Rexroth HG1 Series Internal Gear Pump | HG1-25 HG1-32 HG1-40 HG1-50 HG1-63

The HG1 Series of high-pressure internal gear pumps manufactured by Chengyuan Hydraulic is a premier fluid power solution engineered to fully cross-reference the technical standards of Rexroth. Covering models HG1-25, HG1-32, HG1-40, HG1-50, and HG1-63, this series is designed for industrial applications requiring high pressure, extreme durability, and low noise profiles.

Utilizing an advanced hydrostatic radial and axial gap compensation design, the HG1 series maintains exceptional volumetric efficiency even at continuous pressures of 210 bar. The internal gear geometry inherently provides a smoother flow with significantly less pulsation than standard external gear pumps. Chengyuan ensures 100% original-place interchangeability for all mounting dimensions and performance characteristics. Every unit is subjected to 100% simulated full-load testing before shipment to guarantee “out-of-the-box” reliability for heavy-duty B2B industrial environments.

Technical Specifications 

• Brand Compatibility: Rexroth HG1 Series Replacement

• Pump Type: Internal Gear Design

• Specific Model & Displacement Matrix:

  • HG1-25: 25.2 $cm^3/rev$

  • HG1-32: 32.4 $cm^3/rev$

  • HG1-40: 40.1 $cm^3/rev$

  • HG1-50: 50.4 $cm^3/rev$

  • HG1-63: 63.2 $cm^3/rev$

• Rated Continuous Operating Pressure: 210 bar (3045 PSI)

• Peak Intermittent Pressure: 315 bar (4570 PSI)

• Max Speed Range: Up to 3000 rpm (Depending on displacement)

• Minimum Operating Speed: 600 rpm

• Noise Emission: $\le 65$ dB(A) at 1450 rpm / 210 bar

• Fluid Compatibility: Mineral oils according to DIN 51524, Fire-resistant fluids available

• Shaft & Mounting: Standard ISO/SAE mounting patterns for seamless interchange

Key Technical Advantages:

• Hydrostatic Gap Compensation Mechanism: The pump utilizes floating side plates and radial sealing segments that are energized by system pressure. This automatically closes internal clearances, minimizing internal bypass (leakage). The result is a sustained volumetric efficiency above 95% throughout the product’s lifespan, even under variable temperatures.

• Ultra-Low Flow Pulsation and Noise: The internal gear engagement features a high contact ratio, reducing flow ripple by up to 70% compared to external gear units. Combined with a high-density ductile iron housing, the HG1 series operates with a whisper-quiet profile, making it perfect for noise-sensitive factory environments.

• Reinforced Bearing and Shaft Integrity: High-load composite bushings are utilized to withstand high-frequency pressure cycling without fatigue. The drive shafts are precision-ground and heat-treated for superior torsional strength, preventing shaft failure during 315 bar peak surges.

• Modular Multi-Pump Capability: The HG1 series is designed for easy “through-drive” combinations. It can be coupled with other gear or vane pumps, allowing a single drive motor to power multiple independent circuits, optimizing space in compact hydraulic power units.

Application Areas:

• Plastics Machinery: Injection molding machines, blow molding machines, and hydraulic presses.

• Machine Tool Industry: CNC lathes, high-pressure punching machines, bending and stretching machines.

• Industrial Power Units: Auxiliary circuits for steel mills, metallurgical equipment, and high-pressure logic control systems.

Expert Maintenance Tips:

• Mandatory Pre-Filling Before Startup: After installation, always fill the pump housing through the pressure port with clean hydraulic fluid. Internal gear pumps rely on an initial oil film for sealing; a dry start can cause immediate damage to the radial compensation segments.

• Monitor Inlet Vacuum Levels: Ensure the suction line is appropriately sized and free of obstructions. HG1 pumps are sensitive to cavitation. If sharp “cracking” noises are heard during startup, check for air leaks in the intake manifold immediately to prevent permanent pitting of the gear set.

• Filtration Best Practices: For maximum service life in high-pressure circuits, we recommend a filtration rating of $\beta_{10} \ge 100$. The precision clearances in internal gear pumps are tight; particles larger than 15 microns will accelerate the wear of the compensation components.