421AK02296C 421AK01676C Vickers X20 Piston Pump 41-80cc

Product Overview

The 421AK02296C, 421AK00955B, 421AK00355B, 421AK01676C, 421AK00172B, and 421AK00517B belong to the Eaton Vickers X20 Series of open-circuit axial piston pumps, now supported under the Danfoss Power Solutions product portfolio. Featuring swashplate design with displacements from 41 cc/rev to 80 cc/rev, the X20 Series is engineered for medium-to-high pressure open-circuit hydraulic systems. The series is distinguished by its compact cradle bearing design, low-noise operation, and fast response characteristics, making it widely applicable in loader, excavator, crane, and agricultural machinery applications.

Manufactured to original Eaton Vickers X20 Series technical specifications with full drop-in interchangeability — no piping or mounting flange modifications required. The 421AK01676C corresponds to the 62cc displacement specification (ADU062) with SAE-C 2/4-bolt mounting flange, suitable for medium construction machinery main pump applications. The 421AK00955B corresponds to the 49.2 cc/rev specification (ADU049) with pressure-flow compensator and torque control. Every pump undergoes 100% simulated load testing at the factory, covering pressure hold, flow response, and compensator dynamics.

Note: The 421AK02296C and 421AK00355B do not have complete official parameter records in publicly available technical documentation. Their corresponding ADU model codes are presumed to be ADU080 (80cc class) and ADU062 (62cc class) specifications, respectively. Users are advised to confirm against the original nameplate for final verification.

Technical Specifications 

X20 Series (420 Series) General Specifications:

• Series: Eaton Vickers X20 Series / 420 Series (Danfoss ADU Series)

• Design: Open-circuit axial piston variable pump, swashplate type

• Displacement Range: 41.0 cc/rev (ADU041) / 49.2 cc/rev (ADU049) / 62.3 cc/rev (ADU062) / 80.0 cc/rev (ADU080)

• Rated Continuous Pressure: 280 bar (4060 PSI) — 41/49/62cc; 210 bar (3050 PSI) — 80cc

• Maximum Intermittent Pressure: 320 bar (4600 PSI) — 41/49/62cc; 230 bar (3335 PSI) — 80cc

• Peak Pressure: 350 bar (5000 PSI) — 41/49/62cc; 250 bar (3625 PSI) — 80cc

• Maximum Speed: 3,600 rpm (full series)

• Minimum Speed: 600 rpm

• Control Type: Pressure and flow compensator with torque control, with LS load sense port

• Housing Material: High-strength cast iron

• Mounting Flange: SAE A/B/C standard flange (by displacement size)

• Shaft Type: Parallel key or splined shaft (by configuration)

• Direction of Rotation: Clockwise (R) or counterclockwise (L) available

• Weight (Single Seal): Approx. 22.9 kg (ADU041/049) / 23.8 kg (ADU062) / 24.2 kg (ADU080)

• Response Time: Approx. 20–25 ms

• Fluid Cleanliness: ISO 4406 21/18/13

Verified Model Specifications:

• 421AK01676C: Displacement 62.3 cc/rev (3.8 in³/rev), mounting flange SAE-C 2/4-bolt, shaft 14-tooth 12/24 spline, flow compensator setting 19.31–22.06 bar, inlet/outlet ports SAE 4-bolt flange (Code 61), weight approx. 23.8 kg

• 421AK00955B: Displacement 49.2 cc/rev (≈49 cc/rev), rated pressure 4600 psi (≈317 bar), peak pressure 5000 psi (≈345 bar), max speed 3600 rpm, mounting flange SAE 2-bolt B, shaft 25.4 mm keyed, pressure-flow compensator with torque control, left-hand rotation, cast iron housing

• 421AK00172B: Corresponds to ADU062 specification (62.3 cc/rev), 420 Series open-circuit piston pump, mounting flange 2/4-bolt SAE-C

• 421AK00517B: Displacement 80.0 cc/rev, rated pressure 210 bar, mounting flange 2/4-bolt SAE-C, shaft 31.8 mm (1.250 in) keyed, max input torque 2372 lbs.-in.

Model Code Interpretation:

• 421AK01676C: 421AK as series code, 01676 as configuration code, C as design number. Corresponds to Danfoss ADU062R02AB10C43000000200100CD0B. SAE-C flange, 62cc displacement, pressure-flow compensation control, suitable for loader and excavator main pump applications.

• 421AK00955B: Corresponds to Danfoss ADU049L02AD10A43200000200100CD0B, 49cc displacement, SAE 2-bolt B flange, left-hand shaft, pressure-flow compensator with torque control.

• 421AK00517B: Corresponds to ADU080R33AB10AC1500000002AD5AACD00C, 80cc displacement, SAE-C flange, suitable for higher-flow mobile hydraulic systems.

Data based on Danfoss PowerSource official product database and Eaton Vickers X20 Series technical documentation.

Key Technical Advantages

1. Compact Cradle Bearing Design — High Power Density

The X20 Series employs a cradle bearing design that delivers high power density within a compact installation envelope. Compared to conventional piston pump bearing layouts, the cradle bearing configuration effectively controls overall pump length and weight for easy installation in space-constrained mobile hydraulic equipment. The X20 Series spans displacements from 28 cc to 98 cc, sharing a common design architecture that facilitates flow matching and pump upgrades within the series without changing piping layout.

2. Pressure and Flow Compensator with Torque Control — On-Demand Flow

The X20 Series features pressure and flow compensator control with torque control and an integrated LS load sense port. The control mechanism continuously adjusts swashplate angle based on load pressure and pressure differential across the metering orifice, precisely matching pump output to actuator demand. During standby or light-load conditions, pump displacement automatically reduces to the minimum flow required for leakage compensation, fundamentally eliminating relief losses. Torque control ensures pump drive power does not exceed the engine power curve, preventing engine stall. Response time is approximately 20–25 ms, delivering industry-leading fast response and recovery.

3. Low-Noise Three-Piece Construction

The X20 Series utilizes a three-piece construction (flange, housing, valve block) combined with dual-metal timing plate design, significantly reducing fluid-borne and structure-borne noise. The rigid saddle frame design minimizes deflection and vibration during operation, further optimizing noise performance. This design gives the X20 Series a distinct advantage in loader, excavator, and other mobile hydraulic applications where operator environment is a priority.

4. Steel-Backed Polymer Bearings and Long Service Life

The X20 Series is equipped with steel-backed polymer bearings mounted in a rigid saddle frame, distributing loads evenly to extend bearing service life. The housing material is high-strength cast iron, suitable for continuous high-pressure operation. Bearing design life at rated pressure ranges from 3,320 to 5,510 hours depending on displacement size and operating conditions, maintaining stable operation at speeds up to 3,600 rpm.

Application Areas

• Construction Machinery: Medium excavator main pump (15–25 ton class), wheel loader work equipment hydraulics, backhoe loader hydraulic drive

• Lifting & Material Handling: Truck crane hydraulic systems, telehandler hydraulic drive, rough-terrain forklift hydraulic power units

• Agricultural Machinery: Tractor hydraulic hitch and steering systems, combine harvester hydraulic drive, sprayer hydraulic systems

• Municipal & Road Machinery: Snow removal truck hydraulics, refuse truck hydraulic drive, asphalt paver hydraulic power

• Industrial Hydraulic Power Units: Hydraulic power unit main pumps, pressure test bench hydraulic sources

• Mining & Tunneling Equipment: Mining auxiliary equipment hydraulic drive, tunnel boring equipment auxiliary hydraulic systems

Expert Maintenance Tips

Pre-Installation Cleanliness Control: Before installing X20 Series pumps, verify hydraulic system cleanliness meets ISO 4406 21/18/13 or better. Port plugs should be removed and piping connected immediately after unboxing — environmental exposure should not exceed 15 minutes. Before first start, fill the pump case with clean hydraulic oil to the maximum allowable level. Dry-start is strictly prohibited. Ensure concentricity between the pump shaft and prime mover shaft is maintained within 0.05 mm, and use a flexible coupling to avoid additional radial loads.

Pressure-Flow Compensator Calibration: The X20 Series flow compensator has a factory setting range of 17.24–19.99 bar (250–290 PSI), and the pressure compensator setting range is 275.8–282.7 bar (4000–4100 PSI). Monitor LS port and outlet pressures with a gauge of at least 1.6 accuracy class during adjustment. Turn the adjustment screw clockwise to increase the setting, counterclockwise to decrease. Adjustment increments should not exceed half a turn per step. The LS signal line must be leak-free and not cross-connected to other circuits, otherwise the compensator will malfunction.

Operating Oil Temperature Management: The X20 Series recommended operating oil temperature range is 15–80°C. When starting with oil temperature below 15°C, warm the hydraulic oil or run at low speed and no load until oil temperature reaches 15°C before applying load. Recommended viscosity grade: VG 32–46 mineral hydraulic oil, optimum working viscosity 16–40 cSt. Prolonged operation above 80°C accelerates seal aging and fluid degradation — inspect the cooling system if oil temperature consistently exceeds this threshold.

Oil Maintenance Schedule: Replace hydraulic oil and filter after the first 500 hours of operation. Thereafter, replace every 2,000 hours or 12 months, whichever comes first. Maximum case pressure is 350 bar, and maximum case drain temperature is 220°F (104°C) — exceeding these limits may damage case seals. If the system is equipped with an online particle counter, replace oil and inspect filter differential pressure immediately when cleanliness drops to ISO 4406 20/18/15.

Long-Term Storage Protection: For pumps stored over 3 months, drain case oil, fill with rust-preventive oil, and plug all ports. Before recommissioning, flush with flushing oil for 30 minutes and confirm flushing oil cleanliness meets specification before connecting to the system. Always refill the case to the maximum allowable level before restart.