 Welcome to General Shop Safety, Rigging and Lifting. In this lesson, we will introduce machine shop students to basic lifting and rigging techniques. We will review the required equipment and explore safe operating procedures. This information is not intended to show the student how to perform rigging and lifting, but to help him or her recognize safe and unsafe rigging and lifting practices. Rigging is the preparation of a load prior to being moved. In this unit, we will concentrate on cable sling rigging, chain sling rigging, and synthetic web slings. You can read the following information at your own pace. Click the next button to proceed to the next page. A sling is a synthetic webbing designed in a configuration for hoisting, lifting, and lowering applications. Cable slings or wire rope slings are made up of individual strands of wire. The number of strands and wires, the type of material, and the nature of the core will depend on the intended purpose of the wire rope. We must always determine the weight of the load before we begin selecting the sling type. As with any rigging and lifting efforts, we visually inspect all cable slings before use. Remove from service if the following conditions are present. 10 randomly distributed broken wires in one rope lay, or 5 broken wires in one strand in one rope lay. Wear or scraping of outside wires reducing the individual wire diameter by one third. Kinking, crushing, birdcaging, or any other damage resulting in distortion of the wire rope structure. Evidence of heat damage. End attachments cracked, deformed, or worn. Corrosion of rope or end attachments. Safety precautions. A cutting edge cuts the life of the sling. Use blocking, padding, or a corner saddle when the cable must go around sharp corners. Remove any kinks in the sling before using. Use a sling large enough for the load. The smaller the angle of the sling, the lower the lifting capacity. Do not jerk loads. Jerking may double the stress on your sling. Lift loads gradually. Hang the sling up after every use. This will help to keep it clean, undamaged, and ready for use for the next job. Try to avoid using chains when it's possible to use wire rope. The failure of a single link of a chain results in the complete failure of the chain, whereas a cable is made up of many wires and strands, and they must all fail before the rope breaks. Chains give no warning as to when they are going to fail. A wire rope will show visible signs of impending failure. Chains are better suited for certain jobs as they will withstand rougher handling and they won't kink. Chains are much more resistant to abrasion and corrosion than wire ropes are. Chains are well suited as slings in the machine shop for lifting heavy castings. Use the following chain safety tips as a guide. Take up slack, then start to load slowly. A chain has no elasticity and does not react well to shock loading. Never shorten a chain by tying a knot in it. A chain has its maximum strength with the load running in a straight line. Always use softeners on the corners of rectangular loads. Lift from the center of hooks. Avoid lifting from the point of the hook. Distribute the load evenly on all legs. Inspect chains regularly. Look for elongated links. Never exceed the estimated rating capacity of the chain. And don't drop loads onto the chain. Synthetic web slings are used extensively in the machine shop for rigging purposes because they are easy to use and they won't mar or scratch finished surfaces. Web slings are usually made of nylon or polyester. Nylon has a stronger rating than polyester does. Synthetic web slings, because of their flexibility and elasticity, are a very popular rigging tool. The material with which these synthetic slings are made allows them to be flexible, but it also makes them susceptible to heat and sharp edges. Synthetic web slings must be well taken care of, and the user must always be aware of sharp corners, welding sparks, and metal chips. Slings used in environments where they are subject to continuous exposure to ultraviolet light should be proof tested to two times the rated capacity annually, or more frequently depending on the severity of exposure. The double choker hitch seems to be preferred by many good riggers because it is twice as strong as a single choker hitch in the same sling type. Basket hitches, whether single or double, may be used successfully in a variety of applications. However, they have inherent limitations as indicated in Figure 7. Slings vary in physical dimensions, shape, and weight. Where and how to attach slings is important to a rigger. In a contact sling hitch, the sling passes entirely around the load. In its simplest form, the sling has a loop or eye on each end, and is referred to as a choker sling or choker. One loop passes through the other, forming a slip noose. Where overhead space is limited, a double wrapper choker hitch is acceptable. One of the useful hitches available to riggers is the adjusting hitch. It is particularly useful when lifting an object that is heavier on one end than the other. The adjusting hitch makes it fairly easy to adjust the length of the legs of the bridle to maintain the load level. This hitch should not be loaded any more than a single basket hitch. The effective length of the adjusting hitch can be easily changed to suit job conditions. Once the weight of the load comes onto the sling, no further change in length occurs. Lifting should only be done by a certified lift or crane operator. Before a lift can be used, the operator must know all of the functions of the lift. Although this unit of instruction is not intended to show you how to operate a crane or hoist, here are some safety tips to adhere to while around lifting devices. Start and stop any lift slowly. Lift the load straight up to ensure that the load does not swing. When raising, lowering, or moving the load, ensure that it will safely clear nearby equipment. Make all moves slowly to prevent swinging. Personnel are not permitted to ride on the hook or the load. Make certain that no personnel are ever permitted to pass under a load. Under no circumstances are side pulls permitted. Make sure that the rigging and the hoist will handle the specified load weight. Signals for crane movement are only given by one person. Here are signals for crane movement. Hoist, with the forearm vertical and forefinger pointing up, move the hand in a small horizontal circle. Lower, with the arm extended downward and forefinger pointed down, move the hand in a small horizontal circle. Fingers travel, with the arm extended forward and hand open and slightly raised, make a pushing motion in the direction of travel. Trolley travel, with palm up, fingers closed and thumb pointing in the direction of motion, jerk hand horizontally. Stop, with arm extended palm down, move arm back and forth. Easy stop, both arms extended, palms down, move arms back and forth. Multiple trolleys, hold up one finger for block mark one and two fingers for block mark two. Regular signals follow. Move slowly, use one hand to give any motion signal and place the other hand motionless in front of the hand giving the signal. The signal in the picture shown is hoist slowly. You have completed this activity, general shop safety rigging and lifting.