Product Overview
The 421AK00325B and ADU041R01AE10C28000000200200CD0B both belong to the Eaton Vickers 420 Series open-circuit axial piston variable displacement pump family, ADU041 specification, with a displacement of 41.0 cc/rev (2.50 in³/rev). The 420 Series features a field-proven rotating group designed for continuous working pressures up to 280 bar (4060 psi), intermittent pressures up to 320 bar (4600 psi), and peak pressures reaching 350 bar (5000 psi). It is widely used in construction machinery, agricultural equipment, and industrial hydraulic systems.
The 421AK00325B is the complete part number corresponding to the ADU041 specification, equipped with pressure compensator/pressure-flow compensator control, right-hand rotation, SAE 2-bolt B mounting flange, 0.875″ keyed drive shaft, and rear port configuration.The ADU041R01AE10C28000000200200CD0B is a complete model code for the same specification, featuring pressure-flow compensator control with an LS port. Both pumps share identical mounting interfaces, drive shaft splines, and port layouts, enabling direct bolt-on replacement of original Eaton Vickers pumps without piping modification or adapter plates.
Every pump undergoes 100% simulated operating-condition testing before shipment, including rated pressure hold, flow characteristic verification, and control response validation—delivering immediate reliability upon installation. The product meets ISO 4406 21/18/13 fluid cleanliness requirements.
Technical Specifications
Model Identification:
421AK00325B — Complete part number, ADU041 specification, pressure compensator/pressure-flow compensator control, right-hand rotation
ADU041R01AE10C28000000200200CD0B — Complete model code, ADU041 specification, pressure-flow compensator with LS port, right-hand rotation, SAE 2-bolt B flange, 0.875″ keyed shaft
Displacement:
ADU041: 41.0 cc/rev (2.50 in³/rev)
ADU049: 49.2 cc/rev (3.00 in³/rev)
ADU062: 62.3 cc/rev (3.80 in³/rev)
ADU080: 80.0 cc/rev (4.88 in³/rev)
Pressure Ratings (ADU041):
Continuous working pressure: 280 bar (4060 psi)
Intermittent working pressure: 320 bar (4600 psi)
Peak pressure: 350 bar (5000 psi)
Maximum case pressure: 350 bar (5075 psi)
Speed Range (ADU041):
Minimum speed: 600 rpm
Maximum speed at 1.0 bar absolute inlet: 2650 rpm
Maximum speed at 2.0 bar absolute inlet: 2950 rpm
Maximum allowable speed: 3600 rpm
Theoretical Flow and Power:
Maximum flow: 104 L/min at 2650 rpm
Maximum input power: 50.7 kW (68.0 hp)
Maximum input torque: 183 Nm (1620 lbs.-in.)
Control Types:
Pressure Compensator — Pump automatically reduces displacement to maintain constant pressure when system pressure reaches the set value
Pressure-Flow Compensator (with LS port) — Integrates pressure compensation with load-sensing flow regulation; LS standby pressure setting approximately 17-19 bar
Optional controls: load sensing, torque control, electro-proportional control, remote pressure control, etc.
Structural Parameters:
Pump type: Open-circuit axial piston variable displacement
Mounting flange: SAE 2-bolt B (SAE J744-101-2)
Drive shaft: 0.875″ keyed shaft (SAE J744-22-1, key included)
Rotation: Right-hand (clockwise), viewed from shaft end
Inlet port: 1.875-12 UN-2B SAE O-ring port (rear)
Pressure port: 1.3125-12 UN-2B SAE O-ring port (rear)
Case drain port: 0.875-14 UNF-2B O-ring port, top
Housing material: Cast iron
Weight: Approximately 23.9 kg (52.7 lbs)
Bearing Life:
B10 life at 140 bar (2030 psi): 103,650 hours
B10 life at 210 bar (3045 psi): 17,150 hours
Key Technical Advantages
1. Complete Model Coding Enables 100% Drop-in Interchange
The 420 Series employs a standardized model code system encompassing displacement, control type, mounting flange, drive shaft, port position, and rotation direction. The mounting flange (SAE 2-bolt B), drive shaft spline (0.875″ keyed), and port layout of the 421AK00325B and ADU041R01AE10C28000000200200CD0B are identical, enabling direct bolt-on replacement of original Eaton Vickers pumps without piping modification or adapter plates.
2. Field-Proven Rotating Group Design
The 420 Series utilizes a field-proven rotating group that allows the pump to operate at 280 bar continuous working pressure and 320 bar intermittent pressure.Precision-lapped piston-cylinder interfaces and optimized valve plate design reduce pressure pulsation and flow ripple, maintaining stable volumetric efficiency at rated conditions. Bearing B10 life reaches 103,650 hours at 140 bar and maintains 17,150 hours at 210 bar.
3. Pressure-Flow Compensator Control Optimizes System Efficiency
The ADU041R01AE10C28000000200200CD0B features a pressure-flow compensator with LS port that automatically adjusts pump displacement based on load demand, delivering only the flow required by actuators. When actuators stop, the pump reduces displacement to near zero, maintaining only approximately 17-19 bar standby pressure—significantly reducing system heat generation and energy loss. Control response time is approximately 20 ms.
4. Cast Iron Housing with Compact Architecture
The pump features a one-piece cast iron housing design that reduces leak points and simplifies maintenance. The compact rotating group achieves high power density within constrained installation spaces, suitable for the tight engine compartments of mobile machinery. Multiple control options and through-drive capability enable flexible adaptation to different hydraulic system configurations.
5. Low Noise Operation and Reduced Maintenance Costs
The 420 Series pump incorporates optimized noise-reduction design, operating at low noise levels to help equipment meet noise emission regulations. The field-proven rotating group and long-life bearings reduce maintenance frequency, lowering the total cost of ownership across the equipment lifecycle.
Application Areas
Construction machinery (wheel loaders, backhoe loaders, mini excavators)
Agricultural machinery (tractors, combine harvesters, sprayers)
Forklifts and material handling equipment
Municipal vehicles and sanitation equipment
Road construction machinery (rollers, pavers)
Marine deck machinery and port equipment
Industrial hydraulic systems and hydraulic power units
Expert Maintenance Tips
1. Pre-Installation Model Verification
Verify the complete model code on the pump nameplate before installation. Pay particular attention to control type (pressure compensator or pressure-flow compensator), rotation direction (R or L), drive shaft type, and mounting flange specification. The 421AK00325B is configured for right-hand rotation with a 0.875″ keyed drive shaft. Ensure drive shaft-to-coupling concentricity within 0.05 mm to prevent premature seal failure from radial loads.
2. Hydraulic Fluid Cleanliness Requirements
Use ISO VG46 anti-wear hydraulic oil with cleanliness level no lower than ISO 4406 21/18/13. Optimal operating viscosity range: 16-40 cSt. Suction filter rating should be no coarser than 10 μm. Flush the system thoroughly before first operation to eliminate residual metallic particles.
3. LS Line Connection (Pressure-Flow Compensator Models)
The LS load-sensing port line of the ADU041R01AE10C28000000200200CD0B must be connected to the system load signal port. The line must remain sealed with no leakage. LS line leakage prevents the pump from properly responding to load demand, causing sluggish system operation or abnormal pressure rise.
4. First Start-Up Procedure
Fill the pump housing with clean hydraulic oil before first start. Run at 600-800 rpm unloaded for 5-10 minutes to purge air. Confirm no suction line leakage and steady oil flow from the case drain line before gradually increasing speed and loading to rated conditions. Case drain back pressure must not exceed 0.5 bar, and the drain line end should always remain submerged below the reservoir oil level. Maximum case drain temperature must not exceed 104°C (220°F).
5. Routine Maintenance
Replace hydraulic oil filters every 2,000 operating hours or annually. Periodically inspect the pump exterior for leaks and check the drive shaft seal for aging or cracks. If flow decline or pressure instability is observed, prioritize inspection of the valve plate and piston-cylinder wear. Recommended overhaul interval: no more than 8,000 operating hours or 5 years.
