The surface of the single-layer winding wire rope drum is cut with a spiral groove with an arc-shaped section to increase the contact area between the wire rope and the drum body, and to fix the winding position of the wire rope on the drum to avoid the influence of adjacent wire ropes rubbing against each other.

The surface of the drum body of the multi-layer winding drum is usually a smooth surface without spiral grooves, and there are flanges at both ends of the drum body to prevent the wire rope from slipping out. The disadvantage is that the wire ropes are closely arranged, and the layers are stacked and rubbed against each other, which has a great impact on the life of the wire rope.

Among the structural dimensions of the reel, the key dimension that affects the life of the wire rope is the calculated diameterof the reel.

In order to ensure the reliable fixation of the wire rope tail and reduce the stress on the pressure plate or wedge, when the pick-up device is lowered to the lower limit position, in addition to the fixed loop of the wire rope, 1.5 to 3 safety loops should be reserved on the reel.

Known as the load-relief ring, this has been taken into account in the design of the reel. In use, the more loops of the wire rope tail are retained, the smaller the force on the pressure plate or wedge of the rope tail, and the safer it is.

If the lower limit position of the pick-up device is too low and the remaining number of wire ropes on the drum is less than the designed number of safe loops, the force on the tail of the wire rope will exceed the pressing force of the pressure plate or wedge, resulting in the wire rope was pulled off and the heavy object fell.