Shackles, cables, chains, clamps, and straps are used by riggers to secure loads of equipment to cranes or other structures. They may also use pulleys, winches, lifts, or chain hoists (aka chain motors). For every load, quick load calculations are required, and engineering principles are always in use. Riggers utilise a variety of suspension systems to raise and lower their load to the required location and height above barriers on a building site, loading dock, or event venue.The name dates back to the era of sailing ships, when someone who dealt with rigging, or ropes used to hoist the sails, was known as a rigger. Sailors could use their expertise with rope for hauling and hoisting. Before mechanised haulage and cranes, moving big objects required only the use of ropes, pulleys, and human might. Riggers in the telecommunication and entertainment industries are two examples of a specialised subgroup. Rigging eventually developed into a separate industry, giving rise to contemporary usages while retaining some of its original terminology and almost completely forgetting its roots.