A2F28W1P1 Rexroth Hydraulic Piston Pump | Fixed Displacement 28 cc/rev 350 bar

Product Overview

The A2F28W1P1 is a representative model of the A2F series fixed-displacement bent-axis axial piston pumps, with a displacement of 28.1 cc/rev. Engineered on the proven Rexroth A2F platform, this bent-axis axial piston unit features fixed displacement design and can be used either as a pump or as a motor in hydrostatic drives, in both open and closed circuits.

Manufactured to strict OEM design standards and processes, this product offers 100% interchangeability with the original branded equivalent — direct drop-in replacement without any mounting or plumbing modifications. Every unit undergoes 100% simulated operating condition testing at rated pressure of 350 bar and peak pressure of 400 bar before shipment, ensuring proven reliability and durability in real-world applications.

Model code breakdown for A2F28W1P1:

• A2F = Fixed displacement pump/motor (bent-axis axial piston design)

• 28 = Displacement size (28.1 cc/rev)

• W = Alternating rotation (bidirectional)

• 1 = Series designation (Series 1)

• P = Shaft end — keyed shaft

• 1 = Rear cover / port plate configuration

Technical Specifications 

• Series: A2F — fixed displacement bent-axis axial piston pump/motor

• Model: A2F28W1P1

• Displacement (Vg) : 28.1 cm³/rev (28.1 cc/r)

• Rated Pressure (p_nom) : 350 bar (35 MPa)

• Peak Pressure (p_max) : 400 bar (40 MPa)

• Maximum Speed (n_max) : 6,300 rpm

• Nominal Speed (n_nom) : 2,500 rpm

• Nominal Flow (qV at n_nom) : Approx. 70 L/min (@ 2,500 rpm)

• Shaft End: Keyed shaft (code P)

• Direction of Rotation: W — alternating (bidirectional)

• Mounting: Flange mounting

• Port Connections: SAE standard or threaded ports

• Weight (approx.) : 9.5 kg

Key Technical Advantages

1. Bent-Axis Design for High Power Density
The bent-axis axial piston configuration delivers superior power-to-weight ratio. Compared to inline-axis designs, the bent-axis architecture generates higher torque and power output within the same compact footprint — ideal for space-constrained mobile equipment applications.

2. Spherical Control Area with Self-Centering for High Volumetric Efficiency
The rotating group incorporates a field-proven spherical control area design featuring self-centering characteristics, low peripheral speed, and minimal friction losses. This results in volumetric efficiency consistently exceeding 90%, significantly reducing internal leakage and improving overall system energy efficiency.

3. One-Piece Pistons with Piston Rings for Extreme Durability
Engineered with integrated one-piece pistons featuring piston rings, the design ensures superior sealing performance and precision fit between pistons and cylinder bores. The piston rings effectively minimize metal-to-metal contact wear, dramatically extending the service life of the rotating group under demanding operating conditions.

4. Heavy-Duty Tapered Roller Bearings with Radial Load Capacity
The drive shaft is supported by robust rolling bearings engineered to withstand significant radial loads. Bearing selection and sizing are optimized to deliver the expected service life under rated operating conditions, minimizing maintenance frequency and downtime.

5. 100% Interchangeability — Zero Retrofit Cost
All external dimensions, mounting interfaces, port locations, and shaft end configurations are identical to the original Rexroth A2F28 series. No hydraulic line modifications, no coupling replacements, no mounting bracket alterations — truly “plug-and-play” replacement.

Application Areas

The A2F28W1P1 fixed-displacement piston pump is widely deployed across mobile and industrial equipment:

• Construction Machinery: Compact excavators, wheel loaders, bulldozer hydraulic systems

• Building Equipment: Concrete mixer trucks, pump truck hydraulic drive systems

• Agricultural Machinery: Combine harvesters, tractor hydrostatic drives

• Industrial Hydraulics: Injection molding machines, die-casting machines, hydraulic press power units

• Marine Equipment: Deck machinery, steering gear hydraulic systems

Expert Maintenance Tips

1. Hydraulic Fluid Selection & Viscosity Control
Mineral oil-based hydraulic fluids are recommended, with viscosity grades VG 46 or VG 68 preferred. Operating viscosity should remain within the optimum range (νopt.) at working temperatures. Select lower viscosity grades for colder ambient conditions and higher grades for warmer environments.

2. Case Drain Pressure Limitations
Case drain pressure must not exceed 3 bar (absolute) at normal operating temperature. Maximum permissible case drain pressure is 6 bar (absolute), but only under reduced speed conditions. Exceeding these limits will cause shaft seal damage and inadequate bearing lubrication.

3. Temperature Monitoring
System temperature must not exceed 115°C at any point (for A2F sizes 10 through 200). Case drain oil temperature, which is influenced by pressure and speed, is typically higher than tank temperature and should be closely monitored.

4. Installation & Alignment
Ensure precise coaxial alignment between the pump shaft and the drive shaft during installation. Misalignment will lead to premature bearing failure. The use of flexible couplings is recommended to compensate for minor alignment deviations.

5. First Start-Up & Air Bleeding
Prior to initial start-up, pre-lubricate the pump by filling the housing with hydraulic fluid through the case drain port. After start-up, run the pump at low speed and no load for 5–10 minutes to purge air from the system before gradually applying load up to operating pressure.