| 摘要 |
Roller for shaping an earth bed for a plastic seed drill or film unwinder, possessing at the front two pairs of rollers ensuring the grip on the ground. The first roller of each pair consists of tubular bars assembled between two end flanges, so that the axes of these bars belong to a hyperboloid of revolution of one sheet. This roller is, if appropriate, completed at the centre by a cylindrical sleeve and at its ends by two concave discs, the concavity of which faces outwards. <IMAGE>
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