GB482947A - Improvements relating to mercury switches - Google Patents

Abstract

482,947. Electromagnetic mercury switches. CIANCHI, A. Oct 3. 1936, No. 26899. [Class 38 (v)] In an electromagnetically.operated mercury switch in which a plunger 2 carrying an armature 6, is made to move axially and clear of the containing vessel thereby causing the mercury 3 in which it floats to complete a circuit between electrodes 8 and 9, the plunger 2 is guided at points spaced apart in the direction of its movement by one or more stationary guides on the wall of the enclosing vessel. As shown, the guides may be internal projections 11 and 12 formed in the glass containing vessel 1 by depressing the glass when soft on a former. Other means of guidance described in the Specification which may be used include an outturned upper edge of the plunger 2, an inserted member gripped by the containing vessel 1, through which the plunger passes, and an annular support fixed to the re-entrant upper end of the containing vessel and engaging the inner surface of the plunger. The Provisional Specification describes modifications according to which a ring of balls may be mounted to form a guide. Also the solenoid may be on the float, the armature being fixed to the vessel, or the solenoid may be fixed inside the vessel. The vessel may be filled with inert gas or oil, and enclosed in an iron or other outer screening earthed casing. Specifications 351,830, 479,095, and 481,289 are referred to.