CRANE OVERLOAD PREVENTIVE DEVICE, AND ITS REGULATING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a crane overload preventive device which is capable of obtaining the load of a lifted cargo with excellent accuracy and excellent in reliability. SOLUTION: An overload preventive device comprises a controller 23 in which the boom derricking force detected by a load meter 22, a boom angleθb detected by a boom angle meter 21 and the rope tension in hoisting ropes 10 detected by a rope tension meter are inputted. The self-weight component of a boom 3 is subtracted from the boom derricking force to obtain a first load of a lifted cargo, this first load is divided by the rope tension T obtained from the value detected by the rope tension meter, and the integer part of the value obtained through the division is set to be the number of the hoisting ropes 10, the rope tension T is multiplied by the rope number N to obtain the second load of the hoisted load, and this second load of the hoisted load is compared with the rated load.