Patent ID: 9410633
Filing Date: 2016-08-09
CPC Classification: F16K,Y10T

Claim Text:
1. A dual-pressure relief valve assembly comprising, in combination: a pilot piston housing forming a pilot piston cylinder; a pilot piston movable within the pilot piston cylinder of the pilot piston housing; a relief valve housing secured to the pilot piston housing and forming a first blind bore, a relief valve seat along the first blind bore near a blind end of the first blind bore, and a second blind bore coaxial with the first blind bore and facing opposite the first blind bore; a relief valve piston movable within the first blind bore of the relief valve housing and carrying a relief valve member configured to close the relief valve seat when engaging the relief valve seat; a first resilient spring acting between the pilot piston and the relief valve piston; wherein the pilot piston cylinder is provided with a pilot port to selectively engage the pilot piston with a predetermined pilot pressure to selectively move the pilot piston toward the first resilient spring and the relief valve piston; wherein the first resilient spring biases the relief valve member into engagement with the relief valve seat with a first predetermined relief pressure when the predetermined pilot pressure is not applied to the pilot piston and with a second predetermined relief pressure when the predetermined pilot pressure is applied to the pilot piston wherein the second predetermined relief pressure is larger than the first predetermined relief pressure; and a check valve comprising: