GB470506A - Improvements in safety switches for electrically heated appliances - Google Patents

Abstract

470,506. Thermal switches. BULPITT & SONS, Ltd., and BULPITT, W. H. Feb. 17, 1936, No. 4834. [Class 38 (v)] In a safety switch for an electrically-heated appliance of the kind which includes a safety device having two members normally retained in a certain relative position against spring pressure by means of a fusible metal joint and wherein after operation on melting of the fusible metal the members automatically move back into their initial relative position so that the safety device can then be reset by hand, switch contacts are provided with a spring normally urging said contacts to a closed position and a member connected to or engaging one of said contacts is adapted to be operated by said safety device to open said switch contacts against the action of said spring on operation of said safety device. As shown in the Figure, the end of a fusible release unit 16, 17 of the type described in Specifications 329,406, [Class 38 (v)], and 367,268, bears against the enlarged end 19 of an insulating pin the reduced portion 29 of which extends through a hole 18 and apertures in contact plates 25, 26 into a recess in the end of a resetting knob spindle 35. The contact plates are normally pressed into engagement by a spring 33, but on release of the fusible element the shoulder on the sliding rod 19 is moved into engagement with the contact plate 26 and moves it away from the relatively fixed contact plate 25 so breaking or modifying the heating circuit. The fusible member is reset and the heating circuit reconnected by depression of the knob 35.