| 摘要 |
The unit (2,3) incorporates a spring (30) made of plastic or suchlike and at least one of its cross sectional sides is approximately rectilinear. The spring cross section (50) may have at least two rectilinear sides, and may be four-sided. In the axial plane of the spring the spring cross section preferably has a dimension which differs from its dimension in plane at right angles to the spring axis (10). |
