Patent GB-644772-A (GB)
Title: Improvements in or relating to printing telegraph receivers
Inventor: SALMON REGINALD DENNIS
IPC: H04L13/18
Filed: 1946-06-21
Abstract: 644,772. Type-printing telegraphy. CREED & CO., Ltd. June 21, 1946, No. 18741. [Class 100 (iv)] [Also in Group XL (b)] Platen rotation; line-spacing mechanism.- In a printing-telegraph receiver comprising a platen mounted in a stationary part of the machine and a type-carriage traversable parallel to the platen, two pawls co-operate with two oppositely-directed ratchet wheels for rotating the platen in opposite directions, selective means is operated in response to appropriate signals to select one of the pawls for operation of its corresponding ratchet wheel and the selected pawl is reciprocated to effect rotation of the platen through a given arc in the selected direction. The operation of the line spacing mechanism is under control of function selection members 4, 5 whose position is determined by five setting numbers such as 2, 3, operating as described in Specification 620,682, [Group XL (b)]. Each of the members 4, 5, when selected, moves inwardly under the action of its respective spring 7, 8, Figs. 2, 3. The platen carries a gear-wheel which meshes with an idler gear meshing with a gear 11 on a shaft 12 which carries oppositely-directed ratchet-wheels 13, 14. A pawl 17 associated with the wheel 13 is pivoted on a plate 15 and carries a pin 25 engaged by a suppressor lever 23 pivotally mounted on a shaft 24. A pawl 20, Fig. 3, for operation of the second ratchet-wheel 14, is mounted on a plate 16 and is provided with a pin 27 engaged by a second suppressor lever 26. The suppressor levers are straddled by a frame 28 carrying tappets 29, 30 engaging the levers and connected by an arm 35 to a pin 38 on the plate 16. The plate 15 is operated by a link 56 connected to an adjustable arm 53 on a plate 51 carried by a shaft 41 rotated by links 42, 43, 44, 47, from a cam 50 on a shaft rotated in response to each received signal. The plate 16 is rotated by a lever 39 attached to an arm 40 also mounted on the shaft 41. The plate 53 is adjustable on the plate 51 by means of a slot 55 so that the rotational movement of plate 15 in Fig. 2 is double that effected by the arrangement illustrated in Fig. 4. When the line-spacing operation is not to be effected, neither of the bars 4, 5 is actuated and when the plate 16 is rotated clockwise the frame 28 is rotated to release the suppressor bars 23, 26 which are arrested by the projections 57, 58 on the bars 4, 5 respectively. The pawls 17, 20 are withheld from engagement with the ratchet-wheels 13, 14, and the movements made by the plates 15, 16 are without effect. For normal forward line-feed, the bar 4 is selected and moves inwardly so that the line-feed suppressor bar 23 is not arrested. The pawl 17 moves into engagement with its wheel 13 which is then rotated by the movement of the plate 15 and effects through the gear-wheel 11 and the idler gear the movement of the platen 9. Similarly, for back spacing, the bar 5 is selected and removes the projection 58 from the path of the suppressor lever 26 so that the pawl 20 moves into engagement with the wheel 14 which is consequently rotated clockwise by the movement of the plate 16 and back-spaces the platen. A lever 59, Fig. 4, mounted on the shaft 41, rotates a pivoted lever 61 so that its projection 64 engaging between the teeth of the gear-wheel 11 just before the roller 48 engages the highest part of the cam 50 prevents over-movement of the line-spacing mechanism. A lever carrying a jockey roller 65 holds the gear-wheel 11 in its operated position. Specification 643,153, [Group XL (b)] also is referred to. The Provisional Specification describes an arrangement in which one of two pawls is selectively operated to drive one or the other of two ratchet wheels, the ratchet effecting line spacing engaging a gearwheel on the platen shaft whilst the other ratchet-wheel drives the platen shaft through an intermediate idler gear.