GB517701A - Improvements in or relating to telegraph transmitters - Google Patents

Abstract

517,701. Type-printing telegraphy. CREED & CO., Ltd., and SALMON, R. D. Aug. 5, 1938, No. 23208. Addition to 454,593. [Class 40 (iii)] Relates to telegraph transmitters described in Specification 454,593 in which a selector lever positions a transmitting contact tongue by means of an intermediate lever formed with a knife edge which is adapted to strike, under the control of a cam, against a co-operating knife edge associated with the transmitting contact tongue, means being provided for holding the contact tongue in the position into which it was last moved. According to the present invention, a jockey roller, operating as the means for holding the contact tongue, has pressure exerted on it partly by a spring having a high ratio of force to displacement and partly by a spring having a low ratio of force to displacement. The jockey roller J is mounted on a spindle 20 in a fork at the end of a leaf spring 11 pivoted on a spindle 19 carried by a lever 14 pivoted on a fixed block at 15. To the inner end of the leaf spring 11 is attached one end of a coil spring 12 whose other end is fixed to a bracket 13 on the lever 14. The combination of the two springs 11, 12 produces the necessary downward thrust on the jockey roller J. The position of the roller J relative to the contact tongue C is adjusted by means of a screw 22 abutting against a fixed stop 17 the two being held in contact by a spring 16. The means for actuating the contact tongue is as follows :-Combination bars CB, selectively set by depression of a key may, or may not, be moved to the left to come under the horizontal arms of pivoted bell cranks SL which are successively released, so as to tend to be moved by springs 3, on the rotation of cams SC. When so released a crank SL, not held by a bar CB, moves clockwise and tilts anti-clockwise a frame A on a pivot 4 so sliding a bar 6 to the left against the action of a spring 5. The further end of the bar 6 is carried in an extension 7 of a frame 8 on a pivot 9, this frame 8 carrying an arm B which engages a cam wheel F on the same shaft as the cams SC. When the bar 6 has been set by a crank SL the arm B is depressed by the wheel F, so raising the bar 6, and then rapidly released so that, under the action of a spring 10, a knife edge D on the bar 6 is brought forcibly into engagement with a similar knife edge D<1> on the contact tongue C pivoted on a spindle 18. The set position of the bar 6 determines the direction in which the tongue C is moved.