Slewing Bearings
Slewing Bearing
A slewing bearing (also called a slewing ring) is a large-diameter rolling bearing capable of simultaneously carrying axial loads, radial loads, and overturning moments in a single compact assembly. This makes it the primary structural and load-carrying element in rotating machinery such as construction cranes, excavators, industrial turntables, AGV rotation platforms, and wind turbine pitch and yaw systems. Slewing bearings are available in three main internal configurations: four-point contact ball type (balanced multi-directional load capacity, lower friction), crossed roller type (higher rigidity, better positioning precision), and three-row roller type (highest load and overturning moment capacity for heavy-duty applications). Each type can be supplied with internal teeth, external teeth, or no gear ring, with bolt hole patterns and dimensions customized to the customer's mounting structure. BOM Bearing manufactures standard and fully custom slewing rings for AGVs, automated storage and retrieval systems, hollow rotating platforms, and specialized industrial equipment.
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Slewing Bearings
Large Diameter Capability Gear & Ungeared Options
BOM Bearing manufactures and supplies slewing bearings (slewing rings) across a wide bore range — from compact drives under 200 mm to heavy-duty industrial applications exceeding 5,000 mm in diameter. A slewing bearing integrates axial, radial, and overturning moment loads in a single compact unit, replacing conventional multi-bearing arrangements and eliminating the need for separate thrust and radial bearings. Available with external gear, internal gear, or ungeared (no gear) configurations.
- Load Capacity: Simultaneous axial, radial, and overturning moment loads in one compact bearing unit
- Bore Range: 100 mm to 5,000 mm and beyond; custom diameters available on request
- Gear Options: External gear, internal gear, or ungeared; gear module, tooth count, and pressure angle to specification
- Material: 42CrMo4 alloy steel rings; induction-hardened raceways; stainless steel available for corrosive environments
- Re-Lubrication: Integrated grease nipples with internal distribution channels; sealed configurations for low-maintenance operation
- Mounting: Bolt holes on both inner and outer rings; mounting circle diameter and bolt pattern to specification
Slewing Bearings — Representative Sizes
Indicative reference values — actual capacity depends on load distribution and application factors | This is a partial list — contact us for specific requirements
| Designation |
ID mm |
OD mm |
H mm |
Gear Type |
Axial Load Ca kN |
Tilt Moment Mk kNm |
|---|---|---|---|---|---|---|
| SRB-0162 | 162 | 262 | 43 | External | 90 | 5.5 |
| SRB-0302 | 302 | 432 | 50 | External | 160 | 17 |
| SRB-0456 | 456 | 596 | 60 | External | 240 | 40 |
| SRB-0564 | 564 | 724 | 64 | Internal | 330 | 68 |
| SRB-0710 | 710 | 900 | 75 | External | 480 | 120 |
| SRB-0878 | 878 | 1100 | 85 | Internal | 650 | 190 |
| SRB-1060 | 1060 | 1320 | 90 | External | 880 | 290 |
| SRB-1280 | 1280 | 1580 | 100 | Internal | 1200 | 440 |
| SRB-1600 | 1600 | 1950 | 115 | None | 1750 | 720 |
| SRB-2000 | 2000 | 2380 | 125 | External | 2500 | 1200 |
Custom & Integrated Slewing Bearing Solutions
Integrated Assemblies Engineering Support
Beyond standard catalog configurations, BOM Bearing engineers slewing bearings and integrated slewing assemblies to precise application requirements — including units where the slewing bearing is combined with mounting flanges, structural rings, or drive components as a single manufactured unit.
- Integrated Assemblies: Slewing bearing combined with mounting flange, drive pinion housing, or structural ring as one machined unit — more compact structure, smaller envelope, higher load capacity
- Precision Advantage: One-piece machining eliminates assembly stack-up errors, delivering higher combined accuracy than separately assembled components — critical for equipment with tight alignment requirements
- Gear Customization: Module, tooth count, pressure angle, helix angle, and profile modifications to match existing drive systems
- Raceway Engineering: Custom contact angle, ball or roller element sizing, raceway hardness depth (HRC 55–62), and seal configuration to application requirements
- Material Options: 42CrMo4 standard; Boron steel, stainless steel, and specialty alloys available for extreme load or corrosive environments
Applications
Tower Cranes & Lifting Equipment
Slewing platform support under combined axial, radial, and overturning moment loads. High reliability for continuous-duty lifting cycles.
Wind Turbines
Blade pitch control bearings and nacelle yaw bearings subject to cyclic loading, large diameter requirements, and extended maintenance intervals.
Excavators & Construction Equipment
Turntable rotation under heavy overturning moments and impact loads in mobile construction and mining machinery.
Medical Imaging Systems
CT scanners and C-arm X-ray systems requiring smooth, precise 360° rotation with minimal vibration and low running torque.
About BOM Bearing
BOM Bearing is a professional manufacturer and supplier of slewing bearings, providing integrated axial-radial-moment load solutions for industrial, construction, energy, and medical applications worldwide.
- Quality Assurance: ISO 9001 certified manufacturing with strict quality control at every production stage
- Wide Size Range: Slewing bearings from compact sub-200 mm bore to extra-large diameters exceeding 5,000 mm
- Custom & Integrated Solutions: Application-specific slewing assemblies with integrated flanges, gears, and structural components
- Technical Support: Professional engineering team for load analysis, gear selection, bolt pattern design, and application support
- Fast Delivery: Efficient production lines and global logistics network ensuring timely delivery
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Frequently Asked Questions (FAQ)
What loads can a slewing bearing carry?
A slewing bearing simultaneously supports axial (thrust) loads, radial loads, and overturning (tilting) moments in a single compact unit. This replaces what would otherwise require separate axial and radial bearing arrangements, significantly reducing the envelope size and assembly complexity.
What is the difference between external gear, internal gear, and ungeared slewing bearings?
External gear bearings have teeth on the outer diameter of the outer ring, driven by a pinion outside the bearing circle — common in cranes and excavators. Internal gear bearings have teeth on the inner ring's inner diameter, driven by a pinion inside the bearing — common in turntables where the drive must be enclosed. Ungeared bearings are used where rotation is driven by a separate drive mechanism or where a gear is not required.
What materials are used for slewing bearing rings?
Standard slewing bearings use 42CrMo4 alloy steel for the rings, with raceways induction-hardened to HRC 55–62 for wear resistance. For corrosive environments, stainless steel rings are available. Specialty alloy options exist for extreme temperature or high-impact applications.
What is an integrated slewing assembly?
An integrated slewing assembly combines the slewing bearing ring with its mating components — such as mounting flanges, gear housings, or structural rings — into a single machined unit. This produces a more compact structure with higher load capacity, and eliminates assembly stack-up errors for superior combined precision compared to separately assembled parts.
Can BOM supply non-standard bore sizes or custom slewing bearings?
Yes. BOM Bearing engineers custom slewing bearings across a wide diameter range, with specific gear parameters, mounting bolt patterns, raceway geometry, and material selections. Contact our engineering team with your load requirements, space envelope, and application details.
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