The term "double fold line wire rope groove" currently popular in the lifting industry in China refers to a type of steel wire rope suitable for multi-layer production introduced from abroad winding rope groove form. Due to the fact that this type of rope groove remains parallel to the flange end face in most sections of the drum circumference, only in a very small area the section intersects with the flange end face, so the rope groove will inevitably experience bending, hence the name "double fold line rope groove" and make it for a specialized rope winding technique.
A typical lebus built drum is composed of a welded plain drum and a welded grooved shell. In the event of a malfunction, simply replacing the sleeves can greatly save costs and reduce expenses.