| 摘要 |
<p>The crane has a hollow column slewing on a vertical axis, and supporting a jib slewing with it. On a stationary base and partly under the base of the column are hoist- and derricking rope winches, the ropes being reeved round pulleys at the top of the column, down through the latter, and onto the winch drums via pulleys on stationary mountings near the drums. Between the top pulleys (15, 21) and those (22, 23) on the stationary mountings are one or more intermediate slewing tables (26, 27) coaxial to the column (8), and through which the ropes (12, 18) can pass freely. Pulleys are mounted at intervals on the tables to guide the ropes and hold them apart, and a gear train couples the column and the top table (26) together, while ropes couple the top table to those below.</p> |
