Na Rna Needle Roller Bearings Na4856 Na4860 Na4864 Na4868 Na4872 Na49/8 Na49/9 Na4900 Na4901 Na4902 Na4903 Na4904 Na49/22

• Customization: Available
• Rolling Body: Roller Bearings
• The Number of Rows: Single
• Model NO.: NA4856 NA4860 NA4864 NA4868 NA4872 NA49/8 N
• Outer Dimension: Small and Medium-Sized (60-115mm)
• Material: Bearing Steel
• Spherical: Non-Aligning Bearings
• Load Direction: Radial Bearing
• Separated: Unseparated
• Package: Plastic Tube or Single Box
• Precision: P0 P6 P5
• Clearance: C3
• Transport Package: Single Box
• Specification: small
• Trademark: UJK
• Origin: China
• HS Code: 848210
• Production Capacity: 600000

Product Description

 

UJK NA & RNA Series Needle Roller Bearings: English Introduction

The UJK NA Series and RNA Series represent precision-engineered machined-ring needle roller bearings designed for applications requiring extreme radial load capacity in minimal radial space. The NA Series features an integrated inner ring, while the RNA Series omits the inner ring, enabling direct rolling contact on a hardened and ground shaft. This design significantly reduces the radial footprint, making it ideal for space-constrained assemblies like gearboxes, automotive transmissions, and industrial machinery135.

Key Features & Benefits:

1. Compact Radial Design

   • RNA Series eliminates the inner ring, reducing radial space by 15-30% compared to standard bearings. The shaft itself acts as the inner raceway, provided it is hardened (HRC ≥58) and precision-ground (Ra ≤0.2 μm)139.

   • NA Series includes a separable inner ring, simplifying installation when shaft hardening is impractical57.

2. Exceptional Load Capacity

   • Engineered to withstand ultra-high radial loads despite minimal cross-sections. The machined rings (hardened chromium steel) and caged needle rollers ensure optimal load distribution5710.

3. Precision and Rigidity

   • Machined rings (vs. drawn cups) enhance dimensional stability and running accuracy.

   • RNA Series allows larger shaft diameters, increasing system rigidity39.

4. Versatile Configurations

   • NA Series: Includes inner ring, suited for non-hardened shafts.

   • RNA Series: Requires hardened shaft as raceway; ideal for weight-sensitive designs169.

5. Sealed Options (RS/2RS)

   • Available with single/double seals (e.g., RNA4900RS) pre-lubricated with lithium grease, blocking contaminants in harsh environments29.

Typical Applications:

• Automotive: Transmissions, steering systems.

• Industrial: Gear pumps, compressors, textile machinery.

• Power Tools & Agriculture Equipment268.

 

Dimensional Table: UJK NA & RNA Series

Model	Inner Diameter (mm)	Outer Diameter (mm)	Width (mm)	Series Type
RNA4900RS	14	22	13	RNA (No inner ring)
RNA4908	48	62	22	RNA (No inner ring)
NA4010	50	80	30	NA (With inner ring)
NA6911	55	80	45	NA (With inner ring)
RNA6911	63	80	45	RNA (No inner ring)

Notes:

• RNA Series: Shaft must be hardened/ground to serve as the raceway.

• NA Series: Inner ring included; shaft hardening not mandatory134.

 

Selection Guidance

• Choose RNA Series when:

  • Radial space is critical, and the shaft can be hardened/ground to G2 precision (e.g., robotics, compact actuators).

• Choose NA Series when:

  • Shaft modification is impractical, or frequent disassembly is needed (e.g., modular gearboxes)579.

For full technical specifications (e.g., dynamic load ratings, speed limits), refer to manufacturer datasheets or contact UJK directly.