When people think of slewing bearings, they often imagine massive rings of steel in cranes and excavators. However, a critical and growing segment of this technology exists on a much smaller scale: the small slewing bearing.

These compact components are engineering marvels that pack the same fundamental functionality of their larger counterparts into a minimal space. This guide introduces you to the world of small slewing bearings, exploring their design, function, and the unique benefits they provide.

Defining a Small Slewing Bearing

A small slewing bearing is a compact, precision rotary bearing designed to handle combined loads (axial, radial, and moment loads) while enabling smooth rotational movement in a confined space. There is no official size cutoff, but they are typically characterized by:

• Bore diameters ranging from under 25mm (1 inch) to around 200mm (8 inches).

• Low cross-sections relative to their diameter, making them ideal for space-constrained designs.

• High precision grades, often featuring ground gear teeth and raceways for smooth, accurate operation.

Key Components and How They Work

Despite their size, small slewing bearings share the same core components:

1. Inner and Outer Rings: Two concentric rings made from high-grade, hardened steel.

2. Rolling Elements: Balls or rollers that sit between the raceways of the rings, facilitating smooth rotation.

3. Gear Teeth (Optional): Integrated internal or external gear teeth allow the bearing to be driven by a pinion for powered rotation.

4. Mounting Holes: Holes tapped or drilled through the rings for easy and secure mounting to adjacent structures.

5. Seals: Integrated seals to retain lubrication and protect the rolling elements from contamination.

The principle is simple: the rolling elements distribute complex loads between the two rings while minimizing friction, allowing one ring to rotate relative to the other with high precision.

Advantages of Small Slewing Bearings

Why specify a small slewing bearing over other rotary solutions?

• Space Efficiency: They provide a complete rotational solution in an incredibly compact package, simplifying machine design.

• Load Capacity: They excel at managing combined loads in multiple directions, which other bearings like cross-roller or turntable bearings might not handle as effectively in a single unit.

• Integrated Functionality: The option for integrated gearing creates a ready-to-use drive system without additional components.

• Stiffness and Precision: Their robust design offers high torsional stiffness and precise rotational accuracy, which is critical for applications like robotics and optical equipment.

Common Applications

You'll find small slewing bearings at the heart of precision mechanisms, including:

• Robotic joints and rotary actuators

• Precision rotary tables on CNC machines

• Military and aerospace optical systems (e.g., sighting systems)

• Medical imaging equipment (e.g., CT scanners)

• Radar and satellite communication antennas

• Indexing tables in automated assembly lines

In summary, the small slewing bearing is a testament to precision engineering, enabling complex motion and robust load support in applications where every millimeter counts.