The artist describes this machine:
In a deliberate escalation beyond Victor Rat Traps Nos. 1 and 2, this one is powered by not one, but two rat traps! Both springs are connected by a steel rod, which is attached to a Swiss cheese-like structure that has a cord wrapped around its edge. (The "cheese" is mounted off-center so as to even out the pull on the cord over the full range of the springs' travel.)
This cord pulls the springs back, and through an arrangement of pulleys, connects to a crank-wound gearbox on the right. The gearbox's output shaft connects to a vertical shaft running through a support structure, on top of which is a 'planetary gear' arrangement with two hollow spheres attached.
When the vertical shaft rotates, not only do the "planets" rotate about their own individual axes, they also orbit around the central shaft (hence the origin of the term 'planetary gear'). Connected to the main gearbox is a second gearbox that operates a small fan which not only helps control the speed of the machine through air resistance, it creates a unique whirring sound.
While the machine only runs for about 30 seconds, it's quite interesting to watch, for the movement is reminiscent of a medieval astronomical orrery.
See more amazing mechanical creations from Edmund Dohnert on his web site.