421AK01940B Danfoss X20 Variable Piston Pump 280Bar

421AK01940B

Product Overview

The 421AK01940B is a Danfoss X20 series open circuit axial piston variable pump from the original Vickers/Eaton 421AK product line. Featuring a cradle bearing swashplate design with pressure/pressure-flow compensator control, the pump automatically adjusts the swashplate angle in response to system load changes for on-demand flow delivery. The cast iron housing delivers excellent power density in a compact, lightweight envelope suitable for a wide range of medium-pressure hydraulic applications. Every unit undergoes 100% simulated working-condition testing and supports drop-in interchangeability.

Technical Specifications 

• Full Model Code: 421AK01940B

• Series: Danfoss X20 Series (420 Series)

• Design Type: Swashplate open circuit axial piston variable pump

• Control Method: Pressure/pressure-flow compensator

• Rated Working Pressure: 280 bar

• Housing Material: Cast iron

• Rotation: Right Hand (R = CW)

• Mounting Flange: SAE 2/4-bolt standard

• Pressure Port: 1.00 SAE J518 4-bolt split flange (Code 61)

• Suction Port: 2.00 SAE J518 4-bolt split flange (Code 61)

• Drain Port: 0.875-14 UNF-2B O-ring port

• Fluid Cleanliness: ISO 4406 21/18/13

Key Technical Advantages

1. Compact Cradle Bearing Design

The X20 series features a cradle bearing architecture that delivers a smaller, lighter pump envelope at equivalent displacement. The optimized saddle bearings maintain long-term stability under high-pressure conditions without compromising load capacity.

2. Combined Pressure/Flow Control with Fast Response

The controller integrates pressure compensation and flow compensation. When system pressure reaches the set value, the swashplate destrols to near-zero, delivering only makeup flow to reduce energy consumption and heat generation. Response times as fast as 20–26 ms suit hydraulic systems with rapidly changing dynamic loads.

3. Cast Iron Housing for Durability

The cast iron housing maintains structural rigidity under high-temperature, high-pressure conditions. Core rotating components undergo precision matched-lapping with micron-level clearances to ensure stable volumetric efficiency under sustained heavy loads.

4. Standardized Interfaces for Broad Compatibility

SAE 2/4-bolt mounting flanges and Code 61 split flange ports ensure direct compatibility with mainstream hydraulic systems, enabling drop-in replacement of equivalent imported pumps without piping or bracket modifications.

Application Areas

• Wheel loaders and compact excavator hydraulic systems

• Agricultural tractor hydraulic drive circuits

• Aerial work platform hydraulic power units

• Material handling equipment hydraulic systems

• Municipal vehicles (snow removal, refuse trucks)

• Industrial hydraulic power stations

Expert Maintenance Tips

1. Fluid Cleanliness: Maintain ISO 4406 21/18/13 or better. Install 10μm absolute-rated filter elements on the suction side and replace every 500 operating hours.

2. Suction Port Pressure: The pump is rated at 2,450 rpm at 0.8 bar absolute and up to 2,950 rpm at 2.0 bar absolute. Keep suction lines short and straight to prevent cavitation.

3. Case Drain Line: Connect directly to the reservoir with back pressure within allowable limits (max 350 bar). Drain line diameter no less than half the main pressure port diameter.

4. First Startup Air Bleeding: Fill the housing with clean hydraulic oil through the drain port. Run at no-load below 800 rpm for 5–10 minutes before applying load.

5. Controller Adjustment: Pressure compensator setting typically ranges 199.9–206.8 bar depending on application. Flow compensator setting: 12.41–15.17 bar.

421AK00166A

Product Overview

The 421AK00166A is a Danfoss X20 series open circuit axial piston variable pump from the original Vickers/Eaton 421AK product line. Featuring a cradle bearing swashplate design with pressure/pressure-flow compensator control, it delivers fast response and low energy consumption. The compact, high power-density housing suits medium-pressure mobile and industrial hydraulic applications. Every unit undergoes 100% simulated working-condition testing with flow-pressure characteristics matching the original.

Technical Specifications

• Full Model Code: 421AK00166A

• Series: Danfoss X20 Series (420 Series)

• Design Type: Swashplate open circuit axial piston variable pump

• Control Method: Pressure/pressure-flow compensator

• Rated Working Pressure: 280 bar

• Housing Material: Cast iron

• Rotation: Right Hand (R = CW)

• Mounting Flange: SAE standard

• Pressure Port: SAE J518 4-bolt split flange (Code 61)

• Suction Port: SAE J518 4-bolt split flange (Code 61)

• Drain Port: SAE O-ring port

• Fluid Cleanliness: ISO 4406 21/18/13

Key Technical Advantages

1. Compact and Lightweight Design

The X20 cradle bearing architecture significantly reduces pump envelope and weight compared to conventional designs. Ideal for space-constrained mounting positions in mobile hydraulic equipment.

2. On-Demand Flow and Energy Savings

The pressure/flow compensator automatically adjusts displacement based on actuator load demand, eliminating the inherent overflow losses of fixed-displacement systems. During load-hold or low-pressure standby, the pump delivers only minimal makeup flow, significantly reducing energy consumption and oil temperature.

3. Precision Manufacturing and High Volumetric Efficiency

Piston assemblies and valve plates undergo precision matched-lapping with micron-level clearances, minimizing internal leakage under high pressure. Heat-treated piston materials provide excellent wear resistance and fatigue strength.

4. Standardized Interfaces for Flexible Installation

SAE standard mounting flanges and Code 61 port standards ensure compatibility with mainstream North American and global hydraulic systems. Through-drive configurations available depending on model options.

Application Areas

• Agricultural machinery (tractors, combines)

• Construction machinery auxiliary hydraulic systems

• Municipal vehicle hydraulic power units

• Industrial hydraulic power stations

• Material handling equipment

Expert Maintenance Tips

1. Fluid Cleanliness: Maintain ISO 4406 21/18/13 or better, replace filter elements every 500 operating hours.

2. Suction Port Pressure: Ensure absolute suction pressure meets pump inlet requirements across the speed range.

3. Case Drain: Route drain lines directly to reservoir with back pressure within allowable limits.

4. First Startup: Fill housing with oil and run at low speed for 5–10 minutes to bleed air.

5. Controller Inspection: Every 2,000 operating hours, check controller response. If pressure fluctuation increases or response lags, inspect compensator spool and seals.

421AK00933B

Product Overview

The 421AK00933B is a Danfoss X20 series open circuit axial piston variable pump from the original Vickers/Eaton 421AK product line. Designed with high-efficiency and energy-saving principles at its core, it delivers enhanced reliability, flexible configuration options, and long service life. It is widely used in industrial manufacturing, agricultural machinery, and construction equipment, serving as a common OEM pump for TEREX, JOHN DEERE, EATON and other brand equipment. Every unit undergoes 100% simulated working-condition testing.

Technical Specifications 

• Full Model Code: 421AK00933B

• Series: Danfoss X20 Series (420 Series)

• Design Type: Swashplate open circuit axial piston variable pump

• Control Method: Pressure/pressure-flow compensator

• Rated Working Pressure: 280 bar

• Housing Material: Cast iron

• Rotation: Right Hand (R = CW)

• Mounting Flange: SAE standard

• Port Standard: SAE J518 4-bolt split flange (Code 61)

• Fluid Cleanliness: ISO 4406 21/18/13

Key Technical Advantages

1. High-Efficiency Design with On-Demand Flow

Built around high-efficiency, energy-saving design principles. The pressure/flow compensator ensures the pump delivers flow only when system demand requires it, substantially reducing overflow losses and system heat. Suitable for energy-sensitive mobile hydraulic equipment.

2. Enhanced Reliability and Long Service Life

Core rotating components are manufactured from high-strength materials with precision heat treatment and matched-lapping. Optimized saddle bearings deliver high load capacity and extended overhaul intervals.

3. Flexible Configuration and Broad Compatibility

The X20 series offers multiple control options, mounting flanges, and shaft configurations. The 421AK00933B can be matched to specific equipment interface requirements for diverse installation needs.

4. Compact Cast Iron Housing

The cast iron housing maintains structural rigidity within a compact footprint, delivering high power density for installation space-constrained equipment platforms.

Application Areas

• Industrial manufacturing equipment hydraulic systems

• Agricultural machinery (tractors, harvesters)

• Construction machinery (compact excavators, loaders) auxiliary circuits

• Municipal vehicle hydraulic power units

• Material handling equipment

Expert Maintenance Tips

1. Fluid Cleanliness: Maintain ISO 4406 21/18/13 or better. Install 10μm absolute filter elements and replace every 500 operating hours.

2. Mounting Alignment: Drive shaft-to-power source coaxiality deviation should not exceed 0.1 mm. Use flexible couplings to avoid additional radial loads.

3. Case Drain Line: Keep unobstructed with back pressure within allowable limits. Drain line diameter no less than half the main pressure port diameter.

4. First Startup: Fill housing with clean hydraulic oil and run at low speed for 5–10 minutes before loading.

5. Periodic Controller Inspection: Every 2,000 operating hours, check for pressure compensator setting drift. Flow compensator setting should remain within 12.41–15.17 bar.

421AK00955B

Product Overview

The 421AK00955B is a Danfoss X20 series open circuit axial piston variable pump from the original Vickers/Eaton 421AK product line. With a displacement of 49.2 cm³/rev, it features a pressure/flow compensator with integrated torque control, a maximum input speed of 3,600 rpm, and a rated working pressure of 317 bar (4,600 psi) with 345 bar (5,000 psi) peak capability. This model suits mobile hydraulic systems with frequent load changes, offering fast response and high power density. Every unit undergoes 100% simulated working-condition testing and supports drop-in interchangeability.

Technical Specifications 

• Full Model Code: 421AK00955B

• Series: Danfoss X20 Series (420 Series)

• Design Type: Swashplate open circuit axial piston variable pump

• Displacement: 49.2 cm³/rev

• Control Method: Pressure/flow compensator with torque control

• Rated Working Pressure: 317 bar (4,600 psi)

• Peak Pressure: 345 bar (5,000 psi)

• Maximum Input Speed: 3,600 rpm

• Minimum Input Speed: 600 rpm

• Housing Material: Cast iron

• Input Shaft: Straight Ø25.4 mm, keyed (SAE J744-25-1)

• Mounting Flange: 2-bolt B

• Suction Port: 2.00 SAE J518 4-bolt split flange (Code 61)

• Pressure Port: 1.00 SAE J518 4-bolt split flange (Code 61)

• Drain Port: 0.875-14 UNF-2B O-ring port

• Maximum Input Power: 60.8 kW

• Maximum Input Torque: 219 Nm

• Response Time: 20 ms

• Shaft Seal: Polyacrylate

• Fluid Cleanliness: ISO 4406 21/18/13

• Weight: Approx. 24 kg

Key Technical Advantages

1. Integrated Torque Control with Advanced Control Options

The controller integrates pressure compensation, flow compensation, and torque control for precise input power matching under varying loads, preventing engine or motor overload. Response time as fast as 20 ms provides a market-leading advantage in fast response and recovery.

2. High Power Density in a Compact Envelope

The 49.2 cm³/rev displacement is packaged in a compact cast iron housing delivering up to 60.8 kW maximum input power and 219 Nm maximum input torque. The cradle bearing design reduces pump envelope at equivalent displacement for space-constrained mobile equipment.

3. High-Speed Capability with Wide Operating Range

Maximum input speed reaches 3,600 rpm. At 0.8 bar absolute inlet pressure, rated speed is 2,450 rpm; at 1.0 bar, 2,650 rpm; and at 2.0 bar, 2,950 rpm — accommodating diverse suction conditions. Suitable for direct engine-driven mobile hydraulic systems.

4. Precision Manufacturing and Industrial-Grade Durability

Core piston assemblies and valve plates undergo precision matched-lapping and heat treatment with micron-level clearances. Bearing life at rated pressure reaches 5,510 hours for long-term stable operation.

Application Areas

• Loader backhoes and excavator hydraulic systems

• Agricultural tractor hydraulic drives

• Mining machinery and tunnel boring equipment

• Refuse trucks and off-road dump trucks

• Concrete and asphalt pavers

• Aerial work platform hydraulic power units

• Forklifts and material handling equipment

Expert Maintenance Tips

1. Suction Port Pressure Management: The pump allows 2,450 rpm at 0.8 bar absolute, 2,650 rpm at 1.0 bar, and 2,950 rpm at 2.0 bar. Keep suction lines short and straight to prevent cavitation.

2. Fluid Viscosity Control: Recommended operating viscosity range is 16–40 cSt with maximum recommended operating viscosity of 40 cSt. Ensure adequate cooling to prevent accelerated piston wear from high oil temperature or low viscosity.

3. Case Drain Management: Drain port is 0.875-14 UNF-2B. Continuous allowable case pressure: 320 bar; maximum case pressure: 350 bar. Keep drain lines unobstructed with diameter no less than half the main pressure port.

4. First Startup Procedure: Fill the housing with clean hydraulic oil through the drain port. Run at 600–800 rpm no-load for 5–10 minutes to bleed air. Confirm no abnormal noise before gradually applying load.

5. Controller Maintenance: Every 2,000 operating hours, verify pressure compensator setting (range 275.8–282.7 bar) and flow compensator setting (range 17.24–19.99 bar) for drift. Adjust or replace valve spool seals as needed.

421AK00517B

Product Overview

The 421AK00517B is a Danfoss X20 series open circuit axial piston variable pump from the original Vickers/Eaton 421AK product line. With a displacement of 80 cm³/rev, it features a pressure/pressure-flow compensator with integrated torque control, maximum input speed of 3,600 rpm, and rated working pressure of 230 bar (3,335 psi) with 250 bar (3,625 psi) peak capability. The pump is equipped with an SAE-C 2/4-bolt mounting flange and 31.8 mm straight keyed shaft, suitable for large-flow medium-pressure hydraulic systems. Every unit undergoes 100% simulated working-condition testing.

Technical Specifications

• Full Model Code: 421AK00517B

• Series: Danfoss X20 Series (420 Series)

• Design Type: Swashplate open circuit axial piston variable pump

• Displacement: 80 cm³/rev

• Control Method: Pressure/pressure-flow compensator with torque control

• Rated Working Pressure: 230 bar (3,335 psi)

• Peak Pressure: 250 bar (3,625 psi)

• Maximum Input Speed: 3,600 rpm

• Minimum Input Speed: 600 rpm

• Housing Material: Cast iron

• Input Shaft: Straight Ø31.8 mm, keyway 7.98 × 34.11 mm, shaft extension 55.6 mm

• Mounting Flange: 2/4-bolt C (SAE J744-127-2/4)

• Auxiliary Mounting: Dual SAE J744 flange 82-2 (2-bolt A)

• Suction Port: 2.00 SAE J518 4-bolt split flange (Code 61)

• Pressure Port: 1.00 SAE J518 4-bolt split flange (Code 61)

• Drain Port: 0.875-14 UNF-2B O-ring port

• Maximum Input Power: 61.7 kW

• Maximum Input Torque: 268 Nm

• Response Time: 26 ms

• Continuous Allowable Case Pressure: 230 bar

• Maximum Case Pressure: 250 bar

• Bearing Life at Rated Pressure: 3,320 hours

• Shaft Seal: Single fluorocarbon rubber

• Fluid Cleanliness: ISO 4406 21/18/13

• Weight: Approx. 25.2 kg

Key Technical Advantages

1. High-Displacement, High Power Density

The 80 cm³/rev displacement is packaged in a compact SAE-C flanged housing delivering up to 61.7 kW maximum input power and 268 Nm maximum input torque. Suitable for large mobile hydraulic equipment requiring high flow at medium pressure.

2. Integrated Torque Control with Energy-Saving Operation

The controller integrates pressure compensation, flow compensation, and torque control. Torque control ensures pump input power does not exceed engine or motor limits to prevent overload. Pressure/flow compensation enables on-demand flow delivery, significantly reducing energy consumption during load-hold conditions.

3. Dual Auxiliary Mounting Flange for System Expansion

Equipped with dual SAE J744 flange 82-2 (2-bolt A) auxiliary mounting interfaces, supporting direct installation of auxiliary pumps (gear or piston) on the rear, enabling multi-pump configurations while reducing installation space for large hydraulic systems.

4. High-Load Bearing System

Bearing life at rated pressure reaches 3,320 hours. Optimized saddle bearings sustain continuous operation at 230 bar rated pressure. The cast iron housing maintains structural rigidity under high-pressure conditions, suitable for heavy-duty industrial applications.

Application Areas

• Large wheel loader hydraulic systems

• Excavator main hydraulic circuits

• Mining equipment centralized hydraulic supply systems

• Large agricultural machinery hydraulic drives

• Industrial hydraulic power stations with high-flow medium-pressure supply

• Marine hydraulic power units

Expert Maintenance Tips

1. Mounting Flange Precision: SAE-C 2/4-bolt mounting flange surface flatness should be ≤0.05 mm, and drive shaft-to-power source coaxiality deviation should not exceed 0.1 mm. Use flexible couplings to avoid additional radial loads.

2. Auxiliary Pump Installation Note: If using the dual auxiliary mounting flange for an additional pump, ensure the auxiliary pump input torque does not exceed allowable limits. Apply anti-fretting grease to coupling splines and inspect spline wear every 1,000 operating hours.

3. Case Drain Management: Continuous allowable case pressure: 230 bar; maximum case pressure: 250 bar. Keep drain lines unobstructed with diameter no less than half the main pressure port diameter. Avoid sharing drain lines with other pumps to prevent back-pressure accumulation.

4. Suction Port Pressure Assurance: The pump allows 1,800 rpm at 0.8 bar absolute, 2,200 rpm at 1.0 bar, and 2,800 rpm at 2.0 bar. Keep suction lines short and straight.

5. First Startup Air Bleeding: Fill the housing with clean hydraulic oil through the drain port. Run at 600–800 rpm no-load for 5–10 minutes to bleed air. Confirm no abnormal noise before gradually applying load.