Patent ID: 8534361

Claim:
A pressure equalizing system for a subterranean tool, comprising: a movable component in a housing having a housing passage extending from an uphole end to a downhole end, said component having at least two positions where said passage is open and closed and configured in said passage to trap pressure in a first zone of said housing when said movable component is placed in a first position where said passage is closed and where said trapped pressure is at a lower pressure than pressure isolated adjacent said downhole end by said movable component in said first position; a bypass within a wall of said housing having an inlet in said passage with access to said uphole end and ending in said zone so that pressure at a predetermined level delivered to said uphole end from within said passage selectively opens a re-closable valve mounted wholly in said bypass to equalize pressure in said zone with pressure near said isolated downhole end of said passage to facilitate moving said movable member to a second position, said valve automatically closing on reduction of uphole end pressure below said predetermined level.