A2FK12R4P4 Rexroth Axial Piston Motor 11.6cc 350bar

Product Overview

The A2FK12R4P4 and A2FK28R4P4 are fixed-displacement, bent-axis axial piston motors/pumps from the Bosch Rexroth A2FK series. Featuring a proven bent-axis design, these fixed-displacement axial piston units can be used as either pumps or motors, specifically engineered for precision metering and flow distribution in polyurethane (PU) foaming equipment.

The A2FK series is a highly specialized product line within Rexroth’s hydraulic portfolio, designed exclusively for high-pressure polyurethane foaming machines as their core component. Covering displacements from 2.5 to 107 cc/rev, the series is recognized for its low weight, low-noise operation, minimal flow pulsation, and high volumetric efficiency. The A2FK12R4P4 offers 11.6 cc/rev displacement, while the A2FK28R4P4 delivers 28.1 cc/rev, meeting the precision metering requirements of small to medium-flow polyurethane foaming processes.

Designed as 100% interchangeable direct replacements for the original Rexroth A2FK12R4P4 and A2FK28R4P4, these products match OEM specifications in mounting dimensions, porting interfaces, and performance characteristics. Every unit undergoes 100% simulated duty cycle testing prior to shipment, validating volumetric efficiency, mechanical efficiency, and sealing integrity under actual operating load conditions.

Technical Specifications

• Model: A2FK12R4P4 / A2FK28R4P4

• Series: Rexroth A2FK Bent-Axis Axial Piston Fixed Motor/Pump

• Geometric Displacement (A2FK12): 11.6 cm³/rev

• Geometric Displacement (A2FK28): 28.1 cm³/rev

• Rated Pressure: 350 bar (35 MPa)

• Peak Pressure: 400 bar (40 MPa)

• Max Speed – Closed Circuit (A2FK12): 6000 rpm

• Max Speed – Open Circuit (A2FK12): 4000 rpm

• Max Speed – Closed Circuit (A2FK28): 4750 rpm

• Max Speed – Open Circuit (A2FK28): 3000 rpm

• Input Power (@ 1450 rpm / Rated Pressure – A2FK12): 9.6 kW

• Input Power (@ 1450 rpm / Rated Pressure – A2FK28): 23.3 kW

• Output Torque (@ Rated Pressure – A2FK12): 63.4 N.m

• Output Torque (@ Rated Pressure – A2FK28): 154 N.m

• Control Type: Fixed Displacement

• Direction of Rotation: Bi-directional

• Seal Design: Dual shaft seals with flushing chamber

• Weight (A2FK12): Approx. 5.5 kg

• Weight (A2FK28): Approx. 23 kg

• Circuit Type: Open circuit / Closed circuit

• Typical Application: Polyurethane high-pressure foaming machines

Note: Pressure and speed parameters may vary across different configurations (shaft type, seal, porting, etc.). Please refer to the corresponding Rexroth technical manual for specific model details.

Key Technical Advantages

1. Bent-Axis Fixed Displacement Design – Ultra-High Precision with Low Pulsation

The A2FK series employs a proven bent-axis axial piston architecture with a high-performance rotary group featuring a well-proven spherical control area—delivering self-centering, low peripheral speed, and high efficiency. The fixed displacement design ensures extremely high repeatability and minimal flow pulsation in polyurethane metering and flow distribution, which is critical for consistent foaming quality.

2. Specialized Polyurethane Duty Design – Dual Shaft Seals with Flushing Chamber

The A2FK series is specifically engineered for polyurethane (PU) foam media, featuring dual shaft seals made of special materials with a flushing chamber. This design effectively prevents polyurethane components from penetrating the bearing cavity, facilitates easy damage inspection, and provides environmental protection—significantly extending seal service life in chemically aggressive media.

3. Low Inlet Pressure with High-Viscosity Fluid Capability

The A2FK series features low inlet pressure characteristics, enabling effective pumping of high-viscosity polyurethane raw materials. This allows stable suction and delivery of polyols and isocyanates at various viscosities in foaming equipment, ensuring accurate ratio consistency.

4. 100% Interchangeability – Zero-Modification Drop-In Replacement

Manufactured to exact OEM mounting dimensions, porting specifications, and performance standards, these motors achieve 100% interchangeability with original Rexroth A2FK series units. No machine modifications are required—simply replace and resume operation, minimizing downtime and reducing maintenance costs.

5. 100% Simulated Duty Cycle Testing for Extreme Environment Reliability

Every motor undergoes 100% simulated duty cycle testing before shipment, validating performance under rated pressure (350 bar), peak pressure (400 bar), and maximum speed conditions—ensuring long-term reliability in continuous polyurethane foaming production lines.

6. Robust Roller Bearings for Long Service Life

Robust roller bearings ensure extended service life. The drive shaft is capable of accepting radial loads, accommodating belt or gear drive configurations common in foaming equipment.

7. Compact Lightweight Design for Space-Constrained Foaming Equipment

The A2FK12 weighs only approximately 5.5 kg with a compact footprint. This lightweight design enables easy integration into the limited installation space of foaming equipment while reducing overall machine weight.

8. Special Surface Treatment for Enhanced Corrosion Protection

The housing undergoes special surface treatment processes for enhanced corrosion resistance. In polyurethane chemical environments, this treatment effectively prevents housing corrosion and rust, maintaining appearance while extending service life.

Application Areas

• Polyurethane High-Pressure Foaming Machines: A2FK series is the mainstream core component for this equipment

• Refrigerator/Freezer Manufacturing: Polyurethane insulation foam injection

• Building Insulation Materials: Wall panels, cold storage insulation board foam production

• Automotive Industry: Automotive seats, interior polyurethane foaming

• Pipe Insulation: Insulated pipe polyurethane injection foaming

• Furniture Manufacturing: Flexible/rigid polyurethane foam production

Expert Maintenance Tips

1. Pre-Installation Preparation: Before using the A2FK series motor, read and understand the complete Rexroth instruction manual. For first commissioning, fill the motor housing with hydraulic fluid using a filling unit with filtration not less than 10 µm. Never operate the motor without fluid.

2. Regular Seal Inspection: The A2FK series features dual shaft seals with a flushing chamber. Regularly inspect the flushing chamber for signs of polyurethane leakage and replace seals promptly to prevent chemical media intrusion into the bearing cavity.

3. Oil Cleanliness Control: Recommended system filtration not less than ISO 4406 18/13. Polyurethane foaming equipment requires high fluid cleanliness—regular oil analysis is recommended with filter change intervals adjusted based on contamination levels.

4. Working Pressure Control: A2FK series rated pressure is 350 bar with peak pressure of 400 bar. Pressure fluctuations in polyurethane foaming processes may affect metering accuracy—consider installing accumulators in the system for pressure stabilization.

5. Speed Selection: A2FK12 maximum speed is 6000 rpm in closed circuits and 4000 rpm in open circuits; A2FK28 maximum speed is 4750 rpm in closed circuits and 3000 rpm in open circuits. Select the appropriate speed range based on the actual circuit type to avoid overspeed operation.

6. Regular Inspection Schedule: Regular inspection of the hydraulic system and axial piston unit is recommended. Check hydraulic fluid level daily and monitor operating temperature, noise levels, and case drain flow regularly. Abnormal increases may indicate internal wear or seal degradation.

7. Chemical Compatibility: The A2FK series is specifically designed for polyurethane media with specially selected seal materials. When replacing seals, always use OEM-specification special material seal kits to ensure compatibility with polyurethane chemical components.