Actuator Plunger-Shaft Coupling With Undercut Locking

The connection interface is segmented into two distinct features: an undercut geometry on the plunger and a corresponding recess on the shaft. This segmentation allows each component to contribute a specific geometric feature that together creates a robust mechanical interlock, eliminating the need for separate fastening elements that would be subject to fatigue.

The connection interface uses asymmetric geometry where the undercut on the plunger creates a one-way mechanical lock that prevents both axial and rotational movement. The asymmetric shape of the undercut relative to the shaft recess creates a geometric constraint that is inherently more reliable than symmetric fastening methods like clips or threaded interfaces.

The undercut geometry is pre-formed on the plunger during manufacturing, creating a built-in positioning feature that automatically establishes precise alignment when assembled with the shaft. This preliminary geometric constraint eliminates the need for post-assembly adjustment or complex fixture systems to achieve precise dimensional control.

The undercut-recess interface serves multiple functions simultaneously: it provides mechanical retention, prevents rotation, and establishes precise dimensional alignment. The geometry itself performs the alignment function without requiring additional alignment features, fixtures, or adjustment procedures, making the assembly process self-aligning.