Double-Row Small Steel Balls vs. Single-Row Large Steel Balls: How to Scientifically Select Slewing Bearings?

When selecting slewing bearings, many customers face a dilemma: Which model offers greater load capacity—a double-row design with two rows of 25mm steel balls, or a single-row model with 50mm or even 60mm steel balls?

The answer is clear: Under identical conditions, a double-row 2x25mm ball slewing bearing design typically delivers greater overall load capacity.

The underlying scientific principle lies in the load-bearing mechanism:

Advantages of Quantity and Distribution: The double-row design slewing rings nearly doubles the number of balls sharing the load. According to Hertz contact theory, load capacity is proportional to the square root of the number of balls. This significant increase yields substantial load capacity gains.

Superior Anti-Overturning Capability: The wider “support surface” formed by dual-row balls effectively resists massive asymmetric loads generated by overturning moments. This core advantage is difficult for single-row designs to match, proving critical for applications like boom systems and heavy-duty construction machinery.

More Balanced Load Distribution: Dual-row balls can be optimized to separately bear forces in different directions (e.g., axial and radial forces), resulting in more uniform bearing load distribution and higher rigidity and stability.

How should users choose?

Opt for double-row ball slewing bearings: If your equipment demands extremely high overall load capacity, robust anti-overturning capability, and exceptional operational rigidity (e.g., port cranes, large excavators, wind power equipment), double-row ball slewing bearings are the undeniably superior and more reliable choice.

Consider single-row ball slew bearings: If your equipment experiences relatively uniform loads dominated by axial forces and has cost-sensitive requirements, a single-row large-size ball slewing rings solution offers an economical and practical alternative.

Ultimately, there is no absolute “better”—only “more suitable.” We strongly recommend sharing your detailed operating conditions with SWBTEC engineers. We will provide the most scientifically sound and cost-effective product selection plan to ensure your equipment operates stably and efficiently.