Double-Row Cylindrical Roller Bearings

**NSK Super Precision Bearings: Engineered for Unmatched Accuracy and Performance**

In the world of high-precision motion and control, NSK’s **Super Precision Bearings** stand as a benchmark for reliability, rigidity, and ultra-low friction performance. Among these, the **Super Precision Cylindrical Roller Bearings** and **Double Row Cylindrical Roller Bearings** are engineered to meet the most demanding applications—delivering exceptional rotational accuracy, high load capacity, and extended service life in industries where precision is non-negotiable.

### **Technical Excellence and Design Innovations**
NSK’s **Super Precision Cylindrical Roller Bearings** are designed with optimized roller profiles, precision-ground raceways, and advanced materials to minimize vibration, heat generation, and wear. These bearings feature:
– **Ultra-High Precision (P4, P2, or higher grades)** – Ensuring minimal runout and consistent performance in high-speed applications.
– **Enhanced Load Capacity** – Radial load handling is maximized through superior roller-to-raceway contact, making them ideal for heavy-duty machining and automation.
– **Low Friction & High-Speed Capability** – Special cage designs (e.g., brass or polymer cages) reduce friction, allowing for smoother operation at elevated speeds.

For applications requiring even greater rigidity and load distribution, NSK’s **Double Row Cylindrical Roller Bearings** provide:
– **Increased Radial Stiffness** – Two rows of rollers enhance stability, critical for machine tool spindles and high-precision gearboxes.
– **Optimized Internal Geometry** – Precision alignment minimizes deflection under heavy loads, maintaining accuracy in dynamic conditions.
– **Sealed or Open Configurations** – Options for grease lubrication or integrated sealing solutions extend maintenance intervals in harsh environments.

### **Performance Advantages for Critical Applications**
NSK’s super precision cylindrical roller bearings excel in environments where even micron-level deviations can impact performance. Key advantages include:
– **Extended Service Life** – Advanced heat treatment and surface finishing techniques reduce wear, ensuring longevity even under continuous high-load operation.
– **Reduced Noise & Vibration** – Critical for semiconductor manufacturing, medical imaging equipment, and high-end robotics.
– **Thermal Stability** – Engineered to maintain dimensional stability under thermal fluctuations, crucial for CNC machining and aerospace components.

### **Typical Applications Across Industries**
These bearings are indispensable in sectors demanding the highest levels of precision and durability:
– **Industrial Machinery** – Machine tool spindles, robotic arms, and printing presses rely on their rigidity and speed capabilities.
– **Automotive Systems** – High-performance transmissions, electric vehicle (EV) drivetrains, and turbochargers benefit from their low friction and high-load support.
– **Precision Equipment** – Medical imaging devices, optical alignment systems, and semiconductor wafer handling require the near-zero runout provided by NSK’s super precision designs.

By combining cutting-edge engineering with decades of expertise, NSK’s **Super Precision Cylindrical Roller Bearings** and **Double Row Cylindrical Roller Bearings** set the standard for motion control in the most demanding applications—ensuring efficiency, accuracy, and reliability where it matters most.

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Designations Nominal Dimensions Basic Load Ratings Speeds
Limiting Speeds
d
mm
D
mm
B
mm
r(min.)
mm
Cr
kN
C0r
kN
Grease
min-1
Oil (Oil-air)
min-1
NN3948MB
240
320
60
2.1
525
975
2400
2900
NN3956MB
280
380
75
2.1
695
1460
2000
2500
NN3940MBKR
200
280
60
2.1
480
815
3200
3800
NN3948MBKR
240
320
60
2.1
525
975
2400
2900
NN3956MBKR
280
380
75
2.1
695
1460
2000
2500
NN4940MB
200
280
80
2.1
655
1220
3200
3800
NN4948MB
240
320
80
2.1
720
1450
2400
2900
NN4956
280
380
100
2.1
960
2230
2000
2500
NN4940MBKR
200
280
80
2.1
655
1220
3200
3800
NN4948MBKR
240
320
80
2.1
720
1450
2400
2900
NN4956KR
280
380
100
2.1
960
2230
2000
2500
NNU4940MB
200
280
80
2.1
655
1220
3200
3800
NNU4948MB
240
320
80
2.1
720
1450
2400
2900
NNU4940MBKR
200
280
80
2.1
655
1220
3200
3800
NNU4948MBKR
240
320
80
2.1
720
1450
2400
2900
NN3040MB
200
310
82
2.1
750
1170
3000
3600
NN3048MB
240
360
92
3
980
1600
2200
2700
NN3040MBKR
200
310
82
2.1
750
1170
3000
3600
NN3048MBKR
240
360
92
3
980
1600
2200
2700
NN3944MB
220
300
60
2.1
505
895
2500
3100