KC45DNERNFF55SNNAFF18NNNNNN Danfoss Axial Piston Motor

Product Overview

The KC series swashplate axial piston variable motors are a classic product line within the Danfoss (formerly Sauer-Danfoss) hydraulic transmission platform, classified as K-frame compact cartridge-type variable motors. Featuring a swashplate design with a 9-piston rotating assembly and a maximum 18° swashplate angle, these motors are specifically engineered for travel drive and tool drive applications in both open and closed circuits. Designed to fully comply with Danfoss KC series mounting and interface standards, these motors offer 100% direct interchangeability with original Danfoss units—enabling plug-and-play replacement without any管路 modifications or adapter plates, significantly minimizing downtime and retrofit costs.

The KC series covers a displacement range from 25 to 45 cm³/rev, with core models KC38 (~38 cm³/rev) and KC45 (~45 cm³/rev), featuring 2-position variable (2-speed) control. The compact cartridge-style design enables direct mounting with planetary gearboxes. Every unit undergoes 100% factory testing under simulated real-world working conditions, validating pressure, flow, and control characteristics before shipment—ensuring reliable operation from the very first start.

Model Code Interpretation (using KC45DNERNFF55SNNAFF18NNNNNN as an example) :

• KC – Series code: K-frame swashplate axial piston motor

• 45 – Displacement size: 45 cm³/rev

• D – Enhanced variant: Hardened cylinder blocks, improved seals, optimized hydraulic efficiency, supports advanced control modes

• NERNFF55SNNAFF18NNNNNN – Specific configuration code (mounting flange, shaft, ports, control options)

Technical Specifications

KC45DNERNFF55SNNAFF18NNNNNN (Part No.: 4254801)

• Model: KC45DNERNFF55SNNAFF18NNNNNN

• Part Number: 4254801

• Type: Swashplate axial piston variable motor

• Displacement: 45 cm³/rev

• Rated Working Pressure: 350 bar

• Intermittent Peak Pressure: 400 bar

• Maximum Speed: 4000 r/min

• Maximum Output Torque: 150 N·m

• Piston Count: 9-piston design

• Maximum Swashplate Angle: 18°

• Displacement Ratio: 3.4:1 (max/min)

• Volumetric Efficiency: ≥95% (at rated pressure/speed)

• Overall Efficiency: ≥90%

• Control Type: Hydraulic two-position variable control (2-speed)

• Mounting Flange: SAE B cartridge style

• Weight: Approx. 15 kg

• Housing Material: High-strength cast iron, one-piece gasket-free housing

• Bearings: Heavy-duty tapered roller bearings

• Built-in Features: Closed-circuit flush valve (standard), speed sensor (optional)

• Medium: Mineral-based anti-wear hydraulic oil (ISO VG 32/46/68)

• Operating Temperature Range: 10–60°C (optimal)

• Recommended Filtration: ≥10 μm precision filtration

KC38CNERNFF10SNNAFF18 (Part No.: A190960402)

• Model: KC38CNERNFF10SNNAFF18

• Part Number: A190960402

• Type: Swashplate axial piston variable motor

• Displacement: 38 cm³/rev

• Rated Working Pressure: 350 bar

• Intermittent Peak Pressure: 400 bar

• Piston Count: 9-piston design

• Maximum Swashplate Angle: 18°

• Control Type: Hydraulic two-position variable control (2-speed)

• Mounting Flange: SAE B cartridge style

• Housing Material: High-strength cast iron, one-piece gasket-free housing

• Bearings: Heavy-duty tapered roller bearings

• Built-in Features: Closed-circuit flush valve (standard), speed sensor (optional)

Key Technical Advantages

1. 100% Direct Interchangeability – Zero Modification Required

The KC series is engineered to exact Danfoss mounting and interface specifications, with identical dimensions, port locations, and shaft end configurations. End users can replace original units directly without any管路 modifications or adapter plates—transforming unplanned downtime into scheduled, rapid maintenance while significantly reducing spare parts procurement costs and equipment downtime losses.

2. Swashplate 9-Piston Design – Low Pulsation with High Efficiency

The swashplate structure with a 9-piston rotating assembly and maximum 18° swashplate angle delivers smooth, low-pulsation flow. The 9-piston configuration effectively reduces flow pulsation, maintaining low flow fluctuation and consistent torque delivery. Volumetric efficiency reaches ≥95% with overall efficiency ≥90%, minimizing energy loss and maximizing system performance.

3. Two-Position Variable Control – Flexible Multi-Speed Configuration

The series features hydraulic two-position variable (2-speed) control with a displacement ratio of 3.4:1 (max/min). Displacement switching via control ports enables high/low-speed mode transitions—adapting to the speed and torque requirements of mobile machinery under varying operating conditions. This eliminates the need for additional gear-shifting mechanisms, simplifying system architecture.

4. Compact Cartridge-Style Design – Direct Planetary Gearbox Mounting

The compact cartridge-style design enables direct mounting with standard planetary gearboxes. The one-piece gasket-free housing and heavy-duty tapered roller bearings ensure long-term reliability in the harshest construction site environments. This design makes it the ideal wheel drive travel motor solution.

5. Standard Closed-Circuit Flush Valve – Optimized System Cooling

A built-in closed-circuit flush valve is standard, effectively reducing oil temperature in closed-loop systems and extending motor and system life. Optional speed sensors are available to meet system monitoring and protection requirements. Reliable operation in closed circuits is possible without an external charge pump.

6. 100% Factory Testing Under Simulated Working Conditions

Every KC series unit undergoes rigorous factory testing under simulated real-world conditions, validating pressure, flow, volumetric efficiency, control response characteristics, and thermal performance across the full operating range. Test media match actual operating conditions, ensuring each unit is ready for immediate installation and reliable operation upon delivery—eliminating the risk of “dead on arrival” components.

Application Areas

The KC series motors are widely deployed across the following industries and equipment types:

• Construction Equipment: Mini-excavator travel drives

• Road Construction: Roller travel drives

• Crane Machinery: Mobile cranes

• Aerial Work Platforms: Scissor/boom lift travel drives

• Agricultural Machinery: Combine harvester travel drives

• Mining Equipment: Mining haul trucks

• Specialty Vehicles: Snowplows, road pavers

Expert Maintenance Tips

1. Hydraulic Fluid Cleanliness Management

The KC series utilizes swashplate piston designs with minimal clearances between pistons and cylinder bores, making them highly sensitive to fluid contamination. It is recommended to install precision filters with ≥10 μm filtration rating. Mineral-based anti-wear hydraulic oil (ISO VG 32, VG 46, or VG 68) is recommended, maintaining viscosity at 15–46 cSt. Optimal operating temperature should be maintained within 10–60°C.

2. Two-Position Variable Control Tuning

This series features hydraulic two-position variable (2-speed) control with displacement switching via control ports. During commissioning, verify that the switching control pressure is stable and response is rapid. Avoid frequent switching under load to prevent shock loads. The displacement ratio is 3.4:1—monitor system pressure fluctuations during high/low-speed transitions.

3. Pre-Start Checks

Before initial start-up or after extended shutdown, check that all connections are secure and oil level is adequate. It is recommended to rotate the shaft manually for several revolutions to ensure the motor is properly lubricated before starting.

4. Closed-Circuit Flush Valve Verification

This series is equipped with a built-in closed-circuit flush valve as standard, providing automatic system flushing and cooling in closed-loop applications. Verify that the flush valve operates correctly with appropriate flush flow during initial operation.

5. Periodic Inspection and Maintenance

Replace filters every 2,000–2,500 operating hours. Replace hydraulic oil every 5,000–8,000 operating hours (shorter intervals in dusty/extreme environments). Periodically inspect shaft seals and O-rings for condition, and listen for abnormal operating noise.

6. Coupling Alignment Requirements

Maintain shaft alignment within 0.05 mm concentricity and 0.5° angular deviation between the drive shaft and the load shaft. Excessive misalignment will lead to premature bearing wear and shaft seal leakage. The cartridge-style design enables direct mounting with planetary gearboxes, but ensure the mounting surface flatness requirements are met.