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684 2RS Miniature Deep Groove Ball Bearing 4x9x4mm
Double rubber sealed bearing with 4mm bore, 9mm OD, 4mm width. GCr15 chrome steel rings, ABEC tolerance. 53,000 RPM grease limit. Fits where 624 and 634 bearings are too large.
Key Specifications
- Double NBR rubber seals (2RS), factory-filled grease, no relubrication needed
- 53,000 RPM grease speed limit; 0.64kN dynamic load, 0.22kN static load
- Handles radial load and light axial thrust from both directions
- Operating range -20°C to 120°C; Viton seals available for higher temps
- GCr15 bearing steel, HRC 60-64 raceway hardness, ABEC precision tolerance
For any inquiries, please contact with our Supporting Team at sales@yuanhecd.com.
| Model | 684 2RS |
| Type | Sealed |
| Bore Dia (d) | 4 mm |
| Outside Dia (D) | 9 mm |
| Width (B) | 4 mm |
| ABEC Tolerance | 3 |
| Dynamic Load Capacity (kN) | 0.54kN |
| Static Load Capacity (kN) | 0.22kN |
| Max. RPM | 53,000RPM |
| Temp. Range (℃) | -40~120℃ |
| Material | Steel |
| Seal Material | (NBR+SPCC) Nitrile rubber + mild steel (NBR + SPCC) |
| Lubrication | Grease |
Sealing and Lubrication
The 2RS designation indicates double nitrile rubber seals (NBR+SPCC) on both sides. These seals retain the factory-packed high-temperature grease and block dust and moisture ingress. The 4mm bore limits the internal volume, so the bearing is factory-filled with a precisely metered quantity of low-noise polyurea grease. No relubrication is required across its service temperature range of -40°C to 120°C.
Performance
The 684 2RS miniature deep groove ball bearing uses single-row deep groove geometry to handle combined radial and light axial loads. This bearing is part of our deep groove ball bearing range, available in bore sizes from 3mm to 100mm. Chrome steel (GCr15) construction with ABEC precision tolerance, manufactured to precision bearing standards. Dynamic load rating 0.54kN, static load rating 0.22kN. Supports speeds up to 53,000 RPM with low noise and vibration.
OEM and Customization
Custom internal clearance (C2, CN, C3) and grease type available for volume orders. Batch-level QC reports and dimensional tolerance documentation provided on request. Submit your custom bearing specification for a quote.
Applications
Micro brushless motors, dental drill turbines, RC micro servos, optical encoder spindles, PCB drill spindles, miniature blowers, lab centrifuge rotors, watch movement rotors, pen plotters, camera gimbal motors.
Frequently Asked Questions
What does 2RS mean on a bearing? +
2RS indicates the bearing has two rubber seals, one on each side. These nitrile rubber (NBR) seals with SPCC steel backing prevent lubricant leakage and block external contaminants. 2RS bearings are lubricated for life; no re-greasing required.
What is the load rating of a 684 2RS bearing? +
The 684 2RS has a dynamic load rating of 0.54kN and a static load rating of 0.22kN. Operating speed reaches 53,000 RPM under optimal conditions. With only a 4mm bore, loading is light; exceeding these values shortens bearing life significantly. Contact us for a bearing selection review.
Can I order 684 2RS bearings with different clearance? +
Yes. Standard clearance is CN (normal). C2 clearance (tighter, for low-noise applications) and C3 clearance (looser, for press-fit installations or thermal expansion) are available on volume orders. Specify your clearance requirement when requesting a quote.
What is the difference between 684 ZZ and 684 2RS? +
684 ZZ uses metal shields with a small gap: lower friction, higher speed ceiling, less particle protection. 684 2RS uses rubber contact seals: better dust and moisture protection, marginally higher friction, slightly lower top speed. Choose ZZ for clean high-speed environments; choose 2RS for dusty, wet, or outdoor conditions.
