Abstract: The invention relates to a swimming pool cleaner which is intermittently-turned from its path of travel along an underwater surface. A pair of side wheels (3) connected to be driven by a turbine (8) to move the cleaner in a direction of travel. A cam (12) is provided inwardly of and adjacent to each of the wheels. The cams are rotatably mounted on the wheel axles (5). Each cam intermittently extends a gripping formation (13) beyond the operatively supporting surface of the wheel. 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. The cams are preferably arcuate, with at least one radial gripping formation. The rotation of the cams is opposite to that of the wheels and they are driven in a cycle retarded relative to that of the wheels. The gripping formations are removably securable for adjustment on the cams.