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Slewing Bearings

Slewing bearings, also known as slewing rings or turntable bearings, are large-diameter bearings that allow for rotational movement between two structures.

They are designed to support axial, radial, and moment loads also with impact design, making them essential in applications where space is limited. Slewing bearings are generally equipped with mounting holes, internal or external gears, lubricating oil holes and sealing devices, so that the main machine design structure is compact, the guidance is simple, and the maintenance is easy.

ZMS is a professional slewing bearing and slewing drive supplier in China for 15 years. Externally geared slewing bearing, Internally geared slewing bearing, Gearless slewing ring are available for us.

Main series:

– Single- row crossed roller series
– Single- row four point contact ball series
– Double-row eight point contact ball bearings series
– Double- row ball series
– Roller and ball combination series
– Three-row roller series

High Load Capacity

Slewing bearings are designed to support significant axial, radial, and moment loads, making them suitable for heavy machinery and equipment.

Rotational Movement

They allow for smooth and controlled rotational movement between two structures, which is essential in applications like cranes and excavators.

Compact Design

Slewing bearings have a large outer diameter relative to their thickness, allowing for a compact design that saves space in machinery.

Versatile Configurations

Available in various designs (e.g., single row, double row, crossed roller, three-row roller) to meet specific application requirements and load conditions.

Integrated Gear Options

Some slewing bearings come with integrated gears, allowing for direct connection to drive systems, which simplifies installation and reduces the need for additional components.

Sealing Options

Many slewing bearings feature seals to protect against dirt, dust, and moisture, enhancing their reliability and performance in challenging environments.

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Customization

High temperature of lower temperature out of -30℃-70℃,we can design for you. Special occasions like sea, dust, powder or coal, we can help you design in material choosing and sealing all aspects.

Advanced equipment

We equipped with most advanced heat treatment make sure the surface hardness of HRC55-62. If you have need special hardness we can also produce by your requirements. 3m CNC drilling and milling machine, CNC machining center, Gear hobbing machine, Vertical lathe to make sure the product with high precision and quality.

Experienced workman and technician

With over 30 years dedication on slewing bearings, and keep innovation, we dedicated on this area to make sure we can deep understanding of customer requirements.

Applications

Drives for Solar Trackers The solar energy sector demands extreme reliability. ZMS Bearing provides specialized slewing bearings and enclosed slewing drives (worm gear drives) designed specifically for single-axis and dual-axis solar tracking systems.

Cranes: Used for rotating platforms or turrets, ensuring smooth operation.

Wind Turbines: Support the yaw mechanism for wind-facing adjustment, critical in renewable energy.

Excavators: Enable 360-degree rotation of the operator cab, enhancing efficiency.
Marine: Ship cranes and offshore platforms.

Industrial Machinery: Including welding turnover jigs and robotic systems, supporting precision manufacturing.

Construction Equipment: Meet heavy-duty rotational needs, like tower cranes.

Materials Handling Equipment: Such as grapples and forklift attachments, used for efficient loading and unloading.

Transport Vehicles: Provide smooth rotation and load support, ensuring stability during transport.

Medical Equipment: Used in devices like CT scanners, requiring compact designs for space limitations.

Aerospace and Defense: Applied in systems needing high reliability and precision, such as radar systems.

Factory View

Frequently Asked Question

What is the difference between a slewing bearing and a standard bearing?

Unlike standard bearings that are press-fitted onto a shaft or into a housing, slewing bearings (slewing rings) feature mounting holes on both the inner and outer rings, allowing them to be directly bolted to the seating surface. Additionally, they are specifically designed to handle massive overturning moment loads and often incorporate integral gear teeth for direct driving.

How do I choose between an internally geared and externally geared slewing ring?

The choice depends on your equipment’s design and space constraints. Internally geared slewing rings are ideal when space is limited and you need to protect the gear drive from harsh external environments (like in excavators). Externally geared rings are chosen when the drive pinion is mounted outside the bearing diameter, making inspection and lubrication of the gears much easier (common in cranes).

When should I use a three-row roller slewing bearing?

A three-row roller slewing bearing should be used in applications facing extreme loads and massive overturning moments. Because it uses three separate rows of cylindrical rollers to independently handle axial loads, radial loads, and moment loads, it offers the highest load-carrying capacity of any slewing bearing design. They are essential for offshore cranes, stacker-reclaimers, and tunnel boring machines.

Top Slewing Bearing Manufacturers Worldwide: A Comprehensive Guide for 2025

Integrated Gear Drives: Internal, External, or Ungeared

To simplify your machine design and power transmission, ZMS slewing rings are manufactured with precision-machined integrated gears, ready to be driven by pinions or hydraulic motors:

External Gear: The gear teeth are machined on the outer diameter of the ring. Widely used in tower cranes, aerial work platforms, and radar systems.
Internal Gear: The gear teeth are machined on the inner diameter, protecting the gear drive from external impact and harsh environments. The standard choice for excavators and heavy forestry equipment.
Ungeared: Smooth rings without gear teeth, utilized when an external driving mechanism is used or for simple free-rotating pivot applications.

Choose Your Internal Architecture for Maximum Capacity

Depending on your load requirements and spatial constraints, ZMS offers three primary rolling element configurations:

Single-Row Four-Point Contact Ball: The most versatile and cost-effective design. It provides excellent dynamic capacity and handles combined loads efficiently. Ideal for light to medium-duty cranes, excavators, and automation turntables.
Single-Row Crossed Roller: Features cylindrical rollers arranged in a 90-degree crisscross pattern. This design offers exceptionally high radial stiffness, zero clearance, and high rotational accuracy. Perfect for machine tools, radar antennas, and tunnel boring machines.
Three-Row Cylindrical Roller: The absolute pinnacle of load capacity. By separating the axial and radial loads across three distinct rows of rollers, this design minimizes roller stress and delivers unparalleled resistance to extreme overturning moments. Mandatory for offshore cranes, bucket wheel excavators, and wind turbine pitch/yaw systems.

Rugged Durability for Harsh Environments

ZMS ensures long-lasting reliability by utilizing high-alloy structural steels (such as 42CrMo or 50Mn). Our raceways and gear teeth undergo advanced induction hardening for maximum wear resistance, and we offer specialized anti-corrosion coatings (such as zinc spraying or marine-grade painting) to withstand salt spray and extreme weather.