| 摘要 |
<p>PURPOSE:To drive a pump in a reliable and stable manner, by connecting two pistons in respective cylinders together by means of a piston rod, and feeding compressed air to the two cylinders selectively by means of a changeover valve. CONSTITUTION:In cylinders 4, 5, a first chamber 4A in the first cylinder 4 and a second chamber 5A in the second cylinder 5 serve as control chambers. When the other end 10b of a piston rod 10 urges a subsidiary valve steam 54 with proceeding of returning movement of a first and a second pistons 6, 7, compressed air in a main valve stem lower chamber 43B is discharged to the atmosphere via a clearance S2 and a second and a third passages 50B, 50C. Here, since fluid in the second chamber 5B is carried under pressure into a second valve chamber 21 via a second communicating port 17, so that a fourth valve element 36 is raised upward and opens a sixth fluid communicating port 27. Thus, fluid in the valve chamber 21 is carried under pressure into a fluid delivery passage 25.</p> |
