Alternate flow suction dredge

In a hydraulic suction dredge, the combination of a suction tube ladder, a suction motor in said dredge, a suction head, said suction head having a neck at one end connected to said suction tube ladder and a tubular cross-head on the other end, said cross-head having an unrestricted opening at each end, a wall separating the cross-head from the neck, a central partition dividing said cross-head into two portions, passageways in said wall, one connecting each portion with the neck, an oscillatably rotatable T-shaped gate valve in said neck to manually selectively close either one of said passageways, said suction tube ladder and said cross-head converting suction developed by the suction motor into a linear force propelling the cross-head in a direction toward the open passageway, and a rotary cutter head, including augur means to advance the cross-head toward a work area, arranged on each open end of the cross-head.