GB608857A - Device for switching-in and disconnecting signal apparatus - Google Patents

Abstract

608,857. Substation equipment. AUTOPHON AKT.-GES. March 8, 1945, No. 5806. Convention date. Dec. 4, 1942. [Class 40 (iv)] [Also in Group XL (b)] Substation apparatus such as loudspeaking equipment or teletype equipment is switched in by the operation of the offnormal contacts of a calling dial and switched out by a special operation of the impulse contact. As shown, the operation of the off-normal contact k, Fig. 1, completes a D.C, circuit through the substation equipment N for relay R which thereupon locks and connects the substation equipment to line. Relay R may in addition switch in an amplifier (not shown) and a visual signal SZ. Switching out of the equipment N is effected by dialling a special digit whose corresponding finger hole is situated just beyond the " O " finger hole, which causes a prolonged opening of the impulse contacts i until after the opening of the off-normal contacts k, thereby releasing R. The equipment may also be switched in by an incoming burst of A..C. current which operates R over condenser C, whereafter it locks as before. In case it is necessary to switch in the equipment some time before setting up a call, the dial is provided with another special finger hole corresponding to a closing of the off-normal contacts without operating the impulse contacts. The dial construction for obtaining the prolonged opening of impulse springs i is illustrated in Fig. 3. The cam 1 rotates with the dial face and dialling the special digit causes the cam face 1a to abut the stud 4 on the plate 5 which is thus rotated about its pivot 6, this movement being communicated to a lever 8 whose detent 7 fits into a slot 9 in the plate 5. The detent 10 in the lever 8 is thus pressed on to the impulse spring 11 to hold the impulse contacts (not shown) open. At the end of the return motion of the dial the cam 1a strikes a stud 17 on the plate 5 which is restored to its normal position, thereby closing the impulse contacts. An over-centre spring 13 gives a snap action to the plate 5 whose limits of travel are determined by a stud 15 thereon which moves in the elongated groove 16 in the fixed plate 14.