Sumitomo GH1 GH2 Series Internal Gear Pump | GH1-19C GH2-25W | High Pressure Oil Pump

The GH1 and GH2 Series high-pressure internal gear pumps manufactured by Chengyuan Hydraulic are high-efficiency hydraulic power components engineered to the technical standards of the global Sumitomo QT/GH series. This professional product range focuses on precision engineering replacements for highly demanded market models, including GH1-19C-LL, GH1-19W-LL, GH2-25C-LR, and GH2-25W-LR.

Renowned for their distinct “straight-line conjugate tooth profile” and advanced dual axial/radial pressure compensation architecture, these internal gear pumps maintain exceptional volumetric efficiency under continuous high pressures. Chengyuan guarantees 100% original-place interchangeability concerning flange mounting dimensions (SAE/JIS standards), drive shaft keyways, port configurations (C-style flange or W-style pipeline thread), and rotation kinematics. Every pump is subjected to 100% simulated load testing under high pressure before delivery, ensuring that pressure, flow rates, and acoustic levels meet rigorous industrial standards.

Technical Specifications 

• Compatible Brand: Sumitomo GH1 / GH2 / GH4 Series

• Core Model Codes: GH1-19C-LL, GH1-19W-LL, GH2-25C-LR, GH2-25W-LR

• Nominal Displacement:

  • GH1-19 Models: 19.4 $cm^3/rev$

  • GH2-25 Models: 25.6 $cm^3/rev$

• Rated Operating Pressure: 250 bar (25 MPa)

• Maximum Peak Pressure: 300 bar (30 MPa)

• Speed Range: 600 rpm – 1800 rpm

• Control Type / Structure: Fixed Displacement Internal Gear Pump

• Port Connection Types: C – Flange type / W – Pipeline Thread type

• Rotation: LR – Clockwise (viewed from shaft end) / LL – Counter-clockwise (viewed from shaft end)

• Recommended Hydraulic Fluid: Mineral oil-based anti-wear hydraulic oil

Key Technical Advantages:

• Axial and Radial Dual Pressure Compensation: Incorporates floating side plates for axial clearance compensation along with specialized seal segments for radial gap compensation. The internal clearances self-adjust according to system pressure, maintaining volumetric efficiency above 95% even at 250 bar continuous operation.

• Precision Straight-Line Conjugate Gearing: The internal ring gear and external pinion utilize advanced straight-line conjugate meshing profiles. The teeth interface via pure rolling contact with minimal relative sliding, eliminating trapped oil pockets and geometrically increasing service life.

• Ultra-Low Flow Pulsation & Silent Run: Due to the continuous meshing characteristics, the discharge flow pulsation rate is held under 1%. The hydraulic operation noise is exceptionally low—10 to 15 decibels quieter than standard external gear pumps, making it ideal for acoustic-sensitive workshops.

• Heavy-Duty Ductile Iron Casing & Hardened Shaft: The main pump housing is machined from high-strength ductile iron to resist structural deformation under heavy pressure loading. The integrated gear-shaft assembly is forged from premium alloy steel, vacuum carburized, and precision ground to a surface hardness over HRC 60 for severe impact resistance.

Application Areas:

• Precision Injection Molding Machines: Serving as primary or auxiliary power units for injection and clamping loops, perfectly suited for closed-loop high-frequency servo control.

• Hydraulic Press Brakes & Shearing Machinery: Supplying stable, pulsation-free high-pressure hydraulic fluid to high-end servo-hydraulic configurations.

• Heavy-Duty Forging Machine Tools: Configured as the core high-pressure component within centralized multi-pump hydraulic power stations.

Expert Maintenance Tips:

• Mandatory Initial Fluid Priming: Before initial startup or after extended system storage, always fill the pump housing with clean hydraulic fluid via the outlet port. Manually rotate the drive shaft several turns to prevent immediate dry-friction wear on internal seals during startup.

• High-Standard Oil Cleanliness Control: Internal gear pumps are highly sensitive to abrasive micro-particles. Fluid cleanliness must be monitored and maintained strictly at ISO 4406 19/16/13 or better. High-efficiency absolute filters on the return lines are highly recommended.

• Prevent Suction Line Aeration: Ensure that all inlet suction lines and fittings are completely airtight. If air leaks into the inlet via loose fittings or degraded hoses, severe cavitation accompanied by harsh metallic noise will occur, rapidly destroying the radial compensation components.