What is three-row cylindrical roller slewing bearing?

What is three-row cylindrical roller slewing bearing?

Three-row cylindrical roller slewing bearings, also known as slewing ring bearings with three rows of rollers, feature three separated raceways for upper, lower, and radial loads, enabling each roller row to handle specific load distributions. Their robust structure and large diameter make them suitable for heavy-duty applications such as bucket-wheel excavators, mobile cranes, marine cranes, port cranes, ladle turrets, and other large-scale equipment requiring high load capacity.

Working Principle

These bearings integrate three rows of cylindrical rollers into a precision slewing support system, designed to efficiently manage axial loads, radial loads, and tilting moments. The core structure consists of an inner ring, outer ring, three roller rows, and cages:

Upper and lower horizontal rollers: Aligned parallel to the rotational axis, they primarily bear axial loads (Fₐ) and tilting moments (M). Logarithmic curve crowning (per ISO 10307 standards) optimizes contact stress distribution.

Middle vertical rollers: Positioned perpendicular to the axis, they exclusively handle radial loads (Fᵣ). High-precision grinding (Ra ≤ 0.8μm) ensures raceway conformity.

This configuration splits combined loads into three independent directions, boosting load capacity by 40–60% compared to traditional double-row bearings while reducing weight by 20–30% through 3D load distribution.

Key Technical Features

Materials & Heat Treatment

Rings: 42CrMo alloy steel (tensile strength ≥1080MPa, HRC 30–35), induction-hardened (3–5mm depth, HRC 55–62) for wear resistance.

Rollers: GCr15 bearing steel (1.0–1.1% carbon), bainitic quenched (160℃×3h) to form retained austenite, extending fatigue life to 1×10⁷ cycles.

Cages: PA66 injection-molded, friction coefficient ≤0.15, operating temperature ≤150℃.

Precision Control

Radial runout: ≤0.05mm (P5 class).

Axial play: ≤0.03mm.

Gear ring accuracy: AGMA Q8, pitch cumulative error ≤±0.08mm.

Sealing & Lubrication

Seals: Double-lip fluoroelastomer (70±5 Shore A) with labyrinth grooves, IP67 protection.

Lubrication: Forced oil circulation (ISO VG 220), 40–60℃ temperature control, 15–20L/min flow.

Applications

Marine Engineering

3500-ton full-slewing cranes: 17.75m-diameter split design (168-ton weight), 200,000 ton-m safety load, with multi-segment splicing (error ≤0.02mm). Example: Shanghai Zhenhua Heavy Industry’s 3500-ton crane bearings, CCS-certified for ±25° tilt resistance.

Metallurgical Machinery

Ladle turrets: 500-ton capacity, 100,000-cycle lifespan, preloaded with double-row tapered rollers (50–80kN) to eliminate play.

Tunnel Boring Machines (TBMs)

12m-diameter main bearings: Symmetric roller arrangement, 120MN axial capacity, integrated temperature sensors (±0.5℃ accuracy).

Performance Advantages & Innovations

Load Capacity

Axial load (Fₐ): 275–25,800kN (LDB standard).

Radial load (Fᵣ): 12,400–15,900kN (18m models).

Tilting moment (M): 6,890–25,800kN·m.

Design Innovations

Roller crowning: Unidirectional logarithmic curves (R=500mm) reduce contact stress by 30%, extending fatigue life by 1.5x.

Split structure: Segmented rings (up to 12 segments) with pin positioning (±0.01mm) for on-site maintenance.

Smart monitoring: Strain gauges (2mV/V sensitivity) and accelerometers (±50g range) capture real-time vibration (0–10kHz).

Manufacturing Breakthroughs

Induction hardening: Multi-frequency heating (5–15kHz) ensures ≤5HRC/mm hardness gradient.

Directional assembly: Rollers sorted by diameter (±0.002mm tolerance), circumferential error ≤0.05mm.

Maintenance & Fault Diagnosis

Preventive Maintenance

Lubrication: NLGI 2 grease (260℃ drop point) every 200 hours.

Seals: Ultrasonic leak detection (±0.1dB) every 500 hours.

Gear wear: Laser thickness measurement (±0.01mm) for tooth wear.

Fault Cases

Overheating: Infrared thermography (0.1℃ resolution) identified roller jamming in a port crane; resolved by cage replacement.

Vibration: Spectral analysis detected 1x frequency harmonics, leading to laser cladding repair (0.5mm layer, HRC 58) for 0.3mm surface spalling.

Development Trends

Materials

Ceramic matrix composites (Si₃N₄) rollers: 60% lighter, 200% higher modulus.

Functionally graded materials (FGM): HRC 60 surface with ≥40J/cm² core toughness.

Smart Technology

MEMS sensors (±0.1%FS accuracy) monitor load, temperature, and lubrication.

Digital twin technology: ANSYS Workbench models predict remaining useful life (RUL).

Sustainability

Chrome-free passivation: Phytic acid coatings (1–3μm) replace chromate processes.

Remanufacturing: Laser cladding restores 85% material usage from worn bearings.

Pricing Analysis

Prices vary significantly based on size, complexity, and application:

Base models: 3R25-E-0500 (665mm OD, 2750kN axial load) costs 22,000–45,000 yuan (industrial robots).

Heavy-duty models: 3R45-E-2500 (2820mm OD, 25,800kN axial load) ranges from 180,000–350,000 yuan (ladle turrets).

Customization: Split designs (+20–30%), smart sensors (+15–25%), and ceramic rollers (2.5–3x steel cost).

Brand premiums: SKF’s 3R45-E-2500 costs 450,000–600,000 yuan, 1.8–2.5x domestic equivalents.

Cost Drivers

Materials: 30–40% of costs (ESR steel adds 20% for large sizes).

Processes: 15–20% for heat treatment; 8–12% for certifications.

Market trends: 12% steel price hikes and 35% wind energy demand growth pushed 2024–2025 prices up 15–20%.

Procurement Tips

Volume discounts: 8–15% for bulk orders.

Lead times: 8–12 weeks for standard models; 16–20 weeks for custom designs.

Supplier of three-row cylindrical roller slewing rings

As a global leader in three-row cylindrical roller slewing bearings, LTZC (Luoyang Bearing Manufacturing Co., Ltd.) specializes in delivering high-reliability, customized slewing support systems for heavy machinery. With over two decades of industry expertise, we serve as a core supplier to sectors including marine engineering, metallurgical machinery, and tunnel boring equipment. Our products span a full range of diameters from 665mm to 18 meters, supported by an annual production capacity exceeding 50,000 metric tons. Backed by advanced manufacturing capabilities and rigorous quality standards, LTZC combines precision engineering with innovative designs to meet the most demanding operational requirements worldwide.

Three-row cylindrical roller slewing bearings are critical for heavy machinery, evolving toward lightweight, smart, and sustainable solutions. Chinese manufacturers like LTZC are challenging global leaders through cost-effective innovation, while international brands maintain premium pricing via patented technologies. Future growth hinges on extreme-condition adaptability and lifecycle optimization.