This mechanism is a Geneva drive enhanced with a spring-loaded pin and a shaped guide that allows the driving wheel to extend, retract, and align perfectly with each slot of the pink star wheel. The flexible engagement smooths out the approach, prevents jamming, and produces crisp, reliable intermittent rotation.

Components — The system consists of a green driving disk carrying a radial pin connected to a blue compression spring. The spring lets the pin move axially as needed. A yellow block beside the disk contains a shaped groove that guides the pin’s travel path. Opposite this assembly sits the pink star wheel, whose evenly spaced slots receive the pin during each driving phase.

How it works — As the green disk rotates, the pin follows a controlled path shaped by the yellow groove and the spring: the groove retracts the pin slightly as it approaches the star wheel; the spring then pushes it outward at the right moment so it snaps cleanly into a slot; the engaged pin rotates the star wheel through its indexing arc; and as the pin exits the slot, the groove again pulls it inward to avoid collision with the star wheel’s solid sections.

Applications — Spring-assisted Geneva drives are used in film projectors, feeders, precision motion systems, and devices where intermittent rotation must occur with minimal shock. The added compliance makes them suitable for higher speeds and smoother engagement than traditional rigid-pin Geneva drives.

Why it matters — The combination of a flexible pin and a guiding groove eliminates harsh impacts, reduces wear, and ensures positive engagement even when alignment is not perfect. This produces accurate, stable indexing and longer component life without complicating the overall design.