The dragline component (fig. 12-32) consists of a dragline bucket and fairlead assembly. The wire rope components of the dragline are the drag cable, the bucket hoist, and the dump. Once a crane is rigged with a dragline, the crane is referred to by the name of the attachment,
When you are loading the bucket, the fairlead (fig. 12-33) guides the drag cable onto the hoist drum. The hoist wire rope, which is reeved through the boom point sheaves, raises and lowers the bucket.
On some model of cranes, you must make sure the fairlead is in a vertical position when lowering the boom to avoid bending the cords of the boom base.
Figure 12-31.-Tag line winder.
When changing attachments from hook block or clamshell to dragline, check the operator's manual for the lengths and diameter size of wire rope required for dragline operations. The pulling force of the dragline
Figure 12-30.-Clamshell rigging configuration.
Figure 12-33.-Dragline fairlead.
normally requires a larger diameter drag cable. The length of the hoist wire rope is also shorter than normal to avoid cross winding on the hoist drum. The drag cable pulls the bucket through the material when digging. When the bucket is raised by the hoist wire rope and moved to the dump point, dump the bucket by releasing the tension on the drag cable.
NOTE: Do not lubricate the drag cable. If the drag cable is lubricated and pulled through the dirt, it retains the dirt, which causes damage to the wire rope.
The construction industry rates dragline buckets in different types and classes. The types and classes are as follows: . Type I (light duty)
. Type II (medium duty)
. Type III (heavy duty) . Class P (perforated plate)
. Class S (solid plate)
The most common buckets used by the Navy are the type II, class S buckets. Class P buckets are available for dredging operations. Figure 12-34 shows the makeup of a drag bucket.