GB179157A - Improvements in or relating to automatic switches of the step by step type for use in automatic telephone systems - Google Patents

Abstract

179,157. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Erickson, J.). April 29,1921, [Convention date]. Selectors. - A selector of the ratchet-driven type, designed to allow the various necessary adjustments to be readily effected, comprises an adjustable pole-piece on the armature of the driving magnet, an eccentric cam for adjusting the resting position of the armature, means for adjusting the wiper shaft relatively to the frame carrying the bank contacts so that their axes may be made coincident, and a readily-removable helical spring controlling the driving pawl. Fig. 1 shows a switch in which one or other of the wiper arms 3 makes contact with the series of bank contacts 2, and in which the permanent connection to the wipers is effected bv means of brushes connected with special terminals 29 and wiping over the arms 3. The wipers and the ratchet wheel 28 are rotatably mounted in a frame 20, which also carries the driving magnet 5. A soft-iron screw 14 of large diameter, screwing into the armature 6 and held in position by a spring washer 12 which is prevented from' turning by lugs engaging in holes in the armature, serve to adjust the length of the forward stroke of the armature. The cam-shaped member 26 adjustable by means of the screw 25 adjusts the resting position of the armature. The frame 20 carrying the wiper shaft is angularly adjustable relatively to the bank frame 21 by means of a hollow set-screw 23 which screws into the frame 20, and through which passes the holding screw 22; whilst longitudinal adjustment is effected by means of a slotted hole through which the screw 24 passes and by making the hole through the set-screw 22 sufficiently large. The spring 9 controlling the driving pawl 8 is provided with a loop which fits in a groove in the extended pivot 10 and is made wide enough to permit the easy removal of the spring. A slotted spring 36 engaging with recesses at each end of the rod 35 on which the armature 6 is pivoted prevents axial movement of the rod in its support. A pointer (not shown) on the frame 20 indicates on a dial 27 mounted on the wiper shaft, the particular set of contacts upon which the wipers are resting.