| 摘要 |
An arrangement by a hydraulic jar device, especially for use in underground wells, where the jar device is installed in a pipe string led down into the well, and designed so that e.g. a stuck object in the well may be loosened o r broken up by upward or downward percussions from the jar device. The jar device is actuated by increasing the flow of drill fluid. Alternatively, the device is actuated by compression. A valve (27, 37, 38) closes off the flow of drill fluid, whereby a percussion cycle is initiated. The valve is designed so as also to seal during strong lateral accelerations.
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