close up of a yellow and green crane boom with main block and jib against a clear blue sky. tower building cranes

arm armofcrane automobile background balancecrane bearing block blue boom building cable carryingcapacity cathead clear concept construction contractors crane cranearm craneboom equipment erection frame green height hoist hook industrial industry jib lift lifting line luffing machine machinery main metal mobile riggers rigging rise robust rope safety sky swinging tall wire yellow