Patent GB-801194-A (GB)
Title: Improvements relating to switching arrangements for electric motors for teleprinters
IPC: H04L13/04
Filed: 1954-05-03
Abstract: 801,194. Type-printing telegraphy. GRIFFITH, R. G. July 28, 1955 [May 3, 1954], No. 12816/54. Class 40 (3). A switching arrangement for an electric motor driving a teleprinter includes a delay device controlled by the motor and operating, after a predetermined time period subsequent to the receipt by the teleprinter of the last signal character combination, to move a motor switching-off member from an inactive to an active position in relation to a bail member and also to release the teleprinter to enable it to perform a complete cycle of operation, such as is necessary to record a signal character combination, during which cycle the bail is driven by the motor to act on the member and open a switch and stop the motor, the latter acting to store energy which is released to switch on the motor on subsequent receipt of an incoming signal by the teleprinter. The switch 146 for the motor M comprises a member spring-biased to the " on " condition and actuated to the "off" " condition by counter-clockwise movement of a bell-crank 149 which is latched by the arm 157<SP>1</SP> of a pivoted frame 150. The operation of the key 152 to switch on the receiver rocks a cradle carrying a pivoted member 155 which moves a detent member 144 from engagement with a bar 145 so that the frame 142 rocks clockwise and disengages a tooth 141 from a projection on a cam 161 on the shaft 140 of the receiver. At the same time an arm 156 on the frame 142 engages an extension 157 of the frame 150 to move the latching arm 157<SP>1</SP> out of engagement with the pivoted bell-crank 149 so that the switch 146 closes to operate the motor M. A further cam 158 on the shaft 140 engages an extension 159 of the frame 142 so that the detent 144 re-engages the bar 145 and the tooth 141 engages the cam 161. The operation of the key 152 releases the receiver shaft solely for half a revolution, and if held depressed, the spring-biased pivoted arm 155 on the frame 153 which engages on the ledge 162 of the detent 144 when it moves downwardly, is moved upwardly against the spring when the detent 144 is restored and returns to its normal position on release of the key. During signal reception, in response to the start element, the detent 144 is moved by the receiving magnet 144a to release the shaft 140. The reception of the motor-stop signal reacting in the operation of the shift vane V27 and a combination of the vanes V1 ... V5 allows a code bar 166 to drop, and with it, a hooked bar 167 engaged by an operating bail 76 rocked by a cam 79 on a shaft 212 released by the receiver shaft so that a lever 168 is moved forward to rock the bell-crank 149 to the " off " position in which it is latched by the detent arm 157<SP>1</SP> of the frame 150. The bar 166 is returned to its normal position by a frame 215 operated by a cam 213 on the shaft 212. The motor M is stopped when signals have ceased for a predetermined period. A cam 169 on the shaft of the motor M operates a member 170 having a tooth portion 171 operating a ratchet 173 and an extension 172 associated with a ratchet 174. When the portion 171 engages with one recess 177 of ratchet 173 of greater depth than normal, the extension 172 is able to engage the teeth of ratchet 174 which is advanced one step against the action of spring 178 for each revolution of the ratchet 173. After a predetermined time a pin 183 on ratchet 174 actuates the arm of a cradle 184 which is rocked so that its extension 185 engages the extension 186 on a hooked bar 187 which is pressed downwards. An extension 189 of the cradle 184 also rocks a frame 190 having an extension 190<SP>1</SP>, which rocks the frame 153 to release the receiver shaft for one half-revolution during which the shaft 212 is released so that cam 79 operates the bail 76 to move the bar 187 to the right so that arm 191 operates bell-crank 149 to its latched " off " position. When signals are being received a member 180 operated by the selecting mechanism moves the retraining pawl 179 out of engagement with the ratchet 174 which is returned to its normal position by spring 178. The pawl 179 is held out of engagement by a latch 181 which is moved from its latching condition by a pin 182 when the ratchet 174 reaches its normal position. The predetermined period of the cessation of signals can be adjusted, the ratchet 174 being provided with circumferentially arranged holes for the location of the pin 183. The cradle 184 may be rocked counterclockwise by an extension 194 on a key 193 operated manually to stop the motor, and extension 193a engaging the frame operated by the " on " key to rock the cradle 153 to allow the teleprinter to partake of an operational cycle to operate the bail 76 and bar 187. Specification 777,719 is referred to. The Provisional Specification refers to the operation of a number of junctions by the actuation of a single bail member in conjunction with code bars selected by specified code combinations. An arrangement including gating pawls and latch members for the suppression, where necessary, of the printing operation, is generally described. Specifications 439,745, and 441,090, [both in Group XL], are referred to in the Provisional Specification.