| 摘要 |
A sliding sleeve has an associated shock absorber to limit shock loading to the shifting apparatus when the end of travel is reached. An adjacent sleeve defined an annular cavity in a manner that does not reduce the drift dimension of the shifting sleeve. The cavity has a fluid in it and the movement of the shifted sleeve causes the movement of the shock absorber sleeve to reduce the fluid volume in the annular cavity. The volume reduction forces fluid through a restriction to regulate the speed of the sliding sleeve as a travel stop is reached. The fluid can be a gas, an incompressible fluid or grease. The restriction can be temporarily covered such as with a rupture disc. Room to compensate for thermal expansion can be provided in the annular space.
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