Manufactured by CHG Bearing, the NNU 4948 BK/SPW33 is a precision Super-Precision Cylindrical Roller Bearings. Key dimensional parameters include a 240 mm bore diameter, a 320 mm outer diameter, and a 80 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 4948 BK/SPW33 - Super-Precision Cylindrical Roller Bearings
Technical Specifications
| Overview | |
|---|---|
| Part Number | NNU 4948 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) | 240 mm |
| Width (B) | 80 mm |
| Outer Diameter (D) | 320 mm |
| Minimum Chamfer Dimension rmin | 2 mm |
| Inner Ring Chamfer | 2.1 mm |
| Outer Ring Chamfer | 1.1 mm |
| End-face Height Difference h | 3.7 mm |
| Outer-Ring Land Diameter (L2 / D1) | 292.2 mm |
| Inner Ring Raceway Diameter F | 265 mm |
| Shaft Shoulder Diameter dₐ, min. | 251 mm |
| Shaft Shoulder Diameter dₐ, max. – NNU Design | 262 mm |
| Housing Shoulder Diameter Dₐ, max. | 309 mm |
| Performance | |
| Basic Dynamic Load Rating C (kN) | 528 kN |
| Basic Static Load Rating C₀ (kN) | 1220 kN |
| Limiting Speed – Grease (r/min) | 2200 r/min |
| Limiting Speed – Oil-air (r/min) | 2600 r/min |
| Reference Grease Quantity Gref (cm³) | 171 cm³ |
| Fatigue Load Limit Pᵤ (kN) | 118 kN |
| Axial Static Stiffness – Guideline Value (N/µm) | 6340 N/µm |
| Material | |
| Lubrication Groove Width | 11.1 mm |
| Lubrication Holes (qty × Ø mm) | 3 |
| Weight (kg) | 17.7 kg |
| Radial Internal Clearance | C1 mm |
| Internal Design & Weight | |
| Cage Type | Machined Metal Cage |
| Mounting Dimensions | |
| Lubrication Port Thread / Size Φ1 | 267 |
NNU 4948 BK/SPW33 320 mm 240 mm 80 mm Frequently Asked Questions about NNU 4948 BK/SPW33 Super-Precision Cylindrical Roller Bearings
Find key technical answers regarding dimensions, specifications, and replacement options for this model.
For international ocean and air freight, CHG Bearing packs NNU 4948 BK/SPW33 with industrial VCI anti-corrosion barrier wrapping, sealed polybags, individual cartons, and fumigated ocean-worthy wooden crates. This multi-layer barrier guarantees rust-free storage for a minimum shelf life of 24 to 36 months.
The Open Type engineered for NNU 4948 BK/SPW33 by CHG Bearing utilizes precision non-contact metal shields or reinforced NBR/FKM contact lip seals. This barrier prevents particulate ingress, washdown fluids, and abrasive dust from reaching the raceways while eliminating grease leakage under centrifugal forces.
Beyond standard alloy steel, CHG Bearing can customize the NNU 4948 BK/SPW33 Super-Precision Cylindrical Roller Bearings using AISI 440C stainless steel, black oxide coating, zinc-nickel plating, or hybrid ceramic (Si3N4) balls for applications involving chemical exposure, marine salt fog, or galvanic current hazards.
When fitting NNU 4948 BK/SPW33 over a 240 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.
