Hydraulic casing systems in mine workings

Claim 1

In a hydraulic casing system for working a mine seam comprising: a plurality of automatically advanceable casing structures, a corresponding plurality of motive means for advancing respective casing structures, a corresponding plurality of sensing means for determining when respective casing structures are nominally free to advance, a corresponding plurality of control systems for the respective casing structures, and a plurality of transmission lines interconnecting said sensing means and said motive means with said control means for preparing said control systems when respective casing structures are nominally free to advance and for transmitting selective signals from said control systems to respective casing structures to release and advance the respective casing structures, the improvement comprising; means intercOnnecting the casing structures and their associated control systems in groups for allowing only one casing structure in any one group to be released and advanced at one time, while several casing structures in different groups can be released and advanced simultaneously, said interconnecting means including a logic system into which all the casing structure control systems are incorporated and which includes, for each such casing structure control system, series-connected input and output dominant inhibit function stores, each of said stores comprising an information input terminal, an inhibit terminal and an output terminal, of which the input store is provided at its information terminal with a signal indicating preparedness for advance, and at its inhibit terminal is connected to the output terminal of the output store, the output terminal of the output store producing locking signals for the neighboring casing structures as well as a starting signal for the control system of its own casing structure, the output store having its inhibit terminal supplied through an OR gate with such locking signals fed from neighboring casing structures.