support. Thus, the supply of pressure-fluid to the hydraulic leg means is automatically dependent on the rate at which the support is being advanced by said hydraulic ram and the resistance which the advancing support encounters.

With the arrangement according to the present invention, if the support during its advance should meet with obstruction so that the rate of advance is reduced, there will automatically be a falling :off in the fluid-pressure supply to the hydraulic leg means. The latter will, therefore, be able to lower temporarily so as to clear the obstruction after which, as the rate of advance of the support increases, the pressure-fluid to the leg means will increase so as to maintain the roof-engaging structure of the support in engagement with the roof with the required degree of pressure.

The invention will be further described, by way of example, wit-h reference to the accompanying drawings in which:

FIGURE 1 is a side elevation of a self-advancing mine roof support of the kind to which the present invention may be applied,

FIGURE 2 is a diagrammatic representation of one embodiment of the invention,

FIGURE 3 is a diagrammatic representation of a further embodiment, and

FIGURE 4 is a diagrammatic representation of a still further embodiment.

The support shown iu FIGURE l comprises a base having pivotally mounted on it in t-he usual way four hydraulically extensible telescopic legs 11 arranged in pairs one behind the other.

Mounted on the upper parts of the legs 11 in the usual way is a roof-engaging structure or canopy 12.

Housed in and pivotally attached to the base 10 (eg. by means of laterally projecting trunnions) is the cylinder 13 of a hydraulic advancing ram for the support. The ram 13 has a piston rod 14 connected by means of a vertically slotted clevis 15 to the face conveyor C.

It will be appreciated that a complete installation will comprise many of the supports just described spaced apar-t along the face and connected to the conveyor C.

After the passage of the coal cutting machine -along the face the

ram

13, 14 is extended so as to push over the conveyor C towards the newly exposed face. The support is then advanced by retracting the

ram

13, 14, pressure-fluid having rst been released from the legs 11 to an extent suicient'to enable the support to slide between the floor and roof. During this advancing movement of the support suiicient pressure is maintained in the legs to hold the roof-engaging structure with some pressure against the roof as hereinafter described in greater detail.

Referring now to FIGURE 2, 16 indicates a pressurefluid supply main for supplying pressure-fluid to the

hydraulic legs

11 and 17 indicates a pressure-Huid supply ymain for supplying pressure-duid to the pushing side 13a of the ram 13.

It will be understood that the pressure-fluid supply main 16 and 17 may serve the hydraulic legs and rams of the many supports spaced apart along the face.

The supply of pressure-duid to the legs 11 and pushing side 13a of the ram 13 is controlled by

control valves

18 and 19 respectively. These valves may also control the operation of other supports where a plurality of supports are operatedin groups or banks.

The

valves

18 and 19 also have a position, for the purpose of the present invention, in which they connect the cylinders of the legs^11 to the pushing side 13a of the ram 13 by way of a pipe 20. A non-return valve 21 is provided in the pipe 20 and said pipe 20 also has connected to it a pipe 22 which discharges to atmosphere or is connected to a return main. A regulating valve 23 is provided in the pipe 22.

Assuming that the conveyor C has been pushing over towards the newly exposed coal face lby admitting pressure-fluid to the pushing side 13a of the ram 13, then, to advance the support pressure-duid .is supplied t-o the re- 4tract side 13b of the ram 13 via a pressure-fluid supply pipe 24 and the

valves

18 and 19 operated to a position in which they connect the legs 11 and the pushing side 13a of the ram 13 to the pipe 20.

Thus, pressure-Huid can discharge from the legs 11 via the pipe 22 and regulating valve 23 so that the support is released from between floor and roof sufficiently to enable it to advance under the pull applied to it by retraction o-f the ram 13. During this advance, however, Huidpressure displaced from the pushing side 13a of the ram is made available to the legs 11 so as to maintain the roofengaging structure 12 against the roof.

If the ram advances without impediment fluid will be discharged from the ram 13 to the legs 11 to such an extent that the roof-engaging structure 12 will be applied to the roof with appreciable pressure although, of course, not at a pressure which will materially impede the advance of the support. In other words, pressure-fluid from the ram 13 will, to some extent, overcome the pressure iuid being discharged from the legs via the regulating valve 23. On the other hand, should there be an objectionable increase `in the pressure on the roof or should the support meet an obstruction such as the irregularity in the roof indicated at 2S, the advance of the support Will be retarded. As a consequence, the rate of discharge of fluid from the pushing side 13a of the ram 13 will fall and there will be a corresponding fall in the pressure supplied to the legs 11. This will ease the pressure on the roof and the roof-engaging structure will be enabled to negotiate and move under the obstruction 2S. Once it has done this the rate of discharge of iluid from the ram 13 to the legs 11 will increase and there will be a corresponding increase of pressure on the roof. In other words, the rate of discharge of pressure-Huid from the ram to the legs 11 will again become greater than the rate of discharge from the legs via the valve 23.

It will be appreciated that the pressure applied to the roof during advance of the support can be pre-selected or controlled by an appropriate adjustment of the regulating valve 23.

The embodiment of the invention shown in FIGURE 3 is similar to that already described with reference to FIGURE 2 and where applicable like reference numerals have been used to designate like parts. In the arrangement shown in FIGURE 3, however, the regulating valve 23 is replaced by a spring-loaded bleed or pressure relief or reducing valve 26. When the roof-engaging structure 12 meets an obstruction 25 in the roof the valve 26, which is pre-set to operate at a required pressure, bleeds-oli pressure-fluid, to atmosphere or to a return line, and relieves the pressure of the roof-engaging structure against the roof. Thus, said roof-engaging structure can negotiate the obstruction. After it has done this the bleed valve 26 will cease to bleed-01T fluid and sufiicient pressure will be restored to the legs 11 to maintain the roof-engaging structure in firm sliding contact with the roof. Even if the roofengaging structure should come under a cavity in the roof, such as is indicated at 27, pressure on the roof will be maintained -because further uid will be supplied to the legs 11 from the rarn via the pipe 20. It will also be noted that in the arrangement shown in FIGURE 3 the nonreturn Valve 21 is omitted.

In the case of a walking support, i.e. a support comprising two support elements which advance alternately each using the other as an abutment, the piston rod of the advancing ram may be connected to the one support element and the cylinder to the other. Such an arrangement is shown in FIGURE 4. The hydraulic system is similar to that described with reference to FIGURES l and 2 and like reference numerals have been used with the suflx a attached to those of the second support element 11a, 12a. When the ram is being operated to advance the

element

11, 12 pressure-fluid is made available to the legs 11 from the side 13a of the ram cylinder and when the ram is being operated to advance the element 11a, 12a pressure-Huid is made available to the legs 11a from the side 13b of the ram cylinder.

I claim:

1. A self-advancing mine roof support comprising a base, hydraulically extensible leg means on said base, a roof-engaging structure mounted on said leg means so as to be applied thereby to the roof, a hydraulic ram means operative to advance the support and means for connecting the leg means to the hydraulic circuit of the ram means so that the leg means, during advance of the support, is subjected to duid-pressure, lto maintain the roof-engaging structure against the roof, dependent on the resistance to advance of the support.

2. A mine roof support -as claimed in claim 1 wherein during advance of the support said leg means is subjected to huid-pressure, to maintain the roof-engaging structure against the roof, dependent on the advancing speed of the support.

3. A mine roof support as claimed in claim 1 wherein the fluid-pressure to which the leg means is subjected during advance of the support is controlled by means responsive to the pressure in the cylinder of the advancing ram.

4. A mine roof support as claimed in claim 1 wherein the ram means is double-acting and the cylinder of the ram means has a connection to the leg means of the support so that pressure-fluid discharged from the ram means, during advance of the support, can act on said leg means to apply the roof-engaging structure to the roof, valve means being associated with said connection for controlling the ow of pressure-fluid therethrough.

5. A mine roof support as claimed in claim 1 wherein said connecting means between the hydraulic circuit of the ram means and the leg means of the support has an opening to atmosphere controlled by a regulative valve.

6. A mine roof support as claimed in claim 1 wherein said connecting means between the hydraulic circuit of the ram means and the leg means of the support has an opening to atmosphere controlled by a loaded bleed valve.

7. A mine roof support as claimed in claim 1 wherein the ram means comprises a double-acting ram, a pushing side of the cylinder of said ram being connected to the leg means of the support.

8. A mine roof support as claimed in claim 1 wherein a cylinder of the ram means has 4a connection to the leg means of the support so that pressure-fluid discharged from said cylinder, during advance of the support, can act on said leg means to apply the roof-engaging structure to the roof, valves, for controlling operation of the support `and the ram means, being positioned in said connection so as also to control the ow of pressureuid between the ram means and the leg means during advance of the support, a regulating valve having an outlet to atmosphere being positioned between said control valves.

9. A mine roof support as claimed in claim 1 wherein the duid-pressure to which the leg means is subjected during advance of the support is controlled by a forcemeasuring device between the support-advancing ram means and Aan anchorage it uses to advance the support.

10. A mine roof support as claimed in claim 9 wherein said force-measuring device responds to resistance to movement of the support and said response adjusts valve means controlling the supply of pressure-Huid maintaining the roof-engaging structure of the support against the roof during advance of the support.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

Claims

1. A SELF-ADVANCING MINE ROOF SUPPORT COMPRISING A BASE, HYDRAULICALLY EXTENSIBLE LEG MEANS ON SAID BASE, A ROOF-ENGAGING STRUCTURE MOUNTED ON SAID LEG MEANS SO AS TO BE APPLIED THEREBY TO THE ROOF, A HYDRAULIC RAM MEANS OPERATIVE TO ADVANCE THE SUPPORT AND MEANS FOR CONNECTING THE LEG MEANS TO THE HYDRAULIC CIRCUIT OF THE RAM MEANS SO THAT THE LEG MEANS, DURING ADVANCE OF THE SUPPORT, IS SUBJECTED TO FLUID-PRESSURE, TO MAINTAIN THE ROOF-ENGAGING STRUCTURE AGAINST THE ROOF, DEPENDENT OM THE RESISTANCE TO ADVANCE OF THE SUPPORT.