Patent GB-180994-A (GB)
Title: Improvements in or relating to setting arrangements for selectors in automatic or semi-automatic telephone systems
IPC: H01H67/06
Filed: 1922-05-08
Abstract: 180,994. Hultman, C. A. W. May 28, 1921, [Convention date] Automatic exchange systems; selectors.-In a system in which the operation of a selector is controlled by reverting- impulses, the impulses are sent back by the selector only at every second position, whilst the impulse-receiving device associated with the registering mechanism moves forward one step in response both to the closing and to the opening of the impulse circuit. Figs. 1<a> and 1<b> together show the controlling arrangements for a selector in which a member IS moving with the selector closes contacts IK in the impulse circuit at each alternate position of the selector. Registers RS1, RS2 are set in response to the wanted number, the wipers of the register making contact between the bars KS1, KS5 and the selected contacts of the sets RK1, RK2 respectivelv. The selector in its first direction of motion has twenty-five positions' divided into three groups. The impulse-receiving devices IM1, IM2, of which one is shown in detail in Fig. 2, are provided with sets of contacts IK1, between which and the bars KS2, KS3, KS4 the wipers make contact. The wiper SK, Fig. 2, under the influence of a driving spring KF is held up in any position by an escapement device comprising a double pawl DH engaging with a segment ST. When the driving magnet IM is energized, its armature MA tilts the pawl DH, freeing the segment ST and the wiper SK, which rotate one step until they are held up by the other end of the pawl. When the magnet IM is de-energized, the pawl DH is returned by the spring HF and the wiper and segment move a second step. The wiper is reset in it$normal position after a call ;by a resetting mechanism (not shown) which acts on a projection AV. At the commencement of the operation of the selector, contacts SO1, SO2, SO3, Figs. 1<a> and 1<b>, close the circuit 11, energizing the magnet SM which moves the detent SH from the stop bar SS and energizes the power magnet KM. During the movement of the selector impulses are sent at every second position over the circuit 13 in series with the relay IR, which repeats the impulses to the circuit 14 of the driving magnet IM of the impulse-receiving device IM1. When the wiper SK has been stepped round to a position corresponding to that to which the wipers of the register have been set, a circuit 15 is completed over the wipers of both devices, energizing relay SR which breaks the circuit 11. The power magnet EM remains energized until the wipers are properly centred, when the detent SH drops into a slot in the stop-bar SS and the power magnet is de-energized, stopping the selector. Belay SR locks up and closes a contact K<3> which disconnects the device IM, and connects up the next device IM2 which operates during the next movement of the selector. If the relay SR becomes erergized at a moment when the magnet IM of the device IM, is energized, the device will move forward another step upon the de-energiza. tion of the magnet IM, but, although the circuit 15 is openei, the relay SR remains locked and the selector is not re-started. The member IS mav be in the form of a bar or a disc according as the movement of the selector is linear or rotary.