Product Overview
The KC45DNERNFF07SNNA is a 45 cm³/rev displacement model from Sauer Danfoss’ KC series of axial piston two-position variable displacement motors, with manufacturer part number 4254809. The KC series is Danfoss’ high-pressure variable motor line developed specifically for wheel-drive and compact installation scenarios in mobile machinery, covering displacements from 20 cm³/rev to 45 cm³/rev across LC and KC frame configurations—ideal for wheel-drive systems and integration with planetary gearboxes.
The KC45 employs an axial piston two-position variable displacement architecture, spring-biased to maximum displacement and hydraulically shifted to minimum displacement. Both minimum and maximum displacement are set with fixed internal stops, offering a 3.4:1 displacement range with a minimum angle option down to 1° overcenter. The motor features three high-flatness mounting surfaces with easy-to-access mounting holes for quick assembly. This model is suitable for open-circuit hydraulic systems and serves as a replacement for Sauer Danfoss related models.
The model code breaks down as follows: KC identifies the KC frame series; 45 denotes the 45 cm³/rev displacement; D indicates the design generation; NERN is the control and regulator configuration code; FF07SNNA is the mounting flange, shaft and port configuration; FF18NNNNNN denotes additional options.
Every KC45DNERNFF07SNNA unit undergoes 100% simulated operating-condition bench testing prior to shipment. Mounting flange, shaft end and port dimensions comply with SAE standards and are identical to the original Sauer Danfoss KC45 series, ensuring true drop-in interchangeability with zero modification required.
Technical Specifications
KC/LC Series Frame Size Specifications:
LC25: Displacement 25 cm³/rev (1.50 in³/rev), max output torque ~85 N·m, max speed ~4000 rpm
LC30: Displacement 30 cm³/rev (1.83 in³/rev), max output torque ~100 N·m, max speed ~4000 rpm
KC38: Displacement 38 cm³/rev (2.32 in³/rev), max output torque ~126 N·m, max speed ~4000 rpm
KC45 (This Model): Displacement 45 cm³/rev (2.75 in³/rev), max output torque 150 N·m, rated max speed 3500 rpm, max displacement condition up to 4000 rpm
KC45DNERNFF07SNNA Additional Specifications:
Model Code: KC45DNERNFF07SNNA FF18NNNNNN
Manufacturer Part Number: 4254809
Type: Axial piston two-position variable displacement motor
Displacement: 45 cm³/rev (2.75 in³/rev), two-position variable (max/min)
Displacement Ratio: 3.4:1 (minimum angle down to 1° overcenter)
Maximum Working Pressure: 400 bar (5,800 psi)
Rated Working Pressure: 350 bar (5,076 psi)
Maximum Output Torque: 150 N·m (111 lb-ft)
Rated Maximum Speed: 3500 rpm
Maximum Speed at Max Displacement: 4000 rpm
Minimum Speed: 500 rpm
Variable Control: Spring-biased to maximum displacement, hydraulically shifted to minimum
Displacement Limitation: Fixed internal stops, min/max displacement settable
Servo Piston: Large diameter servo piston for smooth acceleration/deceleration
Mounting: SAE-B two-bolt flange / cartridge mount
Mounting Surfaces: Three high-flatness mounting surfaces
Rotation: Bidirectional (clockwise / counterclockwise)
Circuit Type: Open circuit
Optional Features: Closed-circuit flushing valve, speed sensor
Housing Material: Cast iron
Weight: ~15 kg (33 lbs) net, ~18 kg (40 lbs) packaged
Operating Temperature Range: -30°C to +90°C
Hydraulic Fluid: Mineral oil (ISO VG32/46)
Key Technical Advantages
1. Two-Position Variable Design for Dynamic Torque-Speed Matching
The KC45 employs a spring-biased two-position variable structure with a large diameter servo piston hydraulically shifted to minimum displacement, enabling online switching from low-speed high-torque to high-speed low-torque operation. At maximum displacement, the motor delivers 150 N·m maximum output torque for starting, climbing and precise positioning; at minimum displacement, speed increases to 4000 rpm for fast travel and transport. The large diameter servo piston allows relatively large circuit orificing for smooth acceleration/deceleration transitions without shift shock.
2. Wide Displacement Ratio and Overcenter Capability for Fine Speed Control
The KC45 offers a 3.4:1 wide displacement range with minimum angle settable to 1° overcenter, maintaining a small positive displacement output at the minimum displacement position. This provides significant advantages in travel drive applications requiring extremely low-speed fine control. Both minimum and maximum displacement are set via fixed internal stops, ensuring repeatability and long-term stability of displacement shifts.
3. Compact Three-Surface Mounting Design for Simplified Integration
The KC45 features a compact design with three high-flatness mounting surfaces and easily accessible mounting holes for quick assembly and maintenance. The SAE-B two-bolt flange or cartridge mounting configuration enables direct integration with planetary gearboxes for space-constrained wheel-end drive systems. The compact construction and short axial length further enhance installation flexibility and simplify hydraulic plumbing.
4. High Pressure Capability and Cast Iron Housing Reliability
The KC45 supports up to 400 bar working pressure, leading among compact variable motors. The cast iron housing provides excellent pressure resistance and wear resistance, ensuring long-term reliability under high-pressure, continuous-duty conditions. The nine-piston rotating group enhances volumetric efficiency and smooth operation.
5. 100% Simulated Load Testing & Drop-In Interchangeability
Each KC45DNERNFF07SNNA unit is bench-tested under simulated operating conditions prior to dispatch, covering pressure cycling, displacement response and thermal variation. Mounting flange, shaft end and port dimensions comply with SAE standards, matching the original Sauer Danfoss KC45 series exactly, enabling direct replacement without any interface modification.
Application Areas
The KC45 series is widely deployed in travel drive systems of mobile hydraulic equipment:
Road Rollers: vibratory roller wheel-end drives, integrated with planetary gearboxes
Aerial Work Platforms: self-propelled scissor lifts, boom lift drive systems
Excavators: wheeled excavator travel drives, auxiliary drive systems
Skid Steer Loaders: wheel-end drive systems
Agriculture: tractor front axles, combine harvester travel drives
Material Handling: forklift drive systems, telescopic handlers
Municipal Equipment: street sweepers, snow removal equipment drives
Expert Maintenance Tips
1. Displacement Shift Control and Pilot Pressure Management: The KC45’s displacement shift is controlled by a large diameter servo piston via hydraulic pilot pressure. The spring bias keeps the motor at maximum displacement by default; hydraulic pressure applied to the servo piston shifts to minimum displacement. After installation, verify pilot control pressure is within technical manual range and the pilot circuit is free of air. If shift response is sluggish or excessively harsh, inspect servo piston seals for aging and the pilot control spool for sticking. Shift operations should be performed at low speed or standstill to avoid impact loading on the rotating group.
2. Internal Stop Setting and Verification: The KC45’s minimum and maximum displacement are set by fixed internal stops. In applications requiring specific speed ranges, adjust stop positions per system requirements and verify displacement output matches the control system after adjustment. After stop adjustment, re-verify displacement shift response to confirm minimum and maximum displacement positions meet technical manual specifications.
3. Housing Priming Before First Startup: Before first startup, fill the motor housing with clean hydraulic oil (ISO VG32 or VG46 recommended) through the drain port. An unprimed housing causes dry friction at startup, severely damaging the piston group and swashplate mechanism. After extended shutdown, fill the housing again before restarting. 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.
4. Oil Cleanliness and Temperature Control: Maintain system oil cleanliness at ISO 4406 18/16/13 or better. Operating oil temperature should be kept below 80°C—system temperature must not exceed 90°C at any point. VG 46 is recommended at 60°C operating temperature. Replace hydraulic oil and filter after the first 500 hours, then follow a 2,000-hour or annual replacement cycle.
5. Periodic Piston Group and Servo Mechanism Inspection: The KC45’s piston slippers, swashplate bearings and servo piston are primary wear components. Inspect piston slipper wear, swashplate working surface condition and servo piston seal integrity every 2,000 hours. Abnormal efficiency loss, displacement shift anomalies, noise or vibration requires immediate shutdown and service. Use Sauer Danfoss original specification parts when replacing piston groups or servo seals.
