Expanded scale timer

Abstract

The timer motor drives a non-circular drive gear fixed on the same shaft as the final gear of the reduction gear train. The final gear is driven by a pinion which is mounted on an axially movable spring loaded jackshaft on which a large gear is mounted with clutch members on the pinion and large gear. When the timer is set the shaft carrying the driven non-circular gear and cam is depressed causing the cam face to depress the jackshaft to disengage the clutch permitting easy rotation of the cam to the desired starting point. The angular motion of the driven non-circular gear and cam is substantially logarithmic with the angular motion increasing as 'zero' is approached. When the timer is set the switch is closed to start the motor and the timed device. The lever carrying the cam follower is spring loaded to urge the follower against the cam and to take up the motion in the pin and slot pivot for the lever. When the follower drops into the notch at zero the lever pivots rapidly, hits the fixed stop and pivots about the stop using the motion in the pin and slot. This lets the striker end of the lever hit the bell and then the lever bias spring again takes up the motion to pull the lever off the bell and let the bell 'ring' while the fixed stop holds the lever off the bell. The follower is pivoted so during the initial set motion it moves to present an incline to the cam allowing the cam to push the follower out of the notch.