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US 3,949,496 AGranted
Wave compensating system for suction dredgers
OwnerJan de Konig, Romke VAN DER Veen +1inventors
InventorsJan de Konig, Romke VAN DER Veen, Tjako Aaldrik Wolters
Life of this patent
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Abstract
A suction dredger, comprising a vessel and a suspension conveying conduit provided with a pump and having a nozzle suspended by means of at least one cable of a lifting device on the vessel is improved for preventing breaking of the cable or damage of other dredger parts. To this aim the lifting device comprises a cable length variator delivering cable and each time hauling essentially all delivered cable in work condition with a high cable tension being lower than the inadmissible cable tension, but being higher than a predetermined low cable tension, in order to prevent an inadmissible cable tension during a downward ground reaction upon the nozzle.
Claims5
A suction dredger comprising, in combination:
- a buoyant hull and a suction dredging system associated therewith, said suction dredging system including a nozzle adapted to be inserted into the bottom below the hull, and flexible conduit means connected to said nozzle for conveying dredger spoil to a discharge region;
- winch means on said hull for supporting said nozzle and including at least one cable connected to said nozzle and a motor to operate the winch means for hauling in and paying out said cable whereby to locate said nozzle at a desired depth below said hull;
- a first piston/cylinder device one member of whose piston and cylinder members is connected with said cable to reciprocate as said hull rises and falls while said nozzle remains at said desired depth, a first fluid pressure accumulator chamber connected with said device and acting on said one member continuously to urge it in that direction required to haul in said cable whereby to maintain tension of at least a minimum value on said cable even when said hull falls to the lowermost point in the trough of a wave and to exert an increasing tension on the cable as said hull thereafter rises, the pressure in said first fluid pressure accumulator being such that when said one member approaches its end of stroke position responsive to rising of said hull, the tension on said cable is less than a predetermined maximum value;
- and
- a second piston/cylinder device one member of whose piston and cylinder members is connected with said cable to reciprocate as said hull rises and falls, a second fluid pressure accumulator chamber connected with said second device and acting on said one member thereof continuously to urge it in that direction required to haul in said cable, the pressure in said second fluid pressure accumulator being such that said second device is operable only in response to tension in said cable which exceeds that value prevailing when said one member of the first device reaches said end of stroke position, and the stroke of said one member of the second device being such that at its end of stroke position the tension on said cable is still less than said predetermined maximum value.
2 more elements
A suction dredger comprising in combination:
- a buoyant hull and a suction dredging system associated therewith, said suction dredging system including a nozzle adapted to be inserted into the bottom below the hull, and flexible conduit means connected to said nozzle for conveying dredger spoil to a discharge region;
- winch means on said hull for supporting said nozzle and including at least one cable connected to said nozzle and a motor to operate the winch means for hauling in and paying out said cable;
- and
- tension control means associated with said cable for maintaining tension in said cable greater than an inadmissible minimum tension when the hull falls in the trough of a wave and for maintaining tension in said cable less than an inadmissible maximum tension when the hull rises on the crest of a wave, said tension control means comprising:
- compensating means engaged with said cable for paying out and taking in cable between said winch means and said nozzle as said hull respectively rises and falls due to wave action, said compensating means including at least one piston/cylinder device having relatively movable piston and cylinder members, a fluid pressure accumulator chamber connected with said device and means connected to one member of said device and engaged with said cable whereby said one member reciprocates between stroke end limits respectively as the hull rises and falls with pressure in said accumulator chamber continuously acting on said one member in that direction required to haul in cable;
- and
- tension-modifying means independent of said motor of the winch means for allowing said cable to be payed out in excess of that amount permitted by the effect of said compensating means alone.
4 more elements
Dependencies are inferred from the claim text.