| 摘要 |
<p>A water timer including a housing having an inlet and outlet through which water flows to drive an impeller and speed reducer used to determine the open time of a valve member. The valve member is movable in one direction, corresponding with one direction of axial movement of the timer dial, into a water flow position out of engagement with a valve seat and movable in an opposite direction, corresponding with an opposite direction of axial movement of the dial, into engagement with the valve seat into a water shut-off position. The valve member has a first pressure responsive surface area facing in the opposite direction disposed in communication with water under pressure communicating with the housing inlet and a second pressure responsive surface area facing in the one direction. A controllable water pressure chamber within the timer housing communicates with the second surface area and through a first series of passages with water under pressure communicating with the first surface area when the valve member is in its water shut-off position.</p> |
