| 摘要 |
<p>The crane crab with slewing jib travels on rails in the roof of a farm building in the lengthwise direction and between the columns supporting the central roof purlins. Its telescopic jib is extensible behind the columns and retracts into th area between them, having curved outer and central sections retracting into each other on rollers, and slewing on a vertical axis. During extension or retraction the free end of the job follows a curved path to match the roof angle, and a grab is suspended from this free end by a hoist winch rope. One at least of the two jib sections, pref. the outer one (6) has a portion curving in the opposite direction, the centre of this section lying above the jib section.</p> |
