| 摘要 |
A crane comprises a pedestal (1) having a circular periphery, a base (5) which is supported with respect to the pedestal so as to be rotatable along a substantially vertical axis, a boom (8) which is fitted to the base so as to be rotatable along a horizontal axis, as well as adjustment means (10) for adjusting the angle of inclination of the boom. The base is provided with a series (13) of rolling elements (16) which each have a substantially vertical axis, which series (13) of rolling elements (16) can be rolled over the circular periphery (21) of the pedestal and which is always situated on that side of the pedestal facing the boom (8). As a result thereof, the series of rolling elements (16) is subjected to a tensile load on account of the torque exerted on the pedestal (1) by the boom (8) and is held against the circular periphery (21) of the pedestal. In order to simplify the construction, the base (5) is designed as having a strip-shaped pulling element (14, 14'). |
