Hooks and Shackles

Thimble When an eye is made in a wire rope, a metal fitting, called a thimble, is usually placed in the eye, as shown in figure 13-23. The thimble protects the eye against wear. Wire rope eyes with thimbles and wire rope clips can hold approximately 80 percent of the wire rope strength. After the eye made with clips has been strained, the nuts on the clips must be retightened. Checks should be made now and then for tightness or damage to the rope caused by the clips. Swaged Connections Swaging makes an efficient and permanent attachment for wire rope, as shown in figure 13-25. A swaged connection is made by compressing a steel sleeve over the rope by using a hydraulic press. When the connection is made correctly, it provides 100-percent capacity of the wire rope. Careful inspection of the wires leading into these connections are important because of the pressure put upon the wires in this section. If one broken wire is found at the swaged connection or a crack in the swage, replace the fitting. Hooks and Shackles Hooks and shackles are handy for hauling or lifting loads without tying them directly to the object with a line, wire rope, or chain. They can be attached to wire rope, fiber line, blocks, or chains. Shackles should be used for loads too heavy for hooks to handle. When hooks fail due to overloading, they usually straighten out and lose or drop their load. When a hook has been bent by overloading, it should NOT be Figure 13-25.-Swaged connections. straightened and put back into service; it should be cut in half with a cutting torch and discarded. Hooks should be inspected at the beginning of each workday and before lifting a full-rated load. If you are not sure a hook is strong enough to lift the load, by all means use a shackle. Hooks that close and lock should be used where there is danger of catching on an obstruction, particularly in hoisting buckets, cages, or skips, and especially in shaft work. Hooks and rings used with a chain should have about the same strength as the chain. The manufacturers’ recommendations should be followed in determining the safe working loads of the various sizes and types of specific and identifiable hooks. All hooks for which no applicable manu- facturers’ recommendations tire available should be tested to twice the intended safe working load before they are initially put into use. Mousing is a technique often used to close the open section of a hook to keep slings, straps, and similar attachments from slipping off the hook, as shown in figure 13-26. Hooks may be moused with rope yarn, seizing wire, or a shackle. When using rope yarn or wire, make 8 or 10 wraps around both sides of the hook. To finish off, make several turns with the yarn or wire around the sides of the mousing, and then tie the ends securely. Two types of shackles used in rigging are the anchor (Fig. 13-27) and the chain (fig. 13-28). Both are available with screw pins or round pins. Shackles should be used in the same configuration as they were manufactured. Never replace the shackle pin with a bolt. when the original pin is lost or does not fit properly, do not use the shackle. All pins must be straight and cotter pins must be used or all screw pins must be seated. A shackle should never be pulled from the side, because this causes the shackle to bend which reduces the capacity tremendously. Always attach a screw pin Figure 13-26.—Mousing. 13-12