Geneva
A driver turns without stopping; the star moves only in steps, and holds dead still between them. Most of the motion is the holding. Drag the driver to crank it by hand.
A Geneva drive turns continuous rotation into intermittent rotation. The driver wheel never stops; once each revolution its single pin slides into one of the star’s radial slots and carries it through exactly one sixth of a turn, then leaves the slot and a locking disc cradles the star and holds it perfectly still until the pin comes round again. For two thirds of every cycle the star is doing nothing at all, which is the point of it.
The motion here is not animated by hand. The star’s angle is computed from the pin’s position in the slot, so the way it eases into the step and settles out of it is the true geometry of the linkage, not a curve I chose. The same mechanism, with the slots counted instead of timed, advances a film one frame at a time and holds each frame still long enough to be seen, which is the reason moving pictures move.
The tick ring on the star counts up one place per revolution past the fixed pointer. Drag the driver to turn it by hand and you can inch the star up to the edge of a step and feel how long it waits there. Holding still is most of what it does.