Product Overview
The KF12RF1, KF16RF1, KF20RF1, and KF2.5, KF4, KF5, KF6, KF8, KF10 series gear pumps originate from Germany’s KRACHT KF Series helical transfer pump platform. KRACHT is a family-owned enterprise founded in 1911, headquartered in Werdohl, Germany, and a world-renowned specialist in fluid control. The KF Series is KRACHT’s classic medium-low pressure transfer pump product line, renowned for helical gearing, low pulsation, low noise, and modular design – widely used in wind power low-temperature lubrication, marine gearbox lubrication, compressor lubrication, and other long-term continuous operation heavy-duty applications.
This series features helical external gear pump construction with a modular standard design. Housing parts are manufactured from EN-GJL-250 (GG 25) grey cast iron, with gears made from high-strength case-hardened steel, hardened and mounted in special multi-material plain bearing bushes. All sizes are made with helical gearing, which, in combination with a special gearing geometry, results in extremely low noise levels and low-pressure pulsation.
Wind Power Low-Temperature Advantage: This series is designed for media temperatures as low as -40°C with excellent low-temperature start-up performance. Pressure pulsation is controlled within 1%, ensuring stable oil supply under low-temperature conditions.
Key Interchangeability Advantage: Our KF series gear pumps are manufactured to strict German KRACHT original design specifications, ensuring 100% direct interchangeability with original units. All mounting interfaces, flange dimensions, shaft configurations, and port positions are identical to the original product – no modifications required. Every pump undergoes 100% factory performance testing under simulated operating conditions (covering rated pressure, peak pressure, and full speed range performance curves), guaranteeing plug-and-play reliability with zero performance deviation.
Model Code Breakdown (based on KRACHT KF Series designation rules):
KF = Series: Helical Transfer Pump
2.5 / 4 / 5 / 6 / 8 / 10 / 12 / 16 / 20 = Nominal displacement (cm³/rev)
RF1 = Mounting type: Flange mounting (RF = flange type, 1 = standard shaft configuration)
D15 (optional suffix) = Integral relief valve, set pressure approx. 15 bar for overload protection
Technical Specifications
KF Series – General Specifications
Product Series: KRACHT KF Series Helical Transfer Pump
Brand: KRACHT (Germany)
Pump Type: Helical External Gear Pump
Displacement Range: 2.5 – 3150 cm³/rev
Maximum Operating Pressure: 25 bar
Peak Pressure: Up to 40 bar (instantaneous)
Media Temperature Range: -40°C to +200°C
Media Viscosity Range: 12 – 20,000 mm²/s
Inlet Pressure: -0.4 to +6 bar
Housing Material: Grey cast iron EN-GJL-250
Gear Material: High-strength case-hardened steel
Gear Type: Helical gear with special gearing geometry
Bearings: Multi-component plain bearings P10
Seals: NBR or FKM
Shaft Sealing: Single radial lip-type seal
Mounting: Flange mounting (RF1)
Direction of Rotation: Right-hand (clockwise) or Left-hand (counter-clockwise) optional
KF2.5 Series
KF4 Series
KF5 Series
KF6 Series
KF8 Series
KF10 Series
KF12 / KF12RF1
Displacement: 12.0 cm³/rev
Rated Pressure: 25 bar
Peak Pressure: 30 bar
Rated Flow (@1500 rpm): 18 L/min
Speed Range: 500 – 3600 r/min
Volumetric Efficiency: ≥ 95%
Weight: Approx. 4.2 kg (KF16 reference)
KF16 / KF16RF1
KF20 / KF20RF1
Key Technical Advantages
1. Helical Gear Design for Ultra-Low Noise and Low Pulsation
All KF Series sizes feature helical gearing combined with a special gear geometry, effectively reducing displacement fluctuation and pressure pulsation. Pressure pulsation is controlled within 1%, with operating noise as low as 67 dB(A) . This characteristic makes it particularly suitable for lubrication systems with strict noise and flow stability requirements – especially in wind turbine gearbox low-temperature lubrication applications with stringent noise demands.
2. High-Strength Materials and Composite Plain Bearings for Long Service Life
KF Series housings are manufactured from EN-GJL-250 (GG 25) grey cast iron, with gears made from high-strength case-hardened steel. Combined with multi-component plain bearings P10, the design delivers excellent wear resistance, rugged construction, and impact resistance. Gear surface hardness reaches HRC 58–62, ensuring high reliability during long-term continuous operation.
3. Wide Media and Temperature Adaptability – Optimized for Wind Power Low-Temperature Applications
The KF Series is suitable for pumping various liquids, with a media temperature range of -40°C to +200°C and broad viscosity adaptability (12 – 20,000 mm²/s). The -40°C low-temperature capability makes it the ideal choice for wind power low-temperature lubrication systems. Multiple seal options (NBR/FKM) are available to meet diverse media requirements.
4. Optional Integral Relief Valve (D15) for Integrated Overload Protection
The KF Series can be equipped with a Type D integral relief valve (D15/D25) with a set pressure of approximately 15 bar, providing overload protection for both pump and system. The valve is integrated into the pump body, eliminating external piping requirements and reducing leakage risks.
5. Modular Design and Flexible Configuration
The KF Series features a modular standard design, with displacement, flange, shaft end, rotation direction, and seal materials all customizable. Optional noise-optimized versions (for air-entrained media), ATEX explosion-proof versions, and outboard bearings for absorbing radial loads are available. Supports multiple pump combinations of the same or different sizes.
Application Areas
Wind Power: Wind turbine gearbox lubrication systems – this series is particularly suitable for low-temperature, long-term continuous operation
Marine Gearbox Lubrication: Lubricating oil supply for marine gearboxes
Compressor Lubrication: Compressor lubricating oil supply
Diesel Engines: Pre-lubrication and main lubrication
Filter Systems: Oil delivery and circulation
Fuel Delivery: Fuel supply systems
Industrial Lubrication Systems: Machine tool spindle lubrication, hydraulic power unit oil supply
Pulp and Paper: Lubrication and cooling systems
Mining and Metallurgy: Mining equipment lubrication systems
Expert Maintenance Tips
1. Model Confirmation and Selection
Complete KF series model should include: Series (KF) + Displacement Code (2.5–20) + Mounting Configuration (RF1) + Optional Suffix (D15 with valve) .
RF1 indicates flange mounting with standard shaft configuration. D15 indicates integral relief valve with set pressure approx. 15 bar.
The KF Series is for low-pressure transfer (25 bar) – for high-pressure applications (up to 300 bar), select the KRACHT KP Series.
Verify media temperature during selection: Standard NBR seals are suitable for -20°C to +90°C; for -40°C low-temperature applications (wind power), special low-temperature seal configurations are required.
2. Pre-Installation Checks
KF Series pumps have a fixed rotation direction (R = right-hand/clockwise, L = left-hand/counter-clockwise) – verify matches system drive direction before installation.
Confirm mounting flange type (RF1 square flange mounting) precisely matches system interface.
Inlet pressure must be maintained within -0.4 to +6 bar (speed-dependent).
Never use hammer-driven installation – always use proper tools.
3. First Start-Up & Media Priming
Prime the pump housing with clean media before first start-up; ensure suction line is fully filled – never run dry.
Maintain media temperature within -40°C to +200°C.
Speed range: 200 – 3600 r/min.
Media viscosity should be maintained within 12 – 20,000 mm²/s.
4. Integral Relief Valve Usage Notes
5. Operating Monitoring
Continuous operating pressure must not exceed 25 bar; peak pressure must not exceed 40 bar.
The KF Series is known for low noise and low pulsation – if abnormal noise or pressure fluctuation occurs, first check suction lines for leakage or blockage.
Regularly check torque on pump and piping connection bolts to prevent loosening from vibration.
