Eaton Vickers 420 421 Series Piston Pump | ADU062 421AK Variable Displacement Pump Replacement

Genlu Hydraulic proudly introduces our 420 / 421 / 421AK Series (including the prominent ADU062 specification) high-performance axial piston variable displacement pumps. This series is engineered as a seamless, high-value replacement for the classic Eaton Vickers 420/421 mobile and industrial fluid power platforms (such as 421AK00823B, 421AK01088B, etc.). Specifically developed for demanding open-circuit mobile operations and heavy-duty industrial systems, this series incorporates a highly rigid swashplate design integrated with highly sensitive Load Sensing (LS) and pressure-compensating control blocks. Genlu guarantees 100% Drop-in Interchangeability in SAE mounting flanges, standard splined drive shafts, side/rear port arrangements, and response characteristics compared to original Eaton Vickers units. Every pump assembly undergoes rigorous 100% simulation testing under severe pressure profiles to certify maximum mechanical and volumetric efficiency.

Technical Specifications 

• Product Series: Eaton Vickers 420/421 (421AK) Series Axial Piston Variable Pump

• Key Configuration Models: ADU062, 421AK00823B, 421AK01088B, 421AK00393B, 421AK00394A

• Displacement: 62 cc/rev (for the ADU062 size)

• Rated Operating Pressure: 28 MPa (280 bar)

• Peak Pressure: 32 MPa (320 bar)

• Max Operating Speed: 2900 rpm (under self-priming conditions)

• Control Mechanisms: Load Sensing with Pressure Limiter / Remote Pressure Control

• Drive Shaft Profiles: SAE Standard Spline Shaft

• Case Drain Ports: Dual case drain configuration (facilitates versatile installation alignment)

Key Technical Advantages:

• High-Rigidity Housing & Acoustic Optimizations: Cast from premium compacted graphite iron (CGI), the heavy-duty housing features fluid-dynamically streamlined internal pathways. Paired with a dual-wall noise dampening shell, it drastically reduces airborne casing acoustics and pressure pulsations.

• Bimetallic Valve Pair & Hardened Slippers: Piston shoes are forged and subjected to precision micro-rolling surface hardening, while the valve plate utilizes a bimetallic friction-resistant cladding interface. This delivers superior resistance against adhesive wear or thermal seizing under extreme high-pressure cycling.

• Rapid-Response Load Sensing Volumetric Control: The integrated 421AK-specific control valve monitors downstream actuator changes in milliseconds. It retreats the swashplate angle to its minimum during standby phases, minimizing standby power drop and fluid heat generation.

• High-Torque Through-Drive Versatility: The robust rear housing supports high-torque through-drive configurations, allowing users to couple secondary piston pumps or gear pumps directly for space-saving, multi-circuit mobile layouts.

Application Areas:

• Mobile Construction Machinery: Backhoe loaders, skid steer loaders, and auxiliary pilot or main circuits for mid-sized excavators.

• Agricultural Equipment: Header lift drives for combine harvesters and main implement circuits for heavy-duty tractors.

• Material Handling Vehicles: Truck-mounted cranes, container reach stackers, and heavy forklift hydraulic networks.

Expert Maintenance Tips:

• Mandatory Casing Pre-Priming: The 421AK series is a high-speed self-priming unit. Following installation and prior to initial startup, fill the pump housing completely with clean hydraulic oil via the highest available case drain port. Never dry-start the pump, as this will lead to catastrophic slipper damage.

• De-aeration of the LS Signal Line: If configured with a load-sensing line linked to a proportional multi-way valve, loosen the LS connector slightly during low-pressure priming to purge trapped air. This prevents response lag and high-frequency valve hunting.

• Suction Inlet Vacuum Inspection: Ensure that the inlet plumbing is fully airtight and clear of restrictions. The absolute suction pressure must never fall below 0.08 MPa (-0.2 bar gauge). Implement a comprehensive pre-warming cycle if operating in cold-weather conditions with higher oil viscosities.