Patent GB-315244-A (GB)
Title: Improvements in or relating to electric transmitters suitable for use in telegraphy
IPC: H04L17/06
Filed: 1928-04-10
Abstract: 315,244. Creed & Co., Ltd., and Salmon, R. D. April 10, 1928. Addition to 291,854. Type - printing telegraphs. - The parent Specification describes an antibounce device for controlling telegraph transmitter contacts, wherein a moving contact 4, Fig. 1, which is connected to line, is set against one or other of two fixed contacts 2, 3, connected respectively to positive and negative of the battery, by the forked arm of a .bell-crank 6. According to the present invention the movements of the bellcrank 6 are controlled by keyboard mechanism. Operation of line contacts. The movable contact 4, Fig. 1, lies against the upper fixed contact 3 for a negative (spacing) current but is moved on to the lower fixed contact 2 for a positive (marking) current when the lever 6 tips anticlockwise, the arrangement being similar to that set forth in the parent Specification. The lever 6 is actuated when any one of the five permutation levers 12a, 12b, pivoted at 10, (or a sixth similar lever for sending a starting signal at the beginning of each letter) moves clockwise, its depending arm 12b engaging a horizontal extension 6b of the lever 6 ; such movement of the starting lever and permutation levers 12a, 12b takes place under the control of cams on the sleeve 15, which surrounds the shaft 16, flats on the cams permitting each of the arms 12b to drop in succession unless they be prevented by the interposition of a stop 17a carried by the appropriate combination bar 17. The required combination of positive impulses is thus sent to line. Positioning of combination bars. When the machine is at rest, the combination bars 17, which are adapted to move length-ways, are held in their left-hand positions by a lever 23 which acts upon shoulders 17b formed on the bars and is controlled by a cam on the sleeve 15. As the shaft turns, the cam allows the lever 23 to turn anticlockwise and the combination bars are drawn by springs to the right, so that their stops 17a are withdrawn from the paths of the lever-arms 12a, except in the case of those bars which are held by the horizontal portion 20b. Fig. 4, of the depressed key. At the conclusion of the action the bars 37 are moved to the left by the lever 23 and the appropriate cam on the sleeve 15, which is designed first to move the bars to the left beyond their normal position and then to allow them to move back slightly into the positions shown. Actuation of cam sleeve 15 under control of key. When a key is operated, a projection 20d thereon, Fig. 4, depresses a trip bar 37 which turns the lever 35, Fig. 1. The rod 33 is thus drawn to the right so that its shoulder 33c turns the lever 3J anticlockwise Fig. 7, and permits one of the two pawls 28, which are carried by the cam sleeve 15, to engage a corresponding ratchet 29 fixed to the continuously revolving shaft 16. The sleeve 15 thereupon makes one revolution, at the end of which the pawl 23 is arrested and disengaged by the arm 31, the rod 33 having by this time been pressed down by a cam on the sleeve 15 so as to release the fork 31a which bestrides it. The above clutch mechanism is of the kind described in Specification 260,758, [Class 80 (ii), Gearing, Variable-speed &c.]. Locking of keys. The depressed key is locked in position by a bar which is operated in the same way at the combination bars 17 and functions in known manner to hold the key down. The remaining keys are held against depression by a bar 45a, Fig. 4, which as soon as one key is actuated engages under the horizontal projections 20h carried by the rest. This bar is mounted on the arm 45 projecting from the shaft 44, which moves clockwise in Fig. 4 (anticlockwise in Fig. 3), under the tension of a spring 42, Fig. 3, (which is attached to an arm 40 mounted on the shaft 39) when the shaft 39 is turned by the depression of the bar 37, Fig. 4, by a projection 20<d>, on the actuation of the key. When the key is in its normal position the shaft 39 is held against rotation by the bent arm 41, Fig. 3, which engages the arm 43.