Crossed Roller Slewing Bearing for Deck Cranes Passes Marine Inspection — LTZC Bearings

As a National High-Tech Enterprise with over 30 years of deep-rooted expertise in the field of heavy-duty slewing bearings, LTZC Bearings specializes in the R&D, manufacturing, and sales of large-scale and super-large slewing bearings. Our product portfolio encompasses a comprehensive range of slewing bearing types—including crossed roller, four-point contact ball, and three-row cylindrical roller designs—with precision grades reaching the P4 level. Widely utilized across sectors such as marine and port operations, construction machinery, wind power generation, and tunnel boring machines, our products are exported to over 20 countries and regions worldwide. Most recently, LTZC Bearings’ independently developed Crossed Roller Slewing Bearing successfully passed both the ISO standard for marine crane slewing bearings and the maritime inspection certification of the China Classification Society (CCS). Designed to be compatible with 30-ton to 50-ton marine deck cranes, this product offers global marine crane users a highly reliable and cost-effective slewing bearing solution.

I. Client Requirements: Customized Cross-Roller Slewing Bearing

LTZC Bearings received an urgent customization request from a renowned international manufacturer of marine cranes. The request called for the supply of a cross-roller slewing bearing to serve as a key component for a marine deck crane. The core technical specifications are as follows:

Compatible Crane Model: 35T-30M Marine Deck Crane

Bearing Type: Cross-roller slewing bearing; features rollers arranged in a 90° cross configuration, capable of simultaneously withstanding axial loads, radial loads, and overturning moments.

Dimensional Parameters: Outer Diameter Φ1850mm, Inner Diameter Φ1500mm, Height 220mm.

Load Capacity: Rated Static Load ≥ 2500kN, Rated Dynamic Load ≥ 1800kN, Overturning Moment ≥ 1200kN·m.

Precision Class: Class P5 (Radial Runout ≤ 0.15mm, Axial Runout ≤ 0.20mm).

Environmental Adaptability: Salt Spray Corrosion Resistance ≥ 5000 hours; Operating Temperature Range: -30°C to +60°C.

Certification Requirements: Must comply with marine crane slewing bearing standards and successfully pass the Type Approval Inspection by the China Classification Society (CCS); authoritative inspection reports must be provided to facilitate the classification of the vessel.

Lead Time: Design, manufacturing, inspection, and delivery to be completed within 8 weeks.

II. LTZC Customizes Crane Cross-Roller Slewing Bearings for Clients

Drawing upon over 30 years of R&D experience in heavy-duty slewing bearings, the LTZC technical team has undertaken a specialized technical initiative. They have implemented optimizations and innovations across seven key dimensions—material selection, structural design, heat treatment processes, machining processes, sealing systems, lubrication systems, and anti-corrosion treatments—to ensure that product performance fully complies with both ISO standards and CCS (China Classification Society) marine inspection standards.

2.1 Material Selection: 

Utilizing high-strength, high-toughness, and corrosion-resistant special steels to establish a solid foundation for performance. Bearing material is the critical factor determining load-bearing capacity, fatigue life, and corrosion resistance; based on specific client requirements, LTZC selects 42CrMo steel for its bearings.

2.2 Structural Design: 

Optimizing the cross-roller arrangement to enhance rigidity and load-bearing capacity. The core advantage of a cross-roller slewing bearing lies in its 90-degree crossed arrangement of rollers, which enables it to simultaneously withstand multi-directional loads while offering high rigidity and a compact structure.

2.3 Heat Treatment Process: 

Employing precise temperature control to ensure uniform hardness and minimize deformation. Heat treatment processes are utilized to precisely control the hardness, wear resistance, and fatigue life of the bearing raceways and rollers. For large-sized bearings, heat treatment poses a significant risk of deformation, warping, and uneven hardness—factors that can severely compromise precision and performance. To mitigate these risks, LTZC utilizes CNC-controlled atmosphere heat treatment furnaces to execute a comprehensive process involving segmented quenching, deep cryogenic treatment, and high-temperature tempering.

2.4 Machining Process: 

Combining high-precision equipment with rigorous precision inspection to ensure P5-grade accuracy. The LTZC facility is equipped with a variety of CNC vertical lathes, enabling precise control over dimensional accuracy, raceway precision, and surface roughness.

2.5 Sealing System Design: 

Incorporating multiple seals and anti-corrosive materials. Seal failure in marine bearings is a primary cause of corrosion and grease degradation. To prevent the ingress of seawater, salt spray, and dust into the bearing interior, LTZC employs a composite sealing structure comprising a triple-labyrinth seal, a contact seal, and a dust ring, utilizing sealing materials specifically designed for resistance to seawater and corrosion. 

2.6 Lubrication System Design: 

Long-Life Lubrication + Corrosion-Resistant Grease. In offshore operating environments, grease is prone to dilution and degradation by seawater, leading to accelerated bearing wear. LTZC employs a centralized lubrication system combined with a long-life, corrosion-resistant grease solution. Furthermore, a specialized lubrication channel design ensures the uniform distribution of grease across the contact surfaces between the raceways and rollers, thereby forming a stable oil film that effectively reduces friction and wear.

2.7 Anti-Corrosion Treatment: 

Multi-Layer Anti-Corrosion Process — Salt Spray Resistance ≥ 5000 Hours.

To meet the CCS (China Classification Society) maritime inspection requirements for salt spray corrosion resistance (≥ 5000 hours), LTZC implements a triple-layer anti-corrosion process comprising surface pre-treatment, anti-corrosion coating, and passivation treatment.

Contact LTZC to learn more about our customized solutions.

Following the completion of product R&D and manufacturing, this cross-roller slewing bearing underwent a comprehensive series of maritime inspections, conducted in strict accordance with ISO standards and the specifications of the China Classification Society (CCS). With official inspectors witnessing the entire process, the unit successfully completed a full spectrum of tests—including documentation review, dimensional inspection, material flaw detection, multi-scenario bench load testing, continuous rotation performance testing, a 5,000-hour neutral salt spray corrosion test, sealing and lubrication reliability testing, and high/low-temperature environmental adaptability testing. With all performance indicators meeting—or even exceeding—the required standards, the product successfully obtained the CCS Type Approval Certificate and the corresponding inspection reports.

III. Slewing Bearing Manufacturer — LTZC Bearings

Established in 1992 and headquartered in the Luoyang Bearing Industrial Park in Henan Province, LTZC Bearings is a recognized National High-tech Enterprise, a Technology-based SME in Henan Province, and the host institution for the Henan Engineering Technology Research Center for High-Load Bearings. With over 30 years of deep expertise in the field of heavy-duty slewing bearings, the company specializes in the R&D, manufacturing, and sales of large-scale, extra-large, and high-precision slewing bearings. Our products achieve a precision grade of P4 and feature outer diameters ranging from Φ200mm to Φ13,000mm. Widely utilized across sectors such as marine and port operations, construction machinery, wind power, tunnel boring machines, metallurgy, and mining, our products are exported to over 20 countries and regions worldwide, establishing LTZC as a leading enterprise in China's heavy-duty slewing bearing industry.

3.1 Modernized Bearing Manufacturing Facility

The company has invested in advanced production and inspection equipment, boasting an annual output of over 2,000 sets of various slewing bearings—including more than 500 sets of marine-grade slewing bearings. This capability allows us to respond rapidly to customers' customized requirements and ensure short lead times for delivery.

3.2 Rigorous Quality Control System

LTZC has established a strict, end-to-end quality control system covering the entire production process. Finished products undergo comprehensive performance testing, with all test data being fully traceable. The company holds certifications for the ISO 9001 Quality Management System, ISO 14001 Environmental Management System, and ISO 45001 Occupational Health and Safety Management System. We implement quality inspections at every stage—from raw material procurement to the final delivery of finished products—while adhering to a steadfast quality policy: "Quality First, Customer Foremost, Continuous Improvement, and Zero Defects."

3.3 Comprehensive After-Sales Service System

LTZC has established a comprehensive after-sales service system designed for rapid response, providing global customers with one-stop after-sales support. We offer complimentary services including product selection consultation, operating condition analysis, customized design, and technical solution formulation, assisting customers in selecting the optimal slewing bearing products for their needs. Furthermore, we provide on-site installation guidance, commissioning support, training, maintenance and upkeep guidance, as well as 24-hour online technical support.

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