GB342497A - Improvements in or relating to electric contact making relays - Google Patents

Abstract

342,497. Light current relays. COVENTRY AUTOMATIC TELEPHONES, Ltd., and WILMAN, C. W., of General Electric Co., Stoke, Coventry. Jan. 16, 1930, No. 1549. [Class 38 (v).] The contact blades of telephone relays are eaoh provided with a plurality of contacts so that contact is established and broken between one pair of contacts of one material or materials such as are suitable for resisting the effects of sparking and is maintained by a pair of contacts of another material or materials, which are of low resistance. As shown in Figs. 1 and 2 one of the blades 10 is divided in known manner at its end each bifurcation carrying a separate contact adapted to be engaged by a co-operating contact on the blade. One of the bifurcations is bent down as shown so that the contacts 6 corresponding to the bent-over portion are engaged in advance of and disengaged subsequently to the closing and opening of the contacts 7. Thus the contacts 6 act as sparking contacts and are made of materials such as tungsten adapted to resist oxidization and the maintaining contacts 7 are made of low-resistance material e.g. platinum, gold, iridium, silver or alloys thereof. In an alternative form (Fig. 3) the sequential operation of the contacts is produced by making one or both of the sparking contacts 8 larger than the maintaining contacts 9.