Fault diagnosis and preventive maintenance technology for slewing bearings.

What is Slewing Bearing?

Slewing bearing is a large bearing capable of bearing axial force, radial force and overturning moment at the same time, and is mainly used to achieve 360° rotation or oscillation of equipment components. Its core structure includes the inner ring, outer ring, rolling elements (balls or rollers) and cages, which are widely used in construction machinery (tower cranes, excavators), wind power generation (tower yaw), rail transit (shield machine cutterhead), aerospace (radar base) and other fields, and are known as the "joints" of industrial equipment.

Features of Slewing Bearings

Composite load-bearing capacity

1. It can withstand axial forces (vertical loads), radial forces (horizontal loads) and overturning moments (torques that resist rollover) at the same time. For example, wind power yaw bearings need to carry both the weight of the tower (axial force), the impact of strong winds (radial force) and the rotational bending moment of the wind turbine (overturning moment).

2. The structure type is suitable for different loads: the single-row ball type is suitable for balanced loads, and the three-row column type can cope with over-heavy loads (such as harbor cranes).

High-precision rotation and positioning

1.The rotation accuracy of the crossed roller structure (roller angle 90°) can reach ±0.05°, which meets the needs of precision scenarios such as cutterheads and medical equipment of shield machines.

2.The integrated design of the ring gear (external gear/internal gear) reduces the error of the transmission chain and directly drives to improve the efficiency.

Sealing and protection performance

1.Multi-seal combination (labyrinth + double lip seal) can effectively block water and dust infiltration, and dusty environments need to be equipped with purging devices.

2.For special environments, stainless steel or zinc-aluminum coating (e.g. offshore wind power corrosion resistance) can be selected.

Long life and maintenance-free

1.Carburizing steel (20CrMnTi) or high-strength alloy steel (42CrMo) combined with quenching process (HRC 58-62), wind power bearing life of more than 20 years.

2.Built-in lubrication channel and grease injection hole, partially support automatic lubrication, reduce downtime maintenance.

Modularity and integration

1Integrated hydraulic cylinders, sensors (temperature/vibration monitoring) or drives, such as hydraulic integrated bearings, reduce the size of the machine.

2Toothless design (e.g. magnetic coupling) reduces noise and is suitable for medical equipment.

Lightweight and green manufacturing

1Carbon fiber composite outer ring weight reduction of 15%, reducing energy consumption.

2Dismantling design achieves 90% material recycling, in line with circular economy requirements.

Fault Diagnosis Technology

Anomaly signal analysis

Vibration monitoring: Accelerometers are used to collect time/frequency domain signals, and spectrum analysis is used to identify fault frequencies (such as rolling element passing frequency, cage resonance), and determine the location of spalling, cracks, or wear.

Noise Detection: Acoustic emission technology is used to capture high-frequency stress waves and locate early microcracks or lubrication failures.

Temperature anomalies: Infrared thermography monitors temperature rises, which can indicate increased friction or poor lubrication.

Oil analysis

Ferrometer detection: analyze the shape, size and composition of abrasive particles (such as Fe and Cr content) in lubricating oil, and determine the wear stage of rolling elements or raceways.

Viscosity & Contamination: Regularly test oil viscosity changes and particulate contaminants (ISO 4406) to avoid abrasive wear due to impurities.

Visual and tactile examination

Surface defects: Visual or endoscopic inspection of raceways for peeling, rust and seal breakage.

Abnormal clearance: manually rotate the bearing, sense the stagnation or abnormal noise, and cooperate with the dial gauge to measure whether the axial/radial clearance is out of tolerance (if the clearance of C3 increases to C4, an early warning is required).

Intelligent diagnostic system

Integrate Internet of Things sensors to collect vibration, temperature, and load data in real time, and combine AI algorithms (such as convolutional neural networks) for pattern recognition to achieve early fault classification and life prediction.

Preventive Maintenance Strateg

Lubrication management

Lubricant selection: Lithium grease (high temperature), polyurea grease (long cycle) or synthetic oil (high speed) are selected according to the working conditions to avoid gelatinization caused by mixed grease

Lubrication cycle: Determine the frequency of grease injection according to the DN value of the bearing (inner diameter × speed), and use the automatic lubrication system to accurately control the amount of grease injection (excessive amount is easy to cause seal failure)

Seal maintenance: regularly clean the labyrinth sealing groove and replace the aging rubber sealing ring (such as nitrile rubber temperature resistance -30~120 °C).

Load & Installation Optimization

Load monitoring: Install a stress sensor to monitor the actual load distribution and avoid eccentric load or overload (more than 70% of the rated static load C0 needs to be warned).

Installation accuracy: ensure that the flatness of the mounting surface ≤ 0.1mm/m, and the bolt preload is evenly loaded step by step according to the torque method (such as the torque error of 10.9 bolts ±5%).

Alignment correction: The laser alignment instrument adjusts the coaxiality of the main engine and the bearing to reduce the edge stress concentration caused by the overturning moment.

Environmental Adaptability Protection

Anti-corrosion treatment: zinc-nickel plating (thickness ≥ 20μm) or spraying epoxy resin in coastal or chemical environments.

Dustproof design: External dust cover is installed under multi-dust conditions, or IP65 sealed bearings are selected.

Temperature control: Equipped with heat sink or forced air cooling system in high temperature conditions, low temperature grease is used in low temperature environments (-40°C can still be started).

Predictive maintenance technology

Life model: Calculate the modified life based on the Lundberg-Palmgren theory or ISO 281 standard, and optimize the maintenance plan based on the actual load spectrum

Digital twin: Build a 3D simulation model of the bearing, and simulate the stress distribution under extreme conditions through finite element analysis (FEA) to identify weak links in advance.

Handling of Typical Cases

Gear ring breakage: check the gear meshing clearance (recommended 0.05~0.1× modulus), use carburizing and quenching tooth surface (hardness HRC58-62) and regularly detect flaws.

Raceway spalling: If the spalling area > 1cm², the bearing needs to be replaced, and the lubricant cleanliness and load are checked to see if the load exceeds the standard.

Cage breakage: Nylon cage (impact resistant) or brass solid cage is preferred to avoid centrifugal force overload under high-speed working conditions.

The Maintenance of Economic Assessment

Cost model: Optimize maintenance cycles by comparing preventive maintenance costs (labor, spare parts) with downtime losses (production interruptions, collateral damage).

Spare parts inventory: Establish safety stock of key spare parts based on failure rate analysis (Weibull distribution) to reduce the impact of sudden failures.

Through the comprehensive application of the above technologies, the reliability of slewing ring bearings can be significantly improved, the unplanned downtime rate can be reduced, and the service life can be extended to 1.5~2 times of the design life.

Slewing BearingS Supplier

LTZC is a professional manufacturer of slewing bearings, slewing rings, slewing drives and bearing parts, providing high-quality and advanced slewing bearings to customers worldwide, if you are looking for slewing bearings for your project, please feel free to contact us.