A2FM45/61W-VZB027 Rexroth Plug-In Motor 45cc 400 bar

Product Overview

The A2FM45/61W-VZB027 is a bent-axis axial piston fixed displacement motor built on the Bosch Rexroth A2FM Series 61 platform, in the A2FM45 displacement size (45.6 cm³/rev). The motor features a bent-axis design with an axial tapered piston rotary group, engineered for hydrostatic drives in both open and closed circuits. It offers a nominal pressure of 400 bar, peak pressure of 450 bar, maximum speed of 5,600 rpm, maximum output torque of 290 N·m (Δp=350 bar), and a weight of approximately 14–16.5 kg.

The A2FM series is Bosch Rexroth’s all-purpose high-pressure fixed motor, featuring a bent-axis design with high power density, very high total efficiency, and excellent starting efficiency. The series offers finely graduated displacement sizes from 5 to 1000 cm³/rev, enabling precise matching to specific application requirements.

The model code A2FM45/61W-VZB027 decodes as follows: A2FM45 designates the series and displacement size (bent-axis fixed motor, 45.6 cm³/rev), 61 is the series designation (Series 61), W indicates bidirectional rotation, V designates FKM fluorocarbon seals, Z is the shaft type code (DIN 5480 splined shaft), B is the mounting flange code (ISO 3019-2 four-hole flange), and 027 is the port configuration code (SAE flange ports, A/B side, opposite). The motor’s fixed displacement design eliminates the need for variable adjustment mechanisms, offering simple construction, low failure rate, and low maintenance requirements.

Engineered as a form-fit-function replacement for original Bosch Rexroth A2FM45 series motors, this model maintains identical mounting flange dimensions (ISO 3019-2 125B4 HW), shaft specifications (DIN 5480 splined shaft), and port locations, enabling drop-in interchangeability without modification to the host machine’s mounting interface or hydraulic circuit. Each unit undergoes 100% simulated load testing prior to shipment, validating output torque and volumetric efficiency against original specifications.

Technical Specifications 

• Model: A2FM45/61W-VZB027

• Material Number: R902227535

• Series: Bosch Rexroth A2FM Series 61

• Motor Type: Bent-axis axial piston fixed displacement motor

• Design Feature: Bent-axis configuration, axial tapered piston rotary group, one-piece conical piston with piston rings

• Displacement (Vg): 45.6 cm³/rev (2.78 in³/rev)

• Nominal Pressure (p nom): 400 bar (40 MPa / 5,800 psi)

• Peak Pressure (p max): 450 bar (45 MPa / 6,525 psi)

• Maximum Speed (n max): 5,600 rpm

• Theoretical Torque at Nominal Pressure: 290 N·m (Δp=350 bar)

• Relative Torque: 0.7 N·m/bar

• Rotation: Bidirectional (W)

• Mounting Flange: ISO 3019-2 125B4 HW four-hole flange

• Shaft Type: DIN 5480 splined shaft (Z)

• Port Configuration: 027 — SAE flange ports, A/B side, opposite

• Seal Material: FKM (V)

• Weight (approx.): 14–16.5 kg (30.9–36.4 lb)

• Circuit: Open circuit / Closed circuit

• Optional Features: Integrated pressure relief valve, counterbalance valve (BVD/BVE), flushing valve, boost-pressure valve, speed sensor

Key Technical Advantages

1. Bent-Axis Conical Piston Design with High Mechanical Efficiency

The A2FM45/61W-VZB027 employs the classic bent-axis design of the Bosch Rexroth A2FM series, with pistons arranged at an angle to the drive shaft, transmitting torque through spherical contact between conical pistons and the drive plate. The one-piece conical piston with piston rings ensures reliable sealing with reduced internal leakage and improved volumetric efficiency. The bent-axis design offers higher mechanical efficiency (94–96%) and excellent starting efficiency compared to swashplate motors, maintaining stable torque output during low-speed starts and heavy-load conditions.

2. High Power Density with Finely Graduated Displacement Sizes

The A2FM45 achieves a nominal pressure of 400 bar and a maximum speed of 5,600 rpm at 45.6 cm³/rev displacement, offering high power density within a compact envelope. The A2FM series offers finely graduated displacement sizes from 5 to 1000 cm³/rev, enabling machine manufacturers to precisely match specific application requirements and simplifying system selection and integration. Output speed depends on pump flow and motor displacement, while output torque increases with the pressure differential between high and low-pressure sides and with increasing displacement.

3. Plug-In Design with Direct Gearbox Integration

The A2FM45 features ISO 3019-2 125B4 HW four-hole flange mounting with a DIN 5480 splined shaft, enabling direct insertion into mechanical gearboxes or flange mounting onto host machine interfaces. This design eliminates couplings and external mounting brackets in track drive gearbox and travel drive applications, reducing system component count and potential failure points, while improving drive system rigidity and alignment precision.

4. Multi-Standard Port Configuration with Functional Extensibility

This model features the 027 port configuration (SAE flange ports, A/B side, opposite), suitable for different machine piping connection requirements. The motor can be optionally equipped with an integrated pressure relief valve for additional safety protection. Counterbalance valves (BVD/BVE), flushing valves, and boost-pressure valves can also be mounted directly onto the motor, simplifying system piping design and reducing external connection points and leakage risks. FKM fluorocarbon seals provide compatibility with high-temperature and chemically aggressive media.

Application Areas

• Track Drive Gearboxes: Excavator, bulldozer, and drilling rig travel drive systems

• Construction Machinery Travel Drives: Wheel loader and road roller travel drives

• Rotary Drilling Rigs: Power head drives and chassis travel devices

• Industrial Hydraulic Transmissions: Industrial drive scenarios requiring compact integration and high efficiency

• Other Mobile Applications: Various mobile hydraulic systems requiring plug-in fixed motors

Expert Maintenance Tips

1. Shaft Alignment Requirements: During installation, ensure the coaxiality deviation between the motor shaft and drive-end spline does not exceed 0.05 mm. When installing the DIN 5480 splined shaft, ensure the spline mating surfaces are free of burrs and damage, coated with appropriate grease to prevent corrosion.

2. Case Filling and Venting: Before initial installation or startup after extended idle periods, fill the motor housing with clean hydraulic fluid to prevent dry friction on piston pairs during startup. The case drain port must be connected separately to the reservoir, with return lines below the minimum oil level.

3. Hydraulic Fluid Cleanliness and Viscosity Management: Recommended optimum viscosity range is 16–36 mm²/s (at operating temperature). Maintain hydraulic fluid cleanliness at ISO 18/15 or NAS Level 9 or better. Replace hydraulic fluid and filter elements every 1,000 operating hours or annually, with filter element filtration accuracy no less than 10 μm.

4. Restart After Extended Storage: For motors stored over 6 months, manually rotate the shaft 2–3 revolutions to confirm free rotation, then run at low pressure (10 MPa) under no load for 10 minutes, confirming normal case temperature and leakage before gradually applying load.