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.