Patent GB-226923-A (GB)
Title: Improvements in automatic selecting switches for use in telephone exchange systems
IPC: H01H67/16
Filed: 1923-11-10
Abstract: 226,923. Western Electric Co., Ltd., (Deakin, G.). Nov. 10, 1923. Selectors.-The brush-carrying member of a switch is moved to a desired position by means of a flat cam member selectively set under the control of impulses. In the selector described, the device is utilized by effecting the vertical movement of a co-ordinate clutch-driven switch adapted to be controlled by reverting impulses. The brushes b<1>, b<2>, b<3>, Fig. 1, are fixed in a block 6 of insulating material mounted between end plates 10 screwed on a sleeve 9, slidably but not rotatably mounted upon a tube 3 journaled in the switch-frame 1 in bearings 2. The tube 3 is cut along a portion of its length with a slot 5, through which projects the tongue of a movable member 7, urged upwardly by a helical spring 8. The tongue cf the member 7 partially passes round, and is fixed to, the brush carriage 6. Surrounding the tube 3 in the upper bearing 2 is a rotatable sleeve 11 carrying a flexible disc 33, and a notched cam disc 20, Figs. 1 and 2, on the upper surface of which is mounted a flat cam 19 having a continuous internal face adapted to engage a roller 18 mounted on a stop 17 sliding in a slotted tube 16, fixed in the frame and communicating with the tube 3. Between the stop 17 and the brush-moving member 7 is a series of balls 15. When the flexible disc 33 is clutched to a continuously-driven disc 35 in known manner by the clutch armature 34, the cam disc 20 is rotated in the direction of the arrow, the roller 18 is moved by the cam 19 towards the axis of the switch, and the balls 15 are. forced along the tubes 16, 3, thereby lowering the member 7 and the brushes against the tension of the spring 8. As the disk 20'rotates, a roller 26 passes from one peripheral notch to the next and closes springs 27, 28, Fig. 2, to send back reverting impulses. When the brushes have been lowered to the desired level, the clutch is released and the disc 33 is forced against a back stop 22, thus holding the disc 20 in its advanced position. During this vertical movement of the brushes, the tube 3 is held against rotation by a flexible disc 30 forced into engagement with a back stop 21 by the clutch armature 32. To rotate the brushes, the disc 30 is clutched by the armature 32 to a continuously-rotating disc 31, which by rotating the tube 3 advances the brushes to the desired contacts, when the clutch magnet is de-energized and the discs 30, 31 disengaged. To restore the brush member 6 to its normal vertical position, after the brushes have been rotated to their normal radial position, the cam disc 20 is again rotated in the same direction as before and brought to rest at a point 180 from the previous starting point. The cam disc shown is arranged for two selections per complete revolution, but this number may be increased or decreased as desired. The number of notches controlling the reverting impulses may be more or less than the number of levels : for example, two reverting impulses may be sent back for each vertical level passed by the brushes. The discs 33, 30, may be rotated by step-by-step mechanism, instead of by clutch-controlled power driven apparatus.