| 摘要 |
<p>The crane (1) comprises a main column (2) which is rotatable about a vertical axis and supports an operative arm (3) articulated thereto; the operative arm (3) is movable along axes arranged along vertical planes and is moved by at least one fluid-dynamic jack (7) interposed therebetween; the lower end of the jack (7) is articulated to the column (2) and the upper end of the jack (7) is connected to a hinge (6) for further articulation together with corresponding ends of at least one second jack (8), which is interposed between the first jack (7) and the operative arm (3), and of at least one connecting rod (5), the opposite end whereof is coaxially pivoted in the same point of rotation and articulation between the operative arm (3) and the main column (2); the first jack (7) and the second jack (8) provide lifting torques which have lever arms of presettable minimum and maximum extent.</p> |
