| 摘要 |
A device for mounting on a wheel (2) comprising a hub and a surrounding tyre (4) with a tread (22) is disclosed. The device comprises at least one roller (12, 12a) having a substantially smaller diameter than the wheel and arranged alongside said wheel (2) substantially at ground level so that each roller axis is substantially parellel to the wheel axis; means (8, 10, 24) for rotating a roller (12a) using the rotation of the wheel; and connecting means (18) for linking each roller (12) to the wheel hub in such a way that vertical movement of each roller is prevented.
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