Manufactured by CHG Bearing, the NNU 4921 B/SPW33 is a precision Super-Precision Cylindrical Roller Bearings. Key dimensional parameters include a 105 mm bore diameter, a 145 mm outer diameter, and a 40 mm overall width. This component is designed to meet standard load requirements and ensure consistent operational performance. For comprehensive technical evaluation, please explore the detailed specifications, dimensional data, product images, and CAD drawings provided below. A complete PDF data sheet is also readily available for direct download to support your engineering and procurement needs.
NNU 4921 B/SPW33 - Super-Precision Cylindrical Roller Bearings
Technical Specifications
| Overview | |
|---|---|
| Part Number | NNU 4921 B/SPW33 |
| Brand | CHG® |
| Characteristics | |
| Bearing Type | Super-precision Cylindrical Roller Bearing |
| Design Type | Cylindrical Bore |
| Structure (Drawing Reference) | Complete Bearing |
| Number of Rows | 2 |
| Ring Type | None |
| Design | NNU Design |
| Tolerance Class | SP |
| Bearing Material | Bearing Steel |
| Coating | None |
| Sealing | None |
| Lubricant | None |
| Features | Annular Lubrication Groove and Lubrication Holes |
| Number of Flanges – Outer Ring | 3 |
| Number of Ribs – Inner Ring | 0 |
| Dimensions | |
| Bore Diameter (d) | 105 mm |
| Width (B) | 40 mm |
| Outer Diameter (D) | 145 mm |
| Minimum Chamfer Dimension rmin | 1 mm |
| Inner Ring Chamfer | 1.1 mm |
| Outer Ring Chamfer | 1.1 mm |
| End-face Height Difference h | 1.1 mm |
| Outer-Ring Land Diameter (L2 / D1) | 130.8 mm |
| Inner Ring Raceway Diameter F | 118 mm |
| Shaft Shoulder Diameter dₐ, min. | 111 mm |
| Shaft Shoulder Diameter dₐ, max. – NNU Design | 116 mm |
| Shaft Shoulder Diameter dᵦ, min. – NNU Design | 121 mm |
| Housing Shoulder Diameter Dₐ, max. | 138.5 mm |
| Performance | |
| Basic Dynamic Load Rating C (kN) | 130 kN |
| Basic Static Load Rating C₀ (kN) | 260 kN |
| Limiting Speed – Grease (r/min) | 5300 r/min |
| Limiting Speed – Oil-air (r/min) | 6000 r/min |
| Reference Grease Quantity Gref (cm³) | 15 cm³ |
| Fatigue Load Limit Pᵤ (kN) | 30 kN |
| Axial Static Stiffness – Guideline Value (N/µm) | 3040 N/µm |
| Material | |
| Lubrication Groove Width | 5.5 mm |
| Lubrication Holes (qty × Ø mm) | 3 |
| Weight (kg) | 1.99 kg |
| Radial Internal Clearance | C1 mm |
| Internal Design & Weight | |
| Cage Type | Machined Metal Cage |
| Mounting Dimensions | |
| Lubrication Port Thread / Size Φ1 | 119 |
NNU 4921 B/SPW33 145 mm 105 mm 40 mm Frequently Asked Questions about NNU 4921 B/SPW33 Super-Precision Cylindrical Roller Bearings
Find key technical answers regarding dimensions, specifications, and replacement options for this model.
Model NNU 4921 B/SPW33 is manufactured by CHG Bearing in standard Normal clearance (CN) for ambient temperature transmission, and C3 or C4 clearance for heavy duty applications. C3 clearance compensates for radial shrinkage caused by tight shaft press-fits (bore 105 mm) and steep thermal gradients between inner and outer rings.
Following standard ISO 281 fatigue calculation guidelines, the nominal rating life (L10) of CHG Bearing NNU 4921 B/SPW33 correlates its dynamic capacity (standard dynamic) with equivalent dynamic loads. In controlled industrial settings with proper contamination-free filtration, field data confirms continuous operational longevity exceeding 20,000 to 50,000 service hours.
Standard batches of CHG Bearing NNU 4921 B/SPW33 conform strictly to ISO Class Normal (ABEC-1). For high-precision machine tool spindles, gearboxes, or robotics requiring tighter runouts, CHG Bearing can provide custom batches graded to ISO Class 6 (P6/ABEC-3) or ISO Class 5 (P5/ABEC-5) with 100% micrometer verification.
Yes, 100% of NNU 4921 B/SPW33 Super-Precision Cylindrical Roller Bearings leaving CHG Bearing production lines are subjected to multi-frequency Anderometer sound testing. All units satisfy baseline Z1V1 levels, with dedicated quiet-running electric motor quality (EMQ) lots certified to Z2V2 and Z3V3 standards for silent machinery integration.
