Overview
The Fafnir 311KDD FS50000 is a single-row deep groove radial ball bearing manufactured by Fafnir Bearing, a division of the Timken Company. This bearing combines heavy cross-section durability with quiet, smooth operation. The “DD” designator indicates double metallic shields, which provide contamination protection without contact drag. The 311 series represents the 300K heavy-duty class, designed for demanding applications requiring high radial load capacity and extended service life.
Key Features
- Double Metallic Shields (DD) — Sealed design with non-contact protection against contamination; low friction, full-speed capable
- Deep Groove Conrad-Type Construction — Handles radial loads and moderate axial loads from either direction
- 300K Series Heavy Cross-Section — Substantially greater load capacity than standard 200-series bearings for the same bore
- Precision Radial Ball Design — Standard precision grade, suitable for electric motors, pumps, and general machinery
- Quiet, High-Speed Operation — Well-balanced raceway design enables smooth, low-vibration running
- Made in the USA — Built to industry standards with proven reliability across agriculture, textiles, food & beverage, automotive, and steel mills
Technical Specifications
- Bore Diameter: 55 mm (2.165 in.)
- Outer Diameter: 120 mm (4.724 in.)
- Part Number: 311KDD FS50000
- Bearing Type: Single-Row Deep Groove Ball Bearing
- Sealing: Double Metallic Shields (Contact-Free)
- Series: 300K (Heavy-Duty)
- Internal Play: Normal (Cn)
- Precision Class: Standard Precision
- Lubrication: Standard (requires grease or oil)
- Temperature Rating: Up to 120°C
- Condition: New in Box
Typical Applications
The Fafnir 311KDD FS50000 is widely used in:
- Industrial Electric Motors — Especially where quiet, reliable operation is essential
- Pump & Fan Bearings — Handles mixed radial-axial loads in centrifugal equipment
- Textile Machinery — Spin frames, looms, and yarn-winding systems
- Agricultural Equipment — Harvest machinery and drive trains requiring extended uptime
- Food & Beverage Processing — Conveyor systems, mixers, and packaging machinery
- General Industrial Machinery — Shaft support in gearboxes, crushers, and transmission systems
Compatibility & Replacements
Compatible With
- Timken Company manufacturing standards and bearing housings designed for 55 mm bore, 120 mm OD
- Standard deep groove ball bearing pillow blocks and flanged housings (ISO 15–56mm nominal bore)
- Industrial machinery requiring standard radial and light axial bearing duty
- Electric motor applications rated for 120 mm OD bearing mounting surfaces
Replaces / Drop-In Replacement For
Verify compatibility with your equipment designer or OEM before ordering. The Fafnir 311KDD FS50000 is a direct replacement for equivalent part numbers in the 311KDD series (e.g., 311KDD C2, 311KDD C3 clearance variants). Dimensional equivalents may include other 55×120 mm deep groove bearings from major brands such as SKF, NSK, and FAG, but bearing series specifications and load ratings must be confirmed before installation.
Works With
- Timken CAD & Selection Tools — Free 24/7 bearing calculators and configuration software available at Timken.com
- Bearing Housings & Pillow Blocks — Standard ISO 15 pillow blocks and flange housings sized for 55 mm bore
- Lubrication Systems — Compatible with standard mineral and synthetic greases; oil lubrication supported
- Condition Monitoring — Suitable for vibration monitoring and predictive maintenance programs
