Extendible and retractible mast system

摘要

A telescopic mast system has a base tube, a plurality of axially movable coaxial inner tubes nestable successively within each other and within the base tube, and a winch supported at the lower end of the base tube with a pair of preferably wire ropes driven thereby for extending and retracting the inner tubes. The base and inner tubes have collars at their respective ends, the collars of adjacent tubes engaging each other to limit extension thereof and to provide additional structural support during application of bending loads on the mast system. The ropes are connected to pulleys mounted near or within tube collars so that the ropes and pulleys are totally enclosed within the mast system. As the winch is rotated in one direction, the ropes axially move the inner tubes from a nested or stowed position within the base tube to a fully vertically extended operational position. When the winch is rotated in the opposite direction, the ropes apply a positive retractive force to the inner tubes and return them to the fully nested stowed position.