Product Overview
The KC45DNFRNFF00SNNAFF18NNNNNN and KC38CNARNFF07SNNAFF18NNNNNN are 45 cm³/rev and 38 cm³/rev displacement models from Sauer Danfoss’ KC series of axial piston two-position variable displacement motors, a high-pressure variable motor line developed specifically for wheel-drive systems in light construction machinery including aerial work platforms, road rollers and compact excavators.
The KC series employs an axial piston two-position variable structure with a 9-piston rotating group and 18° maximum swashplate angle, enabling on-line switching between maximum and minimum displacement, combining low-speed high-torque and high-speed cruising capabilities. The KC45 delivers 45 cm³/rev displacement, 400 bar maximum working pressure, 150 N·m maximum output torque, 3500 rpm rated maximum speed and up to 4000 rpm at maximum displacement. The KC38 supports 350 bar continuous working pressure with 400 bar intermittent peak pressure and 3600 rpm rated maximum speed. The KC series features SAE-B two-bolt mounting flange as standard, compatible with direct planetary gearbox installation, with optional cartridge configuration available—an ideal choice for wheel-drive systems.
The model code breaks down as follows: KC45 identifies the KC series 45 cm³/rev frame size; D indicates design generation; NFRNFF00SNNAFF18NNNNNN is the complete control, mounting and option code combination including control type, rotation direction, mounting flange, shaft configuration and port specification. KC38 identifies the KC series 38 cm³/rev frame size; CNARNFF07SNNAFF18NNNNNN is the corresponding control, mounting and option code combination.
Every KC45DNFRNFF00SNNAFF18NNNNNN and KC38CNARNFF07SNNAFF18NNNNNN unit undergoes 100% simulated operating-condition bench testing prior to shipment, covering pressure cycling, displacement response and control signal calibration. Mounting flange, shaft end and port dimensions comply with SAE standards and are identical to the original Sauer Danfoss KC45/KC38 series, ensuring true drop-in interchangeability with zero modification required.
Technical Specifications
KC Series Frame Size Specifications:
KC38: Displacement 38 cm³/rev (2.32 in³/rev), max working pressure 350 bar (5,075 psi), intermittent peak pressure 400 bar, theoretical torque 0.60 N·m/bar (366 lbf·in/1000 psi), rated max speed 3600 rpm, max output torque 127 N·m
KC45: Displacement 45 cm³/rev (2.75 in³/rev), max working pressure 300–400 bar (depending on configuration), intermittent peak pressure 400 bar, theoretical torque 0.72 N·m/bar (439 lbf·in/1000 psi), rated max speed 3500 rpm, max output torque 150 N·m
KC Series Common Specifications:
Type: Inline, axial piston, two-speed variable motor
Number of Pistons: 9
Maximum Swashplate Angle: 18°
Displacement Range: 3.4:1 (minimum angle option to 1° overcenter)
Control Type: Single or dual line hydraulic control, spring-biased to maximum displacement, hydraulically shifted to minimum
Displacement Limiter: Fixed maximum and minimum displacement limiters available
Mounting Flange: SAE-B two-bolt flange / cartridge mounting
Mounting Surfaces: Three clean sides with superior clearance and access to mounting bolts
Output Shaft Options: 13 or 15 tooth 16/32 pitch spline, 0.875 inch straight keyed, 1:8 taper
Port Connections: SAE O-ring boss ports, axial or twin radial
Optional Features: Speed sensor, loop flushing valve
Circuit Type: Open circuit / closed circuit compatible
Fluid Cleanliness Requirement: ISO 4406-1999 class 22/18/13 or better
Recommended Filtration: β10 = 1.5 to 2.0
Housing Material: Cast iron
Weight: ~15 kg (KC45), packaged gross weight ~18 kg
Operating Temperature Range: -25°C to +90°C (cold start capability to -25°C)
Original Design: Sauer Danfoss, Denmark/USA
Key Technical Advantages
1. Two-Position Variable Design for Dynamic Torque-Speed Matching
The KC45 and KC38 employ a spring-biased two-position variable structure, hydraulically shifted to minimum displacement via pilot signal, enabling on-line switching from low-speed high-torque to high-speed low-torque operation. At maximum displacement, the KC45 delivers 150 N·m maximum output torque and the KC38 delivers 127 N·m, suitable for starting, climbing and precise positioning; at minimum displacement, speed increases to 3500–4000 rpm for fast travel and transport. The 3.4:1 displacement range with minimum angle option to 1° overcenter ensures repeatability and long-term stability of displacement shifts.
2. 9-Piston Rotating Group for High Volumetric Efficiency and Low Flow Pulsation
The KC series employs a 9-piston rotating group with 18° maximum swashplate angle, achieving high volumetric efficiency, consistent torque delivery and low flow pulsation. A hydrodynamic oil film forms between pistons and swashplate, minimizing friction losses and maintaining high mechanical and volumetric efficiency across the full speed and pressure range. The cast iron housing provides excellent pressure resistance and wear resistance for long-term reliability under high-pressure, continuous-duty conditions.
3. Compact Three-Surface Mounting Design for Direct Gearbox Integration
The KC series 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 and cartridge mounting configuration enable direct integration with planetary gearboxes for space-constrained wheel-drive systems. This makes the KC series an ideal choice for wheel-drive applications in aerial work platforms and road rollers, achieving efficient transmission without additional reduction gearing or bearing support.
4. Wide Fluid Compatibility and Optional Monitoring Features
KC series motors are suitable for open and closed hydraulic systems, operating without an external charge pump. Optional speed sensors and loop flushing valves meet system monitoring and protection requirements. System filtration requirements are ISO 4406-1999 class 22/18/13 or better with recommended filter β10 ratio of 1.5 to 2.0. Cold start capability extends to -25°C, ensuring reliable operation in cold environments.
5. 100% Simulated Load Testing & Drop-In Interchangeability
Each KC45DNFRNFF00SNNAFF18NNNNNN and KC38CNARNFF07SNNAFF18NNNNNN unit is bench-tested under simulated operating conditions prior to dispatch, covering pressure cycling, displacement response, control signal calibration and thermal variation. Mounting flange, shaft end and port dimensions comply with SAE standards, matching the original Sauer Danfoss KC45/KC38 series exactly, enabling direct replacement without any interface modification. The product is fully interchangeable with POCLAIN KC series hydraulic motors on performance and dimensions.
Application Areas
The KC series is widely deployed in travel drive systems of light construction machinery:
Aerial Work Platforms: self-propelled scissor lifts, boom lift drive systems (core application for this model)
Road Rollers: compact vibratory roller wheel drives
Compact Excavators: mini excavator travel drive systems
Mobile Cranes: compact mobile crane drive systems
Agriculture: tractor hydraulic systems, compact harvester drives
Municipal Equipment: street sweeper drives, snow removal equipment
Material Handling: compact forklift drive systems
Expert Maintenance Tips
1. Displacement Shift Control and Pilot Pressure Management: KC series motors are controlled by 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. Housing Priming Before First Startup: Before first startup, fill the motor housing with clean hydraulic oil 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.
3. Fluid Cleanliness and Filtration System Maintenance: Maintain system fluid cleanliness at ISO 4406-1999 class 22/18/13 or better. Filters with β10 ratio of 1.5 to 2.0 are recommended. For open-circuit systems supplied from a common reservoir, filtration requirements may be considerably higher. Replace hydraulic oil and filter after the first 500 hours, then follow a 2,000-hour or annual replacement cycle. Operating oil temperature should be kept below 80°C—system temperature must not exceed 90°C at any point.
4. Cold Start Precautions: KC series motors have -25°C cold start capability, but run at low speed for warm-up before applying load during low-temperature startup. Use hydraulic fluid with appropriate low-temperature performance to ensure viscosity remains within permissible range during startup. Avoid applying full load directly at low temperatures to reduce initial wear on piston groups and swashplate mechanisms.
5. Periodic Piston Group and Swashplate Inspection: The KC series’ piston slippers, swashplate working surface 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.
