G761/-761 series flow control servo valves are available as three-way and four-way throttling flow control valves for better control performance when used in four-way valves. The valves are high-performance, two-stage electro-hydraulic servovalves with a rated flow rate of 0.5 to 75l/min(0.125 to 19.5 gpm) at 35 bar(500psi) valve pressure drop per throttling edge.
The valve series has simple structure, strong, reliable operation and long service life. The pilot stage of the valve is a symmetrical nozzle flapper torque motor. The output stage contains a 4-sided spool that is finely ground to match the valve sleeve for optimal performance. The spool position is mechanically fed back to the torque motor by a carbide feedback rod. The carbide ball at the end of the feedback lever ensures high accuracy, reliable operation and a long service life. All MOOG servo valves have a reputation for high accuracy and reliable operation even in the most demanding industrial applications.
These valves are suitable for electro-hydraulic position, speed, pressure or force servo control systems with high dynamic response requirements.
The G761/-761 series can be used in a wide range of applications and is one of the most versatile servo valves and the latest model in the 760 series we are known for. The collection draws on Moog’s nearly 70 years of design expertise.

The G761/-761 series flow control servo valves contain a polarized electric torque motor and a two-stage hydraulic power amplifier. The motor armature extends into the air gap of the flux loop, where it is supported by a spring fitting. The spring tube acts as a seal between the electromagnetic and hydraulic parts of the servo valve. There are two groups of motor coils wrapped around the armature, and one group on each side of the spring tube.
The baffle of the first stage hydraulic amplifier is rigidly connected with the center point of the armature. The baffle extends through the spring tube and passes between the two nozzles, forming two variable orifice holes between the nozzle tip and the baffle. The pressure controlled by the baffle and the nozzle variable orifice is fed into the end area of the second stage spool.
The input signal induces a magnetic charge on the armature, which drives the armature and the baffle to deflect. The assembly rotates around a spring tube to increase the area of one nozzle orifice while decreasing the area of the other orifice.
The pressure difference generated by this action will drive the spool movement. The resulting spool displacement generates a linear force in the feedback rod in the direction opposite to the torque in the input signal at the beginning. The spool continues to move until the force of the feedback rod is balanced with the force in the input signal.
The second stage adopts the conventional four-way valve core design, in which the output flow of the valve under the fixed pressure drop is proportional to the displacement of the valve core from the zero position. A cantilever feedback spring rod is fixed to the baffle and meets an opening in the center of the spool. The spool movement causes the feedback spring rod to deflect, which then creates a force on the armature/baffle assembly.