GB297891A - Improvements in mechanism for converting an oscillating movement into a step-by-steprotational movement, particularly applicable to electric clocks - Google Patents

Abstract

297,891. Smith, S. J. Jan. 12, 1928. Electric clocks.-In pawl and ratchet driving mechanism the engagement and disengagement of the pawls is effected electromagnetically. The armature 15 oscillating between the poles 13, 14 of a magnet 12 is pierced laterally at 23 to receive a wire pawl 24 which drives a fibre ratchet wheel 21 of six teeth. The armature is loose on a shaft 20 which has attached to it the ratchet and also a worm 22 which provides an irreversible drive to the clock hands. A tail piece 26 of the pawl moves near the pole 13. When the armature is attracted the pawl is drawn back and a spring 30 is stressed and near the end of this movement the piece 26 is attracted by the energized pole so that the pawl 24 is drawn into engagement with the ratchet. On the return stroke the spring 30 drives pawl 24 and ratchet 21 and an abutment 43 prevents the pawl leaving the ratchet. The pawl 27 preventing retrograde movement of the ratchet is similarly controlled magnetically. A disc 32 on the shaft 20 permits adjustment of the clock hands. The magnet, pole pieces, and shaft 20 are all mounted as a unit on a frame 18 which is attached to the remainder of the clock by a screw 19. A fibre stop 42 prevents overthrow of the armature.