Hydac PGI Series Internal Gear Pump | PGI100 PGI101 PGI102 PGI103

The PGI Series high-pressure internal gear pumps manufactured by Chengyuan Hydraulic are low-noise, high-volumetric fluid power generation components fully engineered to match global Hydac industrial footprints. Spanning four centralized dimensional frame categories—PGI100, PGI101, PGI102, and PGI103—this series is optimized for heavy duty applications demanding near-zero flow ripples, low ambient acoustic levels, and high efficiency retention under persistent high pressures (such as electro-hydraulic servo injection molders, CNC press brakes, forging press platforms, and centralized industrial HPUs). Utilizing advanced straight-line conjugate gear tooth geometries and active axial/radial clearance compensation networks, these pumps outperform standard external options. Every singular PGI gear pump undergoes 100% simulated load testing for volumetric retention at full rated pressures, thermal shift limits, and variable-speed servo response characteristics prior to shipment to ensure original-matching specifications and offer proven 100% original-place interchangeable compatibility.

Technical Specifications:

• Core Product Series: Hydac PGI Series Straight Conjugate High-Pressure Internal Gear Pumps

• Frame Sizes & Groups Supported: PGI100 Group / PGI101 Group / PGI102 Group / PGI103 Group

• Geometric Displacement Array:

  • PGI100 Compact Matrix: ~3.8 $cm^3/rev$ to 8.0 $cm^3/rev$

  • PGI101 Medium Matrix: ~10.0 $cm^3/rev$ to 25.0 $cm^3/rev$

  • PGI102 Mid-Large Matrix: ~32.0 $cm^3/rev$ to 64.0 $cm^3/rev$

  • PGI103 Heavy Industrial Matrix: ~80.0 $cm^3/rev$ to 125.0 $cm^3/rev$

• Maximum Rated Continuous Pressure: Rated up to 30 MPa to 31.5 MPa (300 bar ~ 315 bar / 4567 psi)

• Intermittent Peak Pressure Limit: Reaches up to 35 MPa (350 bar / 5075 psi)

• Maximum Allowed Drive Speed: 3000 rpm to 3600 rpm (perfectly optimized for electric servo motor coupling under dynamic frequency acceleration and variable flow delivery)

• Minimum Stable Preserved Velocity: 200 rpm to 400 rpm (delivering excellent torque holding during closed-loop dead-head pressure-retention states)

• Typical Operational Noise Threshold: $\le 60 \text{ dB(A)}$ to $66 \text{ dB(A)}$ (at full displacement under continuous peak pressure loads)

• Shaft & Mounting Layout Flange: Compliant with SAE 2-bolt/4-bolt templates or ISO metric specifications, configuring straight keyed drives or standard involute male splines (strictly paired to exact catalog codes)

Key Technical Advantages:

• Straight Conjugate Internal Gearing with Trap-Oil Free Flow Path: The inner pinion and external ring gear feature an advanced straight conjugate profile alignment, establishing an exceptionally high contact ratio across adjacent tooth profiles. This not only minimizes output flow ripple to near-zero boundaries but completely eradicates the trapped oil pressure explosions and mechanical hums native to external gear meshes, delivering ultra-smooth rotation.

• Dual-Axis Hydrostatically Balanced Axial & Radial Clearance Compensation: The internal core integrates specialized floating axial side plates paired with a three-piece radial crescent element block. Utilizing internal high pressure discharge oil to automatically back-bias the plates and sealing blocks against the gear edges, the pump mitigates mechanical wear gaps automatically under thermal expansions, keeping continuous volumetric efficiency above 93%.

• Monoblock Ductile Iron Shell Casting with Expanded Inlet Corridors: The central pump body is cast from dense, heavy-duty nodular graphite cast iron, offering excellent structural tensile ratings and ambient vibration/noise attenuation. The internal suction cavity is cast with widened, streamlined geometries, lowering fluid inlet drag at high speeds to protect the pump from oil cavitation or erosion during cold-starts with high-viscosity media.

• Optimized for High-Dynamic Electro-Hydraulic Servo Systems (EHS): Due to its low break-away break torque and active sealing compensation, the PGI series seamlessly adapts to direct electric servo motor regulation. It withstands rapid bi-directional reversals, violent speed step accelerations/decelerations, and long-duration stall pressure-holding states at ultra-low speeds, serving as the premium prime mover for modern servo automation.

Application Areas:

• Precision Plastic Injection Molding Machinery: Central servo HPU pump units for heavy all-electric or hybrid servo injection molding setups and plastic blow-molding loops.

• CNC Metal Forming Machine Tools: Primary high-pressure drive modules governing precision CNC press brakes, heavy forging press slide sheets, and industrial scrap shears.

• High-Response Automated Factory Systems: Automated assembly line power stations for automotive manufacturing plants and high-frequency dynamic simulation flight test platforms.

Expert Maintenance Tips:

• Mandatory Pre-Fill Case Priming and Manual Shaft Rotation: Because the internal clearances of internal gear clusters are extremely tight, you must pre-fill the pump housing with clean hydraulic fluid through the inlet or designated fill plug prior to initial engine turnover. Turn the shaft coupling manually 3 to 5 times to check for binding and ensure the gears are wet. Utilize a soft jog start or inverter ramp-down during the first activation until all trapped air lines bleed clean.

• Rigid Laser Alignment Calibration to Prevent Axial/Radial Wear: The internal tolerances of the PGI elements are built to micron scales. Never treat the coupling alignment of this pump with the loose metrics used for basic external gear options. The axial angular offset and radial runout tolerances must be clocked within $\le 0.05 \text{ mm}$. Any off-center shaft loading transmitted by the motor will score the floating axial side plates and destroy the main drive bearings within days.

• Enforce Strict Fluid Contamination Redlines: The axial and radial clearance compensation slides are highly vulnerable to scratching by micro-abrasive suspended solids. The circuit must be armored with dedicated high-efficiency suction strainers paired with return filtration units rated at $\beta_{10} \ge 100$ (10-micron absolute efficiency). Fluid cleanliness must be continuously locked to ISO 4406 19/17/14 (NAS Class 8) or cleaner. Particulate entry will jam the floating plates, leading to sudden pressure drop-offs during thermal load operations.