| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a jib crane capable of ensuring that a position of ballast follows up a change in a load acting on a jib with a simple structure without providing special drive or controller, and capable of achieving weight reduction of the overall jib crane.SOLUTION: A pendulum ballast 13 configured so that a weight 13b is attached to a lower end of an arm 13a extending vertically is overhung from a top portion of a back stay 2 so as to freely oscillate around an oscillation shaft 14 in parallel to an undulation center shaft 5 of a jib 4, and a rope oscillation mechanism 15 moves the pendulum ballast 13 from an overhung position to a side opposite to the jib 4 to be interlocked with an increase in a rope tensile force as a load acting on the jib 4 increases.</p> |
