Jonnym:
Hi Everyone,Thanks for all the good info. here is a link to the data sheet of the valve.
Direct-Operated Servo Valves for Analog Signals D633 and D634 Series
we have the version that is voltage controlled not amperage controlled.
thanks
jon
That's not the datasheet, that's a catalog entry. This is the datasheet (auf Deutsch!) http://www.moog.com/literature/ICD/Moog-Valves-D633K-D634K-D635K-Manual-multi-en.pdf
If my german is good enough its a 0..10V control signal. But it is differential so you can connect either Ue or Ud to ground and get either sense as (Ud-Ue) is the control voltage (section 3.3.1.3 of the pdf) - anyone got a better grasp of technical german??