GB694954A - Control device for the dredge-tube suspension cables of a suction dredger - Google Patents

Abstract

694,954. Dredgers. ATELIERS ET CHANTIERS DE BRETAGNE ANCIENS ETABLISSEMENTS DE LA BROSSE ET FOUCHE. Feb. 3, 1950. [Dec. 7, 1949] No. 2887/50. Addition to 662,345. Class 113 (ii). In a control device for the suspension cables of a suction dredger dredge-tube, as claimed in the parent Specification, the winding drum for the cable hoisting the knee of the dredge tube is driven in unison with the other cablewinding drums (the clutch of the parent Specification being eliminated), said firstmentioned drum being equal in diameter to the smaller sections of said other drums, and utilising a weighted pulley to take up slack which tends to form in the knee-hoisting cable. The latter cable passes through a tackle-block carried by the supporting arm 20, over a sheave 27 of the movable part 17 and a sheave 28 of the fixed frame 16 of the davit, under a movable sheave 76, over a fixed sheave 77, and a sheave 34 to the winch. The movable sheave 76 carries a counterweight 78 slidable between guides 79 and having an extension 80 to limit upward movement by abutment against a fixed part 81. To sink the dredge-tube from the fully raised position shown in dotted lines in Fig. 4, the counterweight 78 being in its uppermost position, the winch is walked back so that the movable parts of the davits swing to ease the tube overboard and thereafter the tube is lowered horizontally since all the winding drum sections are equal in diameter. When the knee arrives opposite the intake aperture in the ship's side, its downward movement is arrested while the cables relating to the other parts of the tube ride on to the larger sections of their winding drums so that the tube is tilted downwards. The kneehoisting cable continues to be paid out by its drum and the slack is progressively taken up by the simultaneous lowering of the counter weight 78. Conversely, on hoisting the dredgetube on deck, while the tube is returned from its tilted to its horizontal position the counterweight 78 is lifted to its uppermost position, and the tube is then lifted horizontally on to the deck.