Patent GB-240200-A (GB)
Title: Improvements in or relating to telegraphic printing apparatus
IPC: H04L13/18
Filed: 1924-05-19
Abstract: 240,200. Creed & Co., Ltd., and Creed, F. G. May 19, 1924. Letter-spacing mechanism; line-spacing mechanism; carriage-releasing arrangements; carriagereturning mechanism; paper-carriages.-In pageprinting telegraphic apparatus comprising a platen roller mounted in a carriage and movable for letter-spacing on a shaft which is rotatable for line-spacing, letter-spacing is effected by a pinion gearing with a rack on the carriage and operated by a pawl and ratchet-wheel, the pawl being released when a releasing-signal is presented to the selector mechanism, whereupon a spring returns the platen roller, line-spacing mechanism is operated: the platen roller and associated mechanisms are mounted on a support which can be moved away from the main part of the apparatus to afford access to the printing- mechanism and inking-devices for cleaning and renewal. The platen roller a is feathered on a shaft c, journaled in a stationary support d, and is provided with a carriage b running on a rail b<1> on the support. A rack e on the carriage gears with a pinion f on a drum g mounted on the support d and provided with a spring which is wound during letter-spacing movement of the carriage.. Letter-spacing is effected by a pawl i co-operating with a ratchet-wheel h on the drum, the pawl being pivoted to a block i<2> on a lever j<2> which is mounted on the support d and at each operation of the apparatus is reciprocated by means of a crank k having a roller engaging a slot j<4> in the lever. As applied to the apparatus described in Specifications 164,370 and 184,558, the crank is carried by the cam shaft. The ratchet-wheel co-operates also with a detent n pivoted on a block n<2>. Springs maintain the pawl and detent in engagement with the ratchetwheel. The blocks i<2>, n<2> are provided with shock-absorbing members i<3>, n<3> of leather &c. The pawl and detent are released by means of a lever v<2> having a fork v<1> engaging a pin on a longitudinally movable link t provided with a pivoted arm r engaging an arm 1 on a lever controlled by the releasing-signal. When the reJeasing-signal is presented to the selector-mechanism, the arm r is depressed bv the arm 1 and enters the path of a longitudinally movable bar o connected to the lever j<2>, whereupon the link t rocks the lever v<2>, and the pawl and detent are released. The spring drum g then returns the carriage and platen roller to the starting point, the movement being cushioned by a dash-pot consisting of a cylinder 13 on the carriage, and a piston 14 on the shaft c. Line-spacing is effected during carriage-return by a pawl 4 which co-operates with a ratchet-wheel 3 on the shaft c and is carried by a rocking plate 5a connected by a link 6, bellcrank 7a, and link 8 to the lever j<2>. The cam shaft makes four revolutions during carriage-return, and the pawl 4 imparts a one-tooth feed at each revolution. The pawl 4 is normally held out of engagement with the ratchet-wheel 3 by a masking-plate 9, Fig. 3, connected by a bellcrank 12a, 12<b> to the link t. When the link is operated, the masking-plate uncovers four teeth, and the link and masking-plate are then constrained by the ratchet-wheel to return step-bystep to the normal position, the pawl i and detent n re-engaging the ratchet-wheel h at the end of the return movement. The support d carrying the platen roller and carriage and the above described feed-mechanism is mounted on a rod 16 on the main framework 17, and can be turned downwards to afford access to the printmg-mechanism and inking-devices. The support is secured in normal poistion by means of a catch 19 on the frame work 17. As applied to the apparatus described in Specification 228.842, the following modifications are made :-The release-lever for the pawl i and detent h is retained in operative position by a catch-lever which is released at the end of the carriage-return movement by a pin on the carriage. To permit return of the link t, the fork u<1> on the release-lever v<2> is replaced by an arm which abuts on the pin on the link. The revolving crank k is replaced by an intermittently operated rock-arm. The masking-plate 9 is arranged to uncover two teeth of the ratchetwheel 4, and the pawl 3 is operated twice during carriage-return.