The apparatus of this invention relates to an agitating device which is to effect cleaning of metallic parts in a cleaning solution with the parts being submerged in a volume of the solution contained within a container. A valve rod is movably mounted within a housing and the valve rod is low frictionally mounted for movement by a spring biased ball bearing assembly. Pressurized air is to be selectively conducted and discharged into a piston chamber. A piston is movably mounted within the piston chamber against the action of a spring. The piston is tightly sealed with respect to the chamber wall.