A cam with bent up "tripping points" is mounted on the third wheel, moves a trip spring up and down, blocking and releasing the alarm hammer. This patent was used in the Alternating Alarm.
A cam with bent up "tripping points" is mounted on the third wheel. These projections engage with a spring mounted on the front plate. One end of the spring is mounted to the front plate with a screw through a pillar. The other end of the spring has a projection which moves into and out of the path of a tail on a hammer.
William S. Hawthorne, of Peru, Illinois, Assignor To The Western Clock Manufacturing Company, Of La Salle, Illinois, A corporation of Illinois.