| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate any possibility of wire disconnection, improve the visual field, set an arm to be freely extended/contracted, and utilize an extending/ contracting device for a construction and transportation machine by providing it with a device for supporting and driving a plurality of slide rods, a device for connecting them during extension, and a device for releasing the connection for contraction. SOLUTION: A stage part 7 which is prevented from being slipped off by a slide rod 2 raised by a rotary shaft 6 of a rotary drive 9 abuts on a stage part 8 so that a female screw 12 of a slide rod 3 and a male screw 11 of a rotary shaft 6 are engaged with each other and the slide rod 2 and the slide rod 3 are raised together. When a connecting device 10 is raised, the slide rod 2 and the slide rod 3 are connected by engagement of a lock pin 13A emerged from the slide rod 2 with a lock hole 24 to be raised further, the female screw 12 is separated from the male screw 11, the slide rods 2, 3 are raised, and a slide rod 4 is extended till its stage part 7 abuts on the stage part 8 of an arm 5. When the rotary shaft 6 is inversely rotated, the slide rods 2, 3, 4 are lowered to be contracted by a connection releasing device 10.</p> |
