The overtravel-limit control by photo-electricity switch for the requirement of the production is presented. It fulfilled the double insurance control according to the demand of the manufacturer.

针生产实际需要，提出利用光电关实现限位控，并能实现双保险控。

This control effect can be got by designing the size of pokedwheel,using the self locking character of worm wheel and worm pole and connecting the pawl mechanism with overtravel ...

通过有效设计拨轮的尺寸，利用蜗轮蜗杆的自锁特性，将棘轮机构与关联为一体，达到自动输球控的目的。