Abstract: A force limiting device for an actuator rod is used on a valve actuator of the type which includes hydraulic fluid being selectively applied to and discharged from a cylinder at a first side of a piston connected to the actuator rod as high pressure gas of an accumulator mounted on the cylinder acts in opposition thereto on a second side of the piston. The piston includes an interior cylindrical bore narrowing to an opening at the first side thereof which receives the actuator rod slidably therein. The actuator rod extends from the first side of the piston through a hole in the first end of the cylinder for coupling to a valve stem outwardly of the cylinder. An enlarged piston head is secured at a first side thereof to the other end of the rod and disposed within the interior cylindrical bore for sliding, sealed contact with an interior of the bore. Atmospheric pressure communicates with the bore to act on the second side of the piston head.

Abstract: A coupling is mounted between a valve stem of a valve and a rod of a valve actuator. The rod includes an extension having a piston member at the end thereof which is received within a cylinder member mounted on the end of the valve stem. The extension and piston member thereof define with the cylinder member a chamber within the cylinder member. Force can be transmitted from the rod to the stem by full insertion of the piston member within the cylinder member. A pressurized gas is contained within the chamber to limit the force transmitted from the rod to the stem when the relative position of the rod with respect to the stem causes the piston member to be located intermediate of the cylinder member.

Abstract: A coupling is mounted between a valve steam of a valve and a rod of a valve actuator. The rod includes an extension having a piston member at the end thereof which is received within a cylinder member mounted on the end of the valve stem. The extension and piston member thereof define with the cylinder member a chamber within the cylinder member. Force can be transmitted from the rod to the stem by full insertion of the piston member within the cylinder member. Hydraulic fluid under pressure from an accumulator secured to the cylinder member is in communication with the chamber to limit the force transmitted from the rod to the stem when the relative position of the rod with respect to the stem causes the piston member to be located intermediate of the cylinder member.

Abstract: A coupling for drivingly connecting two members operatively coupled at a lost motion connection including first and second sets of Belleville springs separated by a double tapered annular spacer wherein the apex rims of the outer springs engage the members and the base rim of the inner springs engage the outer periphery of the opposed surface of the spacer, the base surfaces of the inner springs fully engaging the spacer at a predetermined tensile load to prevent overdeflection of the springs and to directly couple the members together.

Abstract: A hermetically sealed valve includes a valve body having an annular seat adjacent the valve inlet with a frusto-conical surface diverging outwardly therefrom toward the valve outlet and a fixed diffuser assembly including a fixed disc guide and a slidable spring biased closure disc. The disc guide has a diverging frusto-conical surface spaced from the first surface to define a high efficiency annular diffuser flow passage. The fluid exposed surfaces of the disc are located upstream of the passage. The closure disc is actuated between an open position and a closed position by an axially movable valve stem acting on a flexible diaphragm. The pressure drop in the diffuser passage at high flow conditions establishes a force differential on the diffuser assembly acting toward the valve seat which is borne entirely by the disc guide thereby eliminating any pull down forces on the closure disc.