LTZC Successfully Manufactures Heavy Duty Turntable Bearings Designed for Shield Tunneling Machines

In the field of large-scale underground engineering construction, the shield machine serves as the core equipment for modern tunneling operations; its performance directly determines construction efficiency, safety, and overall project quality. Within the complex structural system of a shield machine, Heavy-Duty Turntable Bearings play an absolutely critical role. These bearings must not only withstand immense axial loads and overturning moments but also maintain stable, long-term operation within challenging underground environments.

As a specialized manufacturer of slewing bearings, LTZC has long been dedicated to the research, development, and production of large-diameter, heavy-duty slewing rings. Leveraging advanced manufacturing processes, a rigorous quality control system, and extensive engineering expertise, LTZC has successfully provided customized slewing bearing solutions for a wide range of large-scale shield machines, ensuring their stable and reliable operation across numerous major infrastructure projects.

I. What Are Heavy-Duty Turntable Bearings?

Heavy-duty turntable bearings—often referred to as extra-heavy-duty slewing bearings or turntable bearings—feature bearing walls that are significantly thicker than those of standard bearings. They are critical mechanical components capable of simultaneously withstanding high axial loads, radial loads, and overturning moments. Their weight varies depending on their dimensions, structural design, and materials, but typically exceeds one ton.

Heavy-Duty Turntable Bearings Features

Compared to standard slewing bearings, heavy-duty turntable bearings possess the following distinct characteristics:

Ultra-high load-bearing capacity

High structural rigidity

Large-diameter design

Long operational lifespan

Adaptability to harsh operating conditions

Heavy-Duty Turntable Bearings Applications

Tunnel boring machines (TBMs)

Mining machinery

Port cranes

Offshore engineering equipment

Wind power generation systems

Metallurgical machinery

Within tunnel boring machine systems, heavy-duty turntable bearings are typically employed in the main drive slewing mechanism or the cutter head support structure; their reliability directly impacts the operational stability of the entire machine.

 Structural Components of Heavy-Duty Turntable Bearings

A typical slewing bearing generally consists of the following core components:

1) Inner and Outer Rings

The inner and outer rings constitute the main structural body of the bearing; they serve to house the rolling elements and bear the primary loads. For heavy-duty turntable bearings, the inner and outer rings are typically integrally forged from high-strength alloy steel. Both rings are designed with substantial thickness to ensure sufficient structural strength and fatigue resistance.

2) Rolling Elements

Depending on the specific structural design, heavy-duty turntable bearings may utilize:

Ball structures

Roller structures

Crossed-roller structures

In equipment subject to extreme heavy loads—such as tunnel boring machines (TBMs)—crossed-roller or multi-row roller structures are more commonly employed, as they offer superior load-bearing capacity and rigidity.

3) Cage

The cage serves to uniformly space the rolling elements, thereby reducing friction and enhancing operational stability. Under heavy-load operating conditions, high-strength copper cages or engineering plastic cages are typically utilized.

4) Gear Teeth

Many heavy-duty turntable bearings also feature gear teeth machined into either the inner or outer ring to facilitate power transmission.

Common gear configurations include:

External gearing

Internal gearing

Non-geared (gearless)

In tunnel boring machines, an internal gearing configuration is typically adopted to facilitate power transmission between the main drive motor and the slewing bearing.

II. Real-World Case Study: LTZC Ultra-Heavy-Duty Shield Machine Bearings

In a major urban subway tunnel construction project, the equipment manufacturer imposed extremely stringent technical requirements for the critical bearings of the shield machine:

Diameter: 4200 mm

Maximum Axial Load: 25,000 kN

Overturning Moment: 12,000 kN·m

Continuous Operating Time: >20,000 hours

Ultimately, the project selected LTZC to provide a customized "Heavy-Duty Turntable Bearing" solution.

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 Case：LTZC’s Customized Shield Machine Bearings

Shield machine construction environments are inherently complex; these machines typically operate continuously amidst slurry, dust, and severe shock loads. The primary challenges faced include: extreme static loads, as well as the immense impact loads generated by the cutter head during rock-breaking and tunneling operations. Furthermore, shield machines typically operate at low speeds, in complex environments, and under high-torque conditions—factors that impose exceptionally high demands on bearing lubrication and structural design. The bearings must not only withstand complex load combinations but also ensure long-term, stable operation.

 LTZC’s Shield Machine Bearings solutions

To address the aforementioned operating conditions, the LTZC engineering team conducted multiple rounds of technical optimization, ultimately selecting the following design:

A Three-Row Roller Heavy-Duty Slewing Bearing Structure

Its key advantages include:

Exceptionally high load-bearing capacity

Enhanced resistance to overturning moments

Superior structural stability

Specifications of the Three-Row Roller Heavy-Duty Slewing Bearing

Outer Diameter: 4200 mm

Inner Diameter: 3650 mm

Height: 320 mm

Number of Rollers: 480

Material: 42CrMo

Surface Hardness: HRC 55–60

Following rigorous quality inspections and assembly/commissioning procedures, this slewing bearing was successfully delivered.

Heavy Duty Turntable Bearings Operational Performance

During the actual construction phase of the shield tunneling project, these LTZC Heavy-Duty Turntable Bearings demonstrated outstanding performance:

Continuous operation exceeding 18,000 hours

No signs of abnormal wear

Consistent rotational precision

Vibration levels maintained below design standards

The equipment manufacturer highly praised the quality of LTZC's products and has subsequently expanded its scope of cooperation with the company.

Technical Advantages of LTZC Heavy-Duty Turntable Bearings

1. Large-Diameter Bearing Manufacturing Capabilities

LTZC is a leading manufacturer of slewing bearings in China, boasting over 30 years of accumulated experience in bearing production. We provide customized bearing solutions for sectors such as port machinery, marine equipment, and crane manufacturing. Furthermore, we possess the capability to produce ultra-large-diameter slewing bearings, with a product size range spanning from 300mm to 13,000mm.

2. High-Precision Machining Equipment

The LTZC facility is equipped with a comprehensive array of processing machinery, including specialized large-scale gear hobbing machines, large-capacity heat treatment equipment, and 5-to-13-meter CNC machine tools, enabling us to fully meet diverse customer requirements. These capabilities guarantee the machining precision and structural stability of our Heavy-Duty Turntable Bearings.

3. High-Strength Materials and Heat Treatment Technology

LTZC utilizes high-quality alloy steels—specifically 42CrMo and 50Mn—and can also supply bearings made from other specialized materials upon request. Our heat treatment processes represent a leading standard within the domestic industry; through techniques such as induction quenching, deep-layer hardening, and tempering, we endow our bearings with exceptional characteristics: high hardness, superior wear resistance, and excellent fatigue resistance.

4. Precision Machining Processes

To ensure the rotational precision of our slewing bearings, LTZC employs a multi-stage precision machining workflow complemented by automated inspection systems. Our bearings are manufactured to precision grades ranging from P0 to P5.

Contact LTZC for customized bearing