Patent GB-200208-A (GB)
Title: Improved switching or like mechanism for use in telephone or like systems
IPC: H01H63/30
Filed: 1922-04-08
Abstract: 200,208. Conrad, H. S. April 8, 1922. Automatic and semt - automatic exchange systems and apparatus; selectors.-An automatic switch is driven by a fluid motor advanced stepby-step under the control of impulses. In the pause following a series of impulses the fluid supply to this motor is cut off and fluid is admitted to a second fluid motor which advances the switch wipers in another direction, a fluid operated side switch being provided to enabledifferent connections and operations to be effected in a definite order. The invention is 'described as applied to a group selector the wiper arms 56, 57, Fig. 1, of which are first moved step-by-step in a horizontal direction to a particular column of contacts by a pneumatic motor 42 controlled by numerical impulses and are then raised vertically in a. continuous motion by another pneumaticmotor 30 until an idle contact set is reached. Construction of the pneumatic motors and valves. The pneumatic motors used in the switch are'of the fast-return type and comprise a fixed head 15, Fig. 9, over which is fitted a cylindrical cap 17. When compressed air is admitted to the top of the head through the axial opening 16 the cap 17 rises and moves any apparatus connected to it. On the fluid supply being cut off the cap 17 falls under the action of gravity or a spring. The valves consist of a cylindrical casing 19, Fig. 10, containing valve members 20, 21, contacting in a restricted passage from which leads the outlet pipe 18. The member 20 is held upon its seating by the air pressure from the inlet pipe, but it may be raised to admit air to the pipe 18 by pressing up a pin 22 extending through the casing. Construction of group selector. The wiper arms 56, 57, Fig. 1, are carried upon a platform fixed on the moving cap of the vertical motor 30, which is mounted on a framework 41 attached to the moving cap of the horizontal motor 42, the stationary portion of which is screwed to the side 28 of the switch frame. The weight of the framework 41 and the apparatus it carries is taken by a wheel 54 riding on a rail 55. The side of the cap of the motor 30 is provided with two racks 36, 33, the former coacting with a stopping pawl 37 and the latter coacting with a holding pawl 34. The pawl 37 is mounted on a sleeve which slides with the wiper carriage upon a squared portion of a shaft 38 adapted to be rotated by a magnet 103 the armature 104 of which is fixed to the shaft. When the magnet 103 is energized, the stopping pawl 37 engages the rack 36 and stops the ascent of the motor 30, and an arm 46 on the other end of the shaft opens a valve 45. After air has been cut off from the motor 30 the cap is held in its raised position by the engagement of the holding pawl 34 with the rack 33. The pawl 34 slides on a squared portion of a shaft 35 which is turned by a motor 92, a collar 94, Fig. 7, on a rod 93 attached to the motor cap being held against an arm 95 on the shaft by means of a spring 96 on a projection 86 of the arm 95. The cap of the horizontal motor 42 is furnished with a rack 47 engaging with a spur wheel 48 fixed upon a journaled spindle 49 upon which is also fixed a toothed wheel 50 associated with an escapement 51 actuated by the armature of a magnet 53. According to a modification, the magnet 53 may operate a valve which admits air to a motor controlling the escapement 51. The cap of the motor 42 also carries two holding pawls 68, 69 coacting with a rack 70 fixed to the switch framework. The pawl 68 is released by the operation of a pawl motor 73, whilst the pawl 69 is released by an extension 71 on the wiper carriage when the latter is in its normal position. An arm 62, Fig. 5, is pivoted on an extension fixed to the frame and carries a roller 63. A projection on the arm 62 normally rides upon a pin 66 on the cap of the motor 42 and holds the contacts 64, 65 closed. When the horizontal motor 42 is operated, the pin 66 permits the roller 63 to fall and ride upon the wheel 50, the contacts 64, 65 being thereafter intermittently closed as the teeth come under the roller 63. The side switch comprises a plate 76, Fig. 6, journaled on a spindle 77 mounted upon an extension 78 of the side 29 of the frame. The plate 76 is toothed at its top and bottom edges and carries a wiper, a pin 102, Fig. 1, on which in the third position of the side switch engages a pivoted lever 98 and causes it to close a normally open valve 99 against the tension of a spring 100. The plate 76 is stepped round by a pawl 82, Fig. 6, pivoted to a bell-crank 80 operated by a fluid motor 81, Fig. 1. An extension 97, Fig. 1, on the bell-crank 80 closes a valve 32 on the actuation of the motor 81. A holding pawl 84 for the plate 76 is also pivoted on the frame extension 78 and is connected by a rod 85 to the arm 86, Fig. 7, on the shaft 35. The pawl 34 in its normal position bears against a button 40 at the end of the shaft 35, which is permitted a slight lateral movement defined by the collars 87 at its other end. When the pawl 34 moves towards the right with the wiper carriage, this small freedom of movement permits a spring 91 bearing against the side switch holding pawl 84 to bring the latter into association with the upper teeth on the plate 76. Similarly when the switch restores, the slight movement of the shaft 35 to the left consequent upon the engagement of the button 40 by the pawl 34, releases the holding pawl 84. Operation of group selector. On the group selector being taken into use in known manner by a line switch, the line relay 105, Fig. 11, is energized over the calling line 117, 118. This relay is provided with an impulse responding armature 110 and a heavy sluggish armature 107 and operates in the manner described with reference to Fig. 1 of Specification 200,207. The attraction of the sluggish armature 107 opens the valve 106 to admit air through the pipe 109 to the switch, thereby actuating the motors 73, 92, which bring the holding pawls 68, 34 into operative relation with the racks associated with the horizontal and vertical driving motors. The armature 107 also closes contacts 120, 121, thereby completing a circuit over the spring 64, 65 for the slow release relay 103 which tilts the shaft 38 and opens the valve 45 to admit ,air to the horizontal motor 42 and the side-switch motor 81. The horizontal motor 42 is unable to actuate since it is held by the escapement mechanism, but the bell-crank 80 is moved by the motor 81, driving the side-switch to its second position and closing the normally open valve 32 which shuts off air from the vertical motor 30. A circuit is then closed over the sideswitch arm 132 for the stepping magnet 53 which operates the escapement 51, Fig. 1, to release the horizontal motor 42 a step each time the line relay closes the contacts 128, 129 in response to a dialling impulse, and which moves the frame carrying the vertical motor 30 until the wipers 59 - - 61 are brought below the desired contact columns. On the cessation of these impulses, the contacts 64, 65 are opened for a prolonged period, the relay 103 relapses, and the valve 45 closes. This causes the side-switch motor 81 to fall back so as to open the valve 32 and admit air to the vertical motor 30 which raises the wipers. When the test wiper 59 engages a test terminal 136 carrying a selective potential, the relay 103 is again energized in a circuit 59, 125, 124, 123, 121, 120, the shaft 38 is tilted to throw the stopping pawl 37 into engagement with the rack 36, and the valve 45 is opened to admit air to the motor 81 which drives the side-switch into its third position. Valve 32 is also closed and cuts off air from the vertical motor 30, the wipers however being held by the pawl 34. The sideswitch in its third position closes the normally open valve 99 and extends the calling line over its arms 113, 132. When the switch at which the engaged trunk terminates disconnects battery from the test contact 136, the relapse of relay 103 withdraws the stopping pawl 37 and closes the valve 45 which cuts off the motors 42, 81. A check valve 43<a>, Fig. 1, in the pipe 43 ensures a gradual exhaust from the motor 42. The motors 30, 42 are held by their holding pawls, but the motor 81 relapses and opens the valve 32 which is without effect since the valve 99 is closed. When the calling party hangs up, the line relay 105 relapses nad the sluggish armature 107 falls. away, closing the valve 106 and cutting off the motors 73, 92, which release the holding pawls. 68, 34. The horizontal motor 42 remains held by the pawl 69 until the vertical motor 30 has. dropped to normal, when the pawl 69 is released by the extension 71, and the motor 42 is returned to normal by a spring in a housing 89, Fig. 1, attached to the spur wheel 48. The wiper carriage and the pawl 34 return with the motor 42, the slight lateral movement of the shaft 35 causing the release of the side-switch holding pawl 84 as described in the previous paragraph. The side switch is restored to normal by a spring 76<a>, Fig. 6.