| 摘要 |
A drive mechanism to reciprocate a finite length elongated flexible member (19) in the direction of elongation thereof, said mechanism comprising two drive units mounted a fixed distance apart, each drive unit comprising motor means (20) operatively coupled to a drive member to reciprocate same. The flexible member (19) extending between and coupled at the ends to the respective drive member and tension means (22) in each drive unit coupled thereto and arranged to in use apply through the respective drive member a force to the opposite ends of flexible member in mutually opposite directions whereby the flexible member is in tension throughout the reciprocating movement thereof in either direction. |
