Excavator Slewing Bearing Replacement Guide: Selection and Maintenance

The slewing bearing is one of the most important components in an excavator’s upper structure. It allows the upper body of the machine to rotate smoothly while supporting heavy loads generated during digging, lifting and other operations.

As excavators operate under demanding conditions, the slewing bearing is continuously exposed to heavy loads, vibration, impact forces, dust, moisture and changing working environments. Over time, wear or damage may occur, affecting machine performance and operational safety.

When an excavator experiences abnormal rotation, excessive clearance, unusual noise or reduced stability, an Excavator Slewing Bearing Replacement may become necessary.

Choosing the correct replacement bearing and working with a reliable supplier are critical steps to ensure equipment reliability, reduce downtime and extend service life.

As an experienced Excavator Slewing Bearing Supplier, LTZC provides reliable slewing bearing solutions for different excavator models and industrial applications, including standard replacement bearings and customized solutions.

What is an excavator swing bearing?

An excavator swing bearing (also known as a slewing bearing) serves several key functions:

Supporting the weight of the excavator's upper structure;

Enabling 360-degree rotation of the equipment;

Withstanding axial loads, radial loads, and overturning moments;

Ensuring stability and smooth operation during use.

During operation, the excavator's bucket encounters soil resistance while the upper frame continuously rotates, subjecting the swing bearing to sustained high loads. Consequently, the bearing's design, material selection, and manufacturing quality directly impact the equipment's operational reliability.

Common types of excavator swing bearings include:

Single-row ball swing bearings;

Double-row ball swing bearings;

Cross-roller swing bearings;

Three-row roller swing bearings.

Different bearing types are suited to excavators of varying tonnages and operating environments; the specific choice depends on a comprehensive assessment of the equipment model, load requirements, and operating conditions.

Common Signs That an Excavator Slewing Bearing Needs Replacement

Detecting slewing bearing issues early can effectively prevent sudden equipment downtime and more severe mechanical damage.

1. Excessive slewing clearance and noticeable equipment wobbling

This is one of the most common signs of wear in excavator slewing bearings. As the bearing operates over long periods under heavy loads and in dusty environments, the internal rolling elements and raceways wear down, causing the internal clearance to gradually increase.

Excessive clearance leads to the following issues:

Noticeable wobbling during the excavator's rotation;

Reduced stability of the upper structure;

Abnormal vibration during operation.

If the bearing clearance exceeds the manufacturer's permissible limits, inspection is required, and replacement of the slewing bearing should be considered.

2. Abnormal noise during rotation

If the slewing bearing produces distinct sounds such as:

Friction noise;

Metallic clanking or impact sounds;

Abnormal clicking;

Grinding noises;

It may indicate:

Raceway damage;

Wear on balls or rollers;

Insufficient lubrication;

Damage to internal components.

Operators should monitor the equipment's operating condition; if abnormal noise occurs, the issue should be investigated and addressed promptly.

3. Visible damage or lubricant leakage

During routine inspections, pay close attention to:

Seal damage;

Signs of rust or corrosion;

Grease leakage;

Abnormal surface wear.

Regular inspections help determine whether the bearing remains fit for service or if replacement is necessary.

Main Causes of Excavator Slewing Bearing Damage

1. Insufficient Lubrication

Lubrication is a critical factor affecting the service life of slewing bearings; regular lubrication maintains performance and extends longevity. Inadequate lubrication can lead to:

Increased friction in the raceways;

Accelerated component wear;

Rising temperatures;

Reduced service life.

Common issues include:

Improper lubrication intervals;

Use of incorrect grease;

Contaminated grease;

Inadequate maintenance.

2. Prolonged Overload Operation

Excavators often operate in demanding environments—such as mines, construction sites, and earthworks—where the machinery must withstand heavy loads, intense impacts, and high levels of dust.

The following conditions accelerate slewing bearing damage:

Operating beyond the equipment's rated load;

Extended periods of high-intensity operation;

Frequent impact-heavy tasks;

Additional loads caused by uneven ground.

Therefore, actual operating loads must be carefully considered when selecting replacement bearings.

3. Incorrect Installation

Installation methods also impact service life; the manufacturer's installation manual must be followed during the process.

Key considerations during installation include:

Ensuring mounting surfaces are clean and flat;

Tightening bolts to specified torque values;

Ensuring installation precision;

Preventing foreign matter from entering the internal structure.