Patent GB-433503-A (GB)
Title: Telegraph receiver
IPC: H04L17/22
Filed: 1934-09-25
Abstract: 433,503. Type-printing telegraphs. TOMLINS, F. C., Melbourne House, Aldwych, London.-(Teletype Corporation ; 1400, Wrightwood Avenue, Chicago, U.S.A.) Sept. 25, 1934, No. 27482. [Class 100 (iv)] [See also Group XL] Relay type-lever actions. -A start-stop printing- telegraph comprises the following mechanism for selectively actuating type-levers. A cam 46, Fig. 3, rocks a lever 157 so as to lower a sleeve 156 and permit all the selector-bars such as 151 to seek the notches in codediscs 118. The selected bar enters an alignment of notches and brings push-bar 168 into the path of the striker-disc 167 which, on being raised by the cam-actuated lever 174, actuates the type-lever 169 through a rack and pinion. The fulcra of levers 157, 174 are adjustable for regulating the clearance between the selector-bars and code-discs. The type-levers 169 have their pivots arranged in two semicircles, Fig. 2, in such a way that numerals are printed on a lower line than letters. The tape-carrier 237 is located between the two sets of type-levers. Letter-spacing mechanism.-The top of the plunger 164, Fig. 3, during the printing stroke, actuates a lever 202 which retracts a pawl, Fig. 8, (not shown) which on the return stroke turns a roller, and the tape is pressed against knurled parts of this roller by two spring-urged pressure rollers 219, Fig. 2, acting upon the edges of the tape 220, so that they do not interfere with the visibility of the tape. The pressure rollers are mounted on a bridge portion 221 having two arms which serve to guide the tape and also to eliminate tape noise by checking the travel of vibrations along the tape, by co-operating with the rollers to produce a depression in it, Fig. 18, (not shown). The lever 202, Fig. 3, also carries a lever 226 having fine teeth which engage with a ratchet on the platen 201, the pitches of the two sets of teeth being different so as to vary the printing point in successive revolutions of the platen. A receptacle for dust from the tape is provided. Ink-ribbon mechanism.-The ink-ribbon 236, Fig. 2, passes from one to the other of two spools 235, transversely across the tape 220, through a ribbon-guide 237 which is so arranged as to make the print at once visible. The ribbon is centralized by curved contours of the guide arms forming the ribbon-guide, so that its edge does not become frayed. The spools 235 are held by being slipped on to split stud shafts 239 having spherical outer ends which keep the spools in place on the ratchets 241, 242 to which they are keyed by pins. The ratchets are friction-braked by springs 248 and washers. They are operated during alternate periods by a pawl 252, Fig. 17, which can be set so that it will coact with either of the two ratchets 241, 242. The pawl is lifted by a lever 253, to which it is universally jointed, under the control of a plunger 256, which is lifted by lever 174, Fig. 3, at every printing stroke. The pawl 252 is set for engagement with one or other of the ratchets 241, 242 by the action of a rivet at the end of the ribbon, which passes through forks 262, so that the rivet at either end rocks the ball 257 about pivots 261 and so brings a foot 264 or 265, as the case may be, to engage under the pawl 252 and to rock this so that it may change its engagement from one to the other of ratchets 241, 242. The bail 257 is held to one side or the other by a jockey member 273, Fig. 3. The pawl 252 is held to one side or the other by a jockey member 275, Fig. 7, which is connected to it through a spring 277 adapted to tip it in one direction or the other. The ratchet which is in action is held against back-lash by a check pawl 286 or 287 as the case may be.