Tower Crane Slewing Motor Bearings: Types, Characteristics, and Their Role in Mechanical Operation

I. Main Types of Tower Crane Slewing Motor Bearings

Deep Groove Ball Bearings

The most common type, suitable for small- to medium-sized tower cranes, capable of handling both radial and axial loads.

Typical model: 6205-2RS (inner diameter 25mm, outer diameter 52mm), maximum speed up to 10,000 rpm (refer to Mechanical Design Handbook, 5th edition).

Tapered Roller Bearings

Used in heavy-duty tower cranes, offering higher load capacity and separable installation.

Example: 32208 bearing (inner diameter 40mm, outer diameter 80mm), dynamic load up to 90 kN (SKF Technical Manual).

Crossed Roller Bearings

High precision and rigidity, suitable for precise slewing control, though more expensive.

Example: RB3010 (inner diameter 30mm, outer diameter 47mm), axial stiffness increased by over 30% (NSK test data).

II. Core Features and Performance Requirements

High Load Capacity

Slewing bearings must withstand overturning moments; for example, the bearing of a QTZ80 tower crane needs to support over 20 tons (Crane Design Specification GB/T 3811-2008).

Shock and Vibration Resistance

Special heat treatment processes (e.g., carburizing and quenching) are applied, achieving hardness of HRC 58–62 and extending service life up to 50,000 hours (FAG Bearing Technical Report).

Low Friction Design

Sealed structures with lubricating grease (e.g., lithium-based grease) reduce friction coefficients to below 0.005, minimizing energy loss.

III. Key Roles in Mechanical Operation

Ensuring Smooth Slewing

Bearing clearance is controlled within 0.05mm to prevent tower crane oscillation (case study: Zoomlion ZCC9800W tower crane).

Transmitting Torque and Distributing Loads

The raceway structure converts motor torque into 360° rotation while distributing wind and lifting loads evenly.

Reducing Wear and Maintenance Costs

High-quality bearings lower replacement frequency; for instance, using SKF Explorer series extended maintenance intervals from 6 months to 2 years (observed on-site).

IV. Extended: Selection and Maintenance Recommendations

Selection Basis

Choose bearing size according to tower crane capacity; for example, an 80-ton tower crane requires bearings with outer diameter ≥ 1m (Tower Crane Design Calculations).

Maintenance Tips

Inspect lubrication every 500 operating hours and prevent contamination by foreign particles (ISO 4406 cleanliness standard).