| 摘要 |
<p>PURPOSE:To simplify the structure and reduce the cross-sectional area of a boom by providing medium and tip side cylinders in a row below a base cylinder and connecting and fixing them together through brackets respectively. CONSTITUTION:When pressure oil is supplied through an extension side oil passage 32 at the time of extending a multiple stage boom, each extension side oil chamber S1, S3, S5 of the first-third hydraulic cylinders 1-3 is filled with pressure oil and each of hydraulic cylinder 1-3 is extended. At this time, a cylinder barrel 1a of the first hydraulic cylinder 1 fixed to the basic end boom slides on each of barrel 2a, 3a through support pads (unillustrated) during extension of the second, the third cylinders 2, 3. Also, a slide pad (unillustrated) fixed to a cylinder barrel 2a which is fixed to a medium boom, slides on the internal surface of a lower wall of the tip boom, while supporting each of hydraulic cylinders 1-3 in stabilized condition during extension of the tip boom.</p> |
