Your mystery item is part of the adjustment mechanism for
roller conveyor guide rails. In a packaging plant, think of
the roller conveyors where boxes (sealed on the bottom and 
open on the top) move around a plant to receive some sort of
product in them. These roller conveyors have guard-rail like
attachments that keep the boxes from going off the sides of
the conveyor. When the box is nearing the filler that will
put product in them, the position of the box relative to the 
filler is important; nylon rods then take the place of the
guard rails and are used to maneuver the box into just the
right position.

The nylon rods contact the indentations in your gizmo, and, 
as it's turned, the gizmo moves the rails in or out (depending
on which way it's turned), allowing for minor adjustment to 
the box position.

This same thing is also used on corrugated boxmaking machinery
to adjust nylon folding rods that fold the cartons during
manufacture.

Sorry it couldn't be something more bizarre or exciting.

Cheers