Slewing bearings are core heavy-duty rotating components widely used in construction machinery, lifting equipment, tunneling machinery and garden machinery. They withstand radial loads, axial loads and overturning moments simultaneously to support 360° continuous rotating operation. Exposed to harsh working conditions with dust, rain and gravel impact, and enduring alternating heavy loads and frequent start-stop shocks during operation, slewing bearings are prone to common failures such as raceway wear, gear tooth damage, operating abnormal noise, jamming and loosening. These defects directly affect the operational stability and construction safety of equipment, making slewing bearings key maintenance parts for heavy machinery.

Raceway wear and surface spalling are the most common chronic failures of slewing bearings. Long-term overload operation, frequent rotation start and stop, and excessive instantaneous impact loads cause continuous ultra-high contact stress on internal rolling elements and raceways, gradually forming tiny fatigue cracks on the metal surface. The cracks eventually expand and develop into pitting, peeling and sheet spalling. Lubrication failure serves as a major inducing factor. Aging lubricating grease, insufficient refueling and improper grease selection will break the lubricating oil film, resulting in dry metal friction, accelerating raceway wear, and causing problems such as rotation jamming and uneven rotating resistance.

Seal failure and impurity intrusion greatly aggravate component wear and failure. Slewing bearings rely on outer ring sealing structures to block external pollutants. After long-term operation, sealing rubber strips are prone to aging, cracking and falling off. Sediment, dust and gravel debris in mining and construction sites invade the bearing interior and cause three-body wear that scratches precision raceways and rolling elements. Accumulated impurities will contaminate lubricants, leading to caking and blackening of grease and complete loss of lubricating performance. In severe cases, it will trigger precision failure, operation jitter and rotation deviation of bearings in a short time.

Assembly deviation and abnormal gear meshing are hidden causes of failures. Uneven mounting base flatness, uneven bolt tightening torque and bolt loosening caused by long-term vibration lead to eccentric stress and local stress concentration on slewing bearings, resulting in uneven wear and deformation. Improper meshing clearance between the driving pinion and bearing gear ring will cause gear tooth impact, gnawing and broken teeth, accompanied by continuous abnormal noise and rotation jitter. Daily maintenance includes regular inspection of sealing conditions, fastening bolts and gear meshing accuracy, timely grease replacement and internal impurity cleaning. Standardized maintenance can effectively avoid various failures, extend the service life of slewing bearings, and ensure the safe and stable operation of heavy equipment.