US3319529A

US3319529A - Advanceable roof support assemblies

Info

Publication number: US3319529A
Application number: US394359A
Authority: US
Inventors: Bolton Douglas Herbert Hewlett; Pawling Frank; Potts Michael Charles
Original assignee: Dowty Mining Equipment Ltd
Current assignee: Dowty Mining Equipment Ltd
Priority date: 1963-09-06
Filing date: 1964-09-03
Publication date: 1967-05-16
Anticipated expiration: 1984-05-16
Also published as: GB1023478A; DE1249796B

Description

y 1967 D. H. H. BOLTON ET AL 3,319,529

ADVANCEABLE ROOF SUPPORT ASSEMBLIES Filed Sept. 5, 1964 2 Sheets-Sheet l Imvanrroe; M c/(ASL c. P Bv bob-am: H. 1 ISoLToAJ FeANK PA-Wuua.

ATIQR w aw i May 16, 1967 D. H. H. BOLTON ET AL 3,319,529

ADVANCEABLE ROOF SUPPORT ASSEMBLIES 2 Sheets-Sheet 2 Filed Sept. 1964 INVENTOR 5 MI HAEL c. P TIS BY )ouGLAS H-H. BQ T'o United States Patent 3 319,529 ADVANCEABLE RODF SUPPORT ASSEMBLIES Douglas Herbert Hewlett Bolton, Winchcornbe, Frank Pawling, Cheltenham, and Michael Charles Potts, Prestbury, England, assignors to Dowty Mining Equipment Limited, Ashchurch, England, a British company Filed Sept. 3, 1964, Ser. No. 394,359 Claims priority, application Great Britain, Sept. 6, 1963, 35,330/63 1 Claim. (Cl. 91-189) This invention relates to advanceable roof support assemblies suitable for use in mines.

The present invention provides an advanceable roof support assembly including a series of advanceable fluidpressure-operated roof supports, each roof support including a first valve assembly whose operation causes the roof support to undergo an advancing operation, the initiation of operation of the first valve assembly being caused by the pressurization of an advance-start line connected to the first valve assembly, each roofsupport also including a second valve assembly connected to the advance-start line of that root support and connected by a signal line to the second valve assembly of the next roof support in the series, and each second valve assembly including a series of non-return valves and a control valve arranged in such a manner that, for each roof support, pressurization of the signal line connected to the preceding roof support or pressurization of the signal line connected to the next roof support each causes pressurization of the advancestart line of the roof support with consequent initiation of operation of the first valve assembly of the roof support, and that the control valve and the series of non-return valves function to prevent pressurization of the signal line not previously pressurized until the control valve is operated to cause pressurization of the signal line not previously pressurized.

The control valve may be operated, to cause pressurization of the signal line not previously pressurized, by the attainment of a predetermined stage of the advancing operation of the roof support. The said predetermined stage may be a satisfactory roof-supporting fluid pressure. Alternatively, or additionally, the control valve may be manually operable. The control valve may operate to cause pressurization of the signal line not previously pressurized, by closing a path including a restrictor through which fluid in the advance-start line can drain to a region of low pressure and by opening a path from the advance-start line to the signal line not previously pressurized.

The control valve, when operated to cause pressurization of the signal line not previously pressurized, may be held in the operated position by locking means which is independent of loss in pressure in the signal line.

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 including a series of advanceable roof supports, the hydraulic connections being omitted,

FIGURE 2 is a diagrammatic view of part of the mining apparatus showing the hydraulic connections between the power unit and the roof supports and,

FIGURE 3 is a diagrammatic view of the hydraulic valve assembly of a roof support such as includes a conveyor-advancing jack means.

' With reference to the accompanying drawings, mining apparatus includes a snakeable conveyor 1 extending along the working face 2 of a coal mine, and a cutting machine 3 which travels along the working face 2 and is situated between the working face 2 and the conveyor 1. The mining apparatus also includes an advanceable roof supice port assembly including a series of roof supports 4 located on the opposite side of the conveyor 1 to the working face 2 and cutting machine 3. Each roof support 4 includes a ground-engaging sole beam 5 carrying three hydraulically-operated 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-operated single-acting jack 7 for advancing the roof support 4 towards the conveyor 1. Some roof supports, for example, every fourth roof support as shown, have a hydraulically-operated double-acting jack 8 for advancing the conveyor 1 relative to the roof supports 4. The jack 8 is not connected to the conveyor 1 and engages the conveyor 1 only when applying an advancing force to it.

The advanceable roof support assembly also includes a hydraulic power unit 9 which has a main pressure source 10 from which a line 11 applying hydraulic fluid under pressure extends along the series of roof supports 4. Each roof support 4 has a valve block 12 connected to the supply line 11 by a branch supply line 13. A hydraulic fluid return line 14 also extends along the series of roof supports 4, and the valve block 12 of each roof support 4 is connected to the return line 14 by a branch return line 15.

The power unit 9 also includes two secondary

hydraulic pressure sources

16, 17. A signal line 18 connected to the secondary pressure source 16 is connected to the valve block 12 of the first roof support 4 and a similar signal line 18 is connected between the valve blocks 12 of adjacent roof supports. A control line 19 extends from the secondary pressure source 17 along the series of roof supports 4 and the valve block 12 of each roof support 4 is connected to the control line 19 by

branch control lines

21, 22.

FIGURE 3, it will be remembered, illustrates the valve block 12 of each roof support 4 such as includes a doubleacting jack 8 for advancing the conveyor 1. It includes a first valve assembly which has six valve units A, B, C, D, E and F. Valve unit A controls the supply of hydraulic fluid to the jack 8 in a jack-extending sense, and is connected to the branch supply line 13 and to a line 23 leading to the extending side of the jack 8. Valve unit B is connected to the line 23 and to the branch return line 15.

Valve unit D controls the supply of hydraulic fluid to the jacks 7 and 8 in a jack-contracting sense, and is connected to the branch supply line 13 and to a line 24 leading to jacks 7 and 8. Valve unit C is connected to the line 24 and to the branch return line 15.

Valve unit E controls the supply of hydraulic fluid to the props 6 when it is desired to set the props 6 by manual operation. Valve unit E is connected to the branch supply line 13 and to the props 6 through a line 25 including a restrictor 26 and a non-return valve 27. Valve unit F controls the release of hydraulic fluid from the props 6, and is connected to a line 28 leading from the props 6 and to the branch return line 15. The line 28 includes a nonreturn valve 29, and a pressure relief valve 31 is connected in parallel with the valve unit F between the line 28 and the branch return line 15. Line 24 is connected to valve unit F by line 30 in such a manner that pressurization of

lines

24 and 30 opens valve uni-t F The valve units A and B are associated with a pivotallymounted lever 32 which is connected to a similar lever 33 associated with the valve units C and D. The levers 32, 33 co-ordinate the action of valve units A, B, C and D. In those roof supports 4 without a double-acting jack 8, valve units A and B and lever 32 are omitted. The levers 32, 33 are ganged to one another by a connection 300. Valve units E and F are associated with a pivotallymounted lever 34. If desired, the first valve assembly 3 can be operated manually by operation of

levers

32, 33 and 34.

The valve block 12 of each roof support 4 also includes a second valve assembly including a ring of four nonreturn valves 35, 36, 37, 38, an unlocking valve 39 and a control valve 41. The four non-return valves 35, 36, 37, 38 are connected together in the manner shown in FIGURE 3. The signal line 18 connected to the adjacent left hand roof support is connected to the ring of non-return valves 35, 36, 37, 38 in such a manner that fluid arriving from the adjacent left hand roof support along signal line 18 can flow through non-return valve 35 only and pass into a line 42 connected to valve unit C and to the control valve 41. The signal line 18 connected to the adjacent right hand roof support is connected to the ring of non-return valves in such a manner that fluid arriving from the right hand roof support along signal line 18 can flow through non-return valve 36 only and pass into the line 42. A line 43, whose other connections will be described in more detail later, is connected to the ring of non-return valves in such a manner that fluid under pressure in line 19 can pass through non-return valve 38 into signal line 18 leading to the adjacent left hand roof support and can also pass through non-return valve 37 into signal line 18 leading to the adjacent right hand roof support.

The control valve 41 includes a valve closure member 44 biased towards a closed position by a spring 45. In the closed position, valve member 44 prevents free communication of line 42 with line 43. Control valve 41 also includes a piston 45 carrying a piston rod 46. A spring 47 acting on piston 45 urges the piston rod 46 away from the valve closure member 44. The piston rod 46 'has a passage 48 extending from its free end to a position adjacent the piston 45 where it communicates with the branch return line 15. The position shown in FIGURE 3, piston rod 46 is spaced from the seated valve closure member 44 and the line 43 is in communication with the branch return line 15 through passage 48 in the piston rod 46.

Piston 45 can be urged towards valve closure member 44, by a predetermined fluid pressure in a line 49 connected to line 25, to cause piston rod 46 to engage valve closure member 44, which then blocks passage 48 and so isolates line 43 from the branch return line 15, and to force valve closure member 44 off its seat to bring line 42 into communication with line 43. This will be further described later. A restrictor 51 is connected in parallel with control valve 41 between lines 42 and 43.

Line 49 includes a non-return valve 52 which traps fluid between piston 45 and locking valve 39. Looking valve 39 includes a valve closure member 53 urged to a closed position by a spring 54. The locking valve 39 also includes a piston 55 and piston rod 56, and a suflicient fluid pressure applied to piston 55 along control line 19 and branch control line 21 causes the piston 55 to move to- Wards valve closure member 53 so that piston rod 56 engages the valve closure member 53 and moves it to the open position to allow fluid trapped against piston 45 by non-return valve 52 to escape to the branch return line 15.

The first valve assembly of the valve block 12 also includes a prop re-setting valve 57 associated with the jack 7. The re-setting valve 57 includes a valve closure member 58 urged to a closed position by a spring 59 to isolate a chamber 61 in the jack 7 from a line 62. Line 62 is connected to valve unit F and to line 25 through a nonreturn valve 63 and through a restrictor 64 in parallel with the non-return valve 63. A piston rod 65 carrying a piston 66 can be moved to engage valve closure member 58 and move it to the open position, as the jack 7 becomes fully contracted, by a trip 67 carried by the piston rod 68 of the jack 7. A spring 69 urges the piston 66 and its rod 65 away from the valve closure member 58. The branch control line 22 is connected to the prop re-setting valve 57 and, when the control line 19 and branch control line 22 have been pressurized to a predetermined value, lower than the pressure required to open locking valve 39, the hydraulic pressure acts on piston 66 to move the piston 66 and piston rod 65 in the same manner as if this had been moved by trip 67. The prop re-setting valve 57 may be self-latching by arranging that, when the valve closure member 58 has been moved to the open position, the hydraulic pressure in line 62 maintains the valve closure member 58 in the open position.

FIGURE 1 shows the cutting machine 3 travelling from left to right along the working face 2. Every roof support is set against the roof and, 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 in turn to cause the jack 8 to apply an advancing 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 32 in an anti-clockwise direction to open valve unit A and allow valve unit B to close, thus pressurizing line 23 and the pushing side of jack 8. This movement of lever 32 may be caused by manual operation of lever 32 or by pressurization of a line 71 connected to valve unit B. Pressurization of line 71 may be controlled by a manually-operated valve or by an automatically-operated valve, for example a valve operated by the cutting machine 3 as it travels along the working face 2. After the lever 32 has been pivoted in the anti-clockwise direction to cause the jack 8 to be pressurized in the conveyor-advancing sense, a spring-operated latch 72 engages beneath a shoulder on the lever 32, in a conventional manner, and holds the lever in its attained position; see the dotted line position of parts in FIGURE 3. The anti-clockwise movement of lever 32 causes a similar movement of lever 33, but such movement does not change the state of valve unitsC and D from that shown in FIGURE 3. The latch 72 is connected to line 42 in such a manner that pressurization of line 42 releases the latch 72 to allow valve unit A to close and return lever 32, valve unit B and lever 33 to the position shown in FIGURE 3, as shown in full lines in FIG- URE 3.

In practice, several jacks 8 will be pressurized in turn, and when the first portion of the conveyor 1 has been advanced in a snaking manner, as shown in FIGURE 1, the advance of the roof supports 4 can then be com menced. The pressure source 16 in power unit 9 is then operated to pressurize the signal line 18 leading to the first roof support 4. Referring now to FIGURE 3, the hydraulic pressure signal reaches the roof support along the portion of signal line 18 shown in the upper left hand part of FIGURE 3. The hydraulic pressure signal in line 18 passes non-return valve 35 and pressurizes line 42. Pressurization of line 42 first releases latch 72 and then operates on valve unit C to cause clockwise movement of levers 33 and 32. 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 {hl'oligh line 24 and valve unit D with the branch supply inc 3.

The conveyor-advancing 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, jack 8 contracts and plays no.

part in advancing the roof support. The jack-extending side of jack 7 is permanently connected to the atmosphere.

Since line 24 is also connected by line 30 to valve unit F, the pressurization of line 24 causes valve unit F to be opened to bring the line 28 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 4 is fully advanced up to the conveyor 1, the trip 67 on the piston rod 68 of the jack 7 engages the piston rod 65 and opens the resetting valve 57. The line 62 is therefore brought into communication with the main supply line 11 through the branch supply line 13, valve unit D, line 24, jack 7 and re-setting valve 57. The pressure in line 62 acts upon valve unit F to close it, and then passes non-return valve 63, restrictor 26 and non-return valve 27 to extend the props 6 and so reset the roof support 4 against the roof.

If the roof support 4 had failed to advance the full distance, trip 67 would not open the re-setting valve 57, but this could be done by pressurizing control line 19 to the predetermined value.

The hydraulic pressure in line 62 is also present in line 49. When a satisfactory roof-supporting pressure is present in the props 6, as evidenced by a build-up of pressure in line 49 to a predetermined value, this pressure overcomes the force exerted by spring 47 in control valve 41 and moves piston 45 to the left. Thus piston rod 46 engages valve closure member 44, resulting in closure of passage 48 and isolation of line 43 from the branch return line 15, and moves valve closure member 44 to the open position to bring line 42 into communication with line 43, thus pressurizing line 43.

The pressure in line 43 can pass through both nonreturn valves 37 and 38. However, the signal line 18 connected to the other side of valve 38 is already pressurized, so that the fluid under pressure in line 43 passes through non-return valve 37 to pressurize the signal line 18 leading to the next roof support 4 in the series, which is thus caused to undergo an advancing operation. Thus each roof support in turn is caused to undergo an advancing operation.

The pressure in line 43 also acts upon valve unit D to cause valve unit D, levers 33 and 32 and valve unit C to return to the position shown in FIGURE 3. Thus pressure is lost in lines 24, in chamber 61 of jack 7 and in line 62. Also pressure in line 25 and in the portion of line 49 between non-return valve 52 and line 25 can drain through restrictor 64 into line 62.

Control valve 41 remains in the open position independently of any loss in pressure from the pressure source 16, since piston 45 is held by fluid trapped under pressure between piston 45, non-return valve 52 and locking valve 39.

When every roof support 4 has advanced, the pressure source 16 in the power unit 9 is switched 011, and the control line 19 is pressurized to a value suflicient to open the locking valve 39 and release the trapped fluid into branch return line 15. The control valves 41 then return to their original positions, and line 43 of each roof support again becomes connected to the branch return line 15 through passage 48 in piston rod 46. Thus the pressure in signal line 18 and line 42 can leak away through the restrictor 51 into the line 43.

While a roof support 4 is undergoing an advancing operation, line 43 cannot become pressurized before control valve 41 is operated by a predetermined pressure in line 49, since the small flow of fluid through the restrictor 51 from line 42 into line 43 is lost through the passage 48 in piston rod 46 to the branch return line 15.

With the ring of non-return valves 35, 36, 37, 38, the advancing sequence can travel along the series of roof supports 4 in either direction, that is to say either from left to right as described, or from right to left. If an advancing sequence from right to left is required, pressure source 16 is operated to pressurize a signal line 73 connected to the position between non-return valves 36 and 37 of the last roof support at the right hand end of the series. Referring to FIGURE 3, it will be seen that pressurization of signal line 18, whether from the adjacent left hand roof support or from the adjacent right hand roof support, causes the pressure signal to pass nonreturn valve 35 or 36 respectively and pressurize line 42. Line 42 may therefore be referred to as an advancestart line whose pressurization causes the roof support to undergo an advancing operation. When a roof support has completed its advancing operation, as evidenced by a satisfactory build-up of pressure in the props 6, control valve 41 is operated to cause pressurization of line 43. This pressure signal in line 43 passes non-return valve 37 or 38 to pressurize the signal line 18 not previously pressurized and so cause the advance of the next roof support 4 in the series.

Besides assisting in the draining of signal line 18 and line 42 when all the roof supports 4 have advanced, the presence of restrictor 51 also enables the advance of the roof support 4 to be stopped part-way through the advancing operation, by switching off the power source 16 or opening a signal line 18 to return, since pressure in line 42 will then drain away through restrictor 51, and valve units C and D will return to the positions shown in FIGURE 3.

If desired, instead of the control valve 41 being operated by a predetermined pressure in line 49, the control valve 41 could be manually operable.

What we claim is:

An advanceable roof support assembly including a series of advanceable fluid-pressure-operated roof supports, each roof support including a first valve assembly operable to cause the roof support to undergo an advancing operation, an advance-start line connected to the first valve assembly to initiate operation of the first valve assembly upon pressurization of the advance-start line, and a second valve assembly connected to the advancestart line of that roof support, and a signal line connected from the second valve assembly of each roof support to the second valve assembly of the next roof sup port, each second valve assembly including a series of non-return valves and a control valve arranged to allow, for each roof support, pressurization of the signal line connected to the preceding roof support or pressurization of the signal line connected to the next roof support to cause pressurization of the advance-start line of that roof support with consequent initiation of operation of the first valve assembly of the roof support, and also arranged to prevent pressurization of the signal line not previously pressurized until the control valve is operated to cause pressurization of the signal line not previously pressurized, each roof support also including locking means which operates to hold the control valve, when operated, in the operated condition, said locking means being independent of loss in pressure in the signal line.

References Cited by the Examiner UNITED STATES PATENTS 2,112,466 3/1938 Maloon 91189 2,607,197 8/1952 Johnson 91-189 2,859,022 11/1958 Frye 91170 3,228,302 1/1966 Bolton 91-189 3,240,125 3/1966 Pawling et a1. 91189 MARTIN P. SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Examiner.