Abstract: A displacing device for a swimming pool cleaner has a hollow housing with a cylindrical wall and end walls. Within the housing are two spaced partitions which divide the interior of the housing into three chambers. A first and second chamber have openings in the cylindrical wall with jet nozzles projecting therefrom. A ball is located in each of the first and second chambers which close off one opening at a time so that water then flows out of the or each other opening that is open. One end wall and the partitions each have an aperture in which a tube is slidable. The tube has holes so that water fed into the tube at one end flows through the tube and out through the holes into the first or the second chamber, depending on the position of the tube. The tube is moved up and down by an engine that does not form part of this invention. The outer end wall has a connector for connection to a source of pressurized water.