GB1011153A - Current impulse transmitter - Google Patents

Abstract

1,011,153. Impulse transmitters. TELEMAXVENKAUFSGESELLSCHAFT FUR WECHSELSPRECHANLAGEN m.b.H. Aug. 2, 1962 [Feb. 20, 1962], No. 29740/62. Heading H4K. In an impulse transmitter provided with a plurality of cams each of which is contoured so as to be representative of a complete telephone number and each of which is associated with a cam follower, a selection operation comprises moving a selected one of said followers into engagement with its cam and a common locking pawl whereby the cams are caused to rotate, the resultant movement of the follower being transmitted via the pawl to a clutch which controls the operation of a pair of impulsing contacts. Depression of a selection key 14 (Fig. 1) in the direction of arrow 15 causes the associated cam follower 6 to move in the direction of arrow 18 whereby a cam-locking lever 46 is released and a switch 29 is operated in order to connect up the drive to the cams and to operate an electromagnet 30 which locks follower 6 in its operative position. Rotation of the cams causes follower 52 to raise the cam followers 6 which are not involved in the present selection process, while the particular follower 6 which is involved co-operates with projections 4 on the associated cam whereby locking pawl 10 is periodically actuated. Movement of pawl 10 is transmitted via levers 56, 58, 60 to an impulse lever 62 which in turn releases clutch 69 and opens contacts 79. The clutch (Fig. 2) comprises a hollow hub 74 which is spring-urged against a friction disc 72 attached to motordriven shaft 71 and it is released when lever 62 is disengaged from one of the teeth 66 (Fig. 3). An impulse wheel 78 (Fig. 4) is thereby caused to rotate and in so doing it periodically opens and closes contacts 80 which in conjunction with contacts 79 determine the number of impulses and the interdigital pause transmitted to the line. At the end of one revolution of the cams, a lever is moved by a projection on a cam 13 whereby the apparatus is switched-off and follower 6 is released. The cams are held in place by means of the shaped rod shown above driving shaft 1 in Fig. 1 and it is itself retained in either the " locked " position shown or in the " release cams" position by means of an arcuate spring (Fig. 7, not shown). A key is provided for rotating this rod to its " release " position (Fig. 5, not shown) and a keyhole and escutcheon plate are also provided (Fig. 6, not shown) whereby the key may only be inserted and operated when the apparatus is in a specified position. Means may be provided whereby the keys 14 are only operable when the handset of an associated telephone subset has been removed from its rest.