| 摘要 |
PROBLEM TO BE SOLVED: To provide a level luffing jib crane which can be horizontally drawn in and out with high accuracy by eliminating an attached element in a mechanical structural part. SOLUTION: In this jib crane 1, provided with a boom derricking machine 6 operating a boom derricking rope 5 derricking a jib 3 and a hoist 10 operating a hoist rope 9 of a sling (hook block 8) slung from a tip end of the jib 3, the hoist 10 is driven by a vector control inverter, an angle signal from an angle detector 25 additionally provided in the jib 3 is input to a drive control part 20, to be calculated by a hoist operation function memory means, a command corresponding to the angle signal is output to the inverter, the hoist 10 is controlled so as to horizontally move the sling 8 relating to the ground surface.
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