| 摘要 |
A land (56) on an index member (32) disposed in the interior chamber of a manifold (38) is aligned with an actuating member (34) and thereby holds open a check valve (36) through which fluid flows into the manifold's interior chamber, through a control valve (12), and out a manifold outlet (74). At the same time, another actuating pin (42) is so aligned with a recess (58) in the indexing member (32) as to permit another check valve (44) to prevent flow through itself into the manifold chamber. When the control valve is closed, flow stops, and pressure builds up in the manifold chamber. The index member (32) is accordingly driven against the force of a bias spring (48) to a lower position, in which a lower cam-follower surface (82) engages a lower cam surface (84). That engagement rotates the index member to a position in which it permits pressure to be communicated through both check valves (36 and 44) into the manifold chamber. When the control valve (12) reopens and thereby again relieves the pressure within the manifold chamber, the return of the index member (32) to the upper position causes an upper cam-follower surface (52) to engage cam pins (54). Those pins thereby cam the index member (32) to a new position, in which it opens the left check valve (44) and allows the right check valve (36) to close. By thus alternately operating the control valve (12) between its two, open and closed positions, the system is advanced through a sequence of three different flow states.
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