Slewing Bearing

Four-point contact ball slewing bearings use balls contacting the raceway at four points, providing balanced axial, radial, and moment capacity in a compact cross-section. This is the most common type for general automation and rotary positioning applications. Crossed roller slewing bearings interleave cylindrical rollers at alternating 90-degree angles, achieving line contact instead of point contact. This gives crossed roller designs significantly higher stiffness and moment resistance for a given size, making them preferred for precision positioning and applications where rigidity under load is the primary design requirement.

External gear slewing bearings have teeth machined on the outer ring, driven by a pinion mounted outside the bearing circle. Internal gear bearings have teeth on the inner ring bore, with the drive pinion located inside the bearing, providing a more compact envelope with the gear protected from external contamination. Ungeared slewing bearings omit the gear ring entirely and are driven by a separate mechanism such as a friction drive, belt, or direct motor coupling. The choice depends on the drive arrangement, available space, and whether the gear needs to be enclosed within the slewing circle.

A standard rolling bearing (deep groove ball, tapered roller, etc.) is designed primarily for radial or axial load in a shaft-and-housing arrangement. A slewing bearing is a large-diameter, thin-section bearing designed to carry simultaneous axial, radial, and overturning moment loads while supporting a rotating structure. Slewing bearings mount via bolt holes on both inner and outer rings (rather than press-fit on a shaft), and can incorporate a gear ring for driven rotation. They replace what would otherwise require multiple separate bearings in a complex structural arrangement.

Slewing bearings require periodic relubrication through grease fittings connected to internal distribution channels. The relubrication interval depends on operating conditions, load, speed, and environment. Bolt torque on the mounting fasteners should be checked periodically, as cyclic loading can cause gradual loosening. Seal condition should be inspected to ensure lubricant retention and contamination exclusion. For geared bearings, the gear mesh condition and backlash should be monitored. Consult BOM's engineering team for application-specific maintenance intervals.

Yes. BOM manufactures custom slewing bearings with application-specific gear module, tooth count, and pressure angle to match existing drive systems; custom bore, outer diameter, and height for proprietary equipment envelopes; non-standard bolt patterns and mounting interfaces; and alternative materials and surface treatments for specific operating environments. Contact BOM's engineering team with your dimensional envelope, load requirements, and drive system details to initiate a custom specification.