Patent GB-959492-A (GB)
Title: Mining apparatus
Inventor: CARNEGIE JAMES
IPC: E21D23/14
Filed: 1961-11-21
Abstract: 959,492. Advancing mine roof supports. DOWTY TECHNICAL DEVELOPMENTS Ltd. Nov. 8, 1962 [Nov. 21, 1961], No. 41622/61. Heading F1P. A mine roof support control apparatus for a roof support assembly having a series of advanceable roof support units A1 . . . G4 some of which have advancing means 5 for a conveyer 3 comprises an address selector 7 for selecting a roof support for an advancing operation and which selector at the same time selects for operation the conveyer advancing means of another roof support unit. In Fig. 1 the roof support units are divided into groups A, B, C ... each group comprising four roof support units each connected to the conveyer by a jack 4, the first support of each group being further connected to the conveyer by a conveyer advancing jack 5. Each roof support includes a beam which rests on the ground and carries two or more hydraulically operable telescopic props surmounted by a roof bar (not shown). The supply of hydraulic fluid to each roof support is controlled by a separate electro-hydraulic valve S, Fig. 2 which is energized by manual or automatic operation of the address selector 7. When a roof support of a group is selected for advance the first roof support of four other groups is also automatically selected for conveyer advance together with a further roof support of a group on the opposite side of the four groups selected for conveyer advance e.g. if support B3 is selected for advance then roof supports C1, D1, E1 and F1 are selected for advancing the conveyer 3 towards the working face 1 and roof support G3 is also selected. A polarity switch 19 in the address selector 7 determines'which of the two roof supports selected is advanced and its position is chosen in dependence on whether the cutter 2, Fig. 1 is moving from left to right or from right to left. Each group of roof supports has a junction box A, B, C ... similar in construction to junction box G (Fig. 2) containing a number of electrical relays connected by wires to the address selector 7, a sequence control 9 and a conveyer advance control 11. The address selector 7 can connect via the solenoid valves S, the props and jacks 4 of any roof support to the sequence control 9 whereby a pair of potentiometers 15, 16 indicate to the sequence control the extension of the jacks and the hydraulic pressure in the props, so that the operator can see the condition of the roof support selected. The sequence control is arranged to supply electrical current of either polarity and also alternating current in sequence so that the solenoid valves S are operable to lower the prop, advance the support unit and raise the prop, and on the first unit of each group to control the conveyer advance. The address selector 7 comprises two parts 17, 18; part 18 can select a wire each from rows b and c, and determines which two groups of supports is selected; and part 17 can select a particular support of the two groups by means of a line selector 20 and the polarity switch 19. Each relay coil has an associated rectifier so that the position of the polarity switch 19 in the part 17 of the selector determines whether the roof support on the left of the conveyer advancing units or those on the right, are available for operation. In Fig. 3 (not shown) is a table showing which of the relays in junction box G are energized when roof supports A1-A4 are selected sequentially during left to right cutter advance (first column) and right to left cutter advance (second column). In another embodiment (Fig. 4 not shown) selection of a roof support for an advancing operation causes the selection for operation of the four conveyer advancing jacks 5 on either side of the roof support selected for advance. Which four conveyer advancing jacks are operated depends on whether left to right or right to left advance of the series of roof supports is taking place, which in turn depends on which of two possible lines, common to all the junction boxes, is being used.