| 摘要 |
A jar for use in facilitating the removal of stuck objects from wells. The jar has a telescoping assembly held in a collapsed position by a latching means urged into latching position by a resilient means so that the hammer of the jar is spaced from the anvil thereof. The release of the latching means is actuated by a predetermined longitudinal force applied to the upper end of the jar which overcomes the resilient means to cause the hammer to strike the anvil with a sudden impact translated by a connecting means from the jar to the stuck object.
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