| 摘要 |
PURPOSE:To make a screw shaft compact as a whole, by composing the screw shaft of a feed screw shaft, a hollow feed screw shaft and a rotary member, and making the directions of the leads of the feed screws opposite to each other. CONSTITUTION:A screw shaft 1 is composed of a feed screw shaft 2, a hollow feed screw shaft 3 and a rotary member 4. The directions of the leads of the feed screws 2a, 3a are made opposite to each other. As a result, the length of the most shortened shaft 1 is not more than a half of that of the most lengthened shaft 1, and the length of the shaft can be altered in a stepless manner between the maximum and minimum. If the screw shaft 1 is applied to a lift or the like, the latter can be made compact. |
