Introduction to "Wild Wild West" Mechanism

The "Wild Wild West" mechanism comes from the book Karakuri: How to Make Mechanical Paper Models That Move (seen in the pictures above). This device is made entirely out of thick paper with glue holding the various pieces together.  The device works by turning the handle on the side, which is attached to a shaft with a gear on it.  This smaller gear drives a larger gear that is perpendicular to it. The larger gear is attached to the "train tracks" on the top of the mechanism, which causes the train attached the tracks to turn with the gear.  Since the tunnel and the piece in the center of the tracks are not attached to the gears, they remain place. This results in the train traveling through the tunnel and around anything placed in the center.