Diaphragm accumulators are used for energy storage, shock and vibration absorption, and leakage oil compensation or volume compensation in hydraulic systems.

They consist of a pressure-resistant vessel (high-tensile steel) the interior of which is split into a gas and a fluid side by an elastic diaphragm. When the operating pressure is increased, hydraulic fluid flows into the accumulator and compresses the gas until the gas pressure is identical to the fluid pressure. When the operating pressure is reduced, the gas expands again and feeds the hydraulic system with hydraulic fluid.