How does the slewing bearing work?

A slewing bearing, also known as a slewing ring bearing or turntable bearing, is a specialized type of rolling-element bearing designed to support axial, radial, and moment loads simultaneously. Slewing bearings are commonly used in applications that require rotational movement, such as cranes, excavators, wind turbines, and other heavy machinery. The working principle of a slewing bearing involves its design, components, and the way it accommodates various loads.

How a slewing bearing works

Components of a Slewing Bearing

Raceways: Slewing bearings consist of two rings, an inner ring and an outer ring, with raceways on both sides. These raceways are typically circular tracks along which the rolling elements move.

Rolling Elements: The rolling elements, often balls or rollers, are positioned between the inner and outer raceways. They facilitate smooth rotation by reducing friction between the rings.

Cage or Spacer: In some slewing bearing designs, a cage or spacer is used to separate and maintain the proper spacing between the rolling elements. This helps ensure even load distribution.

Slewing Bearing Working Principle

Load Transmission

When external loads, including axial, radial, or moment loads, are applied to the slewing bearing, these loads are transmitted through the rolling elements to the raceways.

Axial Load Handling

The axial load is supported by the contact between the rolling elements and the raceways in the axial direction. This allows the bearing to withstand forces acting parallel to the axis of rotation.

Radial Load Handling

Radial loads are supported by the contact between the rolling elements and the raceways in the radial direction. This enables the bearing to handle forces acting perpendicular to the axis of rotation.

Moment Load Handling

Slewing bearings are designed to handle moment loads, which are loads that induce a bending or twisting effect on the bearing. The arrangement of the rolling elements and the design of the raceways allow for effective moment load resistance.

Smooth Rotation

As the external forces act on the slewing bearing, the rolling elements facilitate smooth rotation between the inner and outer rings. This rotation enables the machinery or equipment to turn or pivot as needed.

Lubrication

Proper lubrication is essential for the smooth operation and longevity of the slewing bearing. Lubricants reduce friction between the rolling elements and the raceways, minimizing wear and preventing premature failure.

Sealing and Protection

Slewing bearings often incorporate seals or shields to protect the internal components from contaminants, such as dust and moisture. This helps maintain the integrity of the bearing and ensures reliable performance over time.

In summary, the slewing bearing works by efficiently distributing and transmitting axial, radial, and moment loads through rolling elements positioned between raceways in the inner and outer rings. This design enables smooth rotation and facilitates the pivoting or turning movements required in various heavy machinery applications.