GB740476A - Improvements in or relating to electrical selector switches - Google Patents

Abstract

740,476. Automatic exchange switches. WILMAN, C. W. Feb. 15, 1954 [March 20, 1953], No. 7703/53. Class 40 (4). [Also in Group XXXVII] An automatic telephone selector comprises a pair of magnetic wipers 1 supported on an insulating body 2 having embedded therein a permanent magnet 3, the poles of the magnet being at its upper and lower ends (Fig. 2), whereby the contact pressure of the wipers is obtained by magnetic attraction. Lugs 5 of the wipers 1 are received between upstanding parts 4 of the body 2 and rest on slightly raised parts between the parts 4 whereby the wipers may pivot to align themselves with fixed contacts 7 also of magnetic material. Good contact between the contacts 6, 7 is ensured by the magnetic flux traversing the contacts and causing attraction therebetween. As shown, the contacts 7 are arranged in pairs and separated by insulation 8. The contacts may be of nickel, or of iron or steel plated with nickel or cobalt. Further, the nickel plating may be preceded by a thin plating of copper. Alternatively, there may be a thin non-magnetic plating of a precious metal on the iron or steel. The wipers 1 are mechanically balanced about the lugs 5 by tails 9 and are electrically connected to pins 12 on the body 2 by foils 11 riveted to the wipers at 10. A saddle 16 and screws 17 secure the body 2 to the operating shaft 15.