Crane lifting hook rotation often occurs in the lifting operation of the equipment without any warning. When the lifting device lifts the heavy object, the hook rotates and wraps around the wire rope between the hook and the top pulley block of the boom. The heavy objects that are lifted also rotate with the hooks, and it is no longer possible to continue lifting or lowering the heavy objects that have been lifted. The rotation of the hook will affect the normal operation of the lifting operation, which seriously threatens the safety of the workers and equipment, so it must be avoided.
The reasons for the rotation of the crane lifting hook are the internal and external factors of the crane, and the internal cause of the rotation of the hook is also the root cause of the occurrence of the hook.
Regardless of the type, specification, and grade of the wire rope used by the crane, torque is generated when the force is applied. Torque is caused by the way the wire is made. First, the wires are twisted together to form strands, and then several strands are twisted together to form a wire rope. When the force is applied, the wire and the strand are straightened, but the end of the wire rope is fixed during the lifting operation, so that the torque is formed in the wire rope. Another source of torque is that the wire rope becomes longer after a period of use, so that when the end is fixed, the wire rope is unstressed to generate torque, and the presence of torque causes the crane lifting hook assembly to rotate. .
On the other hand, there are many external factors that directly cause the crane lifting hook to rotate. For example, the external force such as manpower or wind force during the lifting process pushes the hook to rotate. The driver's operation is unstable, so that the crane lifting hook and the weight swing to cause the crane lifting hook to rotate, and the hook is wound. The hook is unbalanced, causing the crane lifting hook to rotate.