GB651737A - Improvements in and relating to depth indicators for mine cages and the like - Google Patents

Abstract

651,737. Depth-position indicators. BRITISH THOMSON-HOUSTON CO., Ltd., and PETCH, T. H. Feb. 11, 1948, No. 4040. [Class 78 (ii)] [Also in Group XIX] A depth indicator associated with winding gear for indicating the position of a mine cage has a main pointer moving through less than 360 degrees over a fixed scale to give the approximate position and a plurality of auxiliary pointers moving behind, yet visible through the fixed scale and driven at a speed proportional to that of the drum of the winding gear, the auxiliary pointers being movable relative to one another and adapted to register with a predetermined mark on the fixed scale to give the exact position of the mine cage. A pointer 4 on a shaft 5 driven by a wheel 6 from the winding drum rotates through less than 360 degrees for a complete wind and co-operates with a scale on a dial, whose divisions correspond to complete twins of the drum, to indicate the approximate position of the cage. The dial is carried by a frame plate upon which it may be mounted by webs which may be transparent or the dial and plate may be formed from a single piece of transparent material rendered opaque except for an annulus round the dial. A number of pointers 7a, 7b, 7c are carried in sleeves in arms 8a, 8b, 8c into which they may be pushed when not required, the arms being mounted behind the dial on hubs 9a, 9b, 9c held on a sleeve 10 between a spring washer 12 and lock nuts 13, 14 so as to be frictionally driven by the sleeve mounted in a bearing 16 and rotated by a wheel 15 driven from the winding drum, preferably at the speed of the drum. The friction drive may be overcome to move the pointers relative to one another. Initially a signal is given to the operator when the cage is at an intermediate stoping place and the position of an auxiliary pointer against the periphery of the dial is noted for future reference. As shown in Fig. 4, the pointers may be in the form of spring slips sprung on to a rim carried by spokes radiating from a hub and may be turned thereon into and out of indicating position. A pointer 28, Figs. 5a, 5b may be mounted on a ball 29 and clamped between members 24 and 25 where it may be turned edge or broadside on as required for indicating. In another form the pointer has a hinged flap which matches the background colour of the annulus and may be turned back to expose the contrasting colour of the pointer when required for use.