The Servo-Proportional Valves of the D671 to D675 series are control valves for 2-, 3-, 4- or even 5-way applications. These valves are suited for electrohydraulic control of position, speed, pressure, or force, and applications involving high dynamic requirements. The integrated valve electronics are a new design, featuring a pulse width modulation driver and a 24 V DC power supply.

Key characteristics of the ServoJet® Pilot Stage, which uses the jet pipe design, are its robust and enhanced design. In past years, it has been particularly successful in Moog Servo-Proportional Valves used applications with moderate dynamic requirements.

The new two-stage pilot Servo-Proportional Valve D670 has been designed for applications involving the highest dynamic requirements. It merges the robust design of a dynamically enhanced ServoJet® pilot stage with the large control flow of a two-stage pilot valve, thereby achieving superior dynamic characteristics.

The Direct Operated Valve D633, when used as the pilot valve, is characterized by its high dynamics and very low leakage. It is suited for very high dynamic requirements, while offering an outstanding efficiency. The very high pressure efficiency makes it the first choice for applications involving low pilot pressures.

In this operating mode of the Servo-Proportional Valve, the spool position is controlled. The applied command signal is proportional to a particular spool position. The command signal (spool position command) is fed to the valve electronics. A position transducer (LVDT) measures the spool's actual position and transfers this information to the valve electronics. The electronics compare the actual spool position and command signal, and control the linear force motor or the ServoJet® Pilot Valve to position the spool as required.

The position command can be controlled through parameters in the valve software (i.e., linearization, ramping, deadband, or sectionally defined amplification).

The digital control electronics are integrated into the valve. The valve electronics contain a microprocessor system performing all important functions via the valve software.

The valves are parameterized, activated, and monitored via the built-in fieldbus interface (e.g. CANopen, Profibus-DP or EtherCAT). To reduce wiring, the fieldbus interface is provided with two plugs. Thus, valves may be integrated into the bus without any external T-joints. In addition, up to two analog input commands and up to two analog actual value outputs are available.

Optionally, the valve is available without a fieldbus interface. In this case, the valve parameters are set using the integrated service connector.

In addition to flow control, the valves are capable of controlling external axis signals such as position, speed, force and similar parameters.