Abstract: A dragged suction dredger, comprising a suction pipe provided with a dragged suction head having a housing with a recessed suction nozzle and a cutting tool extending, in the cutting position, into the ground and being pivotally mounted on the housing and being held in the cutting position by holding mechanism which will deflect at the transgression of a predetermined load of the cutting tool, has the object to avoid loss of time during the dredging operations and inefficient dredging. For this purpose the holding mechanism comprise at least one fluid cylinder for pushing the cutting tool after a deflection back into the cutting position or into the holding position respectively, the fluid pressure of said fluid cylinder being subjected to the action of a gas cushion.

Abstract: Rigid pipe sections of a dredger are pivotally connected to allow universal movement therebetween and a flexible, elastic bellows communicates the adjacent ends of the pipe sections. The bellows in its free state is prestressed so as to be under compression and is further compressed when in place between the ends of the pipe sections.

Abstract: A separating device for separating substances from a liquid to be purified includes a tank having opposing end walls spaced from each other and a separator, comprising two parallel inclined plates spaced from each other, in the tank. The separating device also includes an inlet in one end wall of the tank for the liquid to be purified, a first outlet in the other end wall of the tank for the purified liquid, and an overflow between the first outlet and the separator. The one end wall of the tank and the one of the two parallel plates closest to the one end wall are spaced throughout their extent from each other and define a space therebetween to substantially eliminate turbulence of the liquid to be purified before entering the separator. The separating device also includes a second outlet from said space for substances to be separated that are lighter than the purified liquid. The second outlet is in the upper end of the one end wall of the tank above the inlet.

Abstract: In a method of measuring a pressure of a suspension, for example, slush, wing through a suspension conduit, in which the pressure is transferred through a water-filled sensing duct, whose nozzle opening out in the suspension conduit is rinsed with water, to a pressure pick-up whose output signal is fed to recording and/or display apparatus, the sensing duct and/or the nozzle may become clogged, for example, by the deposition of algae of the rinsing water or the deposition of solid substance from the suspension.In order to render the measurements more reliable the pressure is detected in a sensing zone withdrawn out of the suspension stream, where the risk of deposition of solid substances is limited, while the pressure is detected in consecutive measuring cycles, each including a rinsing phase and a pick-up phase of longer duration than the rinsing phase.

Abstract: A cutting-head suction-dredger comprises a floating body, a ladder and a cutting-head carried by the lower end of the ladder. The ladder supports against the floating body through a rail guide which is adapted to tilt with respect to the floating body and which extends in the direction of length of the ladder. This prevents that the engagement of the cutting-head upon the ground is disturbed during heaving movements of the floating body.

Abstract: In a suction dredger, the connection between the water tube flange and the water duct flange is more reliable in operation, if the slush tube is adapted to turn by means of a rotary gland with respect to the slush tube flange to be rigidly coupled with the floating body, with the slush tube flange being connected through an arm with a water tube piece, while the water tube piece is connected through a flexible tubing with the water tube.

Abstract: A dredging pipe assembly includes at least two rigid sections physically connected together by a cardan joint and connected for fluid continuity by a pair of flexible sections disposed in spaced apart relation with the cardan joint between them. A flexible duct serving additional equipment bridges the cardan joint without interfering with the flexible sections.

Abstract: In an apparatus for collecting light-weight substance floating on a liquid the light-weight substance is sprayed with the aid of a liquid jet into an accumulator tank in that the light-weight substance lands together with the liquid jet as a downward stream about a lower edge of the open bottom of the tank into said tank.In order to keep the liquid jet effective the disintegration of the liquid jet is prevented. To this end the liquid jet is guided above the layer of light-weight substance along a bar or similar guide means.

Abstract: Method of collecting light-weight substance floating on a liquid surface, for example, oil floating on water, said light-weight substance being carried into a collecting reservoir, in that on the outer side of a wall of the collecting reservoir extending below the liquid surface, away from the liquid surface, a down-stream is produced by which the light-weight substance with liquid is passed beneath an edge of the wall located beneath the liquid surface and into the collecting reservoir, after which the light-weight substance rises up in the reservoir to the liquid surface, where it is collected, while the liquid is conducted away through at least one outlet near the bottom side of the collecting reservoir.