| 摘要 |
<p>PURPOSE:To prevent exertion of excessive force on a driving system for loading by permitting the movement of a worm in the direction toward the axial line of a shaft and maintaining the worm within the movement range thereof by means of a spring. CONSTITUTION:A ring 4 is held prevented from rotation any more after a tape guide 3 is pressed to a stopper 6. The ring 4 is held fixed and therefore the worm 8 tries to move in the direction toward compressing the spring 29 when the worm 8 rotates still in this stage. The worm 8 moves together with the shaft 9 in the direction toward compressing the spring 29 when the force trying to move the worm 8 attains the level enough to overcome the force of the spring 29. A spring rest 25 does not move any more and a stopper 27 moves together with the worm 8 and the shaft 9 by as much as the distance at which the spring 29 is compressed when a thrust washer 22 contacts with a bearing 11 while the rest 25 maintains the contact with the washer 22. Exertion of the excessive force on the ring, etc. is prevented by relieving of the force in the above-mentioned way.</p> |
