The capacity of a hydraulic accumulator is generally specified as the maximum energy stored. This means that it indicates the amount of potential energy that can be stored in the accumulator. The capacity is typically measured in joules or watt-hours.

Explanation:
1. Hydraulic Accumulator:
A hydraulic accumulator is a device that stores potential energy in the form of pressurized fluid. It consists of a cylinder and a piston, which separates the fluid and gas sections. The fluid section is connected to the hydraulic system, while the gas section is filled with a compressible gas, typically nitrogen.

2. Quantity of Liquid Accumulated:
The quantity of liquid accumulated refers to the amount of fluid that can be stored in the accumulator. While this is an important parameter, it does not define the capacity of the accumulator. The capacity is determined by the amount of energy that can be stored, which depends on the pressure and volume of the gas section.

3. Maximum Flow Rate:
The maximum flow rate through the accumulator is another important parameter, but it is not directly related to the capacity. The flow rate determines how quickly the fluid can be supplied or withdrawn from the accumulator. It is usually specified in liters per minute or gallons per minute.

4. Height Raising Capability:
The height raising capability of the accumulator refers to its ability to lift a load to a certain height. This parameter is more relevant for hydraulic systems used in lifting applications, such as cranes or elevators. It is not directly related to the capacity of the accumulator, which is a measure of energy storage.

5. Maximum Energy Stored:
The capacity of the hydraulic accumulator is defined by the maximum energy that can be stored in it. This depends on the pressure and volume of the gas section. When the hydraulic system pressurizes the fluid section, the gas in the accumulator is compressed, storing potential energy. The capacity determines the amount of energy that can be stored and released by the accumulator.

In conclusion, the capacity of a hydraulic accumulator is generally specified as the maximum energy stored. This parameter is important for determining the potential energy available in the accumulator, which can be used to perform work in hydraulic systems.