GB1286814A - Mine roof support system - Google Patents

Abstract

1286814 Fluid logic and switching circuits DOWTY TECHNICAL DEVELOPMENTS Ltd 17 Nov 1969 [21 Nov 1968] 55307/68 Heading F1P Each of a plurality of sequentially advanceable mine roof-supports J 1-6 , N 1-6 Fig. 1 is provided with a fluid logic control circuit arranged to receive a fluid address signal for effecting its release, advance and reset; the circuit also operating in response to the resetting of the support to transmit the address signal to the next roof support and to isolate the signal from the justadvanced support. In operation and with a constant fluid-pressure of air in a main supply and pull signal duct B, D, Fig. 5 extending along the whole length of the face 21, a pulse in address duct A1 (assuming the cutter 22 moving to the left) passes at O 2 through a gate 4 to the control inlet C 1 of a gate 6 thereby switching its supply from duct B to an outlet O 1. A portion of said outlet O 1 of gate 6 provides the supply for a gate 8 which is switched by a pull signal in duct D to its outlet O 1 leading to a known main control valve which releases the support controls the pull rams (not shown) and push rams 24 and resets the support. At the end of a support advance a valve 27 opens to connect outlet O 1 of a gate 8 to the control inlet C 3 of a gate 9 having its supply connected to O 1 of gate 6. Gate 9 is then switched to its outlet O 1 which actuates the set portion of valve 25. When the support is reset a valve 28 opens to connect the outlet O 1 of gate 9 to the control inlet C 1 of a one shot gate 7 having its supply connected to the outlet O 1 of gate 6. Gate 7 is thus switched to its outlet O 1 which is connected through a check valve 42 to the control inlet C 1 of a memory gate 5 which is thus switched to its outlet O 1 thus cutting off the main supply duct B from gate 6 and hence isolating the address duct A1 from gates 7, 8, 9 and hence isolating the pull signal duct D from the valve 25. The outlet O 1 of gate 7 is also connected to the control inlet C 1 of gate 4 which is thus switched to its outlet O 1 whereby the address duct A 1 is connected to the control inlet C 1 of a gate 3 which is switched to O 1 whereby the main supply duct B is connected to outlet O 1 . The latter is in conduit connection with the next support to be advanced. and which connection forms the address duct for said next support. Outlet O 1 of gate 7 is also connected through a check valve 41 to a duct C leading to means indicating that support advance is complete. In the event of advance being blocked and valve 27 not being opened, the support is reset in its partially advanced position by applying a command signal from a duct E to a second control inlet C 1 of gate 9. An alternative address duct A2 and gates 1, 2 are used when the cutter 22 moves from left to right. Advance of the conveyer 23 by push rams 24 carried by supports 1, 3 only of each group of supports occurs prior to advance of said supports. To this end and with say support N 3 being advanced, a gate 11 Fig.6 of the fluidic control means carried by N 2 having its supply connected to main duct B has its control inlet C 1 connected to a touch sensor 34 which latter when blocked by the cutter switches gate 11 to its output O 1 which then forms the supply to gates 13, 14. Since control inlet C 1 of gate 13 is connected through gate 4 to the address duct A 1 , gate 13 is switched to O 1 which is connected by a line 36 to the next but one support L2. If Fig.6 is now considered to relate to L2, the signal transmitted from N 2 through line 36 of Fig. 1 is now in line 37 of Fig.6 and is fed to the control inlet C 3 of a gate 15 so that its supply from duct D is switched to connect with lines 32, 33 leading to the control circuits of adjacent supports L 1, L 3 . As seen from Fig. 5 the signal in line 33 switches the supply B of a gate 10 to its output O 1 which latter is connected to the push section of a valve 25. The signal in line 32 similarly advances the pusher 24 of L 1 . When after sequential advance of roof supports it is the turn of say L 3 to be advanced the pull signal at valve 25 Fig. 5 switches valve 10 from O 1 to O 2 so cancelling the push signal to 25.