It continues building a column as long as there is banding and strapping. Driving the motor backwards disassembles the column and its components return to storage.
Lifting systems used to move scenery and props on Broadway and Las Vegas stages have been using a quiet, clean, and reliable device called Spiralift. It is now making inroads into industrial applications. The device, built by Gala Theatrical Equipment, St Hubert, Canada (www.galainfo.com), is purely mechanical, with no hydraulics. The device inserts a horizontal spiral coil of metal between successive vertical spirals of metal banding. The horizontal coil prevents the spiral from collapsing in on itself. The result is a continuous spiral tube of I-shaped cross sections, which is structurally sound, strong, and stable. When not in use, it collapses to a thin, compact package.
A 8.5-in.-tall version of the device extends to 12 ft and can support 8,000 lb. One of the largest, the 18-in. version, is 14 in. tall and extends to 40 ft and supports 40,000 lb.