| 摘要 |
<p>The portal crane has a pair of columns travelling along rails on a ship deck either side of a series of hatchways. A vertical hydraulic ram (5) is mounted on the inner surface (6) of each column (7), and below and axially in line with each ram is a guide in which a block works, coupled to the ram at the upper end. A link (31) secures each block to a hatch cover (31), allowing this to be raised and lowered, and transported away by the crane before loading or discharging cargo. The guides can each comprise a pair of rails for wheels mounted on axles on the block, on which there can be a hook for a link.</p> |
