Fail-safe apparatus for use with fluid valves

摘要

Fail-safe apparatus for use with fluid valves are disclosed herein. An example fail-safe apparatus includes a first piston (342), a second piston (344) movably coupled relative to the first piston, and a fluid chamber (346) between the first and second pistons to receive a con¬ trol fluid. The control fluid is to operatively couple the first and second pistons when the control fluid is provided in the fluid chamber. The first piston is operatively decoupled from the second piston when at least some of the control fluid is removed from the fluid chamber.