| 摘要 |
A shifting tool is provided which is preferably hydraulically actuated. A built-up hydraulic force overcomes a retaining piston, which, in turn, frees up a pivoting linkage whose movements are opposed by a coil spring. The coil spring urges the pivoting linkage outwardly where contact can be made with the internal groove on a shifting sleeve. The shifting tool can be run in with the linkage in the expanded position since the parts are configured to allow the linkage to retract to clear any internal obstructions before reaching the shifting grooves in the shif ting sleeve. The pivoting action of the grip on the groove in the shifting sleeve increases the gripping force when jarring occurs. The parts are configured so th at there is a minimum of movement of shifting parts which have seals to further reduce potential wear on pressure seals. A compact design is provided which can be useful on sleeves with a range of internal bores. The coil springs used in th e preferred embodiment, which act against the linkage, can be easily replaced to adjust the force of engagement with the internal groove on the shifting sleeve.
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