NTN NU307EAT2XC3 CYLINDRICAL ROLLER BEARING

Suitable for high radial loads and for use as a floating or fixed bearing, cylindrical roller bearings feature low friction and good rigidity. They are available in a wide range of models and variants addressing specific conditions: heat, axial displacement, operating noise, speed, capacity, etc.

The ULTAGE™ series from NTN groups cylindrical roller bearings whose internal specifications have been optimized to improve performance, extend service life and reduce maintenance intervals. The separability of the inner ring simplifies mounting and facilitates periodic inspections.

Decoding:
- NU: a single row of rollers, outer ring with two shoulders, inner ring without shoulder. The outer-ring, rollers and cage subassembly is separable from the inner ring; for floating bearing use only.
- EA: denotes NTN's ULTAGE™ series; rollers of larger diameter and in greater number than a standard type, optimized roller generatrix profile, increased load capacity with identical external envelope dimensions.
- T2X: cage made of glass-fiber reinforced polyamide 66; lightweight, wear-resistant, economical, promotes ease of assembly.
- C3: internal radial clearance greater than normal; compensates for tight fits and thermal expansions in service.

Characteristics:
NTN NU-type cylindrical roller bearings are the reference for floating bearing applications. The outer ring has two shoulders that retain the rollers and cage, while the inner ring, without shoulder, allows free axial displacement in both directions. This separability simplifies mounting on long shafts and permits thermal expansion without axial constraint on the bearing.

The EA suffix identifies the ULTAGE™ series: the diameter, length and number of rollers have been increased compared with the standard type, while retaining the same external envelope dimensions. The roller generatrix profile is optimized to better distribute contact stresses and limit pressure concentrations at edges. The allowable speed increases by 20% in oil lubrication compared with equivalent standard references.

The cage made of glass-fiber reinforced polyamide 66 (T2X) contributes to the overall lightness and tolerates usual mechanical loads. It offers good resistance to heat and wear.

The C3 internal clearance, greater than normal, compensates for tight fits and temperature rises in operation, thereby reducing the risk of excessive internal preload.

Maintenance:
Bearings of this NTN series are supplied without grease: the choice and supply of lubricant are the operator's responsibility. Oil lubrication is recommended for high speeds, grease lubrication being suitable for slower or less accessible applications. Extreme-pressure additives of type S or P should be avoided with the T2X polyamide cage, particularly when operating temperature is high.

As with any open bearing, this series must be protected from contamination by seals or baffles installed in the housing. When disassembled for inspection, the raceways, roller surfaces and cage integrity should be checked. Any sign of pitting, flaking or deformation requires replacement of the affected part.

Key advantages:
- Increased radial load at constant envelope: replacement of a standard bearing without modifying the housing.
- Free axial displacement: no parasitic axial force generated on the assembly in case of thermal expansion.
- Inner ring separability: independent mounting on a long shaft without risk of damage.
- Extended maintenance intervals thanks to ULTAGE™ internal specifications, reducing production line stoppages.
- Rated speed increased by 20% (oil lubrication) compared with the equivalent standard type.
- C3 clearance suited to pronounced thermal cycles and frequent starts, without risk of excessive preload.

Applications:
NTN NU-type cylindrical roller bearings are structurally intended for floating bearings, i.e. mounting points where the shaft must remain free to move axially. This requirement is systematically encountered in two-bearing arrangements, where one bearing is fixed and the other floating, to absorb dimensional variations due to temperature or manufacturing tolerances.

In power transmission mechanics, they equip industrial electric motors, speed reducers and general gearboxes. The ability to run at high speed with good rotational accuracy makes them suitable for the high-speed shafts of these machines. Industrial pumps and process fans are also common applications, particularly when the installation requires managing the expansion of a long horizontal shaft.

The C3 clearance makes them particularly relevant for equipment subjected to frequent starts or significant thermal variations, such as construction machinery, cranes or production machines operating in alternating cycles.