Videos, photos and descriptions are here: http://sunnyslopeorchard.blogspot.com/2013/12/our-mobile-chicken-coop.html Two unique features of this coop are its simple lever action to lower the wheels/ raise the coop for moving, and its automatic door to the roosting enclosure. The wheels are two cheapo pneumatic wheels from Harbor Freight. As the video shows, they are mounted on short 5/8" steel spindles that are welded to 1" x 2" channel iron. The channel iron on one side is approx 4' long to serve as a lifting lever. The channel is only about 6" long on the opposite side of the coop. The channel pieces are attached to a 5/8" steel shaft that runs the width of the coop. This shaft is offset 4" from the wheel spindles, so when the lever is rotated 90 degrees the coop lifts 4'' off the ground. The wheels are just behind the balance point of the coop, so once raised it is easy to lift the front of the coop by its handle and pull it around.
I wanted an automatic door for the secure overnight roosting box, and since the coop is mobile it had to operate on 12 volts. So I settled on a used automotive power window controller purchased on ebay. This one was from a Honda Civic. It does not come with switches to limit its travel, so I had to add momentary contact switches for that function. The door is powered by a 12v battery for an automatic gate opener (Lowes). A battery operated Amico model CN101A digital timer (Amazon) controls the automatic opening. A DPDT relay in the circuit allows separate manual operation of the door so I can close it with a switch at night and also open it manually if needed. A cheap 1/2 watt solar panel (Harbor Freight) on the coop roof keeps the 12V battery charged.