| 摘要 |
<p>There is described an operating assembly for a downhole tool, comprising a chamber filled with fluid; a device for biasing fluid at an end of the chamber; a pressure transfer device acting on the fluid at an other end of the chamber; and a piston sleeve having a first and a second shoulder defining a piston support surface therebetween disposed in the chamber between the ends thereof. The assembly also comprises first and second fluid pressure responsive pistons associated with the piston sleeve between the shoulders; a piston biasing device disposed between the first and second pistons; longitudinally spaced first and second piston stops adapted to impede the respective movement of the first and second pistons; and a transfer device adapted to transfer longitudinal piston sleeve movement to a tool element.</p> |
