Movement No. 67 presents yet another modification of the jumping intermittent motion concept first introduced in Movement No. 64 — this time using a weight or tumbler E secured directly on the hollow shaft, operating in combination with pin C in the worm-gear shaft. Where No. 64 used a spring and specially shaped cam, and No. 66 used a weighted arm attached to the worm-gear shaft, No. 67 takes a different structural approach: the weight or tumbler E is fixed to the hollow shaft itself — the output shaft that carries the intermittent motion. The worm-gear’s pin C interacts directly with this hollow shaft tumbler. As the worm-gear slowly rotates via the worm drive, its pin C engages the tumbler E on the hollow shaft and carries it along, lifting the weight to a position of unstable equilibrium — past the tipping point. At this critical moment, the tumbler and the hollow shaft are free to fall under gravity independently of the worm-gear, snapping forward rapidly until the weight settles at its new lowest position. The hollow shaft thus receives a sudden rapid rotational impulse — the characteristic jumping motion — before coming to rest and waiting for pin C to catch up and restart the cycle. Compared to No. 66, where the weight arm was fixed to the worm-gear shaft and rotated with it, in No. 67 the tumbler is on the hollow shaft — the driven element — giving the output shaft a more direct and vigorous snap action as the tumbler’s own mass drives the output shaft forward during the falling phase. This series of three modifications (No. 64, 66, and 67) elegantly demonstrates how the same snap-action intermittent principle can be realized through spring-cam, weighted drive-shaft arm, and hollow-shaft tumbler configurations respectively.
67. Another modification of 64; a weight or tumbler, E, secured on the hollow shaft, being used instead of spring and cam, and operating in combination with pin, C, in the shaft of worm-gear.