How Are Slewing Bearings Fixed to Shafts

What are Slewing Bearings?

A slewing bearing is a large rotary rolling-element part.It supports heavy combined loads (axial,radial,and tilting moment forces) while allowing 360-degree slow rotation or turning movement between connected parts.

The features of Slewing Bearings

Combined Multi-Load Support:Engineered to simultaneously accommodate radial loads,high axial forces,and severe tilting moment forces within a single compact structure.

Integrated Gearing Systems:Available with internal gears,external gears,or non-geared raceways,enabling direct drive engagement with motor-driven pinions without extra transmission components.

Direct Surface Mounting:Features pre-drilled clearance or threaded mounting holes on both inner and outer rings,allowing direct bolt attachment to mating structures without requiring specialized shaft housings.

Large Diameter Range:Manufactured in large sizes-typically ranging from 200 mm to over 5 meters in diameter-while maintaining a low axial cross-section profile.

Versatile Rolling Element Internal Configurations

Single-Row Four-Point Contact Ball:Lightweight and cost-effective for general combined loads.

Double-Row Ball/Cross-Roller:High stiffness and precision for dynamic overturning moments.

Three-Row Roller:Highest load-carrying capacity for extreme heavy-duty industrial applications.

Sealed & Self-Lubricating Designs:Outfitted with integrated contact seals to prevent contamination from dirt and moisture,alongside greasing nipples for easy ongoing maintenance.

The applications of Slewing Bearings

Construction & Earthmoving Machinery

Excavators & Diggers:Connects the upper superstructure (cab and arm) to the tracked or wheeled chassis,allowing continuous 360-degree rotation during digging and dumping.

Mobile & Tower Cranes:Serves as the slewing platform joint between the stationary base and the rotating boom assembly,handling massive tilting forces under heavy lifts.

Renewable Energy & Power Generation

Wind Turbines:Used as yaw bearings (to rotate the nacelle into the wind) and pitch bearings (to adjust blade angles according to wind speed).

Solar Trackers:Allows large dual-axis photovoltaic panel arrays to slowly rotate and follow the sun's trajectory throughout the day.

Material Handling & Port Equipment

Shipyard & Harbor Cranes:Enables smooth rotational movement of heavy container cranes and ship loaders under extreme loads.

Stackers & Reclaimers:Used in mining and bulk material storage facilities to swing large boom conveyors across stockpiles.

Industrial & Specialty Equipment

Amusement Park Rides:Powers the main central rotation of Ferris wheels,carousels,and spinning roller coaster elements.

Medical Scanners:Used in high-end CT scanners and medical positioning tables requiring large inner-diameter openings and quiet,precise movement.

Defense & Aerospace:Integrated into armored vehicle turrets,radar antennae platforms,and satellite communication dishes.

Overview of Fixing Methods

The connection mode between slewing bearings and shafts directly determines equipment stability,anti-loosening performance and service life. Three mainstream mature fixing solutions are widely adopted in industry:

Interference Fit

This is the most widely used reliable fixing method. The shaft outer diameter is manufactured slightly larger than the bearing inner bore (micron-level interference). At normal temperature,the bearing cannot be assembled onto the shaft directly. Operators heat the bearing to around 90°C (max 100°C to avoid material damage) for thermal expansion of the inner hole,then quickly install it on the shaft. After natural cooling,the inner ring shrinks tightly to clamp the shaft,eliminating loosening caused by vibration and alternating dynamic loads during long-term operation.

Set Screw Fixing

Slewing bearings with threaded holes on the inner ring adopt this adjustable scheme. The shaft diameter is slightly smaller than the bearing bore for clearance fit. Tightening the set screws locks the inner ring firmly on the shaft. It features easy disassembly and adjustment,ideal equipment requiring frequent bearing replacement or position calibration,such as small automation rotary fixtures.

Locking Sleeve Fixing

Tapered locking sleeves match the tapered inner hole of slewing bearings. By tightening the end lock nut,the locking sleeve expands radially to clamp both the shaft and bearing inner ring as a whole. This design balances uniform load transmission and simple assembly,suitable for medium-load general machinery without complex shaft machining.

Installation and Positioning Techniques

Hot & Cold Mounting

Hot Mounting:For large interference fit assemblies,heating below 100°C expands the bearing bore for easy fitting,strictly avoiding overheating that damages material hardness and fatigue resistance.

Cold Mounting:Miniature slewing bearings can be shrunk by liquid nitrogen cryogenic treatment before rapid press-fit,used for small precision rotary components.

Hydraulic Press Mounting

Hydraulic equipment exerts uniform pressure only on the end face of the bearing inner ring during installation,never applying force on raceways or rolling elements to prevent surface scratches. It fits mass production and high-precision batch assembly lines.

Copper Rod & Sleeve Manual Mounting

For medium and small slewing bearings without hydraulic tools,copper rods and force transfer sleeves evenly distribute hammer impact force to avoid local stress concentration and raceway damage during manual assembly.

Axial Auxiliary Positioning Measures

Apart from circumferential fixing,axial limiting prevents bearing displacement under bidirectional axial loads:

Shaft Shoulder Positioning:Matches interference fit for double-end fixed heavy-load structures;

Elastic Retaining Ring+Lock Nut:Applies to light-load equipment with limited installation space;

Heavy-Duty Lock Nut:The optimal choice for high-speed,shock-resistant working conditions;

Thrust Washer Positioning:Used on shafts where threading processing is impossible due to compact layout.

Manufacturer of Slewing Bearings

Newbeetrans is a professional integrated manufacturer of full-series slewing bearings,owning complete production workshops including forging,integral heat treatment,ultra-precision grinding and full-performance testing labs,fully complying with ISO 9001 quality management standards.

Core Manufacturing Advantages

Complete Standard Inventory:Mass stock of 50–2500mm slewing rings with internal/external gear or gearless options,delivery within 10–15 working days for standard orders.

Strict Full-Process Inspection:All raw materials pass spectral metallographic inspection; finished bearings undergo rotary runout,rigidity,overturning moment and temperature rise testing before shipment,with full test reports provided upon request.

Multi-Scenario Customization:Develop special slewing bearing solutions for wind power,medical,semiconductor and construction machinery,including stainless steel,low-outgassing vacuum lubrication and heavy anti-corrosion coating customization.

Professional Engineering Support:Our technical team provides load calculation,gear parameter matching,shaft fixing scheme design and on-site installation guidance for equipment manufacturers.

Global Logistics System:Cooperate with sea and air freight suppliers to deliver slewing bearings to customers worldwide with stable lead times.

For technical specifications,pricing,or custom bearing solutions:

Email:paul@newbeetrans.com

Website:www.newbeetrans.com