Patent GB-1117411-A (GB)
Title: Control systems for mine roof supports
Inventor: MARTIN DAVID JAMES REGINALD
IPC: E21D23/20
Filed: 1964-10-23
Abstract: 1,117,411. Advancing mine roof supports. COAL INDUSTRY (PATENTS) Ltd. Oct. 18, 1965 [Oct.23, 1964], No.43344/64. Heading F1P. A mining installation comprises a conveyer 136 advanceable by hydraulic rams 137 associated with at least some of a plurality of hydraulically operated advanceable mine roof supports 1-134 arranged at intervals along the working face 135 and a control system for correlating the advance of the conveyer and roof supports so that only roof supports having rams 137 which have completed the advance of the conveyer can themselves be advanced. Each roof support has an electrohydraulic control unit 141 operable to control the advancing sequence of its support, and every fourth support has a control unit 142 including an electro-hydraulic valve for controlling operation of its associated conveyer advancing ram 137. The units 141 are connected in series with a stepping pulse generator 144. When a control unit 141 receives a pulse from the generator 144 and has previously received a signal from the preceding support, on completion of the advance of that support, relay contacts within the control unit are closed whereby electro-hydraulic valves controlling the advancing sequence are energized. On completion of the advancing sequence the control unit reverts to its initial condition and in turn produces an output voltage signal which prepares the next control unit 141 for operation by the next pulse from the generator 144. The conveyer advance control units 142 are connected in series to the input side of a detector unit 143 which receives signals from the electro-hydraulic valves of the units 142 which control the conveyer advancing rams 137. The detector unit 143 produces an output signal for an indicator 148 and a six stage register 149 which indicates the support units energized for conveyer advance. The control system is adapted to perform a cycle which is repeated progressively along the working face whereby four consecutive support units having conveyer advancing rams 137 are energized at any one time. In operation the stepping pulse generator feeds pulses to the control valve units 141 until the register 149 records that four consecutive supports units having rams 137 have been energized. After the fourth support has been energized the pulses are supplied to the units 141 in the reverse direction, the change in direction being automatic. Pulses continue to be applied to units 141 in the reverse direction until an advancing support register 151 causes a further reversal of the pulses and consequent selection for advance of the eight roof supports trailing behind the four energized conveyer advance supports. Four of the eight supports selected for advance have normally already advanced during the preceding cycle. The output of pulses from the generator 144 is terminated if a coal winning machine position indicator 157 signals that the conveyer advance is not proceeding at a safe distance behind the machine. A section 155 of a logic circuit 152 ensures that the support unit advance follows the conveyer advance at a safe distance.