KC45DNERNFF11SNNAFF18NNNNNN Danfoss Hydraulic Motor 45cc 400 bar

Product Overview

The KC45DNERNFF11SNNAFF18NNNNNN is a compact two-position variable axial piston motor built on the Danfoss/Sauer Danfoss L/K Frame platform, in the KC45 displacement size (45 cm³/rev). The “D” in “KC45D” designates a two-position variable design, enabling hydraulic pilot-controlled switching between full and minimum displacement for dual-mode torque-priority or speed-priority operation.

The KC45DNERNFF11SNNAFF18NNNNNN carries part number 4254805 and belongs to the Danfoss K Frame variable motor series. The motor features a compact cartridge mount design for direct installation into planetary gearboxes, making it ideal for wheel drive applications. Core design features include a nine-piston rotating assembly, a maximum 18° swash plate angle, and a 3.4:1 maximum-to-minimum displacement ratio.

The model code KC45DNERNFF11SNNAFF18NNNNNN follows the Danfoss standard coding system: KC designates the K Frame compact variable motor series, 45 is the displacement size (45 cm³/rev), D is the design code (two-position variable), N indicates the control method (hydraulic pilot control), E is the mounting flange code, R is the rotation direction, N is the shaft type, FF11 is the port configuration code (SAE O-ring ports, size FF11), SNNA is the seal material and special option code, FF18 is a second port configuration code, and NNNNNN is the standard tail code.

Engineered as a form-fit-function replacement for original Danfoss/Sauer Danfoss KC45D series motors, this model maintains identical mounting flange dimensions, shaft specifications, 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: KC45DNERNFF11SNNAFF18NNNNNN

• Part Number: 4254805

• Series: Danfoss/Sauer Danfoss L/K Frame Variable Motor

• Motor Type: Two-position variable axial piston motor

• Design Feature: Swash plate configuration, nine-piston rotating assembly, max 18° swash plate angle, 3.4:1 displacement ratio

• Maximum Displacement: 45 cm³/rev (2.75 in³/rev)

• Minimum Displacement: Approx. 13.2 cm³/rev (3.4:1 displacement ratio)

• Rated Working Pressure: 350 bar (continuous)

• Maximum Working Pressure: 400 bar (intermittent peak)

• Maximum Output Torque: 150 N·m (at maximum working pressure)

• Rated Maximum Speed: 3,500 rpm (at max displacement)

• Maximum Speed: 4,000 rpm (at min displacement)

• Control Method: Hydraulic pilot-controlled two-position switching, spring-biased to maximum displacement

• Displacement Switching: Hydraulically shifted to minimum displacement; min/max displacement settable via internal fixed stops

• Mounting: SAE B cartridge-style flange (planetary gearbox compatible)

• Shaft Type: 15-tooth spline / standard straight key (optional)

• Port Connections: SAE O-ring ports (multiple standard sizes: FF06/07/08/09/11)

• Rotation: Bi-directional

• Seal Material: NBR standard; Viton optional

• Housing Material: Cast iron

• Weight (approx.): 15 kg (motor body)

• Built-in Feature: Standard closed-circuit flush valve

• Optional Features: Speed sensor, multiple SAE port sizes

Key Technical Advantages

1. Two-Position Variable Design with Dual-Mode Drive Capability

The KC45DNERNFF11SNNAFF18NNNNNN features a two-position variable design, switching between full and minimum displacement via hydraulic pilot control. At full displacement, the motor delivers a maximum torque of 150 N·m for heavy-load starting, climbing, and precise positioning; switching to minimum displacement increases speed approximately 3.4 times at the same flow rate for no-load fast travel. The spring-biased design automatically returns the motor to maximum displacement under loss of pilot pressure, ensuring system safety. Maximum and minimum displacements are precisely settable via internal fixed stops for customized machine requirements.

2. Nine-Piston Rotating Assembly with Low Flow Pulsation

The motor employs a nine-piston rotating assembly with a maximum 18° swash plate angle, achieving extremely low flow pulsation and excellent volumetric efficiency. The nine-piston layout provides more discharge strokes per rotation cycle compared to conventional seven-piston or five-piston designs, significantly reducing output flow fluctuation and enabling smoother operation at low speeds. This design characteristic offers significant advantages in applications requiring high smoothness, such as road roller vibratory drives and skid steer loader travel drives.

3. Compact Cartridge Design with Direct Planetary Gearbox Integration

The KC45DNERNFF11SNNAFF18NNNNNN features a compact cartridge mount design for direct installation into planetary gearboxes, optimized for wheel drive applications. Three high-flatness mounting surfaces with easily accessible mounting holes simplify assembly. The one-piece gasket-free housing eliminates leakage risks associated with conventional multi-piece housings under high pressure, while heavy-duty tapered roller bearings accommodate combined radial and axial loads in wheel drive conditions. This design offers significant space advantages in wheel drive systems for compact equipment such as skid steer loaders and aerial work platforms.

4. Closed-Circuit Compatibility with System Integration Convenience

The motor features a standard built-in closed-circuit flush valve, enabling operation in both open and closed hydraulic systems without an external charge pump. An optional speed sensor supports closed-loop speed control for precision drive requirements. SAE O-ring ports are available in multiple standard sizes (FF06/07/08/09/11), adapting to different machine piping systems. The motor’s mounting dimensions, shaft interface, and port configuration are identical to original Danfoss KC45D series motors, enabling direct replacement and significantly reducing downtime and retrofit costs.

Application Areas

• Aerial Work Platforms: Wheel drive travel systems (one of the typical applications for the KC45)

• Road Rollers: Vibratory drive and travel drive systems

• Mini Excavators: Travel drive systems

• Mobile Cranes: Wheel drive systems

• Skid Steer Loaders: Wheel drive travel systems

• Agricultural Machinery: Specialty harvesters, sprayer drive systems

• Other Construction Machinery: Various mobile equipment requiring compact wheel drive solutions

Expert Maintenance Tips

1. Mounting Alignment Requirements: The motor features SAE B cartridge-style flange mounting. During installation, ensure the coaxiality deviation between the motor shaft and planetary gearbox input does not exceed 0.05 mm. When installing a splined shaft, ensure the spline mating surfaces are free of burrs and damage; when installing a straight keyed shaft, ensure key-to-keyway fit clearances conform to standard requirements.

2. Hydraulic Fluid Cleanliness Control: 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. Contaminant particles accelerate piston pair and swash plate surface wear, degrading volumetric efficiency.

3. Two-Position Switching Mechanism Maintenance: Periodically verify the two-position variable switching valve response pressure. Conduct switching tests every 500 operating hours using 3–5 MPa pilot pressure to ensure crisp, non-sticking actuation. If switching is sluggish, check pilot circuit pressure and valve spool wear. Internal displacement stop settings should not be adjusted arbitrarily.

4. Closed-Circuit Flushing Requirements: Although the motor features a built-in flush valve, periodic inspection of flushing flow is recommended when used in closed circuits. Inspect case drain leakage every 200 operating hours; normal leakage should remain below 5 L/min. A sudden increase indicates potential wear on the piston-to-bore clearance or the distribution plate.

5. 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.