Fig. 3 (a) is a schematic diagram of a heavy lifting rod device. Compared with the light hanger device, it is mainly in the head of the derrick, the root and the hanging cargo cable three different aspects. The head of the heavy Derrick does not use a boom hoop and its head device is shown in Figure 3 (B). In most cases, the Derrick seat is arranged directly on deck or platform, as shown in Figure 3 (C).
The cable is not parallel to the boom, the hanging cable through the head of the hanger rod embedded in the pulley and lifting pillar of the guide pulley, and then quoted to the landing winch, this reduces the axial pressure of the derrick.