GUYLESS DERRICK BOOM APPARATUS FOR CRANE

摘要

A guyless derrick boom appts. provides low-cost one-men control. The structure of the device comprises a boom established between posts(1) , a pair of parallel-arms to guide the boom, a turning ring (8) to surround the constants radius peripheries of the turning pivot, and a pair or double-pair of automatic combinations to connect the material (32) permitting undulation of the boom. The boom appts. also is characterized by a turning rope drum (15C) to rotate the boom.