TOWER CRANE, ITS BACKSTOP DEVICE, AND METHOD FOR OPERATING TOWER CRANE

摘要

PROBLEM TO BE SOLVED: To enlarge the operational range of a tower crane by making the minimum operating radius of the tower crane smaller than those of tower cranes of the prior art although the tower crane has a long-size jib. ;SOLUTION: In a tower crane 1 in which a boom is raised and lowered relative to a base machine by a boom-derricking guy line 8 while a jib 5 provided at the end of the boom 4 is raised and lowered by a jib-derricking guy line 9, with the maximum raised angle of the boom 4 limited by a backstop device 10, the maximum raised angle of the boom 4 is permitted up to a backwardly-inclined position where the maximum raised angle is greater than the vertical.;COPYRIGHT: (C)1999,JPO