Danfoss Series 51 Motor Replacement | 51D080 51D060 51D110 Bent Axis Pump

Genlu Hydraulic proudly introduces our comprehensive range of Series 51 (including 51D, 51V, and 51C families) high-performance bent-axis variable displacement axial piston hydraulic motors. This premier line is engineered in strict accordance with the leading engineering standards of Danfoss (formerly Sauer-Danfoss) hydrostatic technology, specifically optimized for high-efficiency, heavy-duty, high-speed power delivery in both open and closed-loop hydraulic drivetrains. Our advanced production lineup delivers seamless drop-in replacements for industry-standard frame sizes: 51D060 (60cc), 51D080 (80cc), 51D110 (110cc), and seamlessly covers complex, highly specified model alphanumeric strings such as 51D080RD2NHSA2CEE1NNN032AAF31230. Serving as the primary traction core for tracked chassis propulsion, asphalt milling wheels, and rotary drilling rig powerheads, Genlu unequivocally guarantees 100% Drop-in Interchangeability in mechanical mounting configurations (standard SAE cartridge or flange options), input shaft spline configurations, primary fluid port dimensions, and the dynamic response characteristics of the internal variable valve manifolds relative to original Danfoss units. Backed by our uncompromising 100% Simulation Load Testing, each bent-axis motor is verified under intense continuous workloads to certify exceptional volumetric performance, displacement switching, and torque scaling under severe slope climbing conditions.

Technical Specifications 

• Product Series: Danfoss Series 51 Bent-Axis Variable Displacement Piston Motor (51D Cartridge / 51V Standard Flange)

• Target Configuration Codes: 51D080RD2NHSA2CEE1NNN032AAF31230, 51D060, 51D110

• Frame Displacement Continuum: 060 (60 cm³/rev) ；080 (80 cm³/rev) ；110 (110 cm³/rev)

• Maximum Displacement Limit: 80 cm³/rev (For the 080 specification, providing stepless scaling down to 0cc)

• Rated Continuous Operating Pressure: 42 MPa (420 bar)

• Peak Dynamic Shock Pressure: 48 MPa (480 bar)

• Maximum Allowed Speed Rating: 4200 rpm – 5200 rpm (Attained via low-inertia bent-axis geometry)

• Control Mechanism Classification (RD2): Two-point hydraulic displacement control (Featuring dual-line internal pilot routing)

• Maximum Swivel Sweep Angle: 45-degree technical high-efficiency large angle displacement geometry

Key Technical Advantages:

• High-Power-Density 45° Bent-Axis Architecture: Features a 45-degree angled design matching spherical piston heads to a synchronized cylinder block. Compared to traditional swashplate configurations, the bent-axis layout drastically reduces moving component centrifugal forces and optimizes contact stress, enabling high speed thresholds and robust shock tolerance.

• Integrated Stepless Variable Control Manifold: The internal housing incorporates highly precise control spool matrices (Control Valve Matrix) capable of modulating cylinder tilt angles within milliseconds in response to pilot or electronic signals. This delivers seamless shifting between high-torque low-speed mode and high-speed low-torque mode, maximizing machine velocity control.

• Bimetallic Vacuum-Sintered Spherical Valve Interface: The core interface utilizes a spherical valve plate profile. Manufactured using advanced vacuum bimetallic fusion, this structure maintains an ideal self-lubricating fluid film under high pressure variations, ensuring overall volumetric efficiency remains above 96% under a continuous 42 MPa load.

• Heavy-Duty Piston Ring Arrays & Rigid Bearings: Piston assemblies are fitted with hardened wear-resistant rings, which are paired with a single-piece forged drive shaft and heavy-duty tapered roller bearings. This structural rigidity effortlessly absorbs massive axial and radial shock forces caused by track shudder or tool impacts.

Application Areas:

• Road Construction & Paving Machinery: Primary ground-drive propulsion units for asphalt pavers and heavy-duty milling drum drives on road cold planers.

• Heavy Construction & Foundation Drilling Equipment: High-load auxiliary winches on rotary drilling rigs and main winch mechanisms for crawler cranes.

• Heavy Forestry & Mining Fleets: Tracked wheel drive packs for high-production tree harvesters and closed-loop hydrostatic propulsion networks for underground mining scoop trams.

Expert Maintenance Tips:

• Perform Rigorous Case Priming and Air Purging Prior to Ignition: Due to the asymmetric layout inside a bent-axis housing, operators must fully flood the motor cavity with clean hydraulic oil through the highest case drain port before initial commissioning. Manually jog the output shaft several rotations to clear air bubbles and coat the spherical piston shoes. Never start the unit dry (Dry Run), as this will gall the bimetallic interfaces within seconds.

• Strictly Restrict Casing Internal Backpressure: The internal displacement servo linkage and shaft dual-lip seals are highly vulnerable to internal casing pressure spikes. The case drain line must run directly back to the reservoir, completely bypassing any filters or shared return headers, stabilizing case backpressure below 0.5 MPa. Excessive backpressure disrupts stroke control scaling and blows out the shaft lip seal.

• Do Not Alter Factory Displacement Limit Adjustments: Series 51 motors are equipped with precision mechanical set screws designed to calibrate the absolute minimum and maximum displacement limits. Field technicians must never alter or loosen these set screws without proper test bench instrumentation; improper adjustments can lead to hazardous motor over-speeding failures or a complete loss of torque.