In modern hydraulic systems, the main pump is no longer just a component that provides pressure.
With the adoption of servo drives, variable-frequency control, multi-circuit architectures and stricter requirements on noise and reliability, the hydraulic power source has become a core element of system design.

It must deliver high pressure capability, stable performance across a wide speed range, low noise and pulsation, durability under real operating conditions, and the flexibility to be reused across multiple machine platforms.

The FG / FG21 high-pressure internal gear pump series is designed as a unified hydraulic power platform, supporting applications from servo-driven machinery to heavy-duty industrial systems.

Industry Positioning and Application Scope

FG series pumps are widely applied in systems where both performance and adaptability are required.

Typical application areas include

Servo-driven equipment such as injection molding machines, die casting machines and rubber processing systems, where stable low-speed holding and wide speed control are critical

Forming and processing machinery including hydraulic presses, press brakes, shears and forging equipment, requiring both precision control and high-pressure stability

Heavy-duty industrial systems such as metallurgy, smelting and rubber production lines, where continuous operation and harsh environments are common

Marine and mobile equipment including deck machinery and logistics vehicles, where long piping, compact layout and low noise are key requirements

For systems requiring multiple hydraulic circuits, FG21 dual internal gear pumps provide an integrated solution by combining main and auxiliary circuits in a compact structure

Core Engineering Features

High Pressure Capability

Most FG and FG21 models are designed for working pressures around 31.5 MPa, with maximum pressure up to 35 MPa.
This range covers demanding operations such as clamping, forging, extrusion, continuous casting and heavy lifting applications.

Large-displacement variants are optimized for high-flow and medium-to-high pressure combinations, allowing flexible use across different system sizes.

Wide Speed Range

FG pumps operate across a broad speed range from low to high speed, making them fully compatible with servo and variable-frequency drive systems.

At high speed, they provide sufficient flow for rapid cycles.
At low speed, they maintain stable volumetric efficiency, supporting holding pressure, positioning and micro-movement control.

This enables effective speed-based flow control without being limited by leakage or instability.

Low Pulsation and Low Noise

The internal gear structure, combined with optimized design features, significantly reduces flow and pressure pulsation.

This results in more stable motion control, reduced vibration in piping systems, and lower overall noise levels.

These characteristics are especially valuable in precision equipment and systems with long piping or multiple circuits.

Durability in Real Operating Conditions

FG and FG21 pumps are built with robust structures and wear-resistant components, making them less sensitive to oil contamination compared with more delicate pump types.

With proper but practical filtration, they maintain stable performance in environments such as metallurgy, smelting, rubber processing and marine applications.

FG21 Dual Pump Configuration

FG21 integrates two pumps on a single shaft

The front pump supplies the main high-pressure circuit

The rear pump supplies auxiliary circuits

This design reduces the number of motors and pump units, simplifies system layout, lowers noise sources and supports efficient multi-circuit operation within limited space

Practical Selection Method

In real engineering practice, pump selection can be simplified into three key steps

Step 1 Determine Flow Level

Small flow and compact systems use FG0

Medium flow and standard equipment use FG1

Large flow and centralized systems use FG2

Step 2 Verify Pressure Requirement

FG1 is suitable for high pressure with medium flow

FG2 is preferred for large flow combined with high pressure

Most industrial applications fall within the typical high-pressure working range

Step 3 Decide on Multi-Circuit Configuration

For systems that include both main and auxiliary functions, FG21 dual pumps provide a compact and efficient solution

The front pump serves the main circuit
The rear pump serves auxiliary circuits

This approach improves system structure while maintaining flexibility

Typical Application Logic

Instead of selecting purely by model number, engineers typically match pump characteristics to application requirements

Servo-driven machines focus on flow calculation based on cycle time and holding pressure

Presses and forming equipment prioritize smooth low-speed operation and stable pressure

Die casting and forging systems emphasize high rigidity under sustained high pressure

Metallurgical and marine systems require durability, low pulsation and tolerance to contamination

Mobile equipment such as forklifts and AGVs require compact size, low noise and efficiency

This approach ensures that pump selection aligns with actual operating conditions rather than theoretical assumptions

System Design Recommendations

For optimal performance, system-level design is equally important

Use appropriate hydraulic oil with practical filtration levels rather than excessive cleanliness requirements

Provide adequate cooling for high-pressure and continuous-duty applications

Optimize piping layout and support structures to reduce vibration and noise

Leverage low pulsation characteristics to improve servo control accuracy and response

Conclusion

FG and FG21 internal gear pumps represent a unified hydraulic power platform rather than isolated components

By combining high pressure capability, wide speed adaptability, low pulsation and noise, durability under real conditions and flexible configuration options, they support a consistent and scalable approach to hydraulic system design

From servo-driven equipment to heavy-duty industrial applications, this platform allows engineers to develop systems that are stable, efficient and easy to extend

Instead of redesigning the hydraulic source for every project, FG and FG21 provide a reusable foundation for modern hydraulic systems