A mnemonic device
used by rigger
s and other stage technician
s when attaching a Crosby clamp to a piece of wire rope
or aircraft cable
The typical use is when forming a loop or bight at the end of a wire rope, such as when attaching flown scenery to a batten or dead hanging a piece of truss. Essentially any application where it is important to maintain strength under a high load or shock.
A Crosby clamp consists of two major pieces. The first is the saddle. It is a piece of metal with a U-shaped gouge just wide enough to contain one piece of whatever gauge wire rope you are using. At risk of injury to yourself or others always use a Crosby which is the proper size for the cable you are using!! The second piece is a simple U-bolt which fits into holes in the side of the saddle perpendicular to the cable. Four nuts (two to a side) attach to the U-bolt on the underside of the saddle and when tightened, clamp the wire rope securely into the saddle.
When clamping a Crosby you always have two parts of the cable to consider. The end of it (called the dead end) and the part which is actually connected to the load (appropriately called the load end). In order for the clamp to work under load, the end of the cable which attaches to the load must be the part in the bottom of the saddle. The dead end is on top. Thus, Don't saddle a dead horse . The dead horse is of course (of course) the dead/non-load bearing end of the wire rope.
Typically riggers will use redundant Crosbies. That is, anywhere you would use one, go ahead and use two. Kind of a nice afterthought considering this is often the clamp responsible for keeping that piece of lighting truss above you where it belongs during a concert.
Don't have the time to tighten down all those nuts, much less learn an old theatre salt's mnemonics? Well, you could always use Nico-press or trim chain.