Abstract: An actuator includes a primary piston and a secondary piston axially movable together in a cylinder assembly; a plurality of chambers comprising: a first chamber, a second chamber, a third chamber, and a fourth chamber, wherein when fluid flows into the first chamber the primary piston extends and when fluid flows into the second chamber the primary piston retracts, wherein an extension fluid force applied by fluid in the third chamber to extend the secondary piston is different from a retraction fluid force applied by fluid in the fourth chamber to retract the secondary piston; and a force-balance chamber configured to receive fluid from the third chamber or the fourth chamber to apply a balancing force on the secondary piston to either oppose fluid force acting on the secondary piston or add to the fluid force acting on the secondary piston, thereby compensating for a difference between the extension fluid force and the retraction fluid force.

Abstract: A self-contained cartridge sealing plug that does not require any torque settings. The sealing plug includes a cylindrical-shaped plug body that carries an O-ring seal. The bottom of the plug body has a hole where a spring is inserted and retained by a spring retainer that locates the spring and/or functions as a backstop for the spring that preloads the plug body against a retaining member. The spring-loaded action allows the plug body to be inserted into a-non-threaded cavity and depressed past a groove in the cavity. Once the shoulder on the plug body passes the groove, a wire ring retainer including one or more arcuate segments can be inserted into the cavity. The spring energy is then released against the ring retainer, retaining the plug body in the cavity.

Abstract: A self-contained cartridge sealing plug that does not require any torque settings. The sealing plug includes a cylindrical-shaped plug body that carries an O-ring seal. The bottom of the plug body has a hole where a spring is inserted and retained by a spring retainer that locates the spring and/or functions as a backstop for the spring that preloads the plug body against a retaining member. The spring-loaded action allows the plug body to be inserted into a -non-threaded cavity and depressed past a groove in the cavity. Once the shoulder on the plug body passes the groove, a wire ring retainer including one or more arcuate segments can be inserted into the cavity. The spring energy is then released against the ring retainer, retaining the plug body in the cavity.