| 摘要 |
The grass sports field (2) has a protective cover (4) which is rolled up on a roller (7). This rotates in a trough (8) on one side (9) of the field which contains liquid (30) in which the roller is partly immersed. The roller is moved by two rotating shafts (24a,24b) joined by an endless belt (25) and one shaft (24a) is turned by a motor (26).The cover is held above the grass when it is unrolled and stiffened by cords threaded through it. It is supported by retractable piles (19) which rest on an infra-structure (18) and are raised by hydraulic jacks (20).
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