| 摘要 |
<p>A method of, and a device for, controlling the rotation of an element (4;14;25;29;35) about an axis by means of a wrap spring (6;16;26;30;39a;39b) having windings extending about a cylindrical part (4;4a;9;14;28;35a;36a;36b). Upon engagement with said part, said windings preclude rotation of the element in one direction and allow rotation in the other direction. A continuous torque (by 2;12;22;22;37) is exerted which, when controlled by the wrap spring, is adapted to rotate the element about the axis. Said control takes place by bringing a control member (7;17;27;31;40a;40b) engaging with one of the ends of the wrap spring out of its starting position. Through rotation of the element by means of the continuous torque as a result of the control member being brought out of its starting position, said control member is returned to its starting position relative to the other end of the wrap spring, so that a relatively large torque can be automatically controlled at a relatively small control force.</p> |
