Four-row Cylindrical Roller Bearing

Four-row cylindrical roller bearings are specialized rolling bearings designed for extreme heavy-load applications, engineered to withstand ultra-large radial loads, strong impacts, and long-term continuous operation. Leveraging their core structure of four rows of rollers for collaborative load-bearing, they serve as the "heavy-load support core" for key equipment in industries such as metallurgy, mining, and heavy machinery, providing high-reliability and high-rigidity technical guarantees for stable equipment operation.​

I. Product Structure: Comprehensive Analysis of Heavy-Load Design​

Four-row cylindrical roller bearings maximize load-bearing capacity and operational stability through refined structural design. The composition and characteristics of their core structures are as follows:​

(I) Core Component Design​

Inner and Outer Rings: Manufactured from high-strength alloy bearing steel (e.g., GCr15SiMn, SUJ3) or carburized bearing steel (e.g., 20Cr2Ni4A) using an integral forging process, ensuring uniform internal material structure free from defects such as porosity and inclusions. Both inner and outer rings are machined with four parallel and symmetric raceways. The raceway surfaces undergo super-finishing grinding, with roughness controlled within Ra ≤ 0.1μm and geometric accuracy error ≤ 0.002mm, reducing frictional wear between rollers and raceways and improving load transmission efficiency. Some models feature a "split inner ring" or "split outer ring" design, where the inner ring consists of 2-3 segments and the outer ring can be split as needed. This facilitates installation and maintenance on the main shafts of large equipment, while also allowing adjustment of the gap between inner ring segments to adapt to load distribution requirements under different working conditions and avoid local stress concentration.​

Cylindrical Rollers: Large-diameter rollers are used, with a diameter 20%-30% larger than that of double-row cylindrical roller bearings. A "crowning modification" process is applied, where the middle of the roller is slightly convex and the ends transition smoothly, effectively reducing contact stress at the raceway edges and preventing overload at the roller ends caused by minor shaft deflection. The roller surfaces undergo super-finishing grinding, achieving a hardness of HRC 62-65 and an impact toughness of ≥ 12J/cm², enabling them to withstand high-frequency impacts and vibrations without cracking, spalling, or other failure modes. For extreme heavy-load models, a "full-complement roller" design (without a cage) is adopted, increasing the number of rollers by 15%-20% compared to caged four-row models, further pushing the limits of radial load-bearing capacity.​

Cages: High-strength solid brass cages (material: HPb59-1) are commonly used, manufactured via CNC machining. These cages offer excellent wear resistance and impact resistance, ensuring stable operation under heavy-load and high-speed conditions without deformation or fracture. For dusty and harsh working environments, some models use segmented steel cages assembled via welding, which provide higher structural strength and superior dust resistance, effectively preventing impurities from entering the cage interior and affecting roller operation.​

(II) Sealing and Lubrication Design​

Sealing Structure: For dusty and impurity-prone working conditions (e.g., mining, metallurgy), the product can be equipped with a combined sealing structure of "labyrinth seal + double-lip seal ring". The labyrinth seal blocks most dust, iron filings, and other impurities through multi-layered tortuous channels; the double-lip seal ring, made of nitrile rubber or fluororubber, fits tightly with the inner ring, further isolating liquid impurities such as cooling fluid and oil, achieving an IP65 protection rating and significantly extending the bearing service life.​

Lubrication Design: Dedicated lubrication channels are reserved inside the bearing, supporting both grease lubrication and oil mist lubrication. For grease lubrication, high-temperature extreme-pressure grease (operating temperature: -30℃-200℃) is used, which offers excellent adhesion and wear resistance, meeting the requirements of long-term operation with a single application. Oil mist lubrication delivers atomized lubricating oil into the bearing to form a uniform oil film, providing excellent heat dissipation. It is suitable for high-speed, heavy-load, and continuous operation scenarios, effectively controlling bearing temperature rise and ensuring operational stability.​

II. Product Performance: Core Advantages in Heavy-Load Scenarios​

Four-row cylindrical roller bearings excel in load-bearing capacity, impact resistance, and operational stability. Their core performance parameters and advantages are as follows:​

(I) Load-Bearing Capacity​

Basic Dynamic Load Rating: 70%-90% higher than that of double-row cylindrical roller bearings of the same size. For some large models (e.g., FC60120), the basic dynamic load rating can exceed 5000kN, enabling stable bearing of ultra-large radial loads.​

Basic Static Load Rating: 80%-100% higher than that of double-row cylindrical roller bearings of the same size, capable of withstanding static loads when equipment is shut down and preventing plastic deformation caused by long-term static placement.​

Applicable Load Range: Primarily designed to bear radial loads, with an applicable radial load range of ≥1000kN. Some extreme heavy-load models can withstand radial loads exceeding 5000kN, far surpassing the load-bearing capacity of single-row and double-row cylindrical roller bearings.​

(II) Impact Resistance and Stability​

Impact Resistance: The bearing features high overall structural strength and a large contact area between rollers and raceways, enabling effective absorption of impact energy. It can withstand a single impact load of up to 500kN, stably resisting impacts in scenarios such as crushing hard ore with mining crushers and rolling thick steel plates with metallurgical rolling mills, preventing roller cracking and raceway spalling.​

Operational Stability: High radial rigidity ensures radial deformation ≤ 0.01mm, effectively controlling radial runout of the shaft and guaranteeing equipment operational accuracy. The vibration velocity is ≤ 2.8mm/s, and the operating noise is low (≤ 75dB), reducing the impact of equipment vibration on surrounding components and extending the overall service life of the machine.​

(III) Service Life and Environmental Adaptability​

Service Life: Under normal maintenance and proper lubrication, the service life is ≥20,000 hours. For models used in large hydro generators, the mean time between failures (MTBF) can exceed 30,000 hours, significantly reducing equipment downtime for maintenance and lowering enterprise production costs.​

Environmental Adaptability: The bearing can operate stably within a temperature range of -30℃-200℃. High-temperature models are equipped with high-temperature grease and heat-resistant sealing materials, enabling operation at temperatures ≤200℃. With excellent dust and water resistance, sealed models can operate normally in environments with dust concentration ≤50mg/m³ and minor cooling fluid splashing, adapting to harsh industrial conditions.​

III. Product Model Classification: Adapting to Different Working Conditions​

Based on structural characteristics and application scenarios, four-row cylindrical roller bearings are mainly classified into the following mainstream model series. The structural features and applicable scenarios of each series are as follows:​

IV. Application Fields: Practical Implementation of Product Value​

With excellent heavy-load performance, four-row cylindrical roller bearings are widely used in key equipment requiring high load-bearing capacity. Specific application scenarios are as follows:​

(I) Metallurgical Industry​

Hot Strip Mills and Cold Strip Mills: Used as bearings for work rolls and backup rolls, they withstand radial rolling forces of thousands of kilonewtons during the rolling process, ensuring uniform thickness of rolled steel plates (thickness deviation ≤ ±0.02mm). For example, FC series bearings applied to the backup rolls of hot strip mills can withstand operating temperatures of 300-400℃ and operate continuously without failure, ensuring 24/7 production of the rolling mill.​

Section Steel Mills and Seamless Steel Pipe Mills: Adapted as roll bearings for mills, they bear radial loads and impacts during the rolling of section steel and steel pipes, ensuring dimensional accuracy of rolled products and reducing rolling defects.​

(II) Mining Machinery Industry​

Large Jaw Crushers and Cone Crushers: Used as main shaft bearings, they withstand strong impact loads (single impact load up to 500kN) and radial heavy loads during ore crushing, ensuring a crushing efficiency of ≥1000 tons per hour. Sealed models effectively block ore dust intrusion, preventing internal bearing wear and extending maintenance intervals.​

Mining Conveyors and Hoists: Applied to bearings for conveyor drums and hoist drums, they bear the weight of conveyed materials and radial loads during operation, ensuring stable material conveyance and reducing conveyance interruptions caused by bearing failures.​

(III) Heavy Construction Machinery Industry​

Large Crawler Cranes: Used as slewing bearings and travel mechanism bearings, they withstand radial loads and slewing impacts when the crane lifts hundreds of tons of heavy objects, ensuring safe and stable lifting operations and preventing safety accidents caused by bearing failure.​

Large Excavators: Adapted as bearings for travel mechanisms and slewing mechanisms, they bear radial loads and ground impacts during excavation, adapting to complex working conditions and ensuring efficient operation of the excavator.​

(IV) Energy Equipment Industry​

Large Hydro Generators: Used as main shaft bearings, they bear the weight of generator rotors (≥500 tons) and radial loads during operation, ensuring long-term stable power generation of the generator with an MTBF of ≥30,000 hours, reducing the risk of energy production interruptions.​

Large Wind Turbines: Applied to gearbox bearings, they withstand radial loads and speed fluctuations caused by wind forces, ensuring efficient power transmission by the gearbox and improving wind power generation efficiency.

V. Installation and Maintenance: Ensuring Product Performance
(1) Installation Tips
Before installation, check if the inner and outer rings, rollers, and other components are intact. Clean the installation surface and remove oil stains and impurities. When installing segmented inner rings, ensure that each segment is aligned and the gaps are uniform to avoid uneven load distribution due to installation errors.
For hot installation, heat the bearing to 80-120°C to avoid material performance degradation due to excessive temperature; for cold installation, use professional tools to apply uniform pressure to prevent bearing components from deforming.
After installation, check the radial runout and axial movement of the bearing to ensure it meets the equipment's precision requirements. Also, add an appropriate amount of lubricating grease to prevent dry friction.
(2) Maintenance Suggestions
Regularly check the operating temperature, vibration, and noise of the bearing. If the temperature rises abnormally (more than 15°C above the normal temperature), the vibration intensifies, or the noise increases, stop the machine immediately for inspection and troubleshooting.
Regularly replenish or replace the lubricating grease according to the equipment's operating conditions. When using grease lubrication, replenish once every 3000-5000 hours of operation and replace once every 10000-15000 hours; for oil mist lubrication, ensure stable lubricating oil supply and appropriate oil mist concentration.
Regularly clean the bearing sealing structure, remove dust and impurities from the sealing surface, inspect the sealing components for damage, and replace them promptly if damaged to ensure the sealing effect.

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