The invention relates to a swimming pool cleaner with wheels driven by a turbine. The pool cleaner is intermittently turned from its path of travel along an underwater surface. A turning cam is provided inwardly of and adjacent to each of a pair of the side wheels. The cams are rotatably mounted on the turbine driven wheel axle which extends between said wheels. Each cam intermittently extends a gripping formation beyond the operatively supporting surface of the adjacent wheel. The cams will preferably comprise a disc with an integral annular internal ring gear formed. An inner gear is fixed for rotation with the axle and an outer gear is supported between the inner gear and the ring gear to rotate the cam. The inner gear is an interrupted gear member to cause intermittent stepwise rotation of the ring gear and the outer gear is a sprocket supported for unidirectional rotation. The cams and gripping formations are arranged so that, when they engage the pool surface, they impart movement to the cleaner which is in the opposite direction to the direction of travel.