Abstract: A rotary valve having a hollow spool with a metering notch rotatable on a sleeve which is pressed into a valve body, the sleeve having an opening selectively and progressively alignable with said notch. A thrust needle bearing is trapped between a shoulder on the spool and a cap threaded into the valve body. A passage freely transmits pressure inside said hollow spool to the side of the bearing opposite said shoulders to reduce the thrust force imposed on said bearing.

Abstract: An apparatus for plugging a pressure piping system includes one or more segments that may be positioned in the system to hold a plug therein. Each segment is held in position by a holding assembly including a plunger slideably mounted within the apparatus and actuable to move the segments to a position for engaging and locking the plug in place. A pin or similar member may be employed to affix the segment to the plunger, and an actuator is threadably mounted within the apparatus and used to adjust the position of the plunger. In the preferred embodiment, the actuator is coupled to the plunger by a threaded stud, with the threads of the actuator and of the stud being cut in opposite directions. The stud threadably engages the plunger such that rotation of the actuator activates the plunger toward and away from the segment.

Abstract: An unloading valve spool with a tapered nose section is urged across a pair of unloading ports at a controlled rate eliminating violent upstream pressure generation. The unloading valve is subjected to equal system fluid pressure on each side of it as the spool is provided with a through passage that is dead headed on the back side of the unloading spool. A return spring urges the unloading spool to a normally closed position. An unloading piston prevents the unloading spool from closing too rapidly preventing the generation of a significant upstream pressure spike.