GB381218A - An improved start-stop mechanism for rotatable typewheels particularly suitable for printing telegraphs - Google Patents

Abstract

381,218. Type-printing telegraphy. CREED & CO., Ltd. and GRIFFITH, R. G., Telegraph House, Croydon, Surrey. July 2, 1931, No. 19079. [Class 40 (iii).] A friction clutch for driving a type-wheel or other rotary type-head is provided with means for absorbing shock and reducing torque when the type-head is arrested to effect printing. A driven member 4, Fig. 1, integral with the type-head is connected to a cup-shaped driving member 1 through a flat spring 5 which is connected to the driven member at 6, comprises 1¢ turns, and is in frictional engagement with the continuously rotating cup 1. The driven member 4 draws after it, by means of a second spring 8, a stop member 13 which, when the type-head is to be arrested in a required position, is engaged by one 3A of a set of selectors 3, the chosen selector 3A being moved for this purpose into the path of a tooth on the stop member 13. When the stop member 13 has been arrested in this manner, the driven member 4 runs on until its part 12 is forced by a cam 13A in an axial direction towards the selectors 3, so that it latches itself to a definite one of these selectors by means of a hook (not shown) and remains in position till the stop member 13 has been released by the withdrawal of selector 3A. The spring, 8 saves the member 4 and type-head shaft from shock, and moreover it is pulled away from spring 5 during the arrest process, so that the driving torque is diminished. Spring 5 is then free to wind up slightly, so as to diminish the frictional drive still further. In a modification, Fig. 6 (exploded perspective), the clutch is of the disc type. The driving disc 1 is pressed by springs 17 against a driven member 4 which, by means of a spring 8 attached to pin 23, draws after it the stop member 13, the relative movement of driven member and stop member being limited by stops 26. The stop member 13 has a tooth for engagement with the selectors 3, and when it is arrested the driven member 4 runs on, stressing the spring 8, until its stop 26 abuts against the stop member 13. A spring 14 carrying a latch 12 is mounted on the member 4 and is, during rotation, held out of engagement with the selectors 3 by a cam roller 27 engaging a cam plate 28. When arrest takes place, however, the plate 28 runs off the roller and latch 12 then engages a selector 3 so as to lock the member 4 and typehead in position. The type-head may comprise a type-wheel or a rotatable type-barcarrier of the kind described in Specification 311,684 [Class 100 (iv), Typewriters &c.]