Patent ID: 6079576
Filing Date: 2000-06-27
Classification: B66D

Abstract:
Control device for a hoist mechanism of a crane, installed with a jib arranged to be varied in length and luffed by a luffing ram, comprising:a hydraulic motor driving a hoist mechanism drum, said hydraulic motor arranged to form a closed hydraulic circuit together with a hydraulic pump, wherein a hoist rope is wound by said hoist mechanism drum,an overload safety unit having a storage for storing measurement values of pressure of hydraulic oil in the luffing ram, angle of the luffing ram and length of the jib, anda processing unit arranged to control pumping capacity by comparing hydraulic pressure in the hydraulic circuit with a moment value of the hoist mechanism drum,a drive shaft coupled to said motor and drum,a brake pulley disposed along said motor and drum and arranged to lock said drum,high pressure lines coupling said motor and pump with a pressure gauge positioned in one of said lines and arranged to constantly feed signals to said processing unit,an engine arranged to drive said pump, anda hoist mechanism which provided with a counter or incremental transducer to determine current winding position of the hoist rope,wherein the moment value of the hoist mechanism drum is determined by the pressure of the hydraulic oil in the luffing ram, the angle of the luffing ram and the length of the jib stored in said overload safety unit.