| abstract |
A portable derrick system for use in hoisting and lowering loads at a plurality of job sites, comprising, in combination: a boom subassembly, a boom head subassembly, a mast support subassembly, a mast head subassembly, a load-carrying line, a winch capable of cooperating with said line, power means for driving the winch, means for pivoting the boom assembly, means for controlling said pivoting means, the foregoing elements of the invention capable of being transported by humans to elevated positions such as, without limitation, rooftops and terraces, and wherein the aforementioned are capable of repeated assembly and disassembly at a plurality of job sites and serving to facilitate the elimination of the need for a street-level crane. |