| 摘要 |
PROBLEM TO BE SOLVED: To provide a boom expansion/contraction mechanism capable of reducing a number of components, simplifying a device, decreasing the weight of the device, saving a cost, and simplifying operation.SOLUTION: A boom expansion/contraction mechanism includes: a cylindrical first boom member; a second boom member which protrudes to and recesses from the first boom member; a pin for reciprocating in a direction intersecting a reciprocating direction of the second boom member; an energizing member for energizing the pin in the other direction of the first boom member and the second boom member; a movement regulating portion for regulating the movement of the second boom member in a direction being stored in the first boom member, by engaging with the energized pin; a pin pressing portion for pressing the energized pin to move against the energizing force of the energizing member, by the movement of the second boom member in a direction projecting out from the first boom member; and a pin control member for holding the pin by pressing and moving the pin with the pin pressing portion, and releasing the holding of the pin by moving the held pin again. |
