Random,
"Does this gauge actually measure pressure of the inert gas pressure in the accumulator instead of of hydraulic pressure itself?"
From my interpretation,(engineers please correct me) it actually reads both. With hyd's pressurised, it is reading system press, approx 3000psi. With hyd's depressurised, the pressure indication will gradually bleed down over time (a long time) to read the accumulator gas precharge pressure, approx 1000psi. I believe a quicker way to read the accumulator gas pressure is to pump the brake pedals about 10 - 12 times, with hyd's off, to bleed system pressure down to accumulator gas precharge pressure (brake pedals go flat ie. no resistance).
Rgds McHale.
