| 摘要 |
A jar up, bump down hydraulic drilling jar is disclosed. A hydraulic tripping valve (46) arrangement permits the storage of large amounts of static force before releasing a hammer (56) to strike an anvil surface (58) with substantial force. The hammer (56) is positioned on the mandrel (8) and interacts with the anvil surface (58) in the housing (10) to deliver upward jarring forces, to the drill string. During the downward jarring movement, the tripping valve (46) is opened to prevent pressure buildup and accidental jarring; thus, a single acting drilling jar is formed.
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