Mechanical directional drilling jar.

摘要

A drilling jar (100) includes a swivel (20) which allows the drilling jar to operate substantially independently of any right hand torque that becomes trapped in the drill string. The swivel (20) includes a bearing cage (9) that engages the polished stem (4) of the drilling jar to the jay stem (5) of the drilling jar. This bearing cage (9) holds a number of bearings (10) against the jay stem (5) and the polished stem (4). The swivel (20) allows the jay stem (5) to rotate substantially independently of the polished stem (4). The drilling jar may further include splines (8) formed onto the outer surface of the polished stem (4) for transmitting torque from the polished stem (4) to the barrel (1) of the drilling jar without simultaneously transmitting torque from the polished stem (4) to the jay stem (5). In addition, the drilling jar may include floating pistons (11,12) that are circumferentially engaged to the polished stem (4) and the washpipe (7) that effect the upper and lower seals on the drilling jar and allow the internal pressure inside the tool to be equalized with the internal and external pressures of the drill string.