90K055NCON8NOS1WOONNNO000E6 Sauer Danfoss Motor 55cc 420bar

Product Overview

The 90K055NCON8NOS1WOONNNO000E6, 90K075, and 90K100 are Sauer Danfoss (now Danfoss Power Solutions) Series 90 K-frame axial piston variable motors with displacements of 55 cm³/rev, 75 cm³/rev, and 100 cm³/rev respectively. The Series 90 platform has been a proven industry standard for over thirty years, employing a parallel axial piston/slipper design with a tiltable cradle swashplate, purpose-built for closed-circuit hydrostatic transmissions in mobile machinery travel and swing drive systems.

Series 90 motors use the same parallel axial piston/slipper design concept as the pumps in the series, with either fixed or variable swashplate. Variable motors achieve bidirectional rotation, with output shaft direction reversal accomplished through pump outlet flow direction changes. The motors can be equipped with loop flushing valves for circulating, cooling, and filtering the hydraulic fluid in closed circuits. Series 90 motors are available in both SAE standard flange mount and cartridge mount configurations.

The model code 90K055NCON8NOS1WOONNNO000E6 contains comprehensive configuration information: 90K for Series 90 motor; 055 for 55 cm³/rev displacement; NC for electrohydraulic 2-position control, enabling motor displacement switching between two set values via electrical control signal; ON8 for coil voltage and connector options; NOS1 for shaft and port configuration; WOONNNO000E6 for other mounting and configuration codes.

Manufactured to exact Danfoss OEM specifications, all mounting dimensions, flange interfaces, and port layouts are fully consistent with the original motor for true drop-in interchangeability. Every unit undergoes 100% simulated operating condition testing before shipment.

Technical Specifications 

Series 90 K-Frame Motor Common Specifications:

• Series: Sauer Danfoss Series 90

• Motor Type: Axial piston variable motor, parallel axial piston/slipper design, tiltable cradle swashplate

• Circuit Type: Closed-circuit only

• Rated Working Pressure: 420 bar (6,000 psi)

• Peak Pressure: 480 bar (7,000 psi)

• Minimum Speed: 500 rpm

• Mounting: SAE standard flange / cartridge mount

• Rotation Direction: Right-hand or left-hand (specified at order)

• Fluid Viscosity Range: Minimum 7 cSt, continuous 12–80 cSt, maximum 1,600 cSt

• Recommended Filtration: β10 ≥ 10

• Main Port Standard: SAE J518 Code 62 4-bolt split flange

• Shaft Options: Splined and tapered shafts available

• Housing Material: High-strength cast iron

• Control Options: PT (hydraulic 2-position) / NA, NB, NC, ND (electrohydraulic 2-position)

90K055 (55 cm³/rev):

• Model: 90K055NCON8NOS1WOONNNO000E6

• Displacement: 55 cm³/rev (3.36 in³/rev)

• Rated Speed: 3,900 rpm

• Maximum Speed: 4,250 rpm

• Theoretical Flow at 3900 rpm: 215 L/min (57 US gal/min)

• Theoretical Torque: 0.88 N·m/bar (530 lbf·in/1000 psi)

• Weight: Approx. 33–35 kg (varies by control configuration)

• Control Type: NC — Electrohydraulic 2-position control

• Mounting Flange: SAE-C flange (ISO 3019-1 127-4)

• Main Port Size: 25.4 mm (1.0 in)

• Case Drain Port: 1.0625-12 UNF

90K075 (75 cm³/rev):

• Model: 90K075

• Displacement: 75 cm³/rev (4.57 in³/rev)

• Rated Speed: 3,600 rpm

• Maximum Speed: 3,950 rpm

• Theoretical Flow at 3600 rpm: 270 L/min (71 US gal/min)

• Theoretical Torque: 1.19 N·m/bar (730 lbf·in/1000 psi)

• Weight: Approx. 33 kg

• Mounting Flange: SAE-C flange (ISO 3019-1 127-4)

• Main Port Size: 25.4 mm (1.0 in)

• Case Drain Port: 1.0625-12 UNF

90K100 (100 cm³/rev):

• Model: 90K100

• Displacement: 100 cm³/rev (6.10 in³/rev)

• Rated Speed: 3,300 rpm

• Maximum Speed: 3,650 rpm

• Theoretical Flow at 3300 rpm: 330 L/min (87 US gal/min)

• Theoretical Torque: 1.59 N·m/bar (970 lbf·in/1000 psi)

• Weight: Approx. 68 kg

• Mounting Flange: SAE-C flange (ISO 3019-1 127-4)

• Main Port Size: 25.4 mm (1.0 in)

• Case Drain Port: 1.0625-12 UNF

Key Technical Advantages

1. Electrohydraulic 2-Position Control for Flexible Displacement Switching (90K055NCON): The NC control type is the defining technical feature of this model. Electrohydraulic 2-position control uses a 12 VDC or 24 VDC solenoid valve to direct pilot oil, driving the motor’s dual-acting servo piston to shift the swashplate between two preset angles, achieving rapid displacement changes between two set values. In travel drive applications, the large displacement is used for low-speed high-torque conditions, while the small displacement is selected for high-speed low-torque conditions, achieving flexible speed-torque matching and improving machine operating efficiency.

2. Parallel Axial Piston/Slipper Design with High Power Density: Series 90 K-frame motors employ a parallel axial piston/slipper design with a tiltable cradle swashplate, effectively reducing lateral piston forces and minimizing eccentric wear between cylinder block and pistons. The compact design weighs only approximately 33–35 kg at 55 cm³/rev, delivering industry-leading power density in its class. This design maintains high volumetric and mechanical efficiency at 420 bar rated pressure, with volumetric efficiency exceeding 94%.

3. Closed-Circuit Dedicated Design with Loop Flushing Function: Series 90 motors are purpose-built for closed-circuit hydrostatic transmissions, operating with Series 90 variable pumps to form complete hydrostatic drive systems. The motors can be equipped with loop flushing valves that direct a portion of hot oil from the closed loop to the case drain circuit for external cooling and filtration before returning to the system, effectively controlling loop oil temperature and maintaining fluid cleanliness. This function is particularly important in continuously heavy-duty mobile machinery.

4. SAE Standard Flange and Cartridge Mount Flexibility: Series 90 motors are available in both SAE standard flange mount and cartridge mount configurations, adapting to different machine mounting interface requirements. Standard flange mounting suits most travel and swing drive applications, while cartridge mounting suits space-constrained integrated drive systems. The compact design enables flexible integration into various mobile machinery drive axles and gearboxes.

5. Series 90 Platform Drop-In Interchangeability with Complete Series Coverage: Series 90 motors cover displacements from 42 to 250 cm³/rev, with high consistency in mounting flanges, shaft ends, and ports across sizes within the series. The 90K055, 90K075, and 90K100 mounting dimensions are fully consistent with same-specification original motors, enabling drop-in replacement without piping or coupling modification. The series also supports PLUS+1™ compliant controls and sensors for integration into modern electro-hydraulic systems.

Application Areas

• Construction Machinery: Excavator travel and swing drives, bulldozer travel drives, crawler crane travel drives

• Mining Equipment: Mining truck travel drives, underground drilling rig drives, mine haul vehicle hydraulic drives

• Agricultural Machinery: Combine harvester travel drives, high-horsepower tractor hydraulic drive systems

• Material Handling: Telehandlers, rough terrain forklift drive systems

• Municipal Vehicles: Street sweepers, refuse compactors hydraulic drive systems

• Forestry Equipment: Timber harvesters, forwarders travel hydraulic systems

• Specialty Vehicles: Various mobile machinery requiring closed-circuit hydrostatic transmissions

Expert Maintenance Tips

1. Shaft Alignment and Flange Connection: Concentricity deviation between the motor and drive shaft or gearbox must be less than 0.05 mm, with angular deviation less than 0.25°. Series 90 motors use SAE standard flange mounting (ISO 3019-1 127-4). Tighten flange bolts in diagonal sequence for even loading. For cartridge mount installation, ensure the mounting bore machining accuracy meets requirements and the O-ring seals are properly seated.

2. Initial Start-Up Filling and Bleeding: Pre-fill the motor with clean ISO VG46 anti-wear hydraulic oil through the case drain port before installation. Start the system at the lowest speed and observe a steady oil flow from the case drain port free of bubbles. The NC electrohydraulic controlled motor typically remains at maximum displacement without a control signal, with a steady leakage flow from the case drain port. Once bleeding is complete, gradually increase to working pressure.

3. NC Electrohydraulic Control Electrical Connection Check (90K055NCON): Verify that the solenoid coil voltage (12 VDC or 24 VDC) matches the machine electrical system and that coil connections are correctly polarized. During commissioning, use a current meter to monitor control signals and confirm proper displacement switching response. Inspect connector seals for integrity to prevent moisture and dust ingress.

4. Loop Flushing Valve Function Verification: If the motor is equipped with a loop flushing valve, check that the flushing circuit operates properly after initial start-up. Flushing flow should meet system cooling requirements, and flushing valve settings should comply with system design specifications. A blocked flushing circuit will cause closed-loop oil temperature rise, accelerating fluid degradation and seal aging.

5. Fluid Cleanliness and Viscosity Management: Use ISO VG46 anti-wear hydraulic oil with a viscosity range of minimum 7 cSt, continuous 12–80 cSt, and maximum 1,600 cSt. System filtration should achieve β10 ≥ 10. Replace filter elements after the first 500 operating hours, then every 1,000 hours or annually thereafter. Closed-circuit systems require high fluid cleanliness — regularly monitor fluid particulate contamination.

6. Case Drain Line Configuration: The case drain line must return directly to the reservoir with backpressure not exceeding 2 bar. The drain line inner diameter must be sufficient to ensure unobstructed drainage during cold-start high-viscosity conditions.