The US NAvy cryptanalytic Bombes had only one purpose: Determine the rotor settings used on the German cipher machine ENIGMA. Originally designed by Joseph Desch with the National Cash Register Company in Dayton, Ohio, the Bombes worked primarily against the German Navy’s four-rotor ENIGMAs. Without the proper rotor settings, the messages were virtually unbreakable. The Bombes took only twenty minutes to complete a run, testing the 456,976 possible rotor settings with one wheel order. Different Bombes tried different wheel orders, and one of them would have the final correct settings. When the various U-boat settings were found, the Bombe could be switched over to work on German Army and Air Force three-rotor messages.
US Navy Cryptanalytic Bombe (by brewbooks)
The Committee to Nuke Elysium 