Patent GB-318246-A (GB)
IPC: G08B25/00
Filed: 1929-08-16
Abstract: 318,246. Siemens & Halske Akt.- Ges. Sept. 1, 1928, [Convention date]. Void [Published under Sect. 91 of the Acts]. Fire, police, and like alarm systems and apparatus.-In order to increase the speed of signalling in a system, more particularly a fire alarm system, wherein a number of transmitting stations are arranged in a single loop circuit, each transmitter has the projections of its code wheel arranged in a definite combination to effect, by the transmission of impulses, the control of a plurality of drums at the central station, which according to their positions selectively control the position of a type wheel and the selecting switch of an indicator board. As shown in Figs. 1 and 2, transmitters 1, 2 are connected in a loop circuit 3 including at the central station line relays 6, 7 which control electromagnets 11, 12 respectively. The electromagnets 11, 12 control levers 13, 14, each of which carries a pawl 39 adapted to co-operate with ratchets 28 on the periphery of drums 21 - - 24 which are rotatably mounted in a tubular body 26. The interiors of the drums also are provided with teeth 27 arranged in a " definite " combination and adapted to co-operate with a common pawl 34 mounted on a type wheel 25 rotatably arranged within the drums. The pawls 39 are given a transverse movement across the respective series of drums 21 - - 24 by a pin 15 which is controlled by a cam 16 driven by a continuously running motor 20. The Specification states that upon operation of one of the transmitters one or other of the electromagnets 11, 12 is impulsed to operate the associated lever 13, 14, which during its transverse movement steps forward the drums 21 - - 24 in sequence. Upon movement of the first drum the pawl 34 is removed from engagement with the teeth 27 to allow, through a clutch 63, rotation of the type disc 25 by the motor 20. The rotation is continued until the pawl 34 cooperates with aligned teeth on all the drums to set the type wheel in a position corresponding to the transmitted signal. At the termination of signalling the cam 38 operates the hammer 37 and effects printing of the signal on strips 35. Simultaneously with setting the type wheel a cam 33 operates a lever 49 which, through a pawl and ratchet wheel 51, 52 and gear wheels 53 - - 57, rotates a contact arm 58 over a bank of contacts 59 to select a particular lamp in the indicator 64 corresponding to the transmitted signal. Upon receipt of the signal, cams 43, 62 driven by the motor 20 effect restoration of the apparatus. Cam 43 operates a lever 44 which trips all the locking pawls such as 40, and thereby allows spring-controlled levers 30 to return the drums 21 - - 24 to their normal positions. The pawl 34 is moved out of engagement with the teeth 27 and the type wheel 25 is driven by the motor 20 into its normal position, i.e. the position in which pawl 34 co-operates with the first teeth on all of the drums. Cam 62 maintains the lever 49 in contact with the cam 33 during the resetting operation. The system may be arranged in such a manner that signals transmitted simultaneously or in rapid succession may be received without interference.