| 摘要 |
<p>A positioning tool engages a profile with retaining members such as dogs so that a pulling force can be applied for a predetermined time as a signal that the tool is at the proper location. The time delay is a fluid system that drives fluid through a narrow restriction. The restriction is variable to allow unloading of the resistance from the fluid system while the dogs are still adequately supported. As a result the dogs are released from the profile without regional overstressing. A lock can prevent the tool from resetting to limit its use to locating at a single location. The lock holds the hydraulic system in a defeated position so that even if the dogs engage another profile when locked they will immediately exit that profile.</p> |
