US Patent 7213287 Swimming pool cleaner

A self-propelled swimming pool cleaner which randomly covers the bottom of the pool. Water pumped from the bottom of the unit filters dirt carried thereby, then uses the pumped water to propel the device either forward or backward. A pivoted front axle causes the path of the unit to vary when changing from forward to backward so that the unit randomly covers the entire pool bottom. Spring loaded doors may be provided to allow water to exit when the unit is lifted out of the pool. A sealed motor unit has a metal portion to transfer heat from the motor.