| 摘要 |
A downhole tool comprises a body, radially extendable members mounted to the body and movable between retracted and extended positions, a cam member operatively associated with the extendable members and movable relative to the body to extend the extendable members, and a support member configurable to permit retraction of the extendable members from an extended position. The tool may be an under-reamer, and the extendable members may be cutting blades.
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