GB1163261A - Remote Control of Mining Machines - Google Patents

Abstract

1,163,261. Radio signalling; inductive control of apparatus. COAL INDUSTRY (PATENTS) Ltd. 6 Jan., 1967 [11 Jan., 1966], No. 1268/66. Headings H4L and H4U. [Also in Division E1] In a control system for a longwall mining machine 10, Fig. 1, which is haulable along a face conveyer 11 into various sections A, B, C control tones (e.g. from 2À4 to 4À7 kc/s.) modulating higher frequency carriers (e.g. of 480 kc/s.) are transmitted from portable controlling stations which are capacitively or inductively coupled with an insulated conductor 17 extending from a receiver. The transmission from each portable station has a distinctive characteristic and switch means responsive to the position of the machine control the receiver to be responsive only to signals from the particular portable station associated with the section in which the machine is located. As described, portable stations 12a, 12b, 12c are associated respectively with the sections A, B, C. Each station transmits on its own carrier frequency and comprises a low frequency oscillator with a push-button operated tone selector, a high frequency oscillator, and an aerial. The insulated conductor 17 terminates on an amplifier 18, the output from which is passed through a station selector 19 to a machine controller 20. A magnet 21 is fixed on the machine 10 and two bi-stable magnetic proximity switches SS1, SS2 which are operable by the said magnet, are mounted upon the conveyer 11 at the junctions of the contiguous sections A, B and B, C respectively, and are connected to the selector 19. When the machine is in section A, the switches SS1 and SS2 are in the positions shown in Fig. 2 and a relay R1 in the station selector 19 is operated by a power supply P so that its contacts R 1 C 1 and R 1 C 2 switch in a circuit TC 1 which is tuned to the carrier frequency of the station 12a. When the machine is in section B, the switch SS1 changes over, and when the machine is in section C, the switch SS2 also changes over, so that a tuned circuit TC 2 or TC 3 (for transmissions from the station 12b or 12c) is switched in by a relay R 2 or R 3 , instead of the tuned circuit TC 1 . Time delays may be introduced in the system to prevent interruption of a master signal when the machine moves from one section to another. In a modification, the portable stations use a common carrier frequency and their transmissions are distinguished by pulse codings, individually allocated. In another modification, the magnetic proximity switches are replaced by means responsive to a machine position transducer, for example, a sensing head which counts the number of teeth passing by on a haulage gear sprocket.