FAG NJ2313-E-XL-M1-C4 CYLINDRICAL ROLLER BEARING

In applications with high temperatures and heavy loads, the choice of radial clearance is decisive for the service life of the rolling bearing. This FAG design features a C4 radial clearance, which is specifically designed for large thermal expansions and very tight fits.

Explanation:
• NJ: Two ribs on the outer ring, one rib on the inner ring; axial guidance in one direction, floating (non-locating) bearing function in the opposite direction
• E: Increased radial load capacity through optimized internal geometry
• XL: FAG/INA X-life designation for extended service life and increased dynamic load ratings thanks to highly precise contact surfaces
• M1: Two-piece brass cage, roller-guided, for improved heat dissipation
• C4: Increased internal radial clearance above C3 level, suitable for high thermal expansions and very tight fits

Features:
The NJ series is based on a separable design: the inner ring can be mounted separately from the assembly of outer ring and rolling elements. This allows both subassemblies to be installed independently. The inner ring can initially be mounted alone on the shaft, which is a significant advantage particularly for shrink fits.
The E version uses an optimized internal geometry to distribute loads more evenly across the raceways. In combination with X-life technology, the bearings benefit from improved surface quality that reduces friction, lowers heat generation and places less demand on the lubricant. The result is higher dynamic basic load ratings and a longer nominal life compared with earlier generations.
The C4 radial clearance is above the C3 clearance, which in turn is greater than the standard CN clearance. It has been specifically developed for applications with large temperature differentials or heavy interference fits. This preserves sufficient freedom for deformation so that no harmful internal preload occurs at operating temperature. The M1 brass cage complements this concept by providing stable guidance of the rollers and efficient heat evacuation.

Maintenance:
For applications with C4 radial clearance, temperature monitoring has the highest priority. Unusually high temperatures can indicate excessive fitting stresses, aged lubricants or insufficient lubricant supply. Regular temperature checks help to detect deviations early and prevent bearing damage.
The type and quantity of lubricant must be adapted to the actual operating temperatures. Although the M1 brass cage reduces internal heat generation within the bearing, it does not replace condition-based relubrication under real operating conditions.
Additionally, vibration analysis and noise checks should be part of preventive maintenance. Even minor changes in the vibration spectrum should be investigated. As this is an open rolling bearing, the bearing environment must be reliably protected from particles, dust and moisture.

Strengths:
• C4 radial clearance prevents harmful internal preload in tight fits and under strong temperature fluctuations
• Higher load capacity enables accommodation of larger loads without changing the envelope dimensions
• Separable design reduces downtime during maintenance and servicing
• M1 brass cage improves heat dissipation and is particularly suitable for high-temperature applications

Applications:
The C4 version is particularly suited to heavy industry. Rolling mills, roller furnaces, heat treatment plants and high-pressure compressors are typical applications. In these plants, heating and cooling cycles alternate, subjecting the radial clearance continuously to thermal expansion. The C4 clearance compensates for these changes reliably without excessively stressing the bearing.
Powerful gearboxes as well as drive and transmission shafts in high-temperature environments also benefit from this increased radial clearance, especially with very tight fit tolerances. Under these conditions the E version reduces the load on the raceways through optimized load distribution, while X-life quality enables longer uptime and extended maintenance intervals.