LDB Slewing Bearings: Purpose, Types, and Selection Guide
What Is a Slewing Bearing? – Basic Definition
A slewing bearing (also known as a slewing ring or turntable bearing) is a large-scale rolling-element bearing designed to support heavy loads while enabling smooth rotational motion between two structures. Unlike conventional bearings that typically handle only one type of load, slewing bearings are engineered to manage axial loads (vertical), radial loads (horizontal), and tilting moment loads simultaneously within a single, compact component.
Slewing bearings consist of an inner ring and an outer ring, with rolling elements (balls or rollers) arranged between them. Many designs also feature integral gear teeth — either on the inner or outer ring — allowing active rotation via a pinion drive.
At LDB, we have specialized in the design, development, and manufacture of precision slewing bearings since 1999, with processing capabilities ranging from 150mm to 4000mm in diameter.
How Does a Slewing Bearing Work?
A slewing bearing works on the principle of rolling-element rotation combined with load distribution. Here is the step-by-step mechanism:
- Load transmission: The equipment’s weight and operational forces are transferred from the rotating platform through the bearing rings.
- Rolling element engagement: Balls or rollers (depending on the bearing type) roll within precision-ground raceways, converting sliding friction into rolling friction for smooth motion.
- Gear interaction (if equipped): A pinion gear — driven by a hydraulic or electric motor — engages with the bearing’s integral gear teeth, producing controlled rotation.
- Position holding: When the drive stops, the bearing’s internal friction and the drive system’s braking mechanism hold the position.
At LDB, all slewing bearings are produced under strict process control and quality management, certified to ISO9001:2015 by German TUV certification body. Every production step, from raw material incoming to finished product leaving the factory, follows rigorous testing protocols.
What Is the Purpose of a Slewing Bearing? – Core Functions
The primary purpose of a slewing bearing is to enable controlled, heavy-duty rotational movement between two large structures while simultaneously supporting complex, multi-directional loads. More specifically, a slewing bearing serves four core functions:
| Function | Description |
|---|---|
| Load support | Handles axial, radial, and tilting moment loads within one component |
| Smooth rotation | Provides low-friction, controlled movement even under heavy loads |
| Structural connection | Serves as the rotating joint connecting the upper and lower structures of machinery |
| Power transmission | When geared, transfers torque from the drive motor to the rotating platform |
By combining these functions into a single, engineered ring, slewing bearings eliminate the need for complex, multi-bearing kingpost structures — saving valuable space and reducing overall machinery weight.
Key Features of LDB Slewing Bearings
Based on LDB’s decades of manufacturing experience, here are the essential features that define a high-quality slewing bearing:
- High load capacity: Designed to support heavy axial, radial, and moment loads simultaneously
- Compact design: Single component replaces multiple bearings, saving space and weight
- Integrated gear option: Available with external or internal gear teeth for active rotation
- Corrosion resistance: Options include stainless steel (SS 304, 316L, duplex) and protective coatings
- Precision raceways: CNC-ground raceways ensure smooth rotation and long service life
- Multiple sealing options: Protects against dust, moisture, and contaminants in harsh environments
- Long service life: With proper maintenance, many years of reliable operation
- Customizable mounting: Bolt holes and thread configurations to match specific equipment designs
At LDB, we implement strict quality control throughout the production process, with detailed written records and reports for every processing procedure to ensure each product meets customer specifications.
Main Types of LDB Slewing Bearings
LDB manufactures a complete range of slewing bearings to meet diverse industrial requirements:
| Type | Description | Best For |
|---|---|---|
| Four Point Contact Ball Slewing Bearing | Single row of balls contacting raceways at four points | Medium loads, precise rotation, cost-effective solutions |
| Double Row Ball Slewing Bearing | Two rows of balls arranged in parallel | Higher radial and axial load capacity |
| Double Row Different Diameter Ball Slewing Bearing | Two rows with different ball diameters | Applications requiring specialized load distribution |
| Three-Row Roller Slewing Bearing | Separate raceways for axial, radial, and moment loads | Extreme loads in heavy equipment (largest load capacity) |
| Cross Roller Slewing Bearing | Cylindrical rollers arranged in 90° V-shaped raceways | High rigidity, precision applications (robots, machine tools) |
| Flanged Slewing Bearing | Pre-drilled mounting holes and flat mounting surface | Simplified installation, reduced machining requirements |
Each type can be manufactured with or without gear teeth, and with internal or external gear configurations based on application needs. LDB provides both standard and non-standard specifications, with OEM customization available according to customer drawings.
Key Industrial Applications of LDB Slewing Bearings
Thanks to their unique combination of load capacity and rotational precision, slewing bearings are essential components across numerous industries. LDB products are widely used in:
- Industrial robots and AGVs: Precision rotation for steering wheels and robotic arms
- Laser cutting machines: Smooth, accurate positioning for cutting heads
- Mist cannon trucks: 360° rotation for dust suppression
- Aerial work platforms: Safe rotation for elevated personnel baskets
- Solar power generation equipment: Sun tracking for CSP systems
- Construction machinery: Excavators, cranes, and concrete pumps
- Port and material handling: Stackers, reclaimers, and container cranes
- Medical equipment: Precision positioning for diagnostic and treatment devices
LDB’s products are exported to 73 countries and regions worldwide, with major markets in Europe, Asia, America, and Oceania. The company has established agent relationships in India, Iran, Turkey, Russia, and other locations.
How to Select the Right Slewing Bearing for Your Application?
Choosing the correct slewing bearing requires careful evaluation of your specific operating conditions. Based on LDB’s engineering experience, consider these key parameters:
| Parameter | What to Evaluate |
|---|---|
| Load type | Axial, radial, and tilting moment loads – calculate maximum values |
| Rotational speed | Typical operating RPM (slewing bearings are designed for slow rotation) |
| Mounting dimensions | Inner/outer ring diameter, bolt circle, mounting hole pattern |
| Gear requirement | External gear, internal gear, or non-geared? |
| Gear specifications | Module, number of teeth, pressure angle (typically 20°) |
| Sealing needs | Dust, moisture, or chemical exposure level |
| Precision requirement | Rotational accuracy and backlash tolerance |
| Environmental factors | Temperature, humidity, corrosive elements |
Installation considerations (from LDB engineering team):
- Mounting brackets should use a cylindrical structure aligned with the raceway center
- Installation surfaces must be machined flat, with internal stress eliminated after welding
- Use high-strength bolts with proper pre-tightening force (70% of bolt material yield limit)
- Locate the “S” mark (soft zone) in non-load or non-recurring load areas
- Tighten mounting bolts in a star-cross pattern and check rotation after installation
LDB provides technical installation consulting services to ensure proper product operation and timely answers to user questions during installation and use.
Why Choose LDB as Your Slewing Bearing Supplier?
Luoyang Longda Bearing Co., Ltd. (LDB) was established in 1999 and is located in Luoyang, Henan province — China’s premier bearing production base. With nearly 30 sets of production and technical inspection equipment and approximately 60 employees, including a team of experienced designers and technicians, LDB specializes in the design, development, manufacture, and sales of precision slewing bearings and precision slew drives.
Why choose LDB?
- Experience: Over 20 years of manufacturing expertise
- Range: Processing diameter from 150mm to 4000mm
- Certification: ISO9001:2015 certified by German TUV
- Global reach: 90% of products exported to 73 countries
- Customization: OEM service according to customer drawings
- Quality control: Strict process control from raw materials to finished products
- Honors: High-tech enterprise, municipal enterprise R&D center
Notable customers include:
- Terberg Group (Netherlands) – truck manufacturer
- Kubota (Japan) – agricultural machinery
- FASSI Group (France)
- TVH (Belgium) – forklift parts
- Zoomlion (China)
- Jiangshan Heavy Industry (China)
- Beijing Aerospace (China)
Service commitment:
| Phase | Service |
|---|---|
| Pre-sale | Production according to selected models or custom requirements |
| In-sale | Progress control, quality control with written records, proper packing in fumigation-free wooden boxes |
| After-sales | 12-month warranty, installation consultation, satisfaction surveys, user file tracking |
LDB adheres to the corporate vision: “Elaborately Manufacture, Serve The World” — dedicated to providing users with high-quality products and full-range service. The company’s development goal is to become an internationally renowned manufacturer of slewing bearings and slewing drives.
For technical specifications, custom designs, or a project quotation, contact LDB’s engineering team with your slewing bearing requirements.