GB346859A - Improvements in and relating to electrical contact making means specially applicable for use in conjunction with shaft revolution indicators and the like - Google Patents

Abstract

346,859. Magnetic interrupters. GRAHAM & CO., Ltd., A. and RICKETS, W. J., St. Andrew's Works, Slough. Jan. 23, 1930, No. 2356. [Class 38 (v).] Indicators.-A magnetically-operated interrupter for indicating the rate of movement of rotary or oscillating bodies has an armature and contacts controlled thereby arranged in a non-magnetic casing provided with a stationary magnetic member or members consisting of a polepiece or polepieces extending through the wall of the casing with their outer ends within the range of movement of a magnetic actuating device arranged to be moved in an intermittent manner past the pole-piece or polepieces, which thereby cause the attraction of the armature against the returning force. As shown in Figs. 1 and 2 the armature a is carried by an arm pivoted at b within a non-magnetic casing c through the lower side of which projects magnetic studs d, d<1> adjacent to the path of movement of a permanent magnet or magnets f secured by a strap g on a rotary shaft h. As the magnets f approach the polepieces d, d<1> their poles f<1> induct polarity so that the armature is attracted causing a contact o on the armature arm to engage a fixed contact o<1> completing the circuit of an indicating lamp n or, alternatively, of an audible indicating device such as an electric bell or of an electromagnetically actuated counting device. In order that the armature may dwell in its attracted position for an appreciable period a number of magnets may be arranged adjacent to each other as shown so that a succeeding magnet comes into effective cooperation with the polepieces before the influence of the passing magnet has passed out of inductive relation. Alternatively, if a single magnet is employed the polepieces may be suitably extended at their ends which come under the action of the magnet poles. The interaction between the magnets, polepieces and armature may be adjusted by mounting the casing c on a pivoted cam and providing an adjusting screw m for varying the gap between the magnets and stationary polepieces. The magnet or magnets may be attached to an oscillating body such as a lift.