| 摘要 |
<p>A shaft (51) is rotatably supported by a case body (21), a part of a travel wheel (52) is positioned around the shaft (51), and coiled springs (53) for pressing the travel wheel (52) against the shaft (51) are provided between the shaft (51) and the travel wheel (52). When the travel wheel (52) collides with an obstacle, the travel wheel (52) absorbs the impact by moving relative to the shaft (51) and a case body (21) while being pressed by a coiled spring (53). Cushioning characteristics can be improved by, for example, making the travel wheel (52) softer or increasing the thickness of the travel wheel (52), and the improvement can be achieved without a reduction in movement characteristics.</p> |
