Manufactured by CHG Bearing, the NNU 4921 BK/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 BK/SPW33 - Super-Precision Cylindrical Roller Bearings
Technical Specifications
| Overview | |
|---|---|
| Part Number | NNU 4921 BK/SPW33 |
| Brand | CHG® |
| Characteristics | |
| Bearing Type | Super-precision Cylindrical Roller Bearing |
| Design Type | Tapered Bore 1:12 |
| 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 | 0.6 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 |
| 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) | 2.05 kg |
| Radial Internal Clearance | C1 mm |
| Internal Design & Weight | |
| Cage Type | Machined Metal Cage |
| Mounting Dimensions | |
| Lubrication Port Thread / Size Φ1 | 119 |
NNU 4921 BK/SPW33 145 mm 105 mm 40 mm Frequently Asked Questions about NNU 4921 BK/SPW33 Super-Precision Cylindrical Roller Bearings
Find key technical answers regarding dimensions, specifications, and replacement options for this model.
To extend the trouble-free lifespan of CHG Bearing NNU 4921 BK/SPW33, preventive maintenance routines should monitor operating housing temperature (normally maintaining below 70°C) and conduct regular vibration FFT analysis to identify early raceway micro-pitting before unexpected line halts occur.
When fitting NNU 4921 BK/SPW33 over a 105 mm shaft, CHG Bearing strictly recommends uniform induction heating (controlled between 90°C and 110°C) or precision hydraulic press sleeves. Under no circumstances should direct impact blows be struck against the rings or cage, as shock loads cause brinelling indents and premature spalling.
Sourcing NNU 4921 BK/SPW33 directly from CHG Bearing eliminates intermediate brokerage markups while granting you factory-direct engineering backup, rigorous ISO-certified quality assurance, competitive volume wholesale pricing, and dependable supply chain stability for Super-Precision Cylindrical Roller Bearings.
Each NNU 4921 BK/SPW33 produced in CHG Bearing manufacturing facilities features accurately profiled corner chamfers complying with DIN 5412 / ISO standard corner radii. When designing mating shafts and housing shoulders, machining an undercut or fillet radius strictly within the inner ring clearance limit (105 mm bore side) ensures perfect planar contact without edge binding.
