MMF025CA5GFBNNN Danfoss Motor | 345 Bar Axial Piston

Product Overview

The MMF025CA5GFBNNN is a 25 cm³/rev displacement model from Danfoss’ (formerly Sauer Danfoss) Series 40 MMF series of axial piston fixed displacement motors, with manufacturer part number 4253036. Series 40 MMF motors are high-performance fixed displacement piston motors engineered for medium-power closed-circuit hydrostatic transmissions, covering displacements from 25 to 46 cm³/rev with maximum working pressure up to 345 bar (5,000 psi) and rated speeds up to 4,000 rpm. The series employs a swashplate design with parallel axial piston/slipper configuration, delivering compact construction and high power density.

The MMF series is a fixed displacement motor configuration, maintaining a constant ratio between working fluid flow and output shaft speed. The series is suitable for both closed-circuit and open-circuit hydrostatic transmissions, widely deployed in material handling, construction equipment, turfcare and specialty vehicle applications.

The model code breaks down as follows: MMF identifies the Series 40 fixed motor family; 025 denotes the 25 cm³/rev displacement; C indicates product version C (swashplate design); A is the input shaft configuration; 5 is the charge pump displacement code; G is the charge relief valve setting; F is the control/filtration configuration; B is the mounting flange and shaft configuration; NNN is the standard option combination. This model weighs approximately 12 kg and features SAE B 2-bolt mounting flange.

Every MMF025CA5GFBNNN unit undergoes 100% simulated operating-condition bench testing prior to shipment, covering pressure cycling, speed stepping and thermal shock. Mounting flange, shaft end and port dimensions comply with SAE standards and are identical to the original Danfoss MMF025, ensuring true drop-in interchangeability with zero modification required.

Technical Specifications

Series 40 MMF Series Frame Size Specifications:

• MMF025 (This Model): Displacement 25 cm³/rev (1.50 in³/rev), mounting flange SAE B, weight 11 kg (26 lbf), mass moment of inertia 0.0018 kg·m²

• MMF035: Displacement 35 cm³/rev (2.14 in³/rev), mounting flange SAE B, weight 11 kg (26 lbf), mass moment of inertia 0.0033 kg·m²

• MMF044: Displacement 44 cm³/rev (2.65 in³/rev), mounting flange SAE B, weight 11 kg (26 lbf), mass moment of inertia 0.0032 kg·m²

• MMF046: Displacement 46 cm³/rev (2.80 in³/rev), mounting flange SAE B, weight 23 kg (51 lbf)

MMF025CA5GFBNNN Additional Specifications:

• Model Code: MMF025CA5GFBNNN

• Manufacturer Part Number: 4253036

• Product Series: Danfoss Series 40 M25

• Type: Fixed displacement axial piston motor, swashplate design

• Displacement: 25 cm³/rev (1.50 in³/rev), fixed and non-adjustable

• Continuous Working Pressure: 210 bar (3,000 psi)

• Maximum Working Pressure (Intermittent): 345 bar (5,000 psi)

• Rated Speed (Max Displacement): 4,000 rpm

• Maximum Speed (Max Displacement): 5,000 rpm

• Case Pressure (Continuous): 1.7 bar (25 psi)

• Case Pressure (Maximum): 5.2 bar (75 psi)

• Rotation: Bidirectional

• Mounting Flange: SAE B 2-bolt flange

• Weight: ~12 kg

• Mass Moment of Inertia: 0.0018 kg·m²

• Circuit Type: Closed circuit / open circuit compatible

• Operating Temperature Range: -40°C to +115°C

• Hydraulic Fluid: Mineral oil (ISO VG46/68), synthetic oil

Key Technical Advantages

1. Swashplate Axial Piston Design for High Power Density

The MMF025 employs Danfoss Series 40’s signature swashplate axial piston design with parallel piston/slipper configuration, providing constant displacement output through a fixed swashplate. This design enables high power density in a compact package weighing only about 11–12 kg. The efficient axial piston design with precision-ground cylinder bores and slippers minimizes internal leakage, maintaining high volumetric and mechanical efficiency across the full speed and pressure range.

2. High Pressure Capability — 210 Bar Continuous, 345 Bar Peak

The MMF025 supports 210 bar continuous working pressure and 345 bar maximum working pressure, enabling adaptation to medium power-density closed-circuit hydraulic systems. Case pressure is limited to 1.7 bar continuous and 5.2 bar maximum, ensuring case seal reliability under demanding conditions. This pressure rating offers significant advantages in material handling and construction equipment travel drive applications.

3. High Speed Capability and Smooth Operation

The MMF025 achieves a rated speed of 4,000 rpm at maximum displacement with maximum speed up to 5,000 rpm, leading among fixed displacement motors of comparable displacement. The inherent balance characteristics of the swashplate design ensure low pulsation and low noise at high speeds, suitable for continuous high-speed operation such as cooling fan drives and travel drives.

4. System Filtration Requirements and High Reliability Design

Series 40 motors require system filtration capable of maintaining fluid cleanliness at ISO 4406-1999 class 22/18/13 or better. This filtration level ensures low wear rates for piston groups and valve plates over extended operation, extending overhaul intervals. Optional radial ports and loop flushing help with heat dissipation and smooth hydraulic flow, improving system efficiency in continuous applications.

5. 100% Simulated Load Testing & Drop-In Interchangeability

Each MMF025CA5GFBNNN unit is bench-tested under simulated operating conditions prior to dispatch, covering pressure cycling, speed stepping and thermal variation. Mounting flange, shaft end and port dimensions comply with SAE B standards, matching the original Danfoss MMF025 exactly, enabling direct replacement without any interface modification.

Application Areas

The MMF025 series is widely deployed across mobile and industrial hydraulic applications:

• Material Handling: trenchers, skid steer loaders, compact track loaders

• Construction Equipment: soil compactors, asphalt compactors, pavers, rollers

• Turfcare: mowers, fairway machines

• Municipal Equipment: sweepers, snow removal equipment

• Agriculture: tractor hydraulic systems, combine harvester drive systems

The MMF series is OEM-installed on BOMAG, CASE, JCB, HAMM, AMMANN, DYNAPAC, Caterpillar and Bobcat machinery platforms.

Expert Maintenance Tips

1. System Filtration and Oil Cleanliness Control: Series 40 MMF motors demand high fluid cleanliness—system filtration must maintain ISO 4406-1999 class 22/18/13 or better. Replace hydraulic oil and filter after the first 500 hours, then follow a 2,000-hour or annual replacement cycle. VG 46 is recommended at 60°C operating temperature.

2. Case Pressure Management and Drain Line: MMF025 case pressure is limited to 1.7 bar (25 psi) continuous and 5.2 bar (75 psi) maximum. The drain port must return to the reservoir independently—housing back pressure must not exceed 2 bar. The drain line end must remain submerged to prevent air ingestion. Fill the housing with clean hydraulic oil before first startup. After extended shutdown, fill the housing again before restarting.

3. Coupling Alignment and Installation: Ensure coupling alignment deviation does not exceed 0.05 mm during installation to prevent abnormal bearing wear and shaft seal leakage. Tighten SAE B 2-bolt flange evenly in a diagonal sequence to Danfoss technical manual torque values. If configured with radial ports and loop flushing, verify flushing flow and pressure settings meet system requirements.

4. Oil Temperature Control: Operating oil temperature should be kept below 80°C—system temperature must not exceed 115°C at any point. Case drain temperature is affected by pressure and speed and is always higher than circuit temperature. High temperatures accelerate seal aging and oil oxidation; install temperature monitoring on the return line.

5. Periodic Piston Group and Valve Plate Inspection: The MMF025’s piston slippers, valve plate and cylinder bores are primary wear components. Inspect piston slipper wear, valve plate sealing surface condition and cylinder bore clearance every 2,000 hours. Abnormal efficiency loss, noise or vibration requires immediate shutdown and service. Use Danfoss original specification parts when replacing piston groups to ensure fit accuracy and assembly torque per technical manual requirements.