| 摘要 |
A fluid inlet passageway communicates at one end with a source of fluid under pressure and at the opposite end with a fluid outlet passageway. A piston type control valve is movable axially in the fluid inlet passageway and is in fluid pressure sealing engagement with the opposite end portions of said passageway but not with an enlarged intermediate portion thereof, at which position of the valve fluid under pressure may pass around the valve and exit the outlet passageway. The valve is switched between said end and intermediate positions by a stepped stop block on the projecting end of the piston rod engageable releasably by an abutment on a cam follower lever which mounts a cam follower roller positioned for engagement with a pair of relatively adjustable cam elements mounted for rotation with a timer shaft driven by a wind-up spring clock timer.
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