NTN NU308EAT2X CYLINDRICAL ROLLER BEARING

Suited to high radial loads and to use as a free or fixed bearing, cylindrical roller bearings offer low friction and good stiffness. They are available in a wide range of models and variants addressing specific conditions: heat, axial displacement, operating noise, speed, capacity, etc.

NTN cylindrical roller bearings of the ULTAGE™ series are a reference solution for applications with high radial loads and sustained rotational speeds. The optimized internal design of this range provides increased load capacity within the same envelope as standard series, with extended maintenance intervals as a result.

Explanation :
- NU: single-row bearing with two shoulders on the outer ring and none on the inner ring; separable inner ring.
- EA: designates NTN's ULTAGE™ series; standard limiting dimensions retained, but internal specifications optimized (increased roller diameter, length and number).
- T2X: cage in glass-fiber reinforced polyamide.

Characteristics :
These NU-type bearings are built around an outer ring with two shoulders and no shoulder on the inner ring. This configuration allows separation of the outer ring–rollers–cage assembly from the inner ring, which simplifies mounting and disassembly. Axial displacement occurs by sliding on the seats, making these bearings a natural solution for free bearings.

The ULTAGE™ series retains the envelope dimensions of standard bearings while incorporating larger-diameter and a greater number of rollers. The roller profile is optimized to limit stress concentrations at the contact ends. These internal changes result in increased dynamic load capacity and an allowable speed improved by 20% compared with the standard, when lubricated with oil. ULTAGE™ type rings are not interchangeable with those of standard series due to a different inscribed circle diameter.

The cage in glass-fiber reinforced polyamide 66 provides good mechanical strength, heat resistance and low wear. This material also offers a degree of flexibility during assembly, particularly useful on constrained geometries.

Maintenance :
Open bearing: lubrication (grease or oil) must be adapted to service conditions. The ULTAGE™ series benefits from extended re-greasing intervals. Shaft/bore mounting tolerances must comply with NTN recommendations to maintain the residual clearance within the permissible range. In operation, monitor temperature, vibrations and noise. Allowable misalignment is 1/500 mm/mm.

Key advantages :
- Increased radial load capacity in the same envelope, without modifying existing bore dimensions.
- Separable inner ring, facilitating mounting and replacement without full removal of the shaft.
- Free axial displacement absorbing thermal expansions without imposing stress on other assembly components.
- Extended maintenance intervals thanks to the technical improvements of the ULTAGE™ series.

Applications :
These NTN bearings are used as a free bearing, paired with a fixed bearing (type NJ or NUP) to form a complete arrangement. They are suitable for industrial drives, gear reducers with long shafts, gearboxes, electric motors and motor-pump units, wherever the shaft is subject to thermal expansion or axial displacement. The robustness of the ULTAGE™ profile and the polyamide cage also make them relevant for equipment with variable loads or frequent starts.