| 摘要 |
A flowline switching apparatus having a tubular housing with end closures and a drum rotatably mounted therein with a passage through the drum aligned with a port in one end closure and positioned to sequentially align with each of a plurality of ports in the other end closure as said drum is rotated, a power cylinder connected to said housing and having a plunger with a ratchet pawl for rotating said drum, a second power cylinder connected to said housing with a plunger adapted to engage sequentially in recesses in the exterior of said drum to lock the drum in preselected positions of passage-port alignment, a third power cylinder connected to the housing with a plunger adapted to engage sequentially in recesses of varying depth on the exterior of said drum to indicate the position of the drum and means balancing fluid pressure between the interior and exterior and between opposite ends of said drum.
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