Patent GB-283680-A (GB)
Title: Improvements in or relating to electrical signalling and recording systems
IPC: H04L19/00
Filed: 1926-11-11
Abstract: 283,680. Baker, E. W., and Lomas, A. E. Nov. 11, 1926. Type-printing telegraphs.-In a printing telegraph, particularly applicable to the signalling of the time of departure of trains, the receiver automatically inserts spaces between and after certain groups of characters. Thus the train-number (three digits) may be printed, followed by two spaces, two digits for the hours, one space, two digits for the minutes, and finally five spaces, thus : 245 -- 12,, 52----. A reverting impulse lights a lamp at the transmitter on the completion of the printing. At the transmitter a dial switch 22, Fig. 1, is manipulated to close the contacts 22<a> the required number of times so that, the key switch 21 being closed by hand, impulses are sent from battery terminals b, b over the line 23 to the line relay 24 of the receiver. Thus, in the example, instanced above, three impulses are first sent over the line, the contact 24m is closed three times and the typewheel magnet 27 moves the typewheel 36, Fig. 2, through three steps by means of pawl and ratchet mechanism 37. The slow-release nelay 26, Fig. 1, has meanwhile been energized, closing at 26b the circuit of a second slow-release relay 28. When the armature 26b is restored on the cessation of the train of three impulses, a, circuit is closed via contact 28m through the printing magnet 29, which actuates the printing hammer 42. At the same time the spacing ratchet magnet 30 is energized, and on de-energization it turns the spacing wheel 39 and wiper 31 through one step, and feeds forwards the tape 43. The typewheel is then automatically stepped forward: as follows to its zero position : the cam 33 on the typewheel shaft having closed the contact 33a at the first movement of the typewheel, the latter is energized via the armature 28b as soon as this armature has been released after the conclusion of the train of impulses. The magnet 27 moves the typewheel a further step, at the same time breaking its own circuit at 27b, and this operation is repeated until the typewheel has been zeroized; the cam 33, moving with the typewheel, then breaks circuit at 33a. The digits 4 and 5 are similarly signalled, completing the number " 245," whereupon the wiper 31 reaches the contact 4 and prints a space by closing a circuit through the printing and spacing magnets 29, 30, via the contacts 28b, 33b, 31, 4, 32. The circuit is broken at 32 on energization of the magnet 30, which thereupon becomes de-energized and moves the arm 31 to the next contact 5, and a further space is recorded. The next two digits, " 12," are then signalled from the transmitter, after which, the arm 31 having reached contact 8, a further space is recorded. The remaining digits, " 52," are then signalled, whereupon the circuit of the dash-pot magnet 25 is completed by wiper 31 through contact 11. Five spaces are then recorded as before, the wiper 31 passing over contacts 12 - - 15 in succession. At the same time the armatures 25<1> are attracted and send a reverting impulse from battery terminals a, a, over the line 23 through contacts 22b and magnet 43, which lights a tell-tale lamp 35 to show that the message has been received. This lamp is not, however, affected by dialling impulses from the transmitter, the contact 22b being broken during dialling. In a modification, printing and spacing may be effected by a single magnet. The printed tape may be fed, manually or automatically, in front of a window, part of which is cut away, so that one indication coincides with the cut-away portion and other indications are visible through the. window on either side. In the arrangement described in the Provisional Specification the relay system differs in detail from that described above, and at the receiver a slow-release guarding relay prevents the typewheel magnet from being affected by impulses unless the line has first been proved by closure of the key switch 21 at the transmitter; a red lamp is normally alight at the transmitter, but on closure of the key switch a green lamp is substituted if the line and receiver are ready for signals.