What is the use of double row ball slewing bearing?

I. What is a Double-Row Ball Slewing Bearing?

The structural design of a double-row ball slewing bearing employs two rows of rolling elements (balls) to distribute the load. These rolling elements establish an eight-point contact configuration with the raceways. The upper and lower rows of rolling elements may consist of balls of either identical or differing diameters. This type of large-scale slewing support structure is specifically engineered to withstand combined loads—comprising axial forces, radial forces, and overturning moments. Compared to traditional single-row structures, it offers superior load-bearing capacity and stability.

From a structural perspective, a double-row ball slewing bearing typically consists of the following core components:

Inner and outer rings (typically available in geared or non-geared configurations)

Two rows of steel balls (which may vary in size to facilitate differentiated load distribution)

Spacer blocks or cages

Sealing mechanisms and lubrication systems

The underlying design philosophy utilizes a combination of "double rows" and "steel balls of differing diameters" to establish a clear division of labor between the primary and auxiliary load-bearing zones. Typically, the larger-diameter steel balls primarily bear the axial loads, while the smaller-diameter steel balls are responsible for distributing the overturning moments; this structural arrangement significantly optimizes the distribution of forces within the bearing.

As a professional manufacturer of slewing bearings, LTZC optimizes the raceway curvature and contact angles in the design and manufacturing of its double-row ball slewing bearings, thereby ensuring that the bearings maintain exceptional fatigue life and operational stability even under complex working conditions.

II. Differences Between Double-Row and Single-Row Ball Slewing Bearings

In practical engineering applications, double-row ball slewing bearings and single-row ball slewing bearings represent two common solutions; they exhibit significant differences in terms of structure, performance, and applicable scenarios.

1. Structural Differences

Single-Row Ball Slewing Bearings: Feature only a single row of steel balls; the structure is relatively simple, and they typically employ a four-point contact design.

Double-Row Ball Slewing Bearings: Feature two rows of steel balls distributed vertically (upper and lower); they typically utilize a differential-diameter design, forming an eight-point contact with the raceways.

Since the double-row configuration incorporates an additional row of rolling elements compared to the single-row design, it offers superior load-bearing capacity and performance.

2. Comparison of Load-Bearing Capacity

Due to the presence of two rows of rolling elements, the load-bearing capacity of double-row ball slewing bearings is typically 30% to 70% higher than that of single-row structures. They perform particularly well in withstanding overturning moments, making them better suited for medium-load applications such as excavators, cranes, or port and marine equipment. Through material strengthening (e.g., 42CrMo quenching and tempering treatment) and raceway induction hardening processes, LTZC ensures that its double-row ball slewing bearings maintain low stress concentration and a high safety factor, even in heavy-load environments.

3. Rigidity and Stability

The double-row structure effectively minimizes swaying and deformation of equipment during operation. It is particularly well-suited for high-altitude work equipment or machinery with long booms—such as cranes, aerial work platforms, and port machinery. In contrast, the single-row ball structure is more suitable for light-to-medium load environments.

4. Cost and Maintenance

Single-Row Ball Slewing Bearings: Lower initial cost and simpler maintenance.

Double-Row Ball Slewing Bearings: Slightly higher initial cost, but offer a longer service life and superior overall cost-effectiveness.

By optimizing production processes and leveraging its mass manufacturing capabilities, LTZC has effectively reduced the manufacturing costs of double-row ball slewing bearings, enabling customers to achieve an optimal balance between high performance and cost efficiency.

Send a quotation to LTZC Bearing

III. What is the use of double row ball slewing bearing?

Double-row ball slewing bearings are typically designed with either external or internal gearing to facilitate easy installation and secure mounting onto equipment. The gear ring interfaces with a reducer to generate rotational drive, thereby enabling the entire platform to rotate. During this rotation process, three distinct types of loads are generated; these loads are borne entirely by the slewing bearing. Consequently, the core function of a double-row ball slewing bearing lies in enabling equipment to achieve both "stable rotation" and "high load-bearing capacity." Specifically, its functions can be summarized in the following aspects:

1. Bearing Multi-Directional Combined Loads

In the context of engineering machinery, equipment typically needs to simultaneously withstand:

Axial loads (the weight of the equipment itself)

Radial loads (wind loads or lateral forces)

Overturning moments (eccentric loads)

Double-row ball slewing bearings distribute these loads across their upper and lower raceways, thereby ensuring safer and more reliable equipment operation.

2. Providing Smooth Rotational Support

Compared to traditional sliding structures, slewing bearings enable low-friction, high-precision rotation. The double-row ball configuration further minimizes vibration, resulting in smoother equipment operation.

LTZC employs high-precision CNC grinding technology in its raceway processing, achieving rotational precision that ranks among the industry's leading standards and effectively enhancing the overall performance of the machinery.

3. Extending Equipment Service Life

Because the double-row ball design distributes the total load generated within the slewing bearing more evenly, contact stress on the raceways is reduced. This, in turn, mitigates wear to a significant degree, delays fatigue failure, and ultimately extends the overall service life of the bearing. In practical project applications, LTZC double-row ball slewing bearings can extend the service life of equipment by 20% to 40%.

4. Enhancing Equipment Safety

For heavy-duty equipment, a failure in the slewing system can pose severe safety risks. The double-row structure offers a higher degree of redundancy; even if localized wear occurs in certain areas, the bearing can still maintain basic operational capabilities—provided, however, that it is not subjected to overloading. Overloading accelerates the wear of the slewing bearing; therefore, if issues such as frequent jamming or abnormal noises are detected during operation, the equipment must be shut down immediately for inspection to prevent safety hazards and avoid damage to the machinery. 5. Adaptability to Complex Operating Conditions

Double-row ball slewing bearings demonstrate exceptional performance in the following environments:

High wind loads (e.g., port cranes)

High shock loads (e.g., mining equipment)

High-frequency start-stop cycles (e.g., automated equipment)

Through optimized sealing and upgraded lubrication systems, LTZC ensures that its bearings maintain stable operation even in dusty, high-temperature, and humid environments.

IV. Application Scenarios for Double-Row Ball Slewing Bearings

1. Construction Machinery Sector

This represents the most typical application scenario for double-row ball slewing bearings, including:

Truck Cranes

Crawler Cranes

Concrete Pump Trucks

In these types of equipment, slewing bearings not only face complex environments characterized by high dust levels and severe shock loads but also bear the critical responsibility of providing rotational support for the entire machine's upper structure; consequently, the sealing and lubrication systems are of paramount importance. LTZC once customized a double-row ball slewing bearing for a European crane manufacturer, which subsequently operated for over 12,000 hours under continuous high-load conditions without a single failure.

2. Port and Logistics Equipment

Port Gantry Cranes

Stacker-Reclaimers

Ship Loaders

These types of equipment typically face severe wind loads, seawater corrosion, and prolonged continuous operation, placing extremely high demands on bearing stability. By optimizing the raceway contact angles, LTZC ensures that its products remain stable even under significant overturning moments. Furthermore, to address these specific environmental challenges, LTZC has developed specialized sealing and lubrication systems that have been successfully implemented and have demonstrated excellent performance in the field.

3. New Energy Equipment

In the new energy sector, double-row ball slewing bearings are increasingly being applied in:

Wind Turbine Yaw Systems

Solar Tracking Systems

While single-row structures are utilized in certain applications, the double-row structure offers distinct advantages in high-power equipment.

4. Mining and Metallurgical Equipment

Ball Mill Rotation Systems

Large-Scale Crushers

Stockpiling Equipment

These types of equipment operate under harsh conditions and are subjected to heavy shock loads. Through enhanced raceway hardness and impact-resistant structural designs, LTZC ensures that its bearings maintain long-term, stable operation within demanding mining environments.

5. Specialized and Automated Equipment

With the advancement of industrial automation, double-row ball slewing bearings are also finding applications in:

Robotic Rotation Platforms

Radar Systems

6. Aviation Ground Support Equipment

Specialized equipment places a heightened emphasis on the performance and precision of slewing bearings. LTZC has supplied numerous sets of slewing bearings for major national projects, thereby accumulating extensive experience in the manufacturing of heavy-duty specialized machinery. LTZC is capable of executing lightweight designs tailored to specific client requirements, achieving an optimal balance between high precision and high rigidity.

Send a quotation to LTZC Bearing

V. Core Advantages of LTZC Double-Row Ball Slewing Bearings

As a professional slewing bearing manufacturer in China, LTZC has accumulated extensive R&D and manufacturing expertise in the field of slewing bearings—particularly regarding ultra-heavy-duty and large-diameter bearings—and stands as a globally trusted supplier of slewing bearing solutions.

1. Customized Design Capabilities: LTZC offers personalized design services tailored to the specific operating conditions of a client's equipment, including raceway structure optimization, customized gear parameters, and specialized machining processes.

2. High-Precision Manufacturing Processes: Utilizing advanced machining equipment and inspection systems, LTZC rigorously controls raceway precision to ensure that every single slewing bearing unit meets national standards.

3. Strict Quality Control System: From raw materials to finished products leaving the factory, LTZC implements a multi-stage inspection protocol—including ultrasonic flaw detection, hardness testing, load testing, and runout testing—to guarantee the high quality and superior performance of its slewing bearings.

4. Global Service Capabilities: LTZC provides reliable supply and technical support to clients worldwide, serving a diverse range of sectors including construction machinery, mining equipment, and the new energy industry.

VI. Conclusion

As a high-performance form of slewing support, the double-row ball slewing bearing plays a pivotal role in modern industrial equipment. Compared to single-row ball slewing bearings, it offers distinct advantages in terms of load-bearing capacity, stability, and service life, making it particularly well-suited for heavy-duty applications and complex operating environments. In this field, leveraging its advanced technology and extensive experience, LTZC not only delivers high-quality products but also provides clients with comprehensive slewing support solutions, thereby facilitating a holistic enhancement of equipment performance.

If you are seeking a reliable solution for your slewing bearing applications, LTZC double-row ball slewing bearings are undoubtedly a trustworthy choice.

Send a quotation to LTZC Bearing