Product Overview
The ADU041, ADU049, ADU062, and ADU080 are Danfoss Power Solutions (formerly Eaton Vickers) X20 Series (420 Series) open-circuit axial piston variable pumps with displacements from 41.0 to 80.0 cm³/rev. The series features a compact one-piece housing design that reduces component count by approximately 25% compared to traditional multi-piece pump bodies, effectively eliminating potential leak points and simplifying maintenance. The rotating group employs steel-backed polymer bearings in a rigid saddle frame, distributing loads evenly and significantly extending bearing service life.
The defining technical feature of the X20 series is its sophisticated pressure and flow compensator control system. Load-sensing control automatically matches pump output power to system load demand, and combined with torque control, enables on-demand flow distribution during combined operations in excavators, loaders, and other mobile machinery — reducing throttling losses and fluid temperature rise. Integrated relief valves provide system overload protection.
The ADU series and 421AK series form a complete cross-reference system: 421AK00955B corresponds to ADU049 (49.2 cm³/rev), 421AK01088B corresponds to ADU062 (62.3 cm³/rev), 421AK00196B corresponds to ADU041 (41.0 cm³/rev), and 421AK00166A and 421AK00188B are additional configuration versions within the series.
Manufactured to exact Danfoss OEM specifications, mounting flanges, shaft dimensions, and port layouts are fully consistent with the original pump for true drop-in interchangeability. Every unit undergoes 100% simulated operating condition testing before shipment.
Technical Specifications
ADU Series Common Specifications:
Series: Danfoss X20 Series (420 Series)
Pump Type: Open-circuit axial piston variable pump, swashplate design
Control Type: Pressure & Flow Compensator, with optional torque control
Rotation Direction: Left-hand (counter-clockwise, viewed from shaft end)
Mounting Flange: SAE 2-bolt B flange (SAE C for some sizes)
Shaft: Straight shaft, 25.4 mm (1.00 in) diameter, keyed (SAE J744-25-1)
Main Ports: Suction 2.00 in SAE J518 Code 61 4-bolt flange; Pressure 1.00 in SAE J518 Code 61 4-bolt flange
Housing Material: Cast iron
Recommended Hydraulic Fluid: ISO VG32 / VG46 anti-wear hydraulic oil
Fluid Viscosity Range: 16–40 cSt (recommended), minimum 16 cSt
Fluid Cleanliness Requirement: ISO 4406 21/18/13
Fluid Temperature Range: -20 °C to +90 °C
Case Drain Port: 0.875-14 UNF-2B O-ring port – top
Model-Specific Parameters:
ADU041 (41.0 cm³/rev):
Displacement: 41.0 cm³/rev (2.50 in³/rev)
Continuous Pressure: 280 bar (4,060 psi)
Intermittent Pressure: 320 bar (4,600 psi)
Peak Pressure: 350 bar (5,000 psi)
Rated Speed (1 bar abs): 2,650 rpm
Max Standby Speed: 3,600 rpm
Max Theoretical Power: 50.7 kW (68.0 hp)
Max Theoretical Torque: 183 N·m (135 lb-ft)
Weight (Single Seal): 22.9 kg (50.4 lb)
Weight (Dual Seal): 24.1 kg (53.1 lb)
Moment of Inertia: 0.0033 Nm-sec²
ADU049 (49.2 cm³/rev):
Displacement: 49.2 cm³/rev (3.00 in³/rev)
Continuous Pressure: 280 bar (4,060 psi)
Intermittent Pressure: 320 bar (4,600 psi)
Peak Pressure: 350 bar (5,000 psi)
Rated Speed (1 bar abs): 2,650 rpm
Max Standby Speed: 3,600 rpm
Max Theoretical Power: 60.8 kW (81.5 hp)
Max Theoretical Torque: 219 N·m (162 lb-ft)
Weight (Single Seal): 22.9 kg (50.4 lb)
Weight (Dual Seal): 24.1 kg (53.1 lb)
Moment of Inertia: 0.0033 Nm-sec²
ADU062 (62.3 cm³/rev):
Displacement: 62.3 cm³/rev (3.80 in³/rev)
Continuous Pressure: 280 bar (4,060 psi)
Intermittent Pressure: 320 bar (4,600 psi)
Peak Pressure: 350 bar (5,000 psi)
Rated Speed (1 bar abs): 2,600 rpm
Max Standby Speed: 2,800 rpm
Max Theoretical Power: 75.6 kW (101.3 hp)
Max Theoretical Torque: 278 N·m (205 lb-ft)
Weight (Single Seal): 23.8 kg (52.4 lb)
Weight (Dual Seal): 25.0 kg (55.1 lb)
Moment of Inertia: 0.0046 Nm-sec²
ADU080 (80.0 cm³/rev):
Displacement: 80.0 cm³/rev (4.88 in³/rev)
Continuous Pressure: 210 bar (3,050 psi)
Intermittent Pressure: 230 bar (3,335 psi)
Peak Pressure: 250 bar (3,625 psi)
Rated Speed (1 bar abs): 2,500 rpm
Max Standby Speed: 2,800 rpm
Max Theoretical Power: 61.7 kW (82.7 hp)
Max Theoretical Torque: 268 N·m (198 lb-ft)
Weight (Single Seal): 24.2 kg (53.4 lb)
Weight (Dual Seal): 25.4 kg (56.1 lb)
Moment of Inertia: 0.0058 Nm-sec²
421AK Series Cross-Reference:
421AK00955B corresponds to ADU049 (49.2 cm³/rev), full model code ADU049L02AD10A43200000200100CD0B
421AK01088B corresponds to ADU062 (62.3 cm³/rev), full model code ADU062R05AB10A2824000A2AB100CD0B
421AK00196B corresponds to ADU041 (41.0 cm³/rev), full model code ADU041R02AA10B4324000A200100CD0B
421AK00166A and 421AK00188B are additional configuration versions; confirm displacement via full model code
Key Technical Advantages
Pressure & Flow Compensator for On-Demand Power Matching: The X20 series’ core technical advantage is its pressure and flow compensator control system. Load-sensing control precisely matches pump output flow to system load demand. Combined with torque control, it enables on-demand flow distribution during combined operations in excavators, loaders, and other mobile machinery. The X20 series delivers the fastest response and recovery times in the open-circuit piston segment (response time of only 20 ms), quickly recovering stable output during load transients. Low standby pressure (approximately 150 psi) significantly reduces system heat generation and energy waste.
Integrated Compact Housing with Lightweight Design: X20 pumps feature a one-piece housing design that reduces component count by approximately 25% compared to traditional multi-piece pump bodies, eliminating multiple potential leak points and simplifying maintenance. The compact installation envelope satisfies Tier 4 engine compartment space requirements, providing greater flexibility in machine design. The ADU041 and ADU049 single-seal configurations weigh only 22.9 kg, delivering an excellent power-to-weight ratio.
Steel-Backed Polymer Bearings with Long-Life Saddle Frame: The rotating group employs steel-backed polymer bearings in a rigid saddle frame, distributing loads evenly and significantly extending bearing service life. At 140 bar, the ADU041 achieves a B10 bearing life of 103,650 hours; even at 280 bar continuous rated pressure, the ADU041 maintains a B10 life of 10,280 hours.
Precision Rotating Group with High Volumetric Efficiency: The pump features precision-lapped piston-to-barrel clearances, with hydrostatic balance design at the slipper-to-swashplate interface. This structure maintains high volumetric efficiency and stable output flow at 280 bar continuous pressure. The ADU041/ADU049/ADU062 support 280 bar continuous working pressure, 320 bar intermittent pressure, and 350 bar peak pressure.
Comprehensive Cross-Reference and Drop-In Interchangeability System: The ADU series and 421AK series form a complete cross-reference network. Models such as 421AK00955B, 421AK01088B, and 421AK00196B directly replace same-specification original pumps with fully consistent mounting flanges, shaft dimensions, and port layouts — no piping or coupling modification required. The pump is compatible with the complete Danfoss X20 series (formerly Eaton Vickers 420 series) product line, widely used in mobile and industrial hydraulic system repair and replacement.
Application Areas
Construction Machinery: Medium excavators (including 20-ton class), wheel loaders, backhoe loaders, cranes
Municipal Vehicles: Truck cranes, container handling equipment, street sweepers
Mining Equipment: Underground drilling rigs, tunnel boring equipment, mining trucks
Agricultural Machinery: High-horsepower tractors, chemical applicator trucks, combine harvesters
Forestry Equipment: Feller/bunchers, forwarders, log loaders
Material Handling: Forklifts, telehandlers, rough terrain forklifts
Road Construction: Concrete pavers, asphalt pavers, vibratory rollers
Railroad Equipment: Railroad maintenance machinery hydraulic systems
Industrial Hydraulics: Injection molding machines, hydraulic presses, test stands
Expert Maintenance Tips
Shaft Alignment and Flange Connection: Concentricity deviation between the pump and drive shaft must be less than 0.05 mm, with angular deviation less than 0.25°. The ADU series uses an SAE 2-bolt B flange (SAE C for some sizes) with a 25.4 mm keyed shaft (SAE J744-25-1). Tighten flange bolts in diagonal sequence for even loading and check the locating step for integrity.
Initial Start-Up Filling and Bleeding: Pre-fill the pump with clean ISO VG46 anti-wear hydraulic oil through the case drain port (0.875-14 UNF-2B O-ring port, located on top) before installation. Start at the lowest drive speed and observe a steady oil flow from the case drain port free of bubbles. Once bleeding is complete, gradually increase to working pressure.
Control Setting Verification: The pressure and flow compensator settings are factory-calibrated to standard specifications (the 421AK00955B has a pressure compensator setting range of 275.8–282.7 bar and a flow compensator setting range of 17.24–19.99 bar). After pump replacement, verify settings match the original system using calibrated pressure gauges. Record original settings before adjustment for restoration.
Rotation Direction Verification: The ADU series is left-hand (counter-clockwise, viewed from shaft end) rotation. Driving it clockwise is strictly prohibited — incorrect drive direction will reverse the suction and pressure sides, causing severe rotating group damage within a short period.
Fluid Cleanliness and Viscosity Management: Use ISO VG32/VG46 anti-wear hydraulic oil with a viscosity range of 16–40 cSt. System filtration should meet ISO 4406 21/18/13. Replace filter elements after the first 500 operating hours, then every 1,000 hours or annually thereafter.
Case Drain Line Configuration: The case drain line must return directly to the reservoir with backpressure not exceeding rated limits. The drain line inner diameter must be sufficient to ensure unobstructed drainage during cold-start high-viscosity conditions.
