Selecting the appropriate slewing bearing is critical for the stability and longevity of your machinery. This guide breaks down the essential calculation formulas and selection criteria for Single-Row Ball and Three-Row Roller slewing bearings.
1. Basic Static Load Rating Calculation (C0)
The static load rating is the foundation of bearing selection.
For Single-Row Ball Slewing Bearings: Formula: C0 = f * D * d
- C0: Static Load Rating (kN)
- f: Static capacity factor (typically 0.108 kN/mm2)
- D: Raceway center diameter (mm)
- d: Nominal ball diameter (mm)
For Three-Row Roller Slewing Bearings: Formula: C0 = f * D * d
- f: Static capacity factor (typically 0.172 kN/mm2)
- D: Raceway center diameter (mm)
- d: Upper row roller diameter (mm)
2. Equivalent Axial Load Calculation (Cp)
To determine the actual load during operation, use the following equivalent axial load formulas:-
- Formula A: Cp = Fa + 4370 * M/D + 3.44 * Fr
- Formula B: Cp = Fa + 4500 * M/D
Variables Definition:
- Cp: Equivalent Axial Load (kN)
- M: Overturning Moment (kN·m)
- Fa: Axial Force (kN)
- Fr: Radial Force (kN)
3. Static Safety Factor (fs)
After calculating C0 and Cp, the safety factor is determined by: fs = C0 / Cp
As a leading exporter, we specialize in providing high-quality slewing solutions for various industrial applications. Below is an example of our products ready for integration into large-scale construction equipment like excavators.
Refer to the application table below to ensure your fs value meets the industry standards.
| Duty Level | Operating Characteristics | Machinery Examples | Recommended fs |
| Light Duty | Infrequent full load, smooth rotation | Truck Cranes, Mobile Cranes | 1.00 – 1.15 |
| Medium Duty | Frequent full load, moderate impact | Tower Cranes, Ship Cranes | 1.15 – 1.30 |
| Heavy Duty | Constant full load, high impact | Port Cranes, Excavators | 1.30 – 1.45 |
| Extra Heavy | Harsh environments, high impact | TBM, Offshore Platforms | 1.45 – 1.70 |
If you need help with specific load calculations, contact us for a free technical consultation.https://liyuandrive.com/contact-us/