A hydraulic accumulator is an energy storage device. It is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. That external source can be a spring, a raised weight, or a compressed gas. The main reasons that an accumulator is used in a hydraulic system are so that the pump doesn't need to be so large to cope with extremes of demand, so that the supply circuit can respond more quickly to any temporary demand and to smooth pulsations.

Types of hydraulic accumulator

Gas accumulators

In gas accumulators, a pressurized gas bladder presses against a hydraulic bladder. The more the bladder fills up, the more it presses against the gas, increasing the pressure.

Spring accumulators

A spring accumulator works in a similar way, except a large spring or springs press against the bladder to compress it.

Raised weight accumulator

In a raised weight accumulator, the hydraulic fluid is pumped into a big piston with a weight on top of it. This weight exerts a constant force, pressing down on the fluid and compressing it as it fills and empties.