GB161806A - Improvements in switches for electric signalling systems and like uses - Google Patents

Abstract

161,806. Blunt, R., and Mitchell, H. F. March 13, 1920. Mine signalling systems.-In signalling systems, especially for mine signalling, a switch is employed comprising an operating lever, which, as it is swung on its way to close a main signalling circuit, closes, momentarily, an auxiliary signal-cancelling circuit. As shown in Figs. 3 and 5, the switch has an operating lever d secured upon a spindle e journaled in the side walls of the casing and carrying a blade contact f and a cam h with the relative dispositions shown. To close the main signalling circuit, the operating lever is brought to the position substantially vertically over its pivot whereupon the contact f bridges the fixed contacts g; if released, the lever falls by its own weight. In the closing movement the cam h rocks an intermediate lever j which may carry a roller o and is normally maintained in the central position by the springs k. The roller o engages a spring arm contact m and presses it into engagement with a companion contact n to close the auxiliary circuit. Subsequently, and before the main circuit is closed, the cam passes away from the roller and the auxiliary circuit is broken. When the operating lever falls, the cam h rocks the intermediate lever j away from the auxiliary contacts so that these contacts are not closed.