What type of accumulator operates at a constant pressure regardless of the system pressure?

The type of accumulator that operates at a constant pressure regardless of the system pressure is known as a weight-loaded accumulator. This design utilizes a weight to maintain the hydraulic fluid at a steady pressure level, ensuring that even as the system's demand for fluid varies, the pressure in the accumulator remains constant.

In this configuration, the gravitational force acting on the weight applies a consistent pressure on the fluid in the accumulator. As the hydraulic system uses fluid, the fluid level decreases, but the weight continues to exert the same force. Consequently, this allows the accumulator to release fluid at a uniform pressure, providing reliable performance in applications requiring constant hydraulic pressure.

Other types of accumulators, such as spring loaded or gas charged accumulators, do not maintain a constant pressure under varying system pressures. They respond to pressure changes by compressing or decompressing the spring or gas, leading to fluctuations in output pressure as the system demands change. Hence, these options do not fulfill the criteria of maintaining constant pressure as required by the question.