| 摘要 |
<p>The invention relates to a roller with rotative sockets in which each socket has, seen from above, a tra?????da? shape they are mounted and idly pivoted on a centre haft in such a way that the great side of a socket be aligned with the small side of the adjacent socket; in which the sockets are fastened the ones to the others in this position for their rotation on the central shaft.</p> |
