MOOG G631-3008B | G631 Series Signal Conditioner for Precision Hydraulic Actuation

G631-3008B: Product Overview​

The G631-3008B is a linear, single-channel servo valve amplifier from the G631 Series, designed to interface electronic controllers with MOOG electrohydraulic servo valves in precision hydraulic systems. In an automation architecture, it functions as a signal conditioner and driver, converting low-power analog command signals (e.g., from PLCs, motion controllers) into the precise current outputs required to modulate servo valve torque motors. This amplifier belongs to MOOG’s industrial-grade servo amplifier family, recognized for stability in closed-loop hydraulic control. Its primary role is to ensure linear, responsive actuation of hydraulic cylinders or motors by maintaining proportionality between the input command and valve spool displacement. The G631-3008B is typically integrated into systems where accurate position, velocity, or force control is critical, such as material testing rigs, robotics, and aerospace simulators. The G631 Series platform emphasizes compatibility with MOOG servo valves (e.g., D633, D634, D661 series) and robust performance in industrial environments, reducing integration complexity for engineers.

G631-3008B: Technical Specifications​

Core Features & Customer Value​

The G631-3008B provides a single-channel ±40mA output, optimized for driving MOOG servo valves with torque motor requirements matching this current range (e.g., D633, D634 series). For engineers, this dedicated output eliminates the need for external signal conversion, simplifying wiring and reducing potential points of failure in systems like small hydraulic presses or robotic joints.

A 10-turn gain adjustment potentiometer allows calibration of the output current slope (0.5–2.0 mA/V), enabling fine-tuning to match specific valve sensitivities. This flexibility is valuable during retrofits, where legacy controllers may have different signal scaling, avoiding costly valve replacement.

Built-in low-pass filtering (10Hz cutoff) rejects high-frequency noise from controllers, ensuring clean current delivery to the valve. For maintenance teams, this reduces erratic actuator behavior caused by EMI, improving system uptime in electrically noisy environments like steel mills.

Protection features—overcurrent limiting (prevents torque motor damage) and thermal shutdown (activates at 85°C)—safeguard both the amplifier and connected servo valve. In applications with transient load spikes (e.g., press brake cycling), these protections extend component life. Reverse polarity protection prevents damage from incorrect power supply connection.

Compact DIN rail mounting and a 0.45 kg weight facilitate dense panel installation, ideal for space-constrained machinery. For procurement managers, this minimizes cabinet space requirements and installation labor compared to bulkier amplifiers. The amplifier’s 50,000+ hour service life (with proper ventilation) reduces long-term replacement costs.

Typical Applications​

The G631-3008B is deployed in systems requiring precise, low-power servo valve control. In material testing laboratories, it drives servo valves in fatigue rigs applying cyclic loads up to 20 Hz, where its 1 ms response ensures accurate force replication. Small industrial robots use it to control joint actuators, with the ±40mA output providing smooth motion during pick-and-place tasks.

Aerospace simulation platforms employ the amplifier to drive auxiliary actuators in flight control simulators, matching pilot input commands with hydraulic response. Manufacturing settings, such as small plastic injection molders, utilize it for clamp/unclamp sequencing, where precise valve control reduces cycle time variability. Its compatibility with MOOG D633/D634 series valves makes it a common choice for retrofitting legacy hydraulic systems with modern controllers.