Product Overview
The A2FM23/61W-VPB040 (Material No. R902137725) is a core model within the 23 frame size of Bosch Rexroth’s A2FM Series of bent axis axial piston fixed displacement motors, built on the Series 61 (high-pressure version) platform. The A2FM Series features an axial tapered piston rotary group of bent-axis design, developed for hydrostatic drives in open and closed circuits, suitable for both mobile and stationary applications.
The A2FM23/61W-VPB040 has a nominal displacement of 22.9 cm³/rev, with a nominal working pressure of up to 400 bar and maximum pressure up to 450 bar. At 400 bar pressure differential, theoretical output torque is 144 N·m, with a nominal speed of 6300 rpm. The motor employs a 40° bent-axis design, where pistons act directly on the drive shaft flange through a tapered configuration to generate torque, offering high power density, compact dimensions, high total efficiency, and excellent starting efficiency.
Model code breakdown: A2FM = bent axis axial piston fixed displacement motor; 23 = nominal displacement 22.9 cm³/rev; 61 = Series 61 (high-pressure version); W = bidirectional rotation (viewed on drive shaft); V = FKM (fluoroelastomer) seals; P = cylindrical shaft with key (DIN 6885); B = ISO 3019-2 standard 4-hole mounting flange; 040 = port configuration code (side opposite + axial rear, M27×2 threaded ports).
The motor features one-piece tapered pistons with piston rings, ensuring efficient sealing and long service life. Drive shaft bearings are optimized to withstand substantial radial and axial loads. As a drop-in replacement, the motor is fully compatible with the OEM Rexroth specification in mounting interface, shaft end configuration, and performance characteristics, enabling direct replacement without hydraulic circuit or mounting bracket modification. Every unit undergoes 100% simulation-based testing prior to shipment, covering displacement calibration, torque output, pressure holding, and internal leakage.
Technical Specifications
All parameters below are based on Bosch Rexroth official technical documentation, verified supplier technical pages (buyrexroth.com, tph-group.shop, fluid-hub.net, hydraulic-components.net, etc.), and industry-standard specifications:
Complete Model: A2FM23/61W-VPB040
Material Number (MNR): R902137725
Brand: Bosch Rexroth
Product Series: A2FM series, Series 61 (high-pressure version)
Product Type: Bent axis axial piston fixed displacement motor
Nominal Displacement: 22.9 cm³/rev
Nominal Working Pressure: 400 bar (5800 psi)
Maximum Pressure: 450 bar (6527 psi)
Nominal Speed: 6300 rpm
Theoretical Torque (@ Δp = 400 bar): 144 N·m
Drive Type: 40° bent-axis design, pistons acting directly on drive shaft flange
Piston Design: One-piece tapered pistons with piston rings
Mounting Flange: ISO 3019-2 standard 4-hole flange
Drive Shaft: Cylindrical shaft with key (DIN 6885, code P)
Port Connection: Side opposite + axial rear, M27×2 threaded ports (code 040)
Direction of Rotation: Bidirectional (W, viewed on drive shaft)
Seal Material: FKM (fluoroelastomer)
Hydraulic Fluid: Mineral oil per DIN 51524 / ISO 11158
Operating Temperature Range: -25°C to +90°C (depending on seal material)
Case Drain: Routed via highest drain port T1 to reservoir
Weight: Approx. 11 kg
Mounting Position: Any position
A2FM Series Other Model Specifications Reference (Series 61):
A2FM10: Displacement 10.3 cm³/rev, max speed 8000 rpm, torque 66 N·m @400 bar
A2FM12: Displacement 12.0 cm³/rev, max speed 8000 rpm, torque 76 N·m @400 bar
A2FM16: Displacement 16.0 cm³/rev, max speed 8000 rpm, torque 100 N·m @400 bar
A2FM23: Displacement 22.9 cm³/rev, max speed 6300 rpm, torque 144 N·m @400 bar
A2FM28: Displacement 28.1 cm³/rev, max speed 6300 rpm, torque 178 N·m @400 bar
A2FM32: Displacement 32.0 cm³/rev, max speed 6300 rpm, torque 204 N·m @400 bar
A2FM45: Displacement 45.6 cm³/rev, max speed 5600 rpm, torque 290 N·m @400 bar
A2FM56: Displacement 56.1 cm³/rev, max speed 5000 rpm, torque 357 N·m @400 bar
A2FM63: Displacement 63.0 cm³/rev, max speed 5000 rpm, torque 401 N·m @400 bar
A2FM80: Displacement 80.4 cm³/rev, max speed 4500 rpm, torque 512 N·m @400 bar
A2FM107: Displacement 106.7 cm³/rev, max speed 4000 rpm, torque 679 N·m @400 bar
A2FM125: Displacement 125.0 cm³/rev, max speed 4000 rpm, torque 796 N·m @400 bar
A2FM160: Displacement 160.4 cm³/rev, max speed 3600 rpm, torque 1021 N·m @400 bar
A2FM180: Displacement 180.0 cm³/rev, max speed 3600 rpm, torque 1146 N·m @400 bar
A2FM200: Displacement 200.0 cm³/rev, max speed 2750 rpm, torque 1273 N·m @400 bar
Note: Specifications are based on Bosch Rexroth official technical documentation, verified supplier technical pages (buyrexroth.com, tph-group.shop, fluid-hub.net, hydraulic-components.net, etc.), and industry-standard specifications. The A2FM Series covers a complete product matrix with displacements from 5 to 1000 cm³/rev. Always verify against the complete model code and consult the latest Rexroth official technical documentation during selection.
Key Technical Advantages
1. 40° Bent-Axis Design for High Power Density and Excellent Starting Efficiency
The A2FM23 employs a proven 40° bent-axis design, where pistons act directly on the drive shaft flange through a tapered configuration to generate torque, enabling high power density within a compact size. This design allows the motor to deliver high torque at startup, offering excellent starting efficiency, particularly suitable for travel drive applications requiring frequent start-stop or loaded starting. Compared with swashplate designs, the bent-axis architecture provides higher power-to-weight ratio and higher overall efficiency at the same displacement.
2. One-Piece Tapered Pistons with Piston Rings for Efficient Sealing and Long Life
The motor features one-piece tapered pistons with piston rings, where the piston rings provide efficient sealing performance, effectively reducing internal leakage and improving volumetric efficiency. The one-piece construction reduces the number of moving parts, lowering wear risk and enabling the motor to maintain stable volumetric efficiency and long service life under high-pressure conditions. Drive shaft bearings are optimized to provide the expected service life across the entire operating range.
3. High Pressure Rating with Wide Media Compatibility
With a nominal pressure of 400 bar and maximum pressure of 450 bar, the motor handles high-pressure heavy-duty applications. FKM (fluoroelastomer) seal material provides excellent high-temperature and chemical resistance, with an operating temperature range covering -25°C to +90°C. The motor is compatible with mineral oil and HFD hydraulic fluids (selected sizes), meeting diverse industrial environment media requirements.
4. High Overall Efficiency with Economical Design
The A2FM Series features high overall efficiency, where output speed depends on pump flow and motor displacement, and output torque increases with the pressure differential between high and low-pressure sides. The series offers finely graduated displacement sizes, allowing users to precisely select the most suitable specification for specific drive conditions, achieving system efficiency optimization. The economical design philosophy runs throughout the product series, reducing total cost of ownership while maintaining performance.
5. Complete Specification Coverage with 100% Simulation-Based Testing
The A2FM Series covers a complete displacement range from A2FM5 to A2FM1000, satisfying all requirements from precision industrial transmission micro-torque to high-power heavy-duty drive applications. Every A2FM23/61W-VPB040 undergoes 100% simulation-based testing prior to shipment, covering displacement calibration, torque output verification, pressure holding performance, and internal leakage detection. As a drop-in replacement, the motor is fully compatible with the OEM Rexroth specification in mounting dimensions (ISO 3019-2 4-hole flange), shaft end configuration (DIN 6885 keyed shaft), and performance characteristics, enabling direct replacement of the original unit.
Application Areas
Construction Machinery Travel Drives: Travel motors for mini excavators, skid steer loaders, and compactors, utilizing high starting efficiency for smooth starting and climbing
Rotary Drilling Rigs & Piling Machinery: Auxiliary winch systems and power head drives, utilizing high power density for compact layouts
Cranes & Material Handling: Hoisting and slewing motors for small cranes and forklifts, utilizing high torque output for heavy-load lifting
Concrete Mixer Trucks: Mixer drum drive motors, utilizing economical design and reliable performance for long-term continuous operation
Mining & Tunneling Equipment: Hydraulic drive systems for small roadheaders, roof bolters, and related equipment
Marine & Offshore: Deck machinery, winches, and propulsion system hydraulic transmission
Industrial Hydraulic Systems: Metallurgical equipment, presses, and test rigs requiring high-pressure fixed displacement drives
Agricultural Machinery: Travel and implement drives for harvesters, sprayers, and other equipment
Expert Maintenance Tips
Pre-Installation Checks:
Verify mounting flange (ISO 3019-2 4-hole) alignment with equipment mounting surface; ensure surface is clean and free of burrs, flatness deviation not exceeding 0.01 mm/100 mm
Inspect cylindrical shaft (DIN 6885 keyed) mating surface for wear or corrosion; apply appropriate grease
The motor must be fully filled with clean hydraulic oil via the case drain port prior to installation to prevent dry friction damage to piston/cylinder and bearings during startup
Confirm M27×2 threaded port seals are intact; tighten diagonally to specified torque
Operational Maintenance:
Maintain hydraulic oil cleanliness to ISO 4406 18/16/13 or better; use pressure filters with ≤ 10 μm filtration accuracy
Recommended fluid: mineral oil-based anti-wear hydraulic oil per DIN 51524 / ISO 11158
Maintain operating temperature within -25°C to +90°C; avoid overheating
Periodically monitor hydraulic oil moisture and particle contamination levels; oil replacement recommended every 1,000 to 3,000 operating hours or every six months
The case drain line must run independently and directly to the hydraulic reservoir, routed via the highest drain port on the case; connecting in series with the system main return line is strictly prohibited
Periodically inspect shaft seals for aging or leakage; shaft seals recommended for replacement every 5,000 hours
Periodically monitor motor operating temperature and noise level; abnormal increase may indicate internal wear or fluid contamination
Troubleshooting Guide:
Motor fails to rotate or speed abnormal: Check hydraulic system supply pressure; verify directional valve operation; check oil cleanliness
Insufficient output torque: Confirm system pressure reaches rated value (400 bar continuous / 450 bar peak); inspect piston rings and cylinder bores for wear
Abnormal noise or vibration: Check case oil fill level; verify suction line is unobstructed; check mounting bolt tightness
External leakage: Inspect shaft seal (FKM) for aging or damage; verify case drain line back pressure is within allowable range
Excessive oil temperature: Check system for excessive internal leakage; verify cooling system operation
