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Slewing Ring Bearings

Slewing ring bearings (slewing bearings) are large-diameter rolling bearings that support and slowly rotate or oscillate large rotating parts in applications such as slewing bodies of cranes and construction machinery and cutter support in tunnel boring machines. A single unit can simultaneously carry axial load, radial load and moment load. They have mounting holes in the outer or inner ring and are bolted directly to the supporting structure. Designs include single-row ball (four-point contact ball) type, double-row ball type, three-row combined cylindrical roller type and double-row tapered roller type. The outer or inner ring may be geared with external or internal teeth, or be ungeared. Geared types mesh with a drive pinion to form the slewing mechanism. Large-diameter products are also available in split designs divided in the circumferential direction to improve assembly.

How to choose Slewing Ring Bearings

  1. 1. Select a structure that suits load and moment

    Single-row ball type is compact and suited to general construction machinery and cranes; three-row combined cylindrical roller type offers high rigidity and rated load for large cranes and tunnel boring machines; double-row tapered roller type can carry high axial load thanks to its large contact angle. Select the type based on the magnitude of moment load and impact.

  2. 2. Allow margin in static rated load

    Because slewing bearings often operate at low speed or oscillate, the basic static rated load in the axial direction, C0a, is the primary selection criterion. Listed products range widely from 341 to 394000 kN. Convert maximum load and moment to equivalent load, and compare products with a safety factor appropriate to the application.

  3. 3. Match mounting diameter and support structure dimensions

    Bore diameter d and outside diameter D determine the mounting surface on the support structure or rotating body, the bolt hole layout, and the space for piping and cables passing through the center. Listed bore diameters range from a few mm to 6457 mm. For large-diameter products, a split design makes transport and assembly easier.

  4. 4. Confirm gear position and specifications

    Whether to choose ungeared, internal-tooth or external-tooth types depends on the layout of the drive pinion. Listed products have a pressure angle of 20°. Match the tooth profile (standard or low-profile teeth) and the JIS gear accuracy grade with the pinion side, and consider surface and root induction hardening as required.

  5. 5. Select sealing and lubrication method for the operating environment

    In environments exposed to soil or water pressure, some products offer pressure-resistant seals with a static withstand pressure of 0.3 MPa in addition to labyrinth and dust seals. Check the presence of grease nipples and drain ports, and whether grease feeding, oil bath or forced circulation lubrication is used, in line with the maintenance plan.

  6. 6. Estimate handling and installation method from mass

    Listed products vary widely in mass, from 1 to 45800 kg. Large units are constrained by lifting equipment, crane capacity and transport dimensions, so verify the mass and, if necessary, consider circumferentially split designs (two-piece or four-piece).

This guide was written by AI based on the listed products' documents and specification items. Check each manufacturer's documents before adopting.