Which accumulator type discharges constant pressure and is large and bulky?

• A. Gas-charged accumulator
• B. Weight-loaded accumulator
• C. Spring-loaded accumulator
• D. Diaphragm accumulator

Answer: (B)

Discharging at a nearly constant pressure comes from how the preload is applied. A weight-loaded accumulator uses a heavy weight on top of a piston to provide a constant, gravity-driven preload. Since the hydraulic pressure equals this constant preload divided by the piston area, the pressure on the fluid side stays almost the same as fluid is drawn off, giving a flat pressure during discharge over a wide portion of the stroke.

This arrangement is inherently bulky because to store useful energy at a given pressure you need substantial mass—the weights themselves—so the unit becomes large and heavy. In contrast, gas-charged and diaphragm types rely on compressible gas to balance pressure, and the pressure changes as the gas expands during discharge, so the pressure isn’t constant. Spring-loaded accumulators depend on a spring’s reaction, which also changes with displacement, leading to varying pressure as the fluid is released.