| 摘要 |
Adjustable torsional type latching means (5) for triggering a mechanical well jar tool comprises torsionally actuated gear racks (20,22) including acme threads or teeth which extend axially on opposite adjacent side portions of telescopic parts (1,2). The gear rack teeth which mesh in the latched position have incline tooth faces that can be disengaged by applying a strong axial force which torsionally stresses and rotates a torsion sleeve (16) portion of one telescoping part (1) and gear rack (20) thereon away from the other part (2) and gear rack (22). Upon release of the latching device (5) the telescopic parts (1,2) of the well jar and the kinetic energy stored therein are freed for a limited longitudinal jarring movement. The torsion sleeve portion (16) has an end portion connected to the other telescopic parts by a second slot-spline-gear (15) of relative short axial length, which serves as a torque support in the latched position and becomes deengaged during a jarring stroke. The second slot-spline-gear (15) is separated and disconnected, by means of a rotatable connection (7) between the opposite end of the torsion sleeve portion (16) and the attached telescopic part (1), from the conventional primary slot spline gear (14) which, usually transmits the rotary drive torque between the telescopic parts (1,2) and thereby rotates the drill string and bit.
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