Product Overview
The PGH4-21/040RE11VU2 is a gap-compensated internal gear pump from the Bosch Rexroth PGH4 series. This model features a displacement of 40.6 cm³/rev (nominal size 40), belonging to the BG4 frame size. It corresponds to Rexroth material number R900086321.
The PGH series represents Rexroth’s premium fixed-displacement internal gear pump line, featuring a unique internal gear principle with leakage gap compensation technology. The pump’s精密 construction includes pump body, gear ring, pinion shaft, sliding bearings, axial plates, end cover, mounting flange, and pressure distribution components.
Every unit is manufactured to original equipment specifications, ensuring 100% drop-in interchangeability with genuine Rexroth PGH4-21/040RE11VU2 pumps without any system modifications. Each pump undergoes rigorous 100% simulated duty-cycle testing on dedicated test benches to validate pressure-flow-efficiency performance curves.
Brand Disclaimer: This product is a high-quality compatible replacement engineered for full interchangeability with Bosch Rexroth original equipment. All Rexroth brand names and model codes are referenced solely to indicate compatibility and interchangeability. This product is manufactured by an independent producer and is not an original Rexroth product.
Technical Specifications
Model Code: PGH4-21/040RE11VU2
Rexroth Material Number: R900086321
Brand Series: Bosch Rexroth PGH4 (PGH Series)
Product Type: Internal Gear Pump
Pump Type: Fixed Displacement
Technology: Leakage Gap Compensation
Component Series: 2X (PGH-2X)
Frame Size: BG4 (Size 4)
Nominal Displacement: 40 cm³/rev
Actual Displacement: 40.6 cm³/rev
Maximum Operating Pressure: 350 bar
Displacement Range (PGH4 Series): 20 – 100 cm³/rev
Viscosity Range: 12 – 20,000 mm²/s
Speed Range: 200 – 3,000 rpm (varies by displacement)
Speed Range (PGH4-21/040): 500 – 3,000 rpm
Rotation Direction: Right-hand (R) / Left-hand (L) available
Shaft Type: Cylindrical (E) or SAE involute spline (R)
Seals: FKM/Viton or NBR
Hydraulic Fluid: Mineral oil HLP, HFC (with W-seal configuration)
Port Connection: Threaded or flanged
Housing Material: Cast iron
Weight (PGH4 Series): 13.5 – 20 kg (varies by displacement)
Flow Rate (Size 40): 57.6 L/min @ 3,000 rpm
Key Technical Advantages
1. Gap Compensation Technology – High Efficiency Across All Operating Conditions
Advanced leakage gap compensation technology with axial pressure field compensation ensures optimal volumetric efficiency even at low speeds or with low-viscosity fluids. This makes the PGH series exceptionally suitable for variable-speed and variable-viscosity applications.
2. Internal Gear Principle – Ultra-Low Noise & Minimal Pulsation
The unique internal gear principle with optimized involute tooth profile and extended meshing length delivers ultra-low noise and minimal flow pulsation. Significantly quieter than conventional external gear pumps—ideal for noise-sensitive environments such as cab-near installations and urban equipment.
3. Ultra-Wide Viscosity Range – One Pump for Multiple Applications
Supports an exceptionally wide viscosity range of 12 – 20,000 mm²/s, from low-viscosity hydraulic fluids to high-viscosity media. Combined with a 200 – 3,000 rpm speed range, a single pump adapts to diverse application requirements—simplifying selection and inventory management.
4. Modular Design – Maximum Flexibility & Expandability
All PGH series sizes (PGH2–PGH5) can be freely combined or paired with PGF gear pumps, axial piston pumps, and vane pumps in multi-pump configurations. Modular design significantly enhances system design flexibility and expandability.
5. High-Pressure Rating – Industrial-Grade Durability
Maximum operating pressure up to 350 bar, far exceeding standard gear pump pressure ratings. Combined with cast iron housing and precision sliding bearings, ensuring long-term reliability under high-pressure, high-frequency, continuous-duty operations.
6. 100% Simulated Duty-Cycle Testing
Every pump is 100% tested on dedicated hydraulic test benches under simulated real-world operating conditions—validating pressure-flow characteristics and efficiency curves at rated pressure (350 bar) and full speed range—ensuring zero-defect, plug-and-play performance upon installation.
Application Areas
Industrial Machinery: Plastic injection molding machines, presses, CNC machine tools
Energy & Wind Turbines: Lubrication systems for wind turbine generators
Mobile Hydraulics: Construction and agricultural equipment
Variable-Speed Drive Systems: Optimized for variable-speed drive applications
Multi-Pump Systems: Combined with PGF gear pumps, axial piston pumps, and vane pumps
Expert Maintenance Tips
1. Fluid Cleanliness Control
Internal gear pumps are highly sensitive to fluid contamination. Maintain system fluid cleanliness to ISO 4406 19/17/14 or better. Install a ≤10 μm absolute filtration filter upstream of the inlet port to prevent particle contamination from damaging precision gear pairs, sliding bearings, and pressure distribution components.
2. Inlet Line Requirements
Keep suction lines short and straight with adequate diameter—not less than the port size. Recommended suction line flow velocity: ≤1.5 m/s to prevent cavitation from excessive inlet resistance. Inlet pressure must be maintained between 0.8 – 2.0 bar (absolute) .
3. Coupling Alignment Precision
Ensure pump shaft-to-drive shaft coaxiality deviation ≤0.05 mm and angular deviation ≤0.5° during installation. Flexible couplings are strongly recommended. If the drive involves sprockets or V-belt pulleys, an independent outboard bearing MUST be installed to protect pump shaft bearings.
4. First-Start Priming Procedure
Before initial startup, prime the pump by bleeding air through the drain port or a loosened outlet fitting. Perform 2–3 jog starts with the outlet open (no load) until oil fills the pump cavity without air bubbles, then connect the load circuit for full operation.
5. Viscosity & Temperature Monitoring
This model supports an ultra-wide viscosity range of 12 – 20,000 mm²/s. During cold starts when viscosity exceeds the recommended range, ensure adequate suction conditions or preheat the fluid to prevent cavitation damage. Recommended operating temperature range: +15°C to +80°C.
6. Rotation Direction Confirmation
The R in the model code indicates right-hand (clockwise) rotation. Always verify that the drive motor/engine rotation matches the pump before installation. Specify left-hand (L) rotation configuration when ordering if required.
