Patent GB-262207-A (GB)
Title: Improvements relating to electric switches such as are used in automatic telephone systems
IPC: H01H67/12
Filed: 1925-09-25
Abstract: 262,207. Siemens Bros. & Co., Ltd., Patterson, W. G., and Richmond, H. Sept. 25, 1925. Automatic exchange selectors.-The wipers of a selector are given two linear movements in the same plane, each movement being effected by means of cams. The cams are rotated by ratchet and pawl mechanism. On release, the cams are advanced to normal position and the wipers returned under spring action. In the construction shown, the wipers A<1> - - D<1> are mounted on a carriage 1 movable sideways on guide rails 6 mounted upon a second carriage 2 which in turn is movable on guide rails 4 mounted upon the main frame plate 3 at right. angles to the rails 6. The carriage 1 is first moved sideways on the rails 6 to bring the wipers opposite a desired row of terminals by a magnet 20 mounted upon the plate 3. The magnet armature 21 has projecting between the carriages 1, 2 an arm 24 upon which is pivoted a pawl 28 which engages a ratchet 29 journaled on a pin 30, fixed in the lower carriage 2 and projecting through a slot 43 in the upper carriage' 1. A heart-shaped cam 33 is secured above the carriage 1 to the sleeve carrying the ratchet 29,- and acts against a pin 34 on the upper carriage. The arm 24 and pawl 28 are respectively held against stops 27, 31 on the plate 3 by springs 25, 32. The magnet 20 advances the ratchet 29 one tooth at each retraction of its armature, thereby rotating the cam 33 and moving the carriage 1 and wipers A' - - D' to the right, against the action of a spring which is wound up by a drum 35 rotated by a chain 36 attached to the carriage. The ratchet 29 is held by a detent 41 mounted on the lower carriage 2. The movement in the second direction is effected by a magnet 12, the armature 13 of which is held against an adjustable back-stop 38 by a spring 39, and at each retraction advances a ratchet 11 and heart-shaped cam 9 secured to a sleeve on a pivot 10 mounted on the frame plate 3. The cam 9 acts against a pin 8 to move the lower carriage 2 on the rail rods 4 against the tension of a drum spring 18. The wiper carriage 1 at this time moves with the lower carriage 2 and the wipers are advanced over the terminals of the selected row. To return the switch to normal, the magnet 12 is operated intermittently to advance the cam 9 to its initial position. The carriage 2 is thereby first moved to its extreme position and is returned to normal by the drum spring 18 which retains the pin 8 against the cam 9. The other magnet 20 is then stepped to restore the carriage 1 in a similar manner. The terminal bank A - - D consists of a rectangular group of parallel bare wires or strips common to a row of switches and running at right angles to the plane of movement of latter, which may be arranged in vertical or horizontal rows. The switches or the terminal banks may be adjusted in position to present a new portion of the terminal wires to the wipers. The circuits may be modified to cause the switch to operate as a connector or an ordinary group selector, or as a group selector which hunts continuously over a group or hunts over groups in succession.