LBS groove is composed of straight line groove and diagonal line groove in each cycle of the drum, and the position of the straight line groove and diagonal line groove in each circle is exactly the same and alternate.

When the wire rope is winding in multiple layers, the position of the cross transition point between the upper wire rope and the lower wire rope is fixed through the diagonal rope groove, so that the cross of the upper wire rope is completed in the diagonal section. In the linear rope groove section, the upper rope completely falls into the groove formed by the two lower ropes, and line contact is formed between the ropes, so that the contact between the upper and lower ropes is stable. When returning the rope, with the ladder stop ring with the return flange at both ends of the drum, guide the wire rope to climb and return smoothly, avoid the chaos caused by the wire rope due to mutual cutting and extrusion, so that the wire rope is arranged neatly and smoothly transition to the upper layer, to achieve multi-layer winding.