According to different energy storage methods, accumulators can be divided into gravity loaded (heavy hammer type), spring loaded (spring type) and gas loaded.

The heavy hammer accumulator converts the pressure energy in the hydraulic system into gravity potential energy and accumulates it by lifting the mass loaded on the sealing piston. The utility model has the advantages of simple structure and stable pressure; The disadvantages are that the installation is limited, it can only be installed vertically, it is not easy to seal, the mass inertia is large, and it is not sensitive. This type of accumulator is generally only used for fixed heavy hydraulic equipment.

Spring type accumulators rely on compression springs to convert the excess pressure energy in the hydraulic system into spring potential energy for storage and release when necessary. Its structure is simple and its cost is low. However, because the expansion and contraction of the spring is limited, and the expansion and contraction of the spring is not sensitive to pressure changes, and its vibration attenuation function is poor, it is only suitable for small capacity, low pressure systems, or as a buffer device.

Both hammer and spring accumulators have certain limitations in application. It is rarely used. At present, gas loaded accumulators are widely used.

The working principle of gas loaded accumulator is based on Boyle's law. When in use, firstly fill the accumulator with gas or nitrogen of predetermined pressure. When the system pressure exceeds the internal pressure of the accumulator, the oil compresses the gas and converts the pressure energy in the oil into the internal energy of the gas; When the system pressure is lower than the internal pressure of the accumulator, the oil in the accumulator flows to the external system under the action of high-pressure gas to release energy. The key to this kind of accumulator is to select an appropriate charging pressure. This type of accumulator can be divided into diaphragm type, piston type, air bag type and non isolated type according to the structure to ensure the sealing performance.