Abstract: An improved hydraulic accumulator is introduced wherein a valve mechanism is used to seal a hydraulic fluid before the pressure charged piston reaches the end of the accumulator to minimize the loss of compressed gas by eliminating the pressure differential when the piston is fully extended, thereby prolonging the fatigue life of the accumulator vessel. Reduction of the pressure loading on the vessel will also prolong the life of the piston seals and metal bellows effectively extending the accumulator life and effectively allowing design for weight reduction and preservation of the integrity of the complete hydraulic or pneumatic system.