| 摘要 |
<p>A hand-wheel (1) operates a valve. Between the valve and the hand-wheel there is a locking housing (2), into which first (3) and second (4) keys can be inserted. These keys can make contact with a coding reel fitted inside the locking housing. They also cause the hand-wheel to be released and consequently the valve or cause the hand-wheel to stop and then the valve as a result.</p> |
