I'm examining a military specification for a servo valve assembly and there are a few requirements/specifications that don't make a whole lot of sense to me...
The spec states that the "valve bias pressure at hydraulic null shall be 5 to 50% of supply pressure." The valve is a hydraulic pilot vlave (where the pilots are supplied by a servovalve). The test procedure reads that the control ports should be sealed and the servo valve adjusted so that "the blocked control port differential pressure is zero" and "the common control port pressure...shall be 415 +/- 340 psig." Does this mean that the servo valve is actuated appropriately to equalize the control port pressures and this common pressure should be within these specifications? If so, what does this tell us about the valve's operation (why is this specification necessary)?
The specification also lists a required hydraulic stiffness of 8,000psid/cubic inch of fluid added @ 750 +/- 25 psi. I did some research and could not find any listed hydraulic stiffnesses with these units: they all had units of lbf/in. Are these equivalent units?
M Woelfersheim
The spec states that the "valve bias pressure at hydraulic null shall be 5 to 50% of supply pressure." The valve is a hydraulic pilot vlave (where the pilots are supplied by a servovalve). The test procedure reads that the control ports should be sealed and the servo valve adjusted so that "the blocked control port differential pressure is zero" and "the common control port pressure...shall be 415 +/- 340 psig." Does this mean that the servo valve is actuated appropriately to equalize the control port pressures and this common pressure should be within these specifications? If so, what does this tell us about the valve's operation (why is this specification necessary)?
The specification also lists a required hydraulic stiffness of 8,000psid/cubic inch of fluid added @ 750 +/- 25 psi. I did some research and could not find any listed hydraulic stiffnesses with these units: they all had units of lbf/in. Are these equivalent units?
M Woelfersheim
