A2FO90/61R-PBB05 Rexroth Hydraulic Piston Pump 90cc/rev 400Bar

Product Overview

The A2FO90/61R-PBB05 is a medium-frame fixed displacement axial piston pump from Bosch Rexroth’s A2FO series, featuring a displacement of 90 cm³/rev under Series 6, Index 1 standard configuration. Built on the proven bent-axis tapered piston rotary group design, this pump is engineered for hydrostatic drives in open-circuit systems, delivering output flow proportional to drive speed and displacement.

As a professional interchange alternative to the genuine Rexroth unit, this pump is manufactured to original drawings and tolerance specifications. Critical rotating group components — pistons, cylinder block, and valve plate — utilize material grades and heat treatment processes matched to OEM standards, ensuring full drop-in interchangeability in terms of mounting dimensions, port connections, and performance characteristics. Every unit undergoes 100% simulated load testing prior to shipment, including flow verification at rated pressure, volumetric efficiency measurement, and temperature rise assessment.

Technical Specifications

• Model: A2FO90/61R-PBB05

• Series: Series 6, Index 1

• Design Type: Bent-axis axial piston fixed displacement pump

• Displacement: 90 cm³/rev

• Nominal Pressure: 400 bar

• Peak Pressure: 450 bar

• Max Speed (nnom) : 1800 rpm

• Max Flow (@nnom) : Approx. 162 L/min

• Circuit Type: Open circuit

• Direction of Rotation: Clockwise (viewed on drive shaft, R)

• Drive Shaft: Parallel keyed shaft (DIN 6885)

• Mounting Flange: ISO 4-hole flange

• Port Connections: Rear ports, threaded/flanged

• Control Type: Fixed displacement, no variable control mechanism

• Weight: Approx. 27 kg

• Hydraulic Fluid: Mineral oil (HL, HLP) and approved environmentally acceptable fluids

• Operating Temperature: Up to 80°C

Key Technical Advantages

1. 40° Bent-Axis Rotary Group for Superior Shock and Contamination Resistance

The A2FO series employs a large tilt angle (up to 40°) bent-axis tapered piston design. Unlike swashplate pumps, the tapered piston-to-cylinder bore interface provides line-contact sealing, offering significantly greater tolerance to particulate contamination in the hydraulic fluid. The one-piece tapered pistons with piston rings maintain stable volumetric efficiency under high-pressure conditions, minimizing internal leakage and ensuring precise system response under heavy shock loads.

2. Precision-Machined Rotary Group for High Volumetric Efficiency

Pistons and cylinder bores are pair-lapped to micron-level clearance tolerances. The cylinder block end face and valve plate are precision-ground to achieve minimal flatness deviation, substantially reducing leakage losses at high pressure. This design enables the pump to maintain industry-leading volumetric efficiency at 400 bar nominal pressure, with excellent overall efficiency that reduces system heat generation and energy consumption.

3. Long-Life Drive Shaft Bearing System for High Radial Load Applications

The drive shaft is supported by purpose-selected tapered roller bearings, designed to meet the bearing service life requirements typical of mobile and industrial hydraulic applications. In applications involving sustained vibration and shock loading — such as tractor PTO systems and construction machinery auxiliary circuits — the bearing system maintains stable long-term operation, significantly extending overhaul intervals.

4. Compact Cast Iron Housing with Excellent Power-to-Weight Ratio

The pump housing is constructed from high-strength cast iron, delivering structural rigidity within a compact envelope. Its power-to-weight ratio is exceptional for its displacement class, facilitating installation in space-constrained mobile equipment.

5. Full Drop-In Interchangeability with Genuine Rexroth Units

Critical mounting dimensions (flange pilot, drive shaft specification, port positions and thread specifications) and hydraulic interfaces are manufactured to match Rexroth OEM standards precisely. Users can directly replace a failed genuine pump without modifying piping or mounting brackets, minimizing equipment downtime and maintenance costs.

Application Areas

• Agricultural Machinery: Tractor hydraulic PTO systems, combine harvester hydraulic drive circuits

• Construction Equipment: Concrete pump truck auxiliary hydraulics, excavator auxiliary circuits, loader work implements

• Lifting Equipment: Crane hydraulic lifting and slewing circuits

• Forestry Equipment: Feller bunchers, log splitters

• Industrial Hydraulics: High-pressure presses, hydraulic power units, material testing rigs

• Marine Hydraulics: Deck machinery and steering gear hydraulic systems

Expert Maintenance Tips

1. Mandatory oil filling and air bleeding before initial start-up. After installation, the pump housing must be filled with clean hydraulic fluid to the specified level, and air bleeding must be performed. This is especially critical in the “drive shaft upwards” mounting orientation, where incomplete filling can cause dry running and rapid destruction of the rotary group within a short period.

2. Correct seal kit replacement procedure. The standard seal kit for the A2FO90 (Rexroth material number R902002218) includes a radial shaft seal (45×62×7 mm) with accompanying O-rings and gaskets. During replacement, always inspect the shaft journal surface for wear grooves. If the journal wear exceeds allowable tolerances, replacing the seal alone will not resolve leakage — the drive shaft must be replaced or the journal repaired. Before installing the new seal, apply clean hydraulic fluid to the lip and press it in evenly using a proper installation tool to prevent lip rolling or damage.

3. Hydraulic fluid cleanliness control. Maintain system fluid cleanliness at NAS Level 9 (ISO 18/16/13) or better. Replace suction and return filter elements at regular intervals, and after the first 500 hours of operation, replace filters and test fluid contamination levels. While bent-axis pumps offer better contamination tolerance than swashplate designs, prolonged operation in high-contamination environments will accelerate wear on the valve plate and cylinder block end face.

4. Shaft alignment requirements. Use a flexible coupling between the pump and drive source. The radial misalignment at both coupling ends should not exceed 0.1 mm, with angular misalignment not exceeding 0.2°. Excessive misalignment causes the drive shaft bearings to experience additional bending moments, accelerating bearing wear and potentially causing uneven seal lip wear and leakage.