US3217603A

US3217603A - Mining apparatus

Info

Publication number: US3217603A
Application number: US282412A
Authority: US
Inventors: Potts Michael Charles; Bolton Douglas Herbert Hewlett
Original assignee: Dowty Mining Equipment Ltd
Current assignee: Dowty Mining Equipment Ltd
Priority date: 1962-05-25
Filing date: 1963-05-22
Publication date: 1965-11-16
Anticipated expiration: 1982-11-16
Also published as: US3228300A; GB991007A; FR1356892A; FR1356891A; DE1189504B; GB991012A; DE1176087B

Description

1965 M: c. POTTS ETAL MINING APPARATUS Filed May 22, 19 3 FIGJ.

4 Sheets-Sheet l 5% E1 E23 m 53 g 4 32 FIG.2.

IN l/EN ak Mic/MEL DPUGLAS #4 .BQLTEN ,4 7'77 mveys A Nov.16, 1965 c. POTTS ETAL MINING APPARATUS 4 Sheets-Sheet 2 Filed May 22, 1963 J s T T r n 2% m Niel boo;

Nov. 16, 1965- c. POTTS ETAL 3,

MINING APPARATUS Filed May 22, 1965 4 Sheets-Sheet 3 IMVE/JTJRS HAs c. Parr; Iowan: AA/y. BoLn/v A mam: y;

Nov. 16, 1965 M. c. POTTS ETAL MINING APPARATUS 4 Sheets-Sheet 4 Filed May 22, 1963 INVENTORS mum/1:1. c. 7 O7"T3- BY DOUGLAS H. H. BOLTON ATTORNEY:

United States Patent 3,217,603 MINING APPARATUS Michael Charles Potts, Prestbury, Cheltcuham, and Donglas Herbert Hewlett Bolton, Winchcornhe, near Cheltenhani, England, assignors to Dowty Mining Equipment Limited, Ashehurch, near Tewlreshnry, County of Gloucester, England, a British company Filed May 22, 1963, Ser. No. 232,412 Claims priority, application Great Britain, May 25, 1962, 20,198/62 8 Claims. (Cl. 91-1) This invention relates to mining apparatus. The present invention provides a roof support assembly including a series of fluid-pressure-operated advanceable roof supports, a source of fluid pressure for operation of the roof supports, a conduit along which fluid flows when each roof support in succession undergoes an advancing operation, means for automatically advancing the roof supports in a predetermined sequence, and means for counting the number of roof supports advanced, as an advancing sequence takes place, by sensing variations in a fluid condition in the conduit, to the end that the attendant or operator may know at all times how far in the series the advancement has progressed.

The conduit may convey fluid under pressure from the pressure source to the roof supports, the counting means sensing variations in the pressure in the conduit. The counting means may include two relatively movable parts, relative movement of which is caused by a variation in pressure in the conduit indicating a roof support advancing operation, the parts being mechanically connected to counting mechanism in such a manner that the relative movement operates the counting mechanism. The two parts may be a cylinder and a piston slidably mounted in the cylinder.

The conduit may convey fluid released from each roof support when undergoing an advancing operation, the

counting means sensing variations in the rate of flow of fluid in the conduit.

The counting means may be reset by completion of an advancing sequence.

One embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, of which,

FIGURE 1 is a diagrammatic view of mining apparatus, but with the hydraulic connections and roof bars omitted,

FIGURE 2 is a similar view on a larger scale showing the hydraulic connections,

FIGURE 3 is a side view, partly in section, of the hydraulically-operated counter,

FIGURE 4 is an opposite view, partly in section, of the counter,

FIGURE 5 is a front view of the counter, and

FIGURE 6 is a diagrammatic view of the hydraulic control valve assembly of a roof support.

With reference to FIGURES 1 and 2 of the accompanying drawings, mining apparatus includes a conveyor 1 extending along the working face 2 of a coal mine and a cutter 3 which passes along the working face 2 and is situated between the working face 2 and the conveyor 1. The conveyor 1 acts as a guide means for the cutter 3. The mining apparatus also includes a roof support assembly located on the opposite side of the conveyor 1 to the cutter 3 and working face 2. The roof support assembly includes a series of roof supports 4 arranged along the Working face 2. Each roof support 4 includes a groundengaginig sole beam 5 carrying three hydraulically-operable telescopic props 6, and the three props 6 carry a roof beam (not shown). Each roof support 4 is connected to the conveyor 1 by a hydraulically-operable jack 7 for advancing the roof support 4- towards the conveyor 1, and

ice

every fourth roof support 4 has a further hydraulicallyoperable jack 8 for advancing the conveyor 1 relative to the roof support 4.

The mining apparatus also includes a hydraulic power unit 9 which has a main pressure source 10 from which a hydraulic pressure line 11 and a hydraulic return line 12 extend along the working face 2. Each roof support 4 includes a hydraulic control valve assembly 13, to each of which the pressure line 11 and return line 12 are connected by branch lines 14 and- 15 respectively. The control valve assembly 13 of each roof support 4, which will be described in detail hereinafter, is connected to its props 6, jack 7 and jack 8 (if provided). The control valve assembly 13 of each roof support that is provided with a jack 8 is so arranged that the jack 8 is urging the conveyor 1 towards the coal face continually except when the roof support 4 is being advanced. Actuation of the control valve assembly 13 causes the following operations to take place in sequence:

(a) The jack 8 (if provided) is caused to cease pushing the conveyor 1 forwardly,

(b) The props 6 are contracted to release the roof support from the roof,

(0) The jack 7 is caused to advance the roof support up to the conveyor 1,

(d) After support advance have been completed, the jack 7 is caused to cease urging the roof support forwardly, the props 6 are extended to reset the roof support against the roof and the jack 8 (if provided) is caused to resume pushing the conveyor 1 forwardly.

Actuation of the control valve assemblies 13 is caused by a hydraulic pilot system. The power unit 9 includes a source 16 of hydraulic pressure for the pilot system and a pilot line 17 extends from the pilot source 16 and passes through the control valve assembly 13 of each roof support 4 in turn. Each control valve assembly initially closes the pilot line 17. When the pilot source 16 is operated to pressurise the pilot line 17, the hydraulic pressure in the pilot line 17 acts as a signal to the control valve assembly 13 of the first roof support 4. This roof support 4 undergoes an advancing operation, as described above, and when the roof support has been satisfactorily reset against the roof, the satisfactory resetting being sensed by the attainment of a desired hydraulic pressure in the props 6, the control valve assembly 13 is caused to open the pilot line so that the hydraulic pressure signal is then applied to the control valve assembly 13 of the next roof support, which then undergoes an advancing operation.

Thus each roof support in turn undergoes an advancing operation. The hydraulic circuit relating to the advancing sequence is described in United States application Serial No. 282,760, filed May 23, 1963.

The operation of the valve assembly 13 of each roof support 4 will now be described with reference to FIG- URE 6. The valve assembly 13 of a roof support 4 with a double-acting jack 8 includes six valve units A, B, C, D, E and F. Valve unit A controls the supply of hydraulic fluid to the jacks in a jack-extending sense and is connected to the branch supply line 14 and to a line 53 leading to the jack 8. Valve unit B is connected to the line 53 and to the branch return line 15.

Valve unit D controls the supply of hydraulic fluid to the jack 7 and jack 8 in a jack-contracting sense and is connected to the branch supply line 14 and to a line 54 leading to the

jacks

7 and 8. Valve unit. C is connected to the line 54 and to the branch return line 15.

Valve unit E controls the supply of hydraulic fluid to the props 6 and is connected to the branch supply line 14 and to the props 6 through a line 55 including a restrictor 56 and a non-return valve 57. Valve unit F controls the release of hydraulic fluid from the props 6 and is connected to a line 58 leading from the props 6 and to the branch return line 15. The line 58 includes a nonreturn valve 59, and a pressure relief valve 61 is connected in parallel with the valve unit F between the line 58 and the branch return line 15.

The valve units A and B are associated with a pivotally-mounted lever 62 which is connected to a similar lever 63 associated with the valve units C and D. The levers 62 and 63 coordinate the action of valve units A, B, C and D. In those roof supports without a double-acting jack 8, valve units A and B and lever 62 are omitted. The action of valve units E and F are coordinated by a pivotally-mounted lever 64. The levers 62, 63 are ganged to one another as shown by the connection 60.

The valve assembly of each roof support 4 includes a pilot valve 65 which, before an advance of the roof support begins, closes the pilot line 17. The pilot valve 65 includes a valve member 66 urged towards a valve seat 67 by a spring 68, and also includes a piston 69 carrying a piston rod 71. The piston 69 can be moved against the force exerted by a spring 72 by a suflicient hydraulic pressure in a line 73 to cause the piston rod 71 to lift the valve member 66 off the valve seat 67. The line 73 is connected to line 55. The piston rod 71 has a bore 75 which, when the piston rod 71 is not engaging the valve member 66, brings one side of the valve member 66 into communication with the branch return line 15. When piston rod 71 engages the valve member 66, the valve member 66 closes the bore 75.

Four nonreturn valves 76 are connected in the pilot line 17 to enable the roof support to be caused to undergo an advancing operation by the receipt of a signal along pilot line 17 from the adjacent left hand roof support or from the adjacent right hand roof support. A small restrictor 74 is connected in the pilot line 17 across pilot valve 65 to ensure that pressure cannot be trapped in the portion of pilot line 17 between valves 76 and valve unit C by providing a leak to the branch return line 15 through the bore 75 in piston rod 71.

A prop resetting valve 83 is associated with the supportadvancing jack 7. The resetting valve 83 includes a valve member 84 urged by a spring 85 onto a valve seat 86 to isolate the chamber 87 of the jack 7 from a line 88 con nected to valve unit F and to line 55 through a nonreturn valve 89. A lifter rod 91 can be moved to lift the valve member 84 off its seat 86, as the jack 7 becomes fully contracted, by a trip 93 carried by the piston rod 94 of the jack 7.

FIGURE 1 shows the cutting machine 3 traveling from left to right along the working face 2. After the cutting machine 3 has passed the first few roof supports 4 in the series, it is necessary to advance the conveyor 1 in front of these roof supports 4 and then to advance the roof supports 4. Each roof support 4 having a conveyor-advancing jack 8 is operated to cause the jack 8 to apply an advancing force or to resume the application of such a force to the conveyor 1, the roof support 4 being set against the roof and acting as an anchorage. This is achieved by pivoting lever 62 in an anticlockwise direction to open valve unit A and thus pressurizing the line 53 and the pushing side of jack 8. This movement of the lever 62 may be caused by manual operation of lever 62 or by pressurization of a hydraulic line 95 connected to valve unit B. The line 95 may be connected through a manually or remotely controlled valve to the main supply line 11. After the lever 62 has been pivoted in the anticlockwise direction to cause the jack 8 to be pressurized in the conveyor-advancing sense, a spring-operated latch 96 holds the lever 62 in this position. The anticlockwise movement of lever 62 causes a similar movement of lever 63, but such movement does not change the state of valve units C and D from that shown in FIG- URE 6. The latch 96 is connected to the pilot line 17 in such a manner that pressurization of the pilot line 17 releases the latch 96 so that valve unit A closes and re- 4 turns lever 62 and consequently lever 63 to the position in FIGURE 6.

When the first portion of the conveyor 1 has been advanced, as shown in FIGURE 1, the roof supports 4 can then be advanced. The source 16 is operated to pressurize the pilot line 17 and hence a hydraulic pressure signal is sent along line 17 to the first roof support 4. Referring now to FIGURE 6, the hydraulic pressure signal reaches the roof support through the portion of line 17 shown in the upper left-hand part of FIGURE 6. The hydraulic pressure signal releases the latch 96 and operates on valve unit C to cause clockwise movement of levers 62 and 63. As a result, valve unit A closes, valve unit B opens, valve unit C closes and valve unit D opens. Thus the pushing or jack-extending side of jack 8 is connected to the branch return line 15, and the jack-contracting sides of the

jacks

7 and 8 are connected through the line 54 with the branch supply. line 14. The conveyoradvancing jack 8 is not actually connected to the conveyor 1 but merely pushes against the conveyor 1 when applying an advancing force to it. Therefore, at this stage, the jack 8 contracts and takes no part in advancing the support.

Line 54 is also connected by a line 99 to valve unit F, and the pressurization of line 54 causes the valve unit F to be opened to bring the line 58 into communication with the branch return line 15, thus releasing the hydraulic pressure in the props 6 and so releasing the roof support 4 from the roof. The jack 7 then contracts and advances the roof support 4 towards the conveyor 1 with the conveyor 1 acting as an anchorage.

When the jack 7 is fully contracted, or in other Words when the roof support is fully advanced up to the conveyor 1, the trip 93 on the piston rod 94 of the jack 7 engages the lifter rod 91 and opens the resetting valve 83. The line 88 is therefore brought into communication with the main supply line 11 through the branch supply line 14, now-open valve unit D, line 54, jack 7 and resetting valve 83. The pressure in line 88 acts upon valve unit F to close it and then passes through nonreturn valve 89, restrictor 56 and nonreturn valve 57 to extend the props 6 and so reset the roof support 4 against the roof.

The hydraulic pressure in line 88 is also present in line 73. When the props 6 have been extended to give a satisfactory roof-supporting force, as evidenced by a buildup of pressure in line 73 to a predetermined value, this value of pressure is arranged to operate on the piston 69 and to open pilot valve 65. Thus the portion of the pilot line 17 between the control valve 16 and the first roof support 4 is brought into communication with the portion of the pilot line 17 between the first roof support and the second roof support (that is the portion of the pilot line 17 in the lower left portion of FIGURE 6) with the result that the hydraulic pressure signal in the pilot line 17 reaches the second roof support in the series and causes it to undergo an advancing operation. In this way, each roof support in the group is advanced in turn.

If it is desired to operate the valve assembly 13 manually, this can be done by manually operating levers 62, 63, 64.

The power unit 9 will usually be located at one end of the working face, and consequently it will not be possible for a man controlling the power unit 9 to see, While an advancing sequence is in progress, how many roof supports 4 have been advanced. If a fault occurs and an advancing sequence stops, it is important for the power unit operator to know how far along the series the advancing sequence has progressed. The power unit operator may also control the operation of the cutter 3 and the conveyor 1 and it is important for the operator to know at all times how far along the series of roof supports an advancing sequence has progressed. The operator requires this knowledge in order to make decisions regarding the operation of the cutter and conveyor and consequently regarding the coal-mining operation as a whole. Therefore, in mining operations where roof sup ports advance in sequence automatically, it is desirable that the mining apparatus should include some means of indicating how far along the series of roof supports an advancing sequence has progressed.

In the described mining apparatus, as has already been described, the roof supports include hydraulically-operated props and jacks which are supplied with hydraulic fluid under pressure from the pressure line 11 and which discharge hydraulic fluid into the return line 12. As each roof support 4 undergoes an advancing operation, the operation of the props and jacks will cause the pressure in the pressure line 11 to fluctuate in a definite manner and will cause the rate of flow of fluid in the return line 12 to fluctuate in a definite manner.

In accordance with this invention, a hydraulically-operated counter 20 is located on the power unit 9 and is connected to the pressure line 11 in such a manner that the counting mechanism of the counter 20 is actuated each time the pressure in the pressure line 11 varies in the manner which indicates that a roof support 4 is undergoing an advancing operation. When no roof support 4 is undergoing an advancing operation, the hydraulic pressure in the pressure line 11 will be a maximum and when a roof support 4 is undergoing an advancing operation the pressure in the pressure line will, although fluctuating, reach a minimum value. This variation of pressure is arranged to operate the counter 20, which will now be described with reference to FIGURES 3 to 5.

The counting mechanism is contained in a housing 18 provided with a window 19 in which the figures indicating the number of advanced roof supports appear. An operating shaft 21 projects from the housing 18 and is connected by a lever 22 to a piston rod 23 carrying a piston 24 slidably mounted in a bore 25 in a housing 26. The piston 24 is urged towards a stop 27 by a spring 28 and by a fluid pressure which enters the bore 25 through a port 29. In this embodiment, the fluid-pressure is supplied by the pilot source 16, although the particular source is immaterial. The use of this fluid pressure means that a weaker spring 28 can be used instead of a stronger spring which would be necessary if a fluid pressure was not used. The spring 28 and the assisting fluid pressure in the bore 25 act upon the left hand side of the piston. The pressure in the pressure line 11 is communicated to the chamber 31 on the right hand side of the piston 24 through a port 32.

When the pressure in the pressure line 11 is at the maximum, that is, when no advance is in progress, the force exerted by the fluid in chamber 31 on the right hand side of the piston 24 is greater than the force exerted by the spring 28 and the assisting fluid pressure on the left hand side of the piston 24, and the greater force moves the piston 24 and consequently piston rod 23 and lever 22 to the left, from the position shown in FIGURE 3.

When the pressure in pressure line 11 is at the minimum (that is, sometime when a roof support is undergoing an advancing operation) the combined force of the spring 28 and the assisting fluid pressure on the left hand side of piston 24 overcomes the force exerted by the fluid on the right hand side of the piston 24 and moves the piston to the right until it engages the stop 27, that is, to the position shown in FIGURE 3. This latter movement of the piston rod 23, lever 22 and shaft 21 operates the counter to add one to the number shown in the window 19.

When an advancing sequence has been completed, the control valve assembly 13 of the last roof support in the series opens the pilot line 17 into a secondary pilot line 33 which therefore becomes pressurized. The secondary pilot line 33 is connected to the counter 24) in such a manner that the fluid-pressure in the secondary pilot line 33 operates on the counter 29 to reset the counting mechanism by returning the number indicated in the window 19 to zero. Referring to FIGURE 4, the secondary pilot line 33 is connected to a port 34 leading to a chamber 35 on the left hand side of a piston 36 slidably mounted in a bore 37 in a housing 38. The piston 36 is carried by a piston rod 39, which is connected by a lever 41 to a shaft 42 projecting from the housing 18 and associated with the counting mechanism in the housing 18. When there is no pressure in the secondary pilot line 33 and the chamber 35, the piston 36 is urged against a stop 43 by' a spring 4-4. When the secondary pilot line 33 and the chamber 35 are pressurised, the piston 36 is forced to the right and consequent movement of the piston rod 39, lever 41 and shaft 42 resets the counter to zero.

In this described apparatus, the number of changes in pressure in the pressure line 11 which each indicate that a roof support is undergoing an advancing operation are counted. Whether the changes in the pressure line be counted, or those in the return line, is immaterial. It is also within the scope of the invention to alternatively include a flowmeter in the return line 12, and to arrange that variations in the rate of flow of fluid in the return line 12, which each indicate that a roof support is undergoing an advancing operation, are sensed by the flowmeter, which then operates a counting mechanism to indicate the number of roof supports which have been advanced. In the return line 12, the maximum rate of flow occurs when the props 6 of a roof support collapse.

We claim as our invention:

1. A roof support assembly including a series of fluidpressure-operated advanceable roof supports, a source of fluid pressure for operation thereof, conduit means along which fluid flows between said source and each given roof support to effect an advancing operation of the roof support, and in which each advancing operation creates in the conduit means a change in the fluid condition that is characteristic of a given stage in such operation, each roof support including at least one fiuid-pressureoperated prop and a control valve operable to cause its roof support to undergo an advancing operation, means operable to send a signal from each roof support, as a result of completion of its advancing operation, to the control valve of the next roof support to cause such next roof support to undergo an advancing operation, and counting means responsive to a change in the fluid condition in the conduit means, such as is characteristic of the aforesaid given stage in the advancing operation of each roof support, to increase by one the number of roof supports counted.

2. A roof support assembly for a mine including a series of roof supports distributed along the working face, and each including at least one contractible and extensible fluid-pressure-operated prop to support the roof, and fluid-pressure-operated means to advance the roof support, a source of fluid pressure, conduit means connected to said source, a control valve assembly individual to each roof support and all connected to said conduit means to regulate the supply of pressure fluid to cause its own roof support to contract its prop, to undergo an advancing operation, and then to extend its prop, and by such operations causing variations in pressure in the conduit means, each control valve assembly being arranged to supply a signal to the control valve assembly of the next roof support to initiate an advancing operation of the latter as a result of completion of the advancing operation of the preceding roof support, and counting means responsive to attainment of a given pressure in the conduit means, such as is characteristic of a stage in the advancing operation of each roof support, to increase by one the number of roof supports counted.

3. A roof support assembly as in claim 2, wherein the counting means includes two parts relatively movable under the influence of a variation in pressure in the conduit means such as is characteristic of a. stage in the advancing operation, and a mechanical counter operatively connected thereto and operable thereby.

4. A roof support assembly as in claim 2, including a resetting mechanism connected in said conduit means beyond the last roof support in the series, and actuated following advance of such last roof support, said resetting mechanism being operatively connected to said counting means to reset the latter.

5. A roof support assembly as in claim 2, wherein the conduit means includes a pilot pressure conduit connected to the control valve assemblies and a main pressure conduit connected to the props and to the advancing means, and the counting means includes a cylinder connected at its opposite ends to the respective conduits, a piston reciprocable in said cylinder and a mechanical counter operatively connected to the piston, and a spring arranged to assist pressure in the pilot pressure conduit to move said piston in one direction and to actuate the mechanical counter when pressure drops in the main pressure conduit during an advancing operation, but of a strength to be overcome when pressure in the main pressure conduit is a maximum, and no advancing operation is taking place, thereby to move said piston in the opposite direction.

6. A roof support assembly as in claim 5, wherein the conduit means includes a further conduit connected to the control valve assembly of the last roof support in the series, and pressurized Only when such last roof support has been advanced, and the mechanical counter includes resetting means, a cylinder connected to and pressurized from said last-mentioned conduit, and a piston reciprocable therein and operatively connected to said resetting means, to reset the mechanical counter to zero upon completion of an advancing sequence.

7. A roof support assembly for a mine including a series of fluid-pressure-operated advanceable roof supports distributed along the working face, a source of fluid pressure, conduit means connecting said source with 10 initiate advance thereof, upon completion of the advancing operation of its own roof support, and means re sponsive to attainment of a given fluid pressure in the conduit means, created by each roof support reaching a desired stage in its advancing operation, to count the 15 number of roof supports advanced.

8. A roof support assembly as in claim 6, wherein the conduit means includes a conduit connected to the control valve assembly of the last roof support in the series, to be pressurized upon completion of the advancing opera- 20 tion of such last roof support, and fluid-pressure-operated means for resetting said counting means to zero, said resetting means being connected to said conduit.

References Cited by the Examiner 25 UNITED STATES PATENTS 627,661 6/1899 Symons et a1 235-91 1,312,787 8/1919 Hopkins. 2,711,634 6/1955 Joy 248356 2,753,036 7/1956 Joy 248356 FOREIGN PATENTS 1,201,174 12/1959 France.

5 SAMUEL LEVINE, Primary Examiner. FRED E. ENGELTHALER, Examiner.

Claims

1. A ROOF SUPPORT ASSEMBLY INCLUDING A SERIES OF FLUIDPRESSURE-OPERATED ADVANCEABLE ROOF SUPPORTS, A SOURCE OF FLUID PRESSURE FOR OPERATION THEREOF, CONDUIT MEANS ALONG WHICH FLUID FLOWS BETWEEN SAID SOURCE AND EACH GIVEN ROOF SUPPORT TO EFFECT AN ADVANCING OPERATION OF THE ROOF SUPPORT, AND IN WHICH EACH ADVANCING OPERATION CREATES IN THE CONDUIT MEANS A CHANGE IN THE FLUID CONDITION THAT IS CHARACTERISTIC OF A GIVEN STAGE IN SUCH OPERATION, EACH ROOF SUPPORT INCLUDING AT LEAST ONE FLUID-PRESSURE-OPERATED PROP AND A CONTROL VALVE OPERABLE TO CAUSE ITS ROOF SUPPORT TO UNDERGO AN ADVANCING OPERATION, MEANS OPERABLE TO SEND A SIGNAL FROM EACH ROOF SUPPORT, AS A RESULT OF COMPLETION OF ITS ADVANCING OPERATION, TO THE CONTROL VALVE OF THE NEXT ROOF SUPPORT TO CAUSE SUCH NEXT ROOF SUPPORT TO UNDERGO AN ADVANCING OPERATION, AND COUNTING MEANS RESPONSIVE TO A CHANGE IN THE FLUID CONDITION IN THE CONDUIT MEANS, SUCH AS IS CHARACTERISTIC OF THE AFORESAID GIVEN STAGE IN THE ADVANCING OPERATION OF EACH ROOF SUPPORT, TO INCREASE BY ONE THE NUMBER OF ROOF SUPPORTS COUNTED.