RETRACTILE BOOM WITH SAFETY STRUCTURE FOR TRUCK CRANE

摘要

When extending or shortening the length of the load to be ensured the safety of the part that acts big, rotating the pole frame possibly fixed boom and which is installed, is inserted into the fixed boom and a plurality of multi-stage multi-stage boom that is installed to be movable by sliding, the fixed boom hydraulic cylinder and connecting the first end of the multi-stage boom, and fixed by a hydraulic cylinder and the multi-stage boom extension means for extending the length of the clearance in accordance with the multi-stage boom pushed from the inside of the boom, comprising a pulling means according to the multi-stage speed-boom into the interior of the fixed boom via a hydraulic cylinder to reduce the length of the multi-stage boom and, means for extending one end portion is fixed by way of one end of the first stage of the multi-stage boom is fixed to the fixed boom to the other end of the second stage, and one pair is made of a tank which is installed at a predetermined distance and the first extension rope, one end portion fixed to any one of the multi-stage boom and then through one end of the stage is fixed to the other end of the next stage and one pair is made of a tank at a predetermined distance to be installed and a plurality of sets of second elongated rope and provides a high-place work having an extensible boom borrowing safety structure comprises at least one first safety rope to the first auxiliary rope extension.