Danfoss SNW SNP Series Tandem Gear Pump | SNW2NN SNC1NN Hydraulic Pump

The SNP, SNW, and SNZ Series external gear pumps and tandem assemblies from Chengyuan Hydraulic are premium, modular power components fully compatible with Sauer-Danfoss (Danfoss Power Solutions) standards for mobile and industrial applications. Built with high-strength extruded aluminum bodies and a robust three-piece design, these pumps are engineered to withstand rigorous high-pressure impulses. For the complex tandem code SNW2NN011… + SNC1NN1.7…, we provide a precision-coupled dual-circuit solution: the front stage (SNW2NN) delivers an 11cc displacement for main system flow, while the rear stage (SNC1NN) provides a 1.7cc displacement for pilot or steering circuits. Every tandem pump undergoes 100% simulated dual-circuit full-load testing to ensure zero performance cross-interference, guaranteeing 100% original-place interchangeability.

Technical Specifications :

• Pump Configuration: Tandem High-Pressure Gear Pump (Dual Stage)

• Front Pump Model: SNW2NN011R302AC… (Group 2, 11.0 $cm^3/rev$)

• Rear Pump Model: SNC1NN1.7RN21DE… (Group 1, 1.7 $cm^3/rev$)

• Rated Operating Pressure: Front Stage: 250 bar (25 MPa) / Rear Stage: 230 bar (23 MPa)

• Peak Pressure: Up to 280 bar (28 MPa) intermittent spikes

• Maximum Rated Speed: 3000 – 3500 rpm (excellent high-speed capability)

• Direction of Rotation: R (Clockwise rotation)

• Shaft & Flange Specification: 302/21D standard splined or parallel shaft with SAE/Euro mounting flange

• Housing Material: Heavy-duty, fatigue-resistant extruded aluminum alloy

• Sealing Elements: Premium FKM (Viton) shaft seals for superior thermal and shear resistance

Key Technical Advantages:

• Multi-Stage Pressure-Balanced Side Plates: Independent floating thrust plates are integrated into both pump stages. Utilizing hydrostatic balance principles, they automatically minimize axial clearances, sustaining over 93% volumetric efficiency across both circuits regardless of load variations.

• High-Torque Internal Spline Coupling: The connecting shaft between the front and rear pumps utilizes a proprietary heat-treated spline sleeve. Its torsional strength exceeds standard limits by 30%, preventing coupling shearing during high-pressure startups or sudden system stalls.

• DU Bushings with Relief Groove Geometry: Equipped with heavy-duty DU composite bushings and precision-engineered fluid relief grooves. This design eliminates liquid trapping during gear meshing, drastically reducing mechanical vibration and hydraulic noise ripples.

• Seamless Drop-in OEM Replacement: Manufactured to micron-level dimensional tolerances. All mounting dimensions, shaft extensions, and port center-to-center distances line up perfectly with original Danfoss codes (such as SNZ234301852AS), allowing direct installation without reworking pipelines.

Application Areas:

• Compact Construction Machinery: Mini-excavators requiring a primary circuit for boom/bucket functions and a secondary circuit for pilot/steering.

• Agricultural Equipment: Utility tractors utilizing the tandem setup for rear hitch lifting and auxiliary steering circuits.

• Roadwork Vehicles: Vibratory system and travel steering assist for compact rollers and pavers.

• Material Handling: Main hydraulic power stack for warehouse forklifts and specialized aerial work platforms.

Expert Maintenance Tips:

• Dual Inlet Pre-Priming Rule: Tandem pumps have independent suction zones (even when sharing a single housing inlet). You must pre-fill both stages with clean hydraulic oil through the ports before initial start-up. Never spin the shaft with a dry rear chamber.

• Zero Axial Impact During Installation: Never use a hammer to force couplings or pulleys onto the pump drive shaft. Axial impact can distort or crush the internal thrust plates and thrust bearings within the aluminum housing.

• Rigid Multi-Circuit Filtration: Since the rear stage (1.7cc) supplies highly precise pilot components, ensure the return and pilot lines are equipped with high-efficiency filters to maintain oil cleanliness at ISO 19/17/14 (NAS Class 8) or better.