| 摘要 |
A downhole tool 100 includes a closure seat 116, 176 for seating with a closure, such as a ball. Shear pins or other connectors temporarily limit axial movement of the closure seat which is initially housed within a restricted diameter portion of the central throughbore in the tool body. The closure seat may be lowered to engage a stop 108, 157, thereby positioning the seat within an enlarged diameter bore portion of the tool and allowing radial expansion of a closure seat to release the ball.
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