US3216201A - Mine roof supports - Google Patents

Description

1965 J. D. KIBBLE ETAL 3,215,201

MINE ROOF SUPPORTS I Filed Oct. 7, 1960 2 Sheets-Sheet 1 FIG. 2.

FIG. I.

171 vehfbr John Du nbar Klbble Mar-3m; James WI'I I' 'S Nov. 9, 1965 J. D. KIBBLE ETAL 3,216,201

MINE ROOF SUPPORTS Filed Oct. 7. 1960 2 Sheets-Sheet 2 FIG. 3.

In V8 n 'OI'S K mm D. mu

J Morgan Hiams United States Fatent O 3,216,201 MINE RGGF SUPPORTS John Dunbar Kibhle, London, and Morgan James Williams, Harmondsworth, West Drayton, England, assignors to Coal Industry (Patents) Limited, London,

England, a company of Great Britain Filed Oct. 7, 1960, Ser. No. 61,210 Claims priority, application Great Britain, Oct. 12, 1959, 34,500/59; June 16, 196i), 21,211/60 9 Claims. (CI. 61-45) This invention relates to mine roof support systems.

The present invention provides a mine roof support system comprising a plurality of mine roof supports advanceable in a predetermined sequence, in which the arrangement is such that in operation of the system the operation of the next support to be advanced is initiated by a signal passed to that support automatically upon completion of operation of the preceding support in the sequence.

Preferably, the arrangement is such that the signal is only passed on automatically to the next support to be advanced when the preceding support has been proved fully re-set against the roof and/ or such that the signal is only passed on automatically to the next support to be advanced when the preceding support has been proved to be advanced by a predetermined amount.

The signal may be constituted by a fluid pressure or by an electrical signal.

One embodiment of the invention will now be described in greater detail, by way of exam le only, with reference to the accompanying drawings, of which:

FIGURES 1 and 2 being partly sectional and diagrammatic end and side elevations respectively of part of an arrangement according to the invention, and

FIGURE 3 is a diagram showing a section of a hydraulic circuit.

In FIGURES 1 and 2 is shown a hydraulic self-advancing mine roof support unit which is one of a plurality (the others not being shown) linked to an armoured flexible face conveyor.

FIGURE 1 is a view in a direction parallel to the coal face, and FIGURE 2 which is an end elevation at right angles to the coal face looking towards the unexcavated coal. The unit consists of a base 1 upon which are mounted resiliently two single acting hydraulic jacks, 2 and 3, which will be termed legs. A roof bar 4 is mounted, also resiliently, upon the legs 2 and '3. Within the base 1 a double-acting hydraulic cylinder 5 is mounted in a gimbal bearing 6 which permits a limited amount of angular movement of the cylinder 5. The piston rod 7 of the cylinder 5 is connected by means of a pin 8 and a bracket 9 to the armoured flexible face conveyor 10. The conveyor carries a spill plate 11 upon which are mounted at intervals brackets 12 which carry the flexible pipes 13 passing along the length of the face. The pipes 13 are connected to each support unit by branch flexible pipes as may be required. A hydraulic valve block 14 is mounted in a suitable position on the base. This is connected with the cylinder 5 and the legs 2 and 3 by pipes which are not shown. Similar support units are placed at short intervals throughout the length of a long wall coal face.

The manual operation of this will now be described. After a web of coal has been cut and loaded on to the conveyor hydraulic pressure is applied to the cylinder 5 in such a way as to cause the rod 7 to be pushed out. At the same time the other support units are Operated similarly. This will cause the conveyor to move forward into the space vacated by the cut coal. It may only be necessary to push the conveyor with the cylinder of a proportion of the support units. The support units are then moved forward one at a time in sequence along the face by means of lowering the legs of each, and reversing the hydraulic pressure connections to the cylinder 5 so that the rod 7 is pulled in. As the conveyor will be held in position by the pushing action of adjacent support units this operation will cause the support unit in question to move forward until its cylinder 5 is fully contracted. Hydraulic pressure is then re-applied to the legs 2 and 3 so that they extend until the roof bar 4 is forced against the roof. The hydraulic connection to the cylinder 5 are then reversed so that it resumes pushing against the conveyor. The next support unit may then be lowered, advanced, and reset similarly, but it is imperative for reasons of safety that no unit is lowered from the roof unless the adjacent one has been reset.

The means by which these operations may be perform-ed without manual intervention is shown in FIG- URE 3 which is a diagram of the fluid pressure operated equipment of three adjacent support units in the system. These three units and their associated equipment are identical to each other both in construction and in operation. For this reason it is considered necessary only to describe in detail the operation and construction of one of them. For convenience the center support unit will be described. The elements of the left and right hand support units together with the associated equipment are respectively identified in the drawing by using the letters A or B with the reference numerals employed for describing the center unit and its associated equipment. In FIGURE 3 the legs of the support unit are shown at 2 and 3 and its horizontal cylinder at 5. The necessary valves may be constructed in one block represented by the dotted line 15, except for the valve 16, which is mounted on the rear end of the cylinder 5, and is also shown in FIGURE 1. The flexible pipe running along the face conveying hydraulic fluid from the pump is shown at 17 and that returning fluid to the tank at 18. Two additional flexible pipes 19 and 20 are also required.

In the normal state of the circuit only the pipe 17, has fluid pressure applied to it. Thi pressure is fed through the non-return valve 21 to the leg control valve 22, which is a 3-ported two-position valve spring loaded into the hydraulic position shown in which the hydraulic pressure is allowed to pass through the connection 23 to the legs 2 and 3. If convergence of the roof should take place the fluid contained in the legs 2 and 3 cannot return to the line 17 because of the action of the valve 21. The pressure is therefore built up until it is sufficient to operate a relief valve 24 through which the fluid escapes to a reservoir or to waste.

The cylinder 5 is controlled by means of the hydraulic valve 25, which is a 5-ported two-position valve normally held by a spring in the position shown in which the pump pressure, though applied to port 26 of the valve 25, is there sealed off.

When it is desired to advance the conveyor, pressure is applied to the pipe 19, and the valve 25 allows this pressure to pass through to the end 27 of the cylinder 5 to cause extension of the piston rod. The purpose of the separate pressure line 19 is to permit control of the pressure with which the conveyor is advanced, as'is required for certain mining operations such as the use of coal ploughs. If this is not desired the port 28 may be connected to the main pressure line 17 instead of to the pipe 19.

When it is desired to advance the support units, fluid pressure is applied to the pipe 20. This pressure is applied to a pilot cylinder 29 of the valve 22, causing it to move to its alternative position in which the legs are connected through the port 30 to the return line 18, thus permitting them to lower. The pilot pressure is also applied to the cylinder 31 of the valve 25 causing it to move to its alternative position in which the pushing side 27 of the cylinder is connected throughthe port 32 of the valve 25 to the return line 18; the port 28 is sealed to cut off the pressure supplied by the line 19; and also the other end 33 of the cylinder 5, previously connected through the ports 34 and 32 of the valve 25 to the return line 18, is then connected through the port 26 to the pump pressure in the main pipe 17.

Therefore, at the same time the legs are lowered from the roof and the support unit is brought forward.

Pressure in the pilot line 20 is also connected to the port 35 of the valve 16. This valve is a fluid flow shutoft valve in the form of a 3-ported two-position valve having a shut-off member in the form of a double landed spool which is normally held by a spring in the position shown, but when, as the support unit is being pulled forward, the piston of the cylinder 5 nears the end of its travel it strikes the plunger 36 forcing the valve 16 into its alternative position. Connection is then established from the port 35 to the port 37 previously connected to atmosphere through port 48. The port 37 is connected to a further pilot cylinder '39, of the valve 22. The piston of the cylinder 39 has an area equal to or greater than that of the pilot cylinder 29. Therefore the valve 22 will be restored to its initial position.

Therefore, when the support unit has been pulled forward to the limit of its travel pressure is re-applied to the legs so that they are reset against the roof.

Pilot pressure from the port 37 is also applied through the port 40 to the valve 41. This is a fluid flow shut-off valve in the form of a 3-ported two-position valve having a shut-off member in the form of a double landed spool which is normally held by a strong spring in the position shown. The valve is operated by fluid pressure from the legs of the support unit being applied to the pilot cylinder .42. The characteristic of the valve 41 is such that it will move to its alternative position when the pressure in the cylinder 42 approaches that supplied through the line 17 by the main pump. Thus, when the legs of the unit are completely reset, the valve 41 will operate, connecting the port 40 to the port 43. This port is connected to a second pilot cylinder 44, of the valve 25. This cylinder has an area equal to or greater than that of the pilot cylinder 31, so that the valve 25 is restored to its initial position, restoring the original pressure connections to the cylinder 5.

The support unit has now completed its advancing operation. The port 43 of the valve 41 is also connected to the flexible pipe 45, which passes along the face to connect with the pipe 20B of the adjacent (right hand side) support unit, where it fulfils a function like that of the pipe 20 in conveying pilot fluid pressure to initiate the operation of that support unit. It will be noted that this cannot occur until the center unit whose operation has been described has completed its forward motion, as indicated by operation of the valve 16, and ha been reset against the roof as indicated by the operation of the valve 41. The safety requirements are thus fulfilled. If it is desired to operate the support unit manually, this may be done by operating the valve 22 directly by means of the screw 46 or the valve 25 by means of the screw 47.

It is to be understood that the equipment described is only one example of that which could be used and the principle described may have other embodiments.

Thus the invention is applicable to support units with only one leg or to those with more than two. If it is desired to divide the legs of the unit into two or more hydraulically independent groups, this may be done by providing for each group a further set ofvalves equivalent to valves numbers 21, 22 and 24 in FIGURE 3. It should only be necessary to provide one valve 41.

Support systems of the kind in which the units are of more than one type may also be operated by an adaptation of the principle which has been described. For example, the pilot pipe 45, may be connected, not to the immediately adjacent unit, but to the adjacent unit of the same type. For each other type of unit a further system of pilot pipes corresponding to 20 and 45 is then provided.

Further, the valves are represented in the diagram as slide valves only for clarity, and may in fact alternatively be rotary or poppet valves.

In a practical example the main pump supplies a hydraulic fluid consisting of an emulsion of Water with 2% of soluble oil at 1,000 p.s.i. and the relief valve 24, are set to open at 10,000 p.s.i. The pressure to advance the conveyor applied to the pipe 19, is adjustable between and 500 p.s.i. and is not applied to all support units but only to those at 10 yard intervals. The pilot pressure applied to the pipe 20, is also a water and soluble oil emulsion at 1,000 p.s.i. Alternatively compressed air at 70 p.s.i. has been used. The valves are of the multiple poppet type.

If desired, the above described roof support system may include in each support unit the arrangement described and claimed in our co-pending application, Serial No. 57,462, filed September 21, 1960, now Patent No. 3,120,105, whereby the extent of lowering of the legs of the unit is controlled in accordance with the resistance to advance of the unit.

It will be appreciated that the above described arrangement does not provide for snaking of the conveyor as is customary with machines such as shearers and trepanners under conventional manual control. If the system is used with such machines it is necessary to adopt the alternative to snaking, namely, that the conveyor advancing pressure conduit is divided into sections which are controlled by valves controlling the admission of pressure fluid. After the coal-winning machine has traversed a certain section of the face, the conveyor in the whole of that section may be advanced by manual or remote operation of the appropriate valve. The support units in that section may then be operated remotely.

When the pressure in the legs 2 and 3 reaches a value indicative of their being adequately set against the roof, the pressure switch 68 operates to move its contacts from the position shown in FIGURE 4 into the position in which the supply of current to the coil 70 of valve 51 is cut off (by opening of contact 69) and (by closing of contact 67) current to initiate operation of the next succeeding support is passed to that support over lead 71, this current energising the valves 50 and 51 of the next succeeding support.

This arrangement of FIGURES 4 and 5 shows the electrical circuit of the supports arranged in series along the face but, if desired, this arrangement may be modified by referring back to a control panel the electric connections to the solenoid valves and to limit switch and the pressure switch. There is then the great advantage of being able, from the control point, to observe the position and the leg pressure of each support unit and of being able to control each operation individually if desired.

The system has, however, the disadvantage of requiring two solenoid valves per support unit. This may be expensive and, particularly, it may prevent the use of intrinsically safe electric circuits as the power re quired may be too high.

These disadvantages can be avoided by the use of the circuit shown in FIGURE 7.

Further embodiments of the present invention Will now be described in greater detail, by way of example only, with reference to the accompanying drawings, of which:

FIGURE 6 is a diagram of parts of an electro-hydraulic control arrangement for a mine roof support unit of the kind referred to to be operated at a plough face as referred to above,

FIGURE 7 is a diagram similar to FIGURE 6 of a modified control arrangement,

FIGURE 8 is a diagram similar to FIGURE 6 of another modified control arrangement suitable for a roof support unit employed at a shearer face as referred to above, and

FIGURES 9 and 10 are electrical circuits suitable for use with the arrangement of FIGURES 6 and 7 and FIG- URE 8 respectively.

Referring to FIGURE 6, the diagram includes the double-acting horizontal hydraulic ram comprising a cylinder 5 accommodating a piston rod 102 connected pivotally to an armoured flexible face conveyor (not shown). Two legs 2 and 3 of the roof support unit are indicated, but it will be realised that each such unit may comprise any desired number of legs. Extending along the length of the face are a main pressure flexible hose 17, a return flexible hose 18, and a conveyor advancing pressure flexible hose 19. A hydraulic valve block is connected to both ends of the cylinder 5 and to the legs 2 and 3 and to the flexible hoses 17, 18 and 19 by flexible branch pipes indicated by single lines. A solenoid-operated valve 163 is connected in an appropriate electrical circuit shown in FIGURE 9, the circuit also including a limit switch 57 and a pressure switch 68 whose functions are similar to the equivalent switches shown in FIGURE 5. The control arrangement also comprises a hydraulic leg control valve 22, a hydraulic ram control valve 120, a hydraulic leg relief valve 24, and a non-return valve 21.

The various valves 103, 22, 126, 24 and 22 may either be formed in internal passages of the block 15 or they may have separate bodies mounted on block 15.

The solenoid valve 103 is of similar construction as valves 56 and 51 of FIGURES 4 and 5 and controls the application of a pilot pressure to the hydraulic valves 22 and 121). The valve 103 is a two-position, threeported valve, and in its normal de-energised state, the output port 52 is connected to the return port 53 and the input port 54 is blocked. On the solenoid becoming energised, the valve 1113 operates so that the input port 54 is connected to the output port 52 and the return port 53 becomes blocked. This then allows a pilot pressure from line 17 to be applied to the pilot cylinders 29 and 121 of the hydraulic valves 22 and 120.

The hydraulic leg control valve 22, which controls the raising and lowering of the legs 2 and 3 and also returns the hydraulic valve 120 to its normal position, is a two-position valve with three main ports and one pilot port. In the normal position of the valve 22 the input port 1194 is connected to the output port 165 and thence to the legs 2 and 3, and also to a pilot port 1116 of the hydraulic valve 120. On applying a pilot pressure to the pilot cylinder 29, the valve 22 operates so that the input port 1134 becomes blocked and the output port 105 is connected to a return port 107. This allows the pressure in the legs 2 and 3 and the pressure of pilot port 106 on hydraulic valve 126 to be released. On releasing the pilot pressure from pilot cylinder 39, a spring 1113 returns the valve 22 to its normal position.

The hydraulic ram control valve 120 which cont-rols the action of the double-acting cylinder 5, is a two-position valve with five main ports and three pilot ports. In its normal position the conveyor advancing pressure input port 1119 is connected to the output port 111) and thence to the pushing port 111 of the cylinder 5. At the same time, the pulling port 112 of the cylinder 5 is connected to the return port 113, via the output port 114. On applying a pilot pressure to the pilot cylinder 121, the valve 120 operates (so long as pressure is not applied to pilot port 106 at the same time) so that the conveyor advancing pressure input port 109 becomes blocked and the output port 116 is connected to the return port 113. This will stop the pushing forward of the face conveyor. At the same time the main pressure input port is connected to the output port 114 and thence to the pulling port 112 of the cylinder. This allows the roof support unit to be pulled forward. The output port 114 is also connected to the pilot port 116. This allows the valve 25 to be kept in its operated position after the pilot pressure at pilot cylinder 121 has been released. This is known as self-holding. The valve will remain in its operated position until the pressure at the pilot port 1116 creates a force great enough to overcome that due to pressure at the pilot port 116. The valve 120 will then return to its normal position.

The electrical circuit of the above described apparatus is shown in the accompanying FIGURE 9 and includes in addition to the coil 122 of the valve 103 a limit switch 57 similar to the limit switch 57 of FIGURE 4 and a pressure switch 68 similar to the pressure switch 68 of FIGURE 4 but having only a single contact 123 instead of the double contacts 67 and 69.

The operation of the whole circuit can now be described. With the valves 103, 22 and 120 in their normal position, it can be seen that the conveyor advancing pressure from the hose 19 is applied to the pushing port 111 of the cylinder 5 and that the main pressure from the hose 17 is applied to the legs 2 and 3 and to the pilot port 106 of the hydraulic valve 121). When it is desired to move the roof support unit forward, the solenoid valve 103 is energised by closing switch 62 (FIGURE 9). On becoming energised, the solenoid valve 103 supplies a pilot pressure to the pilot cylinder 29 of the leg control valve 22 and to the pilot cylinder 121 of the ram control valve 129. This pilot pressure operates the leg control valve 22 which releases the pressure from the legs 2 and 3 and also from the pilot port 106 of ram control valve 120. The ram control valve 121? now operates, which allows the main pressure to flow to the pulling port 112 of the cylinder 5, and this will pull the roof support unit forward. After the roof support unit has moved forward to its required position, the limit switch 57 (FIGURE 9) is operated so that the solenoid valve 103 is de-energised by the opening of contact 58 of switch 57. This allows the leg control valve 22 to return to its normal position and thus re-apply pressure to the legs 2 and 3. The ram control valve 120 remains in its operated position, because of its self-holding feature on pilot port 116 and continues to give the cylinder 5 a pulling force until the legs 2 and 3 come into contact with the roof. As the legs 2 and 3 come into contact with the roof, pressure at pilot port 106 of the ram control valve 120 builds up and returns the ram control valve 120 to its normal position (ie, supplying conveying advancing pressure from line 19 to the pushing port 111 of the cylinder 5).

Because of the non-return valve 21, which is positioned before the leg control valve 22, the main pressure 17 can be switched off without the legs 2 and 3 lowering. On roof convergence taking place, excess pressure in the legs 2 and 3 is bled to atmosphere by the the leg relief valve 24.

When the legs 2 and 3 are fully set against the roof, the pressure in the hydraulic circuit of the legs operates the pressure switch 68 (FIGURE 4) such that its contact 123 is closed. As the contact 59 of the limit switch 57 has also previously been closed (by operation of the limit switch 57 upon the support unit being moved forward to its required position), the current through switch 62 (i.e. from source 63, FIGURE 4) will be passed to the next support unit to be operated such as to energise its solenoid valve 163 and thereby initiate operation of that support. It will be seen, therefore, that the operation of the next support is only initiated when it is proved that the legs 2 and 3 of the preceding support has been fully set and that the preceding support has been fully advanced.

In an emergency, the system can be controlled manually by the manual operation screws 46 and 47. Operation of the manual operation screw 43 on the leg control valve 22 will lower the legs 2 and 3, thus allowing the support to move back if desired. Operation of the manual operation screw 47 on the ram control valve 120 will allow the roof support unit to be moved forward or the face conveyor to be moved back, depending upon the position of the leg control valve 22.

A further alternative circuit that can be used in the operating conditions at a plough face is shown in FIG- URE 7. In this circuit the ram control valve 120 in FIGURE 6 has been replaced by a ram push control valve 130 and a ram pull control valve 131. The operations of the solenoid valve 103 and the leg control valve 22 are the same as described above for FIGURE 6.

The ram push control valve 130, which controls the pushing action of the cylinder is a two-position valve, with three main ports and two pilot ports. In normal position (i.e. the position shown) of the valve 130 the return port 113 is blocked and the input port 1119 is connected to the output port 110 and thence to the pushing port 111 of the cylinder 5. When the pressure from pilot port 132 is released, the valve 130 operates due to the main pressure always being applied to pilot port 133. In the operated position of the valve 130 the input port 199 is blocked and the output port 110 is connected to the return port 113. This will step the pushing forward of the face conveyor. The valve 130 will remain in its operated position until the pressure at the pilot port 132 creates a force great enough to overcome that due to pressure at the pilot port 133. The valve 130 will then return to its normal position.

The ram pull control valve 131 which controls the pulling action of the cylinder 5, is a two-position valve, with three main ports and one pilot port. In the normal position (i.e. the position shown) of the valve 131 the output port 114 is connected to the return port 134 and the input port 135 is blocked. On applying a pilot pressure to the pilot port 136, the valve 131 operates so that the return port 134 is blocked and the input port 135 is connected to the output port 114 and thence to the pulling port 112 of the cylinder 5. On releasing the pilot pressure from pilot port 136, a spring 137 returns the valve 131 to its normal position.

The operation of this circuit of FIGURE 7 can now be described. With the valves 103, 22, 130 and 131 in their normal position, it can be seen that the conveyor advancing pressure from the hose 19 is applied to the pushing port 111 of the cylinder 5 and that the main pressure from the hose 17 is applied to the legs 2 and 3 and to the pilot port 132 of the hydraulic valve 130.

When it is desired to move the roof support unit forward the solenoid-operated valve 103 is energised in the manner described above and illustrated with reference to FIGURE 9. On becoming energised, the solenoid valve 103 supplies a pilot pressure to the pilot cylinder 29 of the leg control valve 22 and to the pilot port 136 of the ram pull control valve 131. This pilot pressure operates the leg control valve 22 which releases the pressure from the legs 2 and 3 and also from pilot port 132 of the ram push control valve 130, thus allowing the ram push control valve 130 to operate. This stops the pushing action of the cylinder 5 and the ram pull control valve 131, which is now in its operated position, due to pilot pressure at pilot port 136, allows the main pressure to flow to the pulling port 112 of the cylinder 5, and this pulls the roof support unit forward. When the roof support unit has moved forward to its required position, the limit switch 57 (FIGURE. 9) is operated such that the solenoid valve 103 is de-energised, and this allows the leg control valve 22 and the ram pull control valve 131 to return to their normal positions. The

pulling action of the cylinder 5 now ceases, and the main pressure from the hose 17 is re-applied to the legs 2 and 3 and also to the pilot port 132 of the ram push control valve 130. As the legs 2 and 3 come into contact with the roof, pressure at the pilot port 132 creates a force larger than that due to pressure at the pilot port 133 of the ram push control valve 130. This valve now returns to its normal position, thus allowing a pushing action to be re-applied at cylinder 5.

The operation of the attendant electrical circuit (which is identical to that shown in FIGURE 9) is the same as described above with reference to FIGURE 9. That is to say, when the support is proved fully set and the support proved fully advanced, operation of the next succeeding support is initiated automatically.

The function of the non-return valve 21 and the leg relief valve 24 is the same as described above for the circuit in FIGURE 6.

This system of FIGURE 7 can also be controlled manually in an emergency by the manual operation screws 46, 137 and 138.

Operation of the manual operation screw 46 on the leg-control valve 22 will lower the legs 2 and 3. At the same time it will cause the pushing action of the cylinder 5 to cease if the main pressure at line 17 is switched on. If the main pressure at line 17 is switched oif it will cause the roof support unit to move back.

Operation of the manual operation screw 137 on the ram push control valve 130 will stop the pushing action of the cylinder 5.

Operation of the manual operation screw 138 on the ram pull control valve 131 will move the face conveyor back if the manual operation screw 137 is also operated at the same time. Operation of the manual operation screw 138 will also move the roof support unit forward if the legs 2 and 3 are released.

The circuit to be now described with reference to FIGURE 8 is particularly suitable for installations requiring snaking of the conveyor.

In FIGURE 8 is indicated a horizontal hydraulic ram comprising a cylinder 5 accommodating a piston rod 102 which is pivotal-1y connected to an armoured flexible face conveyor (not shown). Also indicated are two legs 2 and 3 of a roof support unit but, again, any desired number of such legs may be provided. A main pressure flexible hose 17 and a return flexible hose 18 extend along the face. The arrangement also comprises a solenoid-operated valve 140 for leg control and ram pull control, a ram push control solenoid-operated valve 141, a hydraulic leg control valve 142, a hydraulic ram pull control valve 143, a hydraulic ram push control valve 144, a hydraulic leg relief valve 24, a non-return valve 21, and a hydraulic valve block 15 which is connected to both ends of the cylinder 5 and to the legs 2 and 3 and to the flexible hoses 17 and 18 by means of flexible branch pipes indicated by single lines.

The valves 140 to 144 and valves 21 and 24 may either be formed in internal passages of the block 15 or they may have separate bodies mounted on block 15.

The solenoid-operated valve 140 which controls the application of a pilot pressur to the hydraulic valves 142 and 143 is a three-ported, two-position valve and functions in the same way as the solenoid-operated valve 103 in FIG' 6, i.e.

Normal de-energized state: Input 54 blocked, output 52 connected to return 53.

Operated position: Return 53 blocked, input 54 connected to output 52.

The solenoid valve 141, which controls the application of a pilot pressure to the hydraulic valve 144 is also a three-ported, two-position valve and functions in the same way as the solenoid-operated valve 140, the input port being 145, the output port 146 and the return port 147. The reason for having this second solenoid-operated valve 141 will be stated further on.

The hydraulic leg control valve 142, which in this case only controls the raising and lowering of the legs 2 and 3, is a two-position valve with three main ports and one pilot port 148. It functions in the same way as the leg control valve 22 in FIGURE 6, i.e.

Normal position: Return 149 blocked, input 150 connected to output 151.

Operated position: Input 150 blocked, output 151 connected to return 149.

The hydraulic ram pull control valve 143 which controls the pulling action on the cylinder 5 and also returns the ram push control valve 144 to its normal position is a two-position valve with three main ports and one pilot port 152. It functions in the same way as the ram pull control valve 131 in FIGURE 7, i.e.

Normal position: Input 153 blocked, output 154 connected to return 155.

Operated positions: Return 155 blocked, input 153 connected to output 154.

The hydraulic ram push control valve 144 controls the pushing action of the cylinder 5 and is a twoposition valve with three main ports and three pilot ports. In its normal position the input port 156 is blocked and the output port 157 is connected to the return port 158. On applying a pilot pressure to pilot port 15?, the valve operates (so long as pressure is not applied to pilot port 160 at the same time) so that the return port 158 becomes blocked and the input port 156 is connected to the output port 157 and thence to the pushing port 111 of the cylinder 5. The output port 157 is also connected to the pilot port 159. This connection allows the valve 144 to be kept in its operated position after the pilot pressure at pilot port 159 has been released. (This is known as self-holding) The valve 44 remains in its operated position until the pressure at pilot port 160 creates a force great enough to overcome that due to pressure on pilot port 159; the valve 144 then returns to its normal position.

The electrical circuit for the arrangement shown in FIGURE 8, is shown in FIGURE 10. As can be seen from FIGURE the circuit incorporates the coils 160 and 161 respectively of solenoid valves 140 and 141, a limit switch 57 having contacts 58 and 5? which is similar to and performs the same function as switch 57 of FIGURE 9, a pressure switch 68 which has a single contact 123 and which is similar to and performs the same function as the pressure switch 63 of FIGURE 9, and a main switch 62 controlling the supply of power from source 63. The circuit also includes a selector switch 162 by means of which any one of the solenoid valves 141, or none, may be energised.

The operation of the whole circuit shown in FIGURES 8 and 10 can now be described. With the valves 140 to 144 in their normal position, it can be seen that the main pressure from the hose 17 is applied to the legs 2 and 3.

When it is desired to snake the conveyor the solenoidoperated valve 141 is energised by setting of the selector switch 162 to supply current to the coil 161. On becoming energised, the solenoid-operated valve 141 supplies a pilot pressure to the pilot port 159 on the ram push control valve 144. This pilot pressure operates the ram push contro valve 144 thus allowing the main pressure from the hose 17 to flow to the pushing side port 111 of the cylinder 5 and push the face conveyor forward. Because of the self-holding feature of the ram push control valve 144, the solenoid-operated valve 141 may be de-energized once the face conveyor starts to move forward.

When the face conveyor has been moved forward to its required position, the solenoid-operated valve 140 is energised by closing switch 62. On becoming energised the solenoid-operated valve 140 supplies a pilot pressure to the pilot port 148 of the leg control valve 142 and to th pilot port 152 of the ram pull control valve 143. The leg control valve 142 operates, thus releasing the pressure from the legs 2 and 3. The ram pull control valve 143 also operates thus supplying a pilot pressure to pilot port 160 of the ram push control valve 144, which now returns to its normal position. The main pressure from the hose 17 now flows to the pulling port 112 of the cylinder 5 and the roof support unit moves forward.

After the roof support unit has moved forward to its required position, the solenoid-operated valve is deenergised by opening of the contact 58 upon actuation of the limit switch 57 when the support reaches its fully advanced position. This now allows the leg control valve 142 and the ram pull control valve 143 to return to their normal positions. The pulling action of the cylinder 5 now ceases and the main pressure from line 17 is re-applied to the legs 2 and 3.

The use of the non-return valve 21 and the legrelief valve 24 is the same as that described above for the circuit in FIGURE 3.

When the limit switch 57 is operated upon the support being fully advanced, not only is contact 58 opened but also contact 57 is closed. Further when the pressure switch 68 is operated upon the legs 2 and 3 becoming fully set against the roof, current is then passed to the coil of solenoid valve 140 of the next support. With the energisation of this valve, the operation of the next succeeding support will be initiated.

In an emergency the system shown in FIGURE 8 can be controlled manually by the manual operation screws 163, 164 and 165.

Operation of the manual operation screw 163 of the leg control valve 142 will lower the legs 2 and 3.

Operation of the manual operation screw 164 of the ram pull control valve 143 will either move the support forward or pull the face conveyor back, depending upon the position of the leg control valve 142.

Operation of the manual operation screw 165 of the ram push control valve 143 will either push the face conveyor forward or move the roof support unit back, once again depending on the position of the leg control valve 142.

It is found that on a coal face where this type of circuit (FIGURES 8 and 10) is required, a number of the roof support units are required to push the face conveyor forward at the same time after the coal cutter has passed them. It is found that a sufficiently powerful solenoidoperated valve for these circuits takes so much current, that only one may be energised at a time in an intrinsically safe circuit. It is for this reason that self-holding valves are employed for ram-push control. Alternatively, use may be made of a slide valve with no return spring, or any other type of valve possessing the characteristic that, upon the application of fluid pressure to one of its pilot ports, it will move from the first of its two positions to the second and remain in that position after the removal of that fluid pressure, being restorable to its first position by the application of fluid pressure to another pilot port.

As already mentioned, the solenoid valve 141 may be tie-energised as soon as the roof support unit starts to move the face conveyor forward. This then allows for another solenoid-operated valve 141 to be energised and de-energised on another roof support unit, and so on in sequence along the face. On a face with such roof support units it is not always required for every roof support unit to have a double-acting cylinder 5, perhaps only every fourth roof support unit will need such a double-acting cylinder. This being so, the solenoid-operated valve 141 can be removed and replaced by a blanking plate when only a pulling action is required from the cylinder 5.

If it is required not to have the front legs and the rear legs of a roof support unit connected to the same hose, the leg control valve can be replaced by either:

(i) A front leg control valve and a rear leg control valve, or

l 1 (ii) A leg raise control valve and a leg release contro valve with a system of non-return valves. These two alternative leg circuits apply to the arrangements shown in any of FIGURES 68.

The pressure drops in the hydraulic circuits during operating cycles Will obviously depend upon the character istics of the components involved. It is to be understood that, if convenient, restrictors may be inserted at various points in the hydraulic circuits to obtain the sequence of operations described.

The limit switches 57 shown in FIGURES 5, 9 and 10 may be replaced by posit-ion transducers, that is to say, electrical devices having one part which can move relative to another part and whose output is dependent on the relative positions of the parts, one of the parts being mounted on the cylinder and the other being mounted on or attached to the piston rod 102. Such position transducers are of known construction and are capable of giving an electrical output proportional to the extension of the ram. Such position transducers may be used with an electrical circuit of any of a number of known kinds having the characteristic that a relay operates when the electrical input reaches a predetermined value. Preferably this value is adjustable. The relay has contacts corresponding to the contacts 58 and 59 of the switch 57. By suitable adjustment the relay may then be made to operate when the support unit reaches the end of its advancing travel, or, if desired, when it reaches any other position.

Similarly, the pressure switches 68 may be replaced by proportional pressure transducers used in conjunction with an electric circuit having a relay with contacts corresponding to the contacts 67 and 69 or, as may be required, one set of contacts corresponding to those 123. By proportional pressure transducer herein is meant a pressure-voltage, pressure-current, or pressureother electrical characteristic transducer having the property that it gives an output electrical voltage, current, or other characteristic which is linearly dependent on the input pressure. Such transducers are known and their specific construction forms no part of the present invention.

We claim:

1. A mine roof support system comprising a plurality of extensible fluid operated mine roof support units each having at least one support, the units being arranged at spaced intervals along a mineral face for operation in a predetermined sequence; anchorage mean-s common to all the support units; at least one fluid operated jack associated with and connected between each support unit and the anchorage means foradvancing the associated support unit relative to the mineral face; a fluid pressure supply line for supplying operating fluid to the support units and jacks; control means associated with each support unit and responsive to a control fluid pressure for controlling the operational sequence of the associated support unit and its associated jack; and a fluid pressure connection linking the control means of one support unit with the control means of the next support unit in the sequence for transmitting said control fluid pressure from said one support unit to said next support unit; each said control means including in said connection a first fluid flow shut-off valve for controlling the flow of fluid through said connection, the Valve having a first shut-off member with a first position in which fluid flow through the connection is prevented and a second position in which fluid can flow through said connection and means actuated by the jack for moving the first shut-off member from the first position to the second when the jack is in a predetermined operational position and a second fluid flow shut-off valve in said connection for controlling the flow of fluid through the connection, the second valve having a second shut-01f member with a first position in which fluid flow through the connection is prevented and a second position in which fluid can flow through said connection, and a second fluid pressure connection between said support unit and the second valve for applying support unit pressure to the second shut-off member to urge the latter from its first position to its second position.

2. A mine roof support system as claimed in claim 1, in which the common anchorage is a conveyor arranged along the line of the mineral face.

3. A mine roof support as claimed in claim 1, wherein the control means also include a first hydraulic valve having two positions and a second hydraulic valve having at least two positions, and wherein said system includes a first fluid conduit connecting said one support unit with the fluid pressure line, the first hydraulic valve controlling fluid flow in the conduit and having a first position in which pressure fluid can be supplied through the first conduit to the supports and a second position in which fluid flow is prevented and the pressure fluid can be released from the supports, a second fluid conduit connecting the second hydraulic valve to the fluid pressure line; third and fourth fluid conduits connecting the second valve to the hydraulic jack the latter having a double sided piston, the second valve having a first position in which pressure fluid can be applied through the third conduit to one side of the jack piston and released from the other side of the piston, and a second position in which pressure fluid can be applied through said fourth conduit to said other side of the piston and released from said one side of the piston; and a fluid conduit means connecting the first and second hydraulic valves with said fluid pressure connection whereby the control fluid pressure acts on these valves to change them from their first to the second positions.

4. A mine roof support system as claimed in claim 1, wherein said first hydraulic valve has resilient means for urging it into its first position and said second hydraulic valve has resilient means for urging it into its first position, said fluid conduit means applying said control fluid pressure to both said first and second valves in opposition to said resilient means.

5. A mine roof support system as claimed in claim 3 wherein an additional fluid conduit so connects said first flow shut-off valve to said first hydraulic valve, that when the first shut-off valve is in its open position the control fluid pressure is applied to the first valve in the sense aiding said resilient means to move said first hydraulic valve from its second to its first position, thereby balancing the application of said control fluid pressure to said first hydraulic valve through said further fluid conduit and permitting said first hydraulic valve to be returned by its resilient means to its first position thus re-setting the support against the roof.

6. A mine roof support system as claimed in claim 3 and comprising an additional fluid conduit means connecting said second flow shut-off valve to said second hydraulic valve, so that when the said second flow shutoff valve is in its open position said control fluid pressure is applied to said second hydraulic valve in a sense aiding the action of the resilient means to move the valve from its second position to its first position thereby balancing the eflFect of the control fluid pressure applied to the second hydraulic valve through the further conduit means and permitting said second hydraulic valve to be returned to its first position by the resilient means.

7. A mine roof support system as claimed in claim 3 and comprising a hydraulic fluid pressure line operatively connected to said second valve whereby in the first position of said second hydraulic valve fluid pressure can be applied from the second pressure line to the jack to advance the anchorage connected to said jack.

8. A mine roof support system as claimed in claim 1 wherein a further fluid conduit connects the fluid pressure connection at a point downstream of the first flow control valve to the first hydraulic valve for applying, when the first flow control valve is open, the control fluid pressure to the first hydraulic valve in a sense tending to move said first hydraulic valve from its second to its first position thereby balancing the application of said control 13 fluid pressure applied to the first hydraulic valve through the fluid conduit means to return the first hydraulic valve to said first position and thus re-setting the suport against the roof.

9. A mine roof support system as claimed in claim 8 comprising further fluid conduit means connecting the fluid pressure connection at a point downstream of the second flow control valve with the second hydraulic valve for applying to the latter, when the second flow control valve is in its open condition, the control fluid pressure in a sense tending t change said second hydraulic valve from its second postion to its first position whereby the second hydraulic valve is returned to the first position.

14 References Cited by the Examiner UNITED STATES PATENTS 2,301,028 11/42 Esch 60-97 2,698,517 1/55 Witt 60-97 FOREIGN PATENTS 1,190,532 4/59 France.

781,643 8/57 Great Britain.

823,128 11/59 Great Britain.

EARL J. WITMER, Primary Examiner.

JACOB L. NACKENOFF, BENJAMIN HERSH, BEN- JAMIN BENDETT, Examiners.

Claims (1)

1. A MINE ROOF SUPPORT SYSTEM COMPRISING A PLURALITY OF EXTENSIBLE FLUID OPERATED MINE ROOF SUPPORT UNITS EACH HAVING AT LEAST ONE SUPPORT, THE UNITS BEING ARRANGED AT SPACED INTERVALS ALONG A MINERAL FACE FOR OPERATION IN A PREDETERMINED SEQUENCE; ANCHORAGE MEANS COMMON TO ALL THE SUPPORT UNITS; AT LEAST ONE FLUID OPERATED JACK ASSOCIATED WITH AND CONNECTED BETWEEN EACH SUPPORT UNIT AND THE ANCHORAGE MEANS FOR ADVANCING THE ASSOCIATED SUPPORT UNIT RELATIVE TO THE MINERAL FACE; A FLUID PRESSURE SUPPLY LINE FOR SUPPLYING OPERATING FLUID TO THE SUPPORT UNITS AND JACKS; CONTROL MEANS ASSOCIATED WITH EACH SUPPORT UNIT AND RESPONSIVE TO A CONTROL FLUID PRESSURE FOR CONTROLLING THE OPERATIONAL SEQUENCE OF THE ASSOCIATED SUPPORT UNIT AND ITS ASSOCIATED JACK; AND A FLUID PRESSURE CONNECTION LINKING THE CONTROL MEANS OF ONE SUPPORT UNIT WITH THE CONTROL MEANS OF THE NEXT SUPPORT UNIT IN THE SEQUENCE FOR TRANSMITTING SAID CONTROL FLUID PRESSURE FROM SAID ONE SUPPORT UNIT TO SAID NEXT SUPPORT UNIT; EACH SAID CONTROL MEANS INCLUDING IN SAID CONNECTION A FIRST FLUID FLOW SHUT-OFF VALVE FOR CONTROLLING THE FLOW OF FLUID THROUGH SAID CONNECTION, THE VALVE HAVING A FIRST SHUT-OFF MEMBER WITH A FIRST POSITION IN WHICH FLUID FLOW THROUGH THE CONNECTION IS PREVENTED AND A SECOND POSITION IN WHICH FLUID CAN FLOW THROUGH SAID CONNECTION AND MEANS ACTUATED BY THE JACK FOR MOVING THE FIRST SHUT-OFF MEMBER FROM THE FIRST POSITION TO THE SECOND WHEN THE JACK IS IN A PREDETERMINED OPERATIONAL POSITION AND A SECOND FLUID FLOW SHUT-OFF VALVE IN SAID CONNECTION FOR CONTROLLING THE FLOW OF FLUID THROUGH THE CONNECTION, THE SECOND VALVE HAVING A SECOND SHUT-OFF MEMBER WITH A FIRST POSITION IN WHICH FLUID FLOW THROUGH THE CONNECTION IS PREVENTED AND A SECOND POSITION IN WHICH FLUID CAN FLOW THROUGH SAID CONNECTION, AND A SECOND FLUID PRESSURE CONNECTION BETWEEN SAID SUPPORT UNIT AND THE SECOND VALVE FOR APPLYING SUPPORT UNIT PRESSURE TO THE SECOND SHUT-OFF MEMBER TO URGE THE LATTER FROM ITS FIRST POSITION TO ITS SECOND POSITION.

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