GB342552A - Improvements in telephone dial mechanisms - Google Patents

Abstract

342,552. Impulse transmitters. CONKLIN, S. A., Box 404, Picton, Ontario, Canada. Feb. 20, 1930, No. 5694. [Class 40 (iv).] The finger-plate of a dial transmitter is declutched from the impulse mechanism at the end of the setting movement to prevent the impulse rate being interfered with by manual return of the fingerplate. The clutch mechanism is operated by a movable finger stop, and return of the mechanism is prevented until the movable stop has been operated. The fingerplate 12 is fixed on a spindle 10 rotatably mounted in the main shaft 3 which carries the usual governor drive gear and impulse wheel 7, 8. The clutch comprises a lower plate 4 fixed with respect to shaft 3, an upper plate 9 fixed to spindle 10 and an interposed plate 14 carrying dogs 15, 16 sliding in a diametral groove. The dogs have depending outer ends 15<x> adapted normally to engage notches 4‹, 4<x> in plate 4, and upstanding inner ends 17, 18 which project through radial slots in the upper plate, the dogs being pressed radially inwards by springs 19. A cone 20 fixed on spindle 10 is adapted to engage between the upstanding ends 17, 18. When the finger-plate is set, pressure of the finger against stop 24 mounted on lever 22, presses the forked inner end of the lever towards the spindle 10 so that inclines 25<x> on the lever depress cone 20 whereby the dogs are forced outwardly to release plates 14, 9 from the plate 4. The dial mechanism returns to normal and transmits impulses in the usual manner. Return of the finger-plate before completion of the setting movement is prevented by a pawl 34 and a ratchet 33 on plate 9. On movement of the finger-stop lever 22, a catch 22‹ thereon rides up the end 26<x> of lever 26 and remains locked in its operated position. At the same time, projection 35 on lever 26 releases pawl 34 to permit the dial to be returned by a spring 32, or manually, without effect on the impulse mechanism. When the impulse mechanism reaches normal, a projection 28 on plate 4 engages lug 27‹ on the lever 26 so as to release the finger-stop lever which is returned by a spring (not shown).