A hydraulic accumulator is a device in which potential energy is

stored in the form of a compressed gas or spring, or by a raised weight

to be used to exert a force against a relatively incompressible fluid.

They are used in fluid power systems to accumulate energy

and to smooth out pulsations. A hydraulic system utilizing an

accumulator can use a smaller fluid pump since the accumulator

stores energy from the pump during low demand periods. This energy

is available for instantaneous use, released upon demand at a rate

many times greater than could be supplied by the pump alone.

Accumulators can also act as surge or pulsation absorbers,

much as an air dome is used on pulsating piston or rotary

pumps. They will cushion hydraulic hammer, reducing

shocks caused by rapid operation or sudden starting and

stopping of power cylinders in a hydraulic circuit.