What makes the 6803 bearing a preferred choice for compact machinery such as electric bicycles, small motors, and robotics? The answer lies in its 17x26x5 mm thin-section design combined with the ability to handle both radial and light axial loads. This guide covers technical specifications, key features, seal selection criteria, and common applications.
Introduction to 6803 Bearings
The 6803 bearing is a single-row deep groove ball bearing with an inner diameter of 17 mm, an outer diameter of 26 mm, and a width of 5 mm. It belongs to the 6800 series of thin-section bearings, which have a reduced cross-sectional height compared to standard bearings of the same bore size.
The designation “6803” follows an industry-standard coding system: “6” indicates a deep groove ball bearing, “8” denotes the thin-section series, and “03” represents a 17 mm bore (calculated as 03 × 5 mm).
Technical Specifications
| Parameter | Value |
|---|---|
| Bore (d) | 17 mm |
| Outer Diameter (D) | 26 mm |
| Width (B) | 5 mm |
| Weight | Approx. 8 g |
| Dynamic Load Rating (Cr) | 206 kgf (≈2.02 kN) |
| Static Load Rating (C0r) | 135 kgf (≈1.32 kN) |
| Number of Balls | 13 |
| Ball Diameter (Dw) | 2.778 mm |
The bearing is pre-lubricated with grease and requires no initial lubrication before use. Its compact dimensions make it suitable for applications where space is limited but rotational precision is required.
Key Features of 6803 Bearings
Load Capacity
The 6803 bearing supports radial loads, axial loads in both directions, and combined loads. With a dynamic load rating of 206 kgf and static load rating of 135 kgf, it can handle moderate loads typical of small motors, e-bike hubs, and light industrial equipment. The permissible radial load under normal operating conditions is approximately 1.8 kN (≈184 kgf).
Speed Limit
The limiting speed for grease lubrication is 26,000 min⁻¹. For oil-bath lubrication, the limit reaches 30,000 min⁻¹. The ZZ (metal shield) version has a speed limit of 23,000 RPM under proper lubrication. When synthetic grease such as Kluber Isoflex LDS 18 is used, the bearing can operate up to 20,000 RPM in continuous service.
Material
Standard 6803 bearings are manufactured from high-carbon chrome steel (SAE 52100), which undergoes heat treatment to achieve hardness of 60–64 HRC. For corrosion-resistant applications, stainless steel variants (AISI 440C) are available. Stainless steel bearings offer significantly higher resistance to moisture and chemicals. Hybrid ceramic bearings (ceramic balls with steel rings) and full ceramic bearings are also offered for high-speed or high-temperature environments.
Composition and Seal Types
Components
- Inner and Outer Rings: Both rings are machined from chrome steel with deep groove raceways. The groove geometry optimizes load distribution and reduces stress concentration.
- Steel Balls: Thirteen steel balls of 2.778 mm diameter are held between the inner and outer rings. The balls make point contact with the raceways, minimizing friction and enabling high rotational speeds.
- Cage: The cage maintains even ball spacing, preventing ball-to-ball contact and reducing internal friction. Common cage materials include stamped steel (for high strength), nylon (for low noise), and brass (for high-speed applications).
Seal Types and Selection Guide
The 6803 bearing is available in three closure configurations. Selecting the correct seal is critical for performance and service life.
| Seal Type | Suffix | Description | Recommended Application |
|---|---|---|---|
| Open | (none) | No seals or shields | Systems with external lubrication supply |
| Metal Shield | ZZ | Non-contact metal shield on both sides | High-speed operation in clean, dry environments |
| Rubber Seal | 2RS | Contact rubber seal (NBR) on both sides | Dusty, humid, or outdoor applications; minimal maintenance expected |
The ZZ (metal shield) uses a non-contact labyrinth design that prevents entry of large particles while offering the lowest rotational resistance. It is ideal for applications such as small motors and textile spindles where speed is prioritized over sealing.
The 2RS (rubber seal) uses a contact lip that presses lightly against the inner ring. It provides superior protection against water, dust, and grease leakage. For e-bike hub motors and outdoor equipment, the 6803-2RS is the standard choice. The LLB seal (non-contact labyrinth rubber seal) offers a middle ground between ZZ and 2RS.
Where Are 6803 Bearings Used?
- Automotive Industry: Auxiliary motors such as seat adjusters, window lift motors, and HVAC blowers.
- Electric Tools: Angle grinders, drills, and oscillating tools for spindle support.
- Electric Bicycles (E-Bikes): Standard hub bearing size (6803-2RS) for many e-bike drive systems, bottom brackets, and pedal assist sensors.
- Textile Machines: Spinning frames and winding units requiring continuous high-speed operation.
- Small Motors: Fractional horsepower motors in fans, pumps, and conveyor rollers.
- Robotics: Robotic joints, actuators, and end effectors benefiting from thin cross-section and precise rotation.
- Printing Machines: Roller assemblies and gear trains in commercial printing presses.
Additional applications include medical diagnostic equipment, CNC spindles for light machining, drones (motor and gimbal bearings), and general industrial automation.
Other Electric Bicycle Bearing Specifications
For e-bike maintenance and design, the 6803 bearing is one of several thin-section bearings used in hub motors and bottom brackets. The table below lists common sizes for reference.
| Bearing Series | Inner Diameter (d) | Outer Diameter (D) | Width (B) |
|---|---|---|---|
| 6800 | 10 mm | 19 mm | 5 mm |
| 6801 | 12 mm | 21 mm | 5 mm |
| 6802 | 15 mm | 24 mm | 5 mm |
| 6803 | 17 mm | 26 mm | 5 mm |
| 6804 | 20 mm | 32 mm | 7 mm |
| 6805 | 25 mm | 37 mm | 7 mm |
| 6806 | 30 mm | 42 mm | 7 mm |
These bearings share identical width for the 6800–6803 series, allowing interchangeability in some housing designs. Always verify load and speed requirements before substituting.
Conclusion
The 6803 bearing is a 17x26x5 mm thin-section deep groove ball bearing with a dynamic load rating of 206 kgf and static load rating of 135 kgf. It achieves limiting speeds of up to 30,000 min⁻¹ with oil lubrication. Available in open, ZZ (metal shield), and 2RS (rubber seal) configurations, the 6803 bearing serves diverse industries including automotive, power tools, e-bikes, textile machinery, small motors, robotics, and printing equipment. Select the seal type based on operating environment and maintenance access: ZZ for high speed and clean conditions, 2RS for dusty or outdoor applications. For e-bike hub motors, the 6803-2RS is the standard recommendation.
FAQs
Q1: What is the difference between 6803 ZZ and 6803 2RS?
A1: ZZ bearings have non-contact metal shields, offering lower friction and higher speed capability. 2RS bearings have contact rubber seals, providing better protection against dust and moisture but with slightly higher torque.
Q2: What is the maximum speed of a 6803 bearing?
A2: With grease lubrication, 26,000 min⁻¹; with oil lubrication, 30,000 min⁻¹. Actual speed may vary with load and lubrication method.
Q3: Can 6803 bearings handle axial loads?
A3: Yes. As deep groove ball bearings, they can accommodate moderate axial loads in both directions, in addition to radial loads.
Q4: How do I identify if I need a 6803 or 61803 bearing?
A4: Both share 17x26x5 mm dimensions but have different internal ball complements and load ratings. Check the original equipment manufacturer’s part number before substitution.
Q5: What materials are available for 6803 bearings?
A5: Standard: chrome steel (SAE 52100). Optional: stainless steel (AISI 440C), hybrid ceramic (ceramic balls + steel rings), full ceramic.
Q6: How to properly install a 6803 bearing?
A6: Apply press force only to the ring that is being mounted. For shaft mounting, press on the inner ring. For housing mounting, press on the outer ring. Never press through the balls. Recommended shaft abutment diameter (da) is 19 mm; housing abutment diameter (Da) is 24 mm.
Q7: What is the load capacity of a 6803 bearing?
A7: Dynamic load rating: 206 kgf (≈2.02 kN). Static load rating: 135 kgf (≈1.32 kN). These are basic ratings; actual allowable load depends on speed and operating conditions.
Q8: Why is my 6803 bearing making noise?
A8: Possible causes include insufficient or dried-out grease, contamination ingress, brinelling from improper installation, or internal wear. Inspect seals and relubricate if using an open bearing.
Q9: What grease should I use for 6803 bearings?
A9: Most 6803 bearings come pre-greased. For relubrication, use NLGI Grade 2 lithium-based grease for general purposes. For e-bike hubs, choose waterproof synthetic grease such as Mobilux EP 2 or Kluber Isoflex NBU 12.
Q10: Are 6803 and 61803 bearings interchangeable?
A10: No. While boundary dimensions are identical, internal geometry and load ratings differ. Always consult the original specifications.
