| 摘要 |
There is disclosed an actuator and a kickover tool including an actuator in which force is applied through the actuator by hydraulic means in which force due to the pressure medium in which the tool is submerged is substantially balanced across the seals of the pressure chambers and in which the force acting on the tool due to the pressure of the medium in which the tool is submerged remains balanced in the event any one of the seals becomes ineffective.
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