The flow control servo valves D791 and D792 Series are throttle valves for 3-way and preferably 4-way applications. These three stage servo valves have been especially developed for such demanding applications where high flow rates and at the same time extreme dynamic performance requirements must be met. The design of these valves is based on the well known D079 Series. The integrated electronics has been replaced by a new design applying SMD technology. The valves are offered with pilot valves of D761 or D765 Series, optional standard response or high response versions are available. Series D791 can deliver rated flow up to 250 l/min, Series D792 is available with rated flow up to 1000 l/min.

These valves are suitable for pressure or force control, position and velocity control systems with high dynamic response requirements.

An electrical command signal (set point, input signal) is applied to the integrated control amplifier which drives a current through the pilot valve coils. The pilot valve produces differential pressure in its control ports. This pressure difference results in a pilot flow which causes main spool displacement.

The position transducer which is excited via an oscillator measures the position of the main spool (actual value, position voltage). This signal then is demodulated and fed back to the control amplifier where it is compared with the command signal. The control amplifier drives the pilot valve until the error between command signal and feedback signal is zero. Thus, the position of the main spool is proportional to the electrical command signal.

• Electrical position feedback with pressure isolated position transducer (LVDT), no wear
• Integrated SMD electronics with false polarity protection
• Optional external pilot supply and return connections via fifth and sixth port in valve body
• Low threshold and hysteresis, excellent null stability
• Pre-adjusted at factory