This mechanism uses a helical-groove barrel cam to generate coordinated rotation and radial travel. The green barrel contains a spiral track that forces the yellow follower gear to rotate while also moving sideways along its axis. Because the yellow gear is meshed with the pink gear, this compound motion transfers directly into a complex, time-varying rotation of the pink gear.

Components — Green barrel cam with helical groove, yellow follower gear, pink output gear, purple secondary follower, guide shafts, mounting posts, and supporting frame.

How it works — As the green barrel rotates, the helical groove pushes the red follower pin embedded in the yellow gear, causing the yellow gear to both rotate and translate sideways along the barrel¡¯s length. This compound motion alters the meshing geometry with the pink gear, producing a non-uniform rotational output. The pink gear therefore accelerates, decelerates, and subtly shifts orientation as it tracks the yellow gear¡¯s changing angle and position, creating a uniquely coordinated multi-axis movement.

Applications — Automated machinery timing units, indexing mechanisms, decorative motion displays, packaging systems, and devices needing non-uniform or choreographed rotational output.

Why it matters — Barrel cams with helical grooves allow designers to sculpt highly specific motion profiles without electronics or software. By combining rotation and translation in one follower, the mechanism can generate intricate, repeatable behavior using simple geometric curves cut into a cylinder.