| 摘要 |
<p>The housing of a control device forms a chamber into which opens a milking machine conduit communicating alternately with a vacuum source and a pressure source, there being a separate connection between the chamber and the pressure source which is independent of the conduit. A valve member in the chamber is operable from outside the housing and has a first position where it blocks the opening of the conduit into the chamber while uncovering said separate connection, whereby the valve member is sucked against said opening and thus held in its first position when vacuum prevails in the conduit. When the conduit is placed in communication with the pressure source, the valve member automatically moves to a second position where it uncovers the opening of the conduit into the chamber while blocking said separate connection; and the valve member can be returned to its first position only by manual operation from outside the housing.</p> |
