Derrick crane for dredgecraft.

摘要

The invention relates to a derrick-crane for a dredging vessel, having a compact operating mechanism and a hydraulic system integral with the derrick-crane and which is completely independent of the hydraulic system of the vessel on which the derrick-crane has been installed. According to the invention therefore there is provided on the one hand a hydraulic cylinder (15) which is completely accomodated within the body of the derrick-crane in its rest position and on the other hand is provided with a hydraulic-medium supply tank (34) and a pump (35) which is affixed between the supporting feet (11, 11a) and driven by an electric pump-motor (19) which can be connected to vessel's electrical system. In addition hereto, the crane's body carries an hydraulically-operated swell-compensator (22-26) on its rear side and which is also connected to its own hydraulic system and from which the displacable cable-sheave (26) moves vertically downward to a maximum payout distance (L). The hoisting winch (21) is affixed to the external underside of the derrick-crane.