NJ2308EM Cylindrical Roller Bearing Axial Load For Industrial Motor / Automotive System
NJ2308EM Cylindrical Roller Bearing For Industrial Motors & Automotive Systems
The NJ2308EM cylindrical roller bearing is renowned for its precise design, durability, and high performance, suitable for various modern industrial applications. This bearing features excellent design characteristics, performance capabilities, quality materials, and reliable operation for improving mechanical efficiency and reliability.
Design and Structure
Inner Ring and Outer Ring
The inner ring is precision-machined with an almost mirror-like surface, perfectly fitting a shaft with a diameter of 40mm to ensure smooth power transmission and reduce slippage risk. The outer ring focuses on sturdiness, capable of withstanding large radial loads, with an outer diameter of 90mm and width of 33mm, achieving high load-bearing capacity in limited space.
The inner ring has double ribs on one side, while the outer ring has no ribs. This unique design enables it to bear both large radial loads and a certain amount of unidirectional axial load. The double ribs on the inner ring effectively guide the cylindrical rollers, ensuring correct positioning and rotation under complex dynamic loads for stable bearing operation.
Rolling Elements and Cage
The core components are a row of refined cylindrical rollers made of high-grade bearing steel, processed through strict craftsmanship with surface roughness less than Ra0.1μm, which greatly reduces rolling friction and improves energy efficiency and operational stability. The cylindrical shape, combined with precisely designed raceways, distributes loads evenly through line contact, enhancing radial load-bearing capacity.
The cage is typically made of brass (CuZn37), providing excellent thermal conductivity and mechanical strength. During medium and high-speed operation, it effectively dissipates heat to prevent overheating while maintaining proper roller spacing to avoid interference and collision during rotation, guiding rollers along raceways to improve overall performance and reliability.
Sealing Structure (Optional)
Some models feature optional sealing devices for different environments. In dusty or humid conditions, nitrile rubber contact seals closely fit the inner ring to block contaminants and extend service life. For high-speed scenarios, non-contact labyrinth seals are suitable, allowing rotational speeds up to 6000rpm while reducing friction and providing protection.
Key Parameters
| Parameter |
Value |
| Inner Diameter (d) |
40mm |
| Outer Diameter (D) |
90mm |
| Width (B) |
33mm |
| Basic Dynamic Load Rating (Cr) |
70.5kN |
| Basic Static Load Rating (Cor) |
65.5kN |
| Limiting Speed (Grease Lubrication) |
4500rpm |
| Limiting Speed (Oil Lubrication) |
6000rpm |
Performance Advantages
High Radial Load-Carrying Capacity
The single-row cylindrical roller design and optimized contact geometry provide a basic dynamic load rating of 70.5kN and static load rating of 65.5kN, easily handling large radial loads in various industrial applications. Suitable for motors in large conveying systems and gearboxes of medium and heavy machinery, with minimal fatigue failure risk during prolonged load bearing.
Axial Load Adaptability
The double ribs on one side of the inner ring enable it to bear a certain amount of unidirectional axial load. In scenarios with axial forces (such as motors and specific industrial machinery), it reduces stress concentration on shafts and other components, extending equipment service life and improving reliability.
Low Friction and High-Speed Performance
Precision-ground rollers and smooth cages result in a friction coefficient as low as 0.002, reducing energy consumption and enabling high-speed operation. The limiting speed under grease lubrication is 4500rpm, and under oil lubrication reaches 6000rpm, suitable for equipment requiring high speed and low friction, such as machine tool spindles and high-speed fans.
Good Wear Resistance
The rings and rollers are made of high-carbon chromium bearing steel (GCr15), with hardness of HRC60-65 after heat treatment. The surface is specially treated to enhance wear resistance, maintaining performance in high-load, high-speed, and abrasive environments.
Material Quality
Material of Rings and Rollers
High-purity bearing steel (GCr15) is used, with vacuum degassing process to remove internal pores and inclusions, improving density and mechanical properties. The rollers undergo cold heading, high-temperature tempering and other processes, with uniform internal structure and impact toughness exceeding 10J/cm², enhancing fatigue resistance for long-term reliable operation.
Cage Material
The brass (CuZn37) cage provides excellent thermal conductivity, efficiently dissipating heat to avoid high temperature affecting performance. Its mechanical strength withstands centrifugal force and roller forces during operation, ensuring correct alignment and movement of rollers.
Application Fields
Industrial Machinery
Widely used in drive shafts of large lathes to support axial and radial loads during cutting; in rollers and pulleys of heavy-duty conveying systems, its load-bearing capacity ensures smooth conveying, directly affecting production efficiency.
Electric Motors
Suitable for medium and high-power motors, bearing radial forces generated by rotating components and compensating for axial movement caused by thermal expansion. Its low friction and high-speed performance improve motor energy efficiency and service life.
Automotive Industry
Used in vehicle differentials to cope with complex radial and axial loads, ensuring smooth power transmission; also applicable to water pumps of large internal combustion engines, working reliably in high-temperature, humid and vibrating environments to ensure cooling system operation.
Installation and Maintenance
Installation requires a hydraulic press or special tools to ensure precise fitting and avoid misalignment or component damage. When installing on a tapered shaft, adjust position and preload through a lock nut to improve rigidity and reduce vibration.
For lubrication, lithium-based grease is selected for general applications, with filling amount of 1/3-1/2 of bearing internal space. Oil lubrication (ISO VG 32 or 46) is suitable for high-speed or high-temperature scenarios, with forced lubrication system oil pressure maintained at 0.1-0.3MPa.
Regular maintenance requires monitoring bearing temperature (normally not exceeding 70℃), checking for abnormal vibration and noise, and timely troubleshooting. Use a puller for disassembly to avoid damaging shafts and bearing seats. Early detection of issues reduces downtime and maintenance costs.
Conclusion
The NJ2308EM cylindrical roller bearing integrates high strength, excellent load-bearing capacity and wide adaptability, operating stably under various working conditions. It is an indispensable key component in modern mechanical engineering, helping various industries improve efficiency and development.
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