Patent ID: 7311117

Claim:
A reset relief valve comprising: a body having an inlet port, an outlet port, and an interior wall partially defining an enclosed chamber; a piston disposed in said body and moveable between a first position at which said piston is disposed in fluid flow-blocking relationship between said inlet port and said outlet port of the body and a second position at which said piston is removed from said fluid flow-blocking position; said piston having a head which partially defines an enclosed first chamber and at least one flow passageway extending between said chamber in said body and a second chamber defined in part by a moveable member disposed in a cavity in said piston head; a bonnet attached to said body; a stem bushing disposed in said bonnet in spaced relationship with the head of said piston, said stem bushing having a surface defining another portion of said first chamber and an internal bore in which said stem is slidably supported; at least one spring and at least two pivotally interconnected link members operatively disposed between said spring and said stem; and crank assembly for selectively engaging said pivotally interconnected link members for urging said piston into said first position.