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hydraulic accumulator[hī′drȯ·lik ə′kyü·myə‚lād·ər]
A pressure vessel which oper-ates as a fluid source device or shock absorber. It is used to store fluid under pressure or to absorb excessive pressure increases. The hydraulic accumulator is an energy-efficient component, which allows the use of a smaller pump to achieve the same end results in terms of cylinder rod actuation speeds. In certain circuit designs, the accumulator will permit a pump motor to be completely shut down for an extended period of time while the accumulator supplies the necessary fluid to the circuit.
The operation of the hydraulic accumulator is induced by a pressurized gas (usually nitrogen), a spring, or a weighted plunger. The accumulator supplies fluid for actuator movement or to replace fluid lost by leakage. The gas-charged accumulator and the spring-type accumulator discharge their fluid into the system at pressures which are decreasing as the gas or spring expands. The weighted accumulator allows stored fluid to be discharged into the system at a constant pressure for the entirety of its downward stroke. See Control systems, Hydraulics, Pump