When you need to create a loop at the end of a piece of wire rope-like for a crane choker or a permanent guy wire-you use wire rope clips (often called Crosby clips). It is one of the most common rigging tasks in heavy industry, and it is also one of the most frequently butchered. The fatal error stems from a simple misunderstanding of how the clip mechanically grips the cable.
A wire rope clip consists of two parts: the U-bolt and the saddle. The rule that is drilled into every rigger's head is "Never saddle a dead horse." It is a catchy mnemonic, but if you don't know which part is the horse and which is the dead, it is useless.
The "live" end of the wire rope is the long, main part of the line that is carrying the load. The "dead" end is the short tail that is folded back and looped over to form the eye. The rule means that the saddle-the flat metal piece with the two holes-must always rest on the live end. The U-bolt must always go over the dead end.
Why? The U-bolt is round on the bottom, and when you torque it down, it severely crushes and distorts the wire rope it sits on. If you put the U-bolt over the live end, you are physically crushing the structural core of the load-bearing line. Under a heavy dynamic shock load, those crushed wires will snap, and the cable will pull right through the clips, dropping the load. When the U-bolt is placed over the dead end, it crushes the tail that isn't holding any weight, while the smooth, flat saddle rests gently against the live end, holding it securely without destroying its structural integrity.
You also cannot get away with using just two or three clips. For standard 1/2-inch wire rope, you need a minimum of four clips, spaced exactly six inches apart. And the most critical maintenance step is the re-torque. When you first install the clips and tighten the nuts, the wire rope compresses under the pressure. After the load is applied and relaxed a few times, that compression causes the nuts to loosen. If you do not go back with a torque wrench and re-tighten the nuts to the manufacturer's specified foot-pounds after the first load cycle, the clips will vibrate off the rope under dynamic stress. Finally, wire rope clips are single-use rigging hardware. Once a clip has been torqued down and crushed into a cable, the saddle grooves are permanently deformed. If you unbolt it and move it to a new rope, it will not grip properly and will slip under load.
