Patent ID: 7165691

Claim:
A counterweight attaching and detaching apparatus for a crane, the apparatus comprising: a lower traveling body; an upper rotating body rotatably mounted on the lower traveling body; a gantry serving as a boom raising device provided in the rear of the upper rotating body to be movable up and down; a suspension member hanging from the peak of the gantry; a plurality of weights arranged in the front-rear direction to constitute a counterweight placed in a vertical position, and each of the weights respectively having a ring to which the suspension member is fastened; and a mechanism that sequentially attaches or detaches the weights to or from a rear end of the upper rotating body by moving the gantry up and down while the suspension member is sequentially fastened to the ring of each of the weights, wherein the suspension member includes an extendable member that extends and contracts to vertically move the weights, and a link detachably connected to the extendable member, wherein the distance provided between the peak of the gantry and the upper surface of each of the weights when the gantry is suspending each of the weights at a respective mounting position varies depending on the mounting position, and the length of the suspension member is adjusted by the extendable member and the link in accordance with the distance, and wherein at least three different amounts of protrusion of the rings from the upper surfaces of the weights are set so that the amount of protrusion of the ring of the forefront weight close to the upper rotating body is the largest and so that the amount of protrusion of the ring of the rearmost weight is the smallest in order to complement the adjustment of the length of the suspension member.