Patent ID: 8360158

Claim:
A system usable with a well, comprising: a piston to actuate a downhole tool; a primary control subsystem connected to a first hydraulic line and a second hydraulic line to move the piston in a given direction in response to fluid communicated to the downhole tool via the first hydraulic line and fluid communicated away from the downhole tool via the second hydraulic line; and an override subsystem connected to the first hydraulic line and the second hydraulic line to override the primary control subsystem and move the piston in the given direction in response to fluid communicated to the downhole tool via the second hydraulic line and fluid communicated away from the downhole tool via the first hydraulic line, wherein: said at least one hydraulic line comprises a supply line to communicate fluid having a pressure below a given threshold to the downhole tool to operate the primary control subsystem and a return line to communicate the fluid from the downhole tool to operate the primary control subsystem, and the override system is adapted to respond to pressure in the supply line above the given pressure to move the piston.