Slewing ring bearings have many advantages in applications where the bearing must support an upper structure and facilitate its rotation. Typically large-diameter combination load bearings that lie flat, they are widely used in heavy equipment, such as cranes, excavators, aerial platforms, radar, wind turbines, and material handling equipment. But slewing ring bearings also play key roles in many military applications (tank turrets, missile launchers) and high-precision applications, like machine tool indexing tables and optical devices.
Compared to a kingpost-type design, which features a large spindle for the turntable supported by two bearings spaced along the length of the spindle, a slewing ring bearing saves considerable space and weight. They also make low-profile designs more practical. In a kingpost configuration, resistance to moment loads or overturning is a function of bearing spacing along the spindle. With slewing ring bearings, however, the diameter of the bearing and its internal geometry provide the necessary moment resistance.
The applications in which these bearings are used, both commercial and military, put a premium on performance and reliability. Premature bearing failure can damage costly equipment and expose the people who operate the equipment to risk. When specifying slewing ring bearings, especially for lifting devices, equipment designers need to consider not just the bearing but its mounting, supporting structure, installation, and even storage before it is used.