| 摘要 |
<p>The crane i.e. tower crane (1), has an extension arm (3) rotatably supported around an upright tower axis (5), and an inoperative brake permitting and braking rotational movements of the extension arm in an inoperative condition of the crane under wind loads. The brake operates in a rotational speed-dependant manner such that applied braking torque during large rotational speed of the crane is larger than during small rotational speed of the crane. The brake comprises a centrifugal brake, and a deactivating unit deactivates the inoperative brake during crane operation.</p> |
