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A hydraulic actuator comprised of a toroidal piston within a toroidal enclosure, with differential fluid pressure alternatively applied to upper and lower surfaces of the piston to cause a reciprocating motion, and with plural double ended piston rods extending in parallel above and below the piston, and slidably extending in fluid sealed relation through end caps of the toroidal enclosure to distribute the vibrational force produced by the reciprocating piston over plural points of a surface area of the mass to be vibrated, thereby reducing the likelihood of stress, strain, or harmonics in the mass.anation: