Patent ID: 6422530
Filing Date: 2002-07-23
Classification: F15B

Abstract:
A fail-safe fluid actuator, comprising, in combination:a cylinder housing with opposed ends forming an enclosed chamber; a piston slidably disposed in said chamber and having a coaxial piston rod with opposed ends, one of said rod ends being connected to said piston and extending through one of said housing ends for connecting to a controlled device; a rod extension having, opposed ends, one of said ends being connected to the other of said rod ends and extending through the other of said housing ends; a sleeve slidably receiving the other of said rod extension ends and slidably received in an opening in said other housing end, said sleeve having a plurality flat sides; a plurality of pairs of parallel upright members secured to said other housing end and aligned lengthwise with respective ones of said flat sides; and a constant force spring rotatably supported between each pair of said upright members on an axis parallel to an adjacent one of said flat sides, said spring having an extended end secured to said one flat side.