Patent GB-213063-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H01H63/30
Filed: 1923-02-03
Abstract: 213,063. Conrad, H. S. Feb. 3, 1923. Automatic exchange systems; selectors.-In a system in which a connection is set up by pneumatically-operated switches in serial relationship, a valve controlling the operation of a pneumatic motor which prepares a switch for operation, is actuated mechanically from the preceding switch in the series. Release is controlled by an electric relay which causes the release of the first switch, which thereupon exercises a pneumatic control over the second switch and in turn causes its release. The release of the second switch actuates a pneumatic release device in the third switch, and so on. The invention is described as applied to line switches and group selectors in which the hunting movement is arrested mechanicallv when an idle line is reached: the mechanical device which pneumatically prepares a succeeding switch for operation, also being used to mark the seized switch mechanically non-selectable to other switches of the preceding switching stage. Construction of terminal banks. The terminals are formed as projecting portions 1, 2, Fig. 2, on multipling strips 3, 4, extending across the switch panel. Each pair of strips 3, 4 has associated with it a journaled crank-bar 5 which is rotated when the associated outgoing line is taken into use, thereby mechanically marking the engaged line busy and opening a valve 15 which admits compressed air to a pneumatic preparation motor in the selected switch. Construction of line switches. The brushes 7, 8, Fig. 1, which are mounted upon a vertically movable carriage, are connected to wipers 9, 10 which wipe over rods 11, 12 adapted to be connected to the subscriber's line conductors 29, 30. The brush carriage is raised by a pneumatic motor 6 which comprises an outer closed cylinder telescopically mounted upon an inner cylinder. When compressed air is admitted to the inner cylinder, the outer cylinder is lifted and raises the brush carriage until a catch 42 carried by the outer cylinder engages the crank-bar 5 of an idle trunk. The seized bar 5 is then rotated until the cranks assume a vertical position in which they are out of the path of the catches 42 of subsequentlyoperated switches. At the same time the upward movement of the motor 6 is arrested and the brushes 7, 8 engage the terminals 1, 2 of the idle trunk. An arm 63 on the end of the crankbar 5 also opens the valve 15 to actuate the preparation motor 65, Fig. 5, of the seized group selector. The brushes 7, 8 are retained in engagement with the terminals 1, 2 by the engagement of a holding pawl 51 with a rack 52 mounted on the movable cylinder of the motor 6. Construction of group selectors. The terminals and their associated crank-bars 150 are similar to those of the line switches, but a plurality of vertical rows are provided, one vertical row for each group of outgoing lines. The brushes 104, 105 and the crank-catch 106 are mounted upon a carriage 97 which is first stepped along horizontally to select a vertical row, and then raised to cause the brushes to engage an idle line in this row. The brush-carriage 97 is slidably mounted upon a bar 96 which is carried by a member 87 which slides upon a rod 89. The brush-carriage 97 is also connected by a link 100 to a bell-crank lever 101 pivoted upon an extension 103 of the sliding member 87, and carrying a pawl 75 adapted to engage but normally held clear of the teeth 75<1> of a slidable racked bar 76, a pin 80 on which engages in a slot 79 in a bar 77 carried bv the movable cylinder of a motor 78. The sliding member 87 is provided with teeth 86 and is adapted to be stepped to the right, to select a vertical contact row, by a pawl 139 operated by a.pneumatic impulse motor 13'7. The pawl 75, and holding pawls 81<1>, 82 for the bar 76 and the sliding member 87, respectively, are rendered operative by the downward movement of a plate 79, pins 73, 74 on which work in inclined slots 71, 72 and cause the plate 70 to be lowered when it is moved to the left by the preparation motor 65. After the brushes 104, 105 have been moved' to a selected contact row by the member 87, the pawl 75 engages a tooth 75', and subsequent relative movement of the bar 76 by the motor 78, through the medium of the pawl 75 and the levers 101, 100, raises the brush carriage 97 until the catch 106 engages the crank 150 of an idle line. The rotation of the crank-bar mechanically marks the seized line busy and opens a valve 132 to prepare the engaged switch for operation, in the same manner as the line switch prepared the first group selector. The horizontal stepping motor 137 and the vertical lifting motor 78 are successively brought into operation by a kind of pneumatic side-switch. This comprises a pneumatic motor 116 the movable cylinder of which carries a pin 117 connected by a link 118 to a pawl 122 pivoted upon a sliding member 121. The pawl 122 is adapted to engage escapement teeth 123 arranged in staggered relation on the opposite flanges of a channel-shaped bar 124, pivoted at its ends and adapted to be racked by a sylphon motor 127. When the motor 116 is first operated, the pawl 122 engages the first tooth 123, and thereafter is advanced tooth-by-tooth upon expansions and contractions of the sylphon 127. In this manner the motor 116 is permitted to operate step-by-step and when the pawl 122 reaches the third tooth 123, a cam 144 on the motor-head engages a pivoted member 146 which is actuated to open the valve 130 and close the valve 131, thereby transferring the air-supply from the horizontal motor 137 to the vertical motor 78. Operation of line switch. When the calling subscriber removes his receiver the line relays 34, 39, Fig. 1, are energized over the calling line 29, 30. The relay 34 opens a valve 16 which admits air to the sylphon motor 13 and through the normally-open valve 17 to the lifting-motor 6, which raises the brushes 7, 8 to an idle. line as described in a previous paragraph. The motor 13 is made slow-to-act by a check valve 19, or it may be arranged to operate at a higher pressure than the motor 6, in order that it does not expand appreciably until the upward movement of the motor 6 has ceased. The expansion of the motor 13 lifts a bar 43, a pin 45 on which snaps in the holding pawl 51, which is normally held inoperative by a wedge 46 supported between the bellcrank 44 and a spring 47 mounted upon a bellcrank 48. At the same time the bell-crank 48, which is rotated counter-clockwise, closes the contacts 53, 54 to extend the calling line 29, 30 to the seized outgoing trunk 58, 59, and shuts the valve 17 to disconnect air from the motor 6. The motor 14, to which air is admitted on the opening of a valve 18 by the relay 39, is rendered slowto-act by a check valve 20 and before it can actuate to operate the contact group 35, the armature of the relay 39 is pressed down by a lever 55 connected to the bar 43, and its air supply is cut off by the closure of the valve 18. Operation of group selector. The actuation of the preparation motor 65, Fig. 5, in the manner already described, when the line 58, 59 is seized, moves the plate 70 to the left through the levers 67, 69, and brings the pawls 75, 81<1>, 82 into operation. At the same time, the line relay 62 is energized and opens the valve 108 and closes the valve 109. The valve 108 admits air to the sylphon motor 110, which opens the valve 114 to operate the side-switch motor 116, which drives the pawl 122 on to the first escapement tooth 123. The motor 110 is made slow-to-rele.ase by a check valve 128 and does not retract during impulsing de-energizations of the line relay 62. On the first relapse of the line relay armature 107, when the first series of impulses is dialled, the valve 109 is opened and admits air (1) to the sylphon 127, which rocks the escapement bar 124 and causes the pawl 122 to engage the second tooth, and (2) to the horizontal stepping motor 137, which advances the brushes 104, 105 to the first contact row. Further impulses advance the brushes in like manner and at the end of the train the sylphon 127, which is slow-to-release, retracts and causes the pawl 122 to move to the third escapement tooth. The cam 144 now engages the member 146 which by closing the valve 131 and opening the valve 130 shuts off the motor 137 and admits air to the vertical motor 78, which moves the bar 76 and raises the brushes 104, 105, until an idle line in the selected vertical row is reached and a valve 132 is opened to prepare the next switch in known manner. On the first deenergization of the line relay 62', when the next series of impulses are sent to the switch beyond. the valve 109 is opened and the sylphon 127 expands, moving the pawl 122 to the last tooth 123. The member 146 now drops upon the depressed end of the cam 144 closing both valves 130, 131 and causing the motor 78 to retract. The cam portion of a spring 61, normally held raised by a projection on the bar 76, falls into a notch 81 in the bar 77, and the spring group 60 is operated to disconnect the line relay 62. The valve 108 is now closed and the side-switch motor 116 returns to normal. Release. When the calling party replaces his receiver, the relay 34 is de-energized and cuts off air from the motor 13, which releases the holding pawl 51. The brushes 7, 8 fall and the crank-bar 5 rotates to its normal position, permitting the valve 15 to close and cut off air from the preparation motor 65 of the group selector. The motor 65 moves the bar 70 to the right and upwardly by reason of its pin-and-slot mounting, thereby releasing the pawl 75. The brush carriage 97 thereupon falls under gravity or a spring, and the release of the pawls 81<1>, 82 shortly afterwards permits the bar 76 and the brush-carriage mounting 87 to restore horizontally. The succeeding switches are released in like manner.