Abstract: The invention relates to a dragging type head (1) of a suction dredger, the head having a driven cutting device in front of the suction tube mouth, which cutting device (5) rotates about a horizontal transverse axis and has cutting blades at its outer circumference. The main part of the cutting device (5) is enclosed by a cap (6) connected to the suction tube mouth (4). The cutting blades (e.g. 15,16,17,18,19 and 16', 17', 18', 19') are arranged in the form of several V-shaped patterns (11,12) upon the circumference with a channel digging type blade (15,20,27) at the leading top of each V. All the blades are shaped such that they move the cut material laterally towards the plane of the channel digging blades (15,20,27) and all the blades may be in the shape of a plough (28).

Abstract: A method for controlling the operation of a dredging apparatus provided with a cutting tool according to changes in at least one parameter such as soil resistance, comprises performing a working stroke with the cutting tool, measuring that parameter during that one stroke, recording the measured parameter as a function of the distance covered during that one working stroke, and regulating the hauling speed during the following working stroke according to that function. In this way, maximum permissible hauling speed can be achieved without overloading.

Abstract: The invention relates to a method of manufacturing large diameter axial sealing rings from hard-metal blocks which are placed in an annular groove said blocks being secured within said groove by filling said groove with liquid solder and circumferentially pressing the radial end faces of the blocks within said liquid solder filled groove against each other by means of radially acting clamp bolts.

Abstract: A digging wheel for a suction dredger vessel which digging wheel rotates about a horizontal axis and has at its circumference a plurality of closely spaced partly overlapping scoops while the suction mouth in the interior of the wheel has an extension which extends into the scoops and fits through the outlet of the scoops. The effective passage between the leading edge of a scoop and the outlet edge of a preceding scoop is smaller than the outlet and any further passage towards the pump is of the same or larger magnitude than the outlet of a scoop.

Abstract: A suction dredger and in particular a dredging tube having between a suction head and its connection to the hull of the vessel a motor pump unit which unit according to the invention is placed upon a frame which by pivotable joints interconnects the lower part and the upper part of the dredging tube. The frame has fenders protecting the dredging tube and in particular the motor pump unit against damage in case the dredging tube bounces against the hull of the vessel. The frame allows for easy maintenance and repair.

Abstract: The present invention relates to a seal of a shaft being rotatable relative to a stationary housing, said shaft being provided with a groove (3, 13), said groove being spiraled such that during rotation of the shaft the groove will pump fluid from the high-pressure side towards the low-pressure side. The shaft portion provided with the helical groove coacts with an abutting flexible sleeve (6) so that the amount of fluid which is allowed to escape in a controlled manner can be determined.

Abstract: A dragging type cutter head for a suction dredger has a cutting member that rotates about a horizontal axis and has at its periphery a series of cutting teeth disposed side-by-side in the axial direction. At the lowermost point in their rotation, the cutting teeth rotate in the dragging direction. The dragging head has an inlet opening for cut material, whose edges extend to the outer circle of rotation of the cutter teeth with the lower edge of that opening at the same level as the lower part of the cutting member. The cutting teeth are pivotal on horizontal axes spaced from that of the cutting member; and springs urge the cutting teeth about their axes in the cutting direction.

Abstract: A device for sucking up solid objects, such as manganese modules, from the sea bed having a suction tube within which the density of the water is reduced by feeding in to said tube form-retaining light objects by means of a vertical supply conduit filled with air under high pressure through which the light objects fall down to enter the suction tube through a water slot, the said supply conduit being connected at its lower and upper end to an air filled return conduit to form a closed circuit, mechanism being provided to generate a downward flow of air in said supply conduit.