Abstract: The invention relates to an apparatus for the entrenching of pipes in underwater beds, of the type in which a framework, provided with excavating means, is positioned across the pipe to be entrenched and dragged along the pipe so as to excavate two parallel trenches adjacent to both sides of the pipe, the pipe being entrenched due to the collapsing (either spontaneous or caused by disgregating means) of the bed zone thus remaining under the pipe already laid onto the bed. The excavated material is removed by means of a pump and discharged again, at a predetermined distance from and rearwardly of the framework, on the entrenched pipe. The framework is provided with side supporting skid members, by which furthermore the entrenching height is adjustable.

Abstract: An apparatus for conveying liquids mixed with solid substances to a distance is disclosed, comprising a compressed air pump formed by two or more cylindrical chambers, each provided with an inlet valve for the liquid and with a connection for the inlet and discharge of compressed air, which is cyclically and alternatively fed into and expelled from the cylinders under the control of a proper distributor, the apparatus comprising a free surface loading hopper located upstream and above the pump body, having an outlet communicating with said inlet valves of the cylindrical chambers, whereby the flow rate of the liquid arriving to the hopper is continuously compensated so as to uniformly feed the liquid by gravity to the cylindrical chambers, the apparatus further comprising at least a spare cylindrical chamber adapted to be used in substitution for one of the normally operating cylindrical chambers, for servicing and/or maintenance purposes.

Abstract: A watercraft mounted pneumatically operated dredging plant comprising a dual shovel assembly in combination with a pumping unit, the shovel assembly including two shovels, each of which has a working edge facing in a direction opposite from that of the other, and the pumping unit having at least two pumping chambers for alternately connecting one of the shovels to a source of compressed air. The shovel assembly and pumping unit in assembly being adjustably suspended from the watercraft with respect to height and with the inclination of the working edge of each shovel with respect to the vertical being controllable to effect to-and-fro dredging strokes by the shovel assembly.

Abstract: Air operated dredging apparatus comprising a submerged pumping unit adapted to be dragged along an underwater bed which unit includes at least two pumping chambers periodically filled with loose material in admixture with water entering the chamber through a duct connecting a dredging shovel to the chamber, and emptied by feeding compressed air into the said chamber. A check valve is provided on the duct upstream of the entrance to the chamber whereby escape of air through the duct and the shovel is avoided.

Abstract: An improved dredging apparatus comprising a plurality of pumping chambers, each pumping chamber having a separate inlet pipe branched off from a single intake duct, the intake duct in turn being either connected to the dredging shovel or directly adapted to take out samples from an underwater bed, the pumping chambers in operation being cyclically filled with dredged material and emptied by air pressure. The pump body is slidably mounted to a rigid frame structure, whereby the intake duct is surrounded and protected during sampling operations.