Overhead platform on derricking boom - has force transmitting rigid chain for thrust loads, with reaction housing and sprocket

摘要

The overhead working platform is attached to a derricking boom, on which is a mechanical system for transmitting thrust and tension forces to the boom or the platform itself. The forces are transmitted by a chain (17), rigid when transmitting thrust loads, together with a reaction housing (18) containing a pinion or sprocket (19). The boom can comprise to or more sections (7,8) extended and retracted by the chain, and telescoping into each other. One chain can form a parallel guide for the platform (11).