The NACOL oil port housing features a heavy duty spring to withstand hydraulic pressure.

The NACOL Accumulator uses a much stronger poppet spring to hold the poppet open. So even though there is a pressure drop across the poppet, the spring holds the poppet open until all of the oil has been discharged from the accumulator. The net result is that you get full oil discharge from the NACOL accumulator.

See NACOL'S spring vs. competitor's design.