| 摘要 |
<p>The board (1) has transverse front and rear rollers (7 and 8). Each roller is symmetrical with a maximum diameter at its centre and has a length which is at least twice said maximum diameter. The front roller (7) is mounted to rotate about a vertical pivot axis against the action of a recoil spring incorporated in the mounting (5) such that by transferring his/her weight the roller automatically steers the board.</p> |
