A2FM180 Rexroth Fixed Piston Motor 400 bar

Product Overview

The Bosch Rexroth A2FM180/61W is a fixed displacement axial piston motor from the A2FM Series 6x. Featuring a bent-axis design, the motor is engineered for hydrostatic drives in both open and closed circuits. With a geometric displacement of 180 cm³/rev, a nominal pressure of 400 bar and a maximum pressure of 450 bar, the A2FM180 is designed for high-load hydraulic drive applications requiring high torque density and reliable power transmission. Bosch Rexroth identifies the A2FM Series 6x by its high power density, very high total efficiency and high starting efficiency.

Two configurations in the requested product range should be distinguished:

• A2FM180/61W-VAB010: SAE working ports A and B positioned at the rear.
• A2FM180/61W-VAB027: SAE working ports A and B positioned at the side and opposite to each other, with a mounted flushing and boost-pressure valve.

The VAB027 configuration is particularly relevant to closed-loop systems where housing flushing and boost-pressure management are required for thermal control and circuit reliability.

The A2FM180 is a bidirectional fixed displacement motor. Because displacement is fixed, motor speed is primarily determined by hydraulic flow rather than by a variable displacement control system. Proper system matching therefore requires coordinated selection of pump flow, motor displacement, differential pressure and operating speed.

For replacement applications, engineering verification should include the complete type code, shaft configuration, mounting flange, working-port position, seal material and auxiliary valve configuration. Our replacement process focuses on dimensional and interface compatibility together with simulated operating-condition testing.

Technical Specifications

• Manufacturer: Bosch Rexroth
• Series: A2FM Series 6x
• Model: A2FM180/61W-VAB010
• Model: A2FM180/61W-VAB027
• Operating Mode: Fixed displacement hydraulic motor
• Design: Bent-axis axial piston motor
• Geometric Displacement: 180 cm³/rev
• Nominal Pressure: 400 bar
• Maximum Pressure: 450 bar
• Nominal Speed: 3,600 rpm
• Intermittent Maximum Speed: 4,000 rpm
• Theoretical Flow at Nominal Speed: 648 L/min
• Theoretical Torque at Nominal Pressure: 1,146 Nm
• Direction of Rotation: Bidirectional
• Seal Material: FKM fluoroelastomer
• Drive Shaft: Splined shaft
• Mounting Flange: 4-hole configuration for nominal size 160/180
• VAB010 Port Configuration: SAE working ports A and B at rear
• VAB027 Port Configuration: SAE working ports A and B at side, opposite
• VAB027 Auxiliary Function: Mounted flushing and boost-pressure valve
• Speed Sensor: No speed sensor in the standard configuration
• Approx. Base Motor Weight: 45 kg; final assembly weight may increase according to installed options and auxiliary valve configuration.

The 3,600 rpm figure is the nominal speed for size 180, while 4,000 rpm is an intermittent maximum speed rather than a continuous operating rating. Bosch Rexroth defines the intermittent maximum-speed condition for specific unload and overrunning processes and limits the corresponding operating conditions.

Key Technical Advantages

1. High Torque Output from a 180 cm³ Displacement

At 400 bar nominal pressure, the A2FM180 provides a theoretical torque of approximately 1,146 Nm. This combination of large displacement and high permissible pressure provides a strong torque base for high-load hydraulic drive applications. Actual output is influenced by volumetric efficiency, hydro-mechanical efficiency, pressure, temperature and system conditions.

2. Proven Bent-Axis Piston Architecture

The A2FM Series 6x uses a bent-axis axial piston configuration for hydrostatic transmission in open and closed circuits. Its fixed-displacement architecture avoids the additional control mechanisms required by variable-displacement motors, making the hydraulic function straightforward for appropriately matched systems.

3. High Power Density and Starting Efficiency

Bosch Rexroth specifies high power density, very high total efficiency and high starting efficiency as key characteristics of the A2FM Series 6x. These characteristics are valuable in machinery requiring compact hydraulic power transmission and dependable starting torque.

4. FKM Shaft Seal Configuration

The “V” designation in the ordering code specifies an FKM fluoroelastomer seal. FKM provides a high-temperature sealing option for suitable hydraulic-fluid and operating-temperature conditions, subject to the limits specified in the Rexroth technical data.

5. Integrated Flushing and Boost-Pressure Function on VAB027

The A2FM180/61W-VAB027 uses port plate 027 with the flushing and boost-pressure valve mounted directly on the motor. In a closed hydraulic circuit, the valve removes hydraulic fluid from the low-pressure side, routes it through the motor housing for flushing and returns it with the housing leakage to the reservoir. The resulting fluid must be replaced by cooled make-up flow from the boost pump.

6. Engineering-Oriented Replacement Compatibility

A2FM180/61W-VAB010 and A2FM180/61W-VAB027 share the same 180-size A2FM Series 6x platform but differ in working-port arrangement and auxiliary flushing/boost configuration. For field replacement, matching the complete type code is essential; the A2FM180 nominal size alone is not sufficient to confirm interchangeability.

Application Areas

The A2FM Series 6x is designed for hydrostatic drives in both open and closed circuits.

Typical application areas include:

• Construction and heavy mobile machinery
• High-load hydraulic drive systems
• Industrial hydraulic transmission equipment
• Closed-loop hydrostatic drive systems
• High-torque rotary drive mechanisms
• Machinery requiring high hydraulic power density

Final application suitability should be verified against actual hydraulic flow, pressure, speed, inertia, radial and axial shaft loads, mounting dimensions and operating temperature.

Expert Maintenance Tips

Installation Verification

Always verify the complete ordering code before installation. In particular, distinguish between A2FM180/61W-VAB010 and A2FM180/61W-VAB027, because their working-port positions and auxiliary valve configurations differ. Bosch Rexroth recommends obtaining a binding installation drawing before finalizing the design.

Hydraulic Fluid and Cleanliness

The A2FM Series 6x is designed for mineral-oil-based HLP hydraulic fluids according to DIN 51524, subject to the applicable fluid and temperature requirements. Bosch Rexroth specifies a minimum hydraulic-fluid cleanliness level of 20/18/15 according to ISO 4406 under normal conditions. Improved filtration can increase the service life of the axial piston unit.

Speed Management

Do not treat 4,000 rpm as the continuous rated speed. For the 180 size, the nominal speed is 3,600 rpm and 4,000 rpm is the intermittent maximum. Systems involving overrunning loads, high inertia or frequent braking should be checked against the manufacturer’s speed, pressure and shaft-seal limitations.

Case Drain Pressure

Housing pressure has a direct influence on shaft-seal service life. The housing drain circuit should therefore be designed to prevent excessive back pressure, and the Rexroth case-pressure limits should be respected during commissioning and operation.

VAB027 Flushing Circuit

For A2FM180/61W-VAB027, inspect the flushing and boost-pressure valve, low-pressure-side pressure and cooling/make-up flow during service. The flushing function is intended to remove heat and maintain the required boost-pressure condition in closed circuits, so the cooling and charge-flow capacity should be matched to the actual thermal load.