Automatic swimming pool cleaners of various types are widely known. One group of these has driven wheels, which carry them across submerged surfaces. They may either be suction or pressure operated.
As with all such automatic cleaners, the ongoing quest is to provide random navigation, without a repeated pattern, and to avoid the cleaner getting trapped against obstacles.
U.S. Pat. No. 6,782,578 which is limited to a pressure operated pool cleaner suggests at temporarily lifting one wheel or propping one side of the cleaner away from the pool surface to interrupt synchronous rotation of first and second wheels on the pool surface. The suggestion is anticipated by U.S. Pat. No. 5,197,158. The earlier patent discloses a random travel mechanism, located centrally between front and rear wheels and to one side of the cleaner. The mechanism periodically lifts the wheels on that side to cause a skewing of the direction of travel. These teachings with regard to such steering or interrupting mechanisms are respectively insufficient and complicated. From a commercial point of view, it is submitted that there remains room for improvement.