Brief introduction of slewing bearing types

Slewing bearing is a common and essential component of tools and machinery. It is an important part, which provide for free linear movement of the moving part. Most slewing bearings facilitate the desired motion by minimizing friction. And slewing bearings are classified broadly. This article would introduce you different types of slewing parts and application of slewing bearing. These information would help you learn about slewing bearings. Let’s start.

Here are main points of this article:

• Definition of slewing bearing

• Different types of slewing bearing

• Application of slewing bearing

Definition of slewing bearing

A slewing bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. Slewing bearings can prevent a motion by controlling the vectors of normal forces that bear on the moving parts.

A slewing bearing or slewing ring is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill. (To "slew" means to turn without change of place.) Compared to other rolling-element bearings, slewing bearings are thin in section and are often made in diameters of a metre or more; the slewing bearings on the Falkirk Wheel are 4 meters diameter and fit over a 3.5 metre axle. Slewing bearings often use two rows of rolling elements. They often use three race elements, such as an inner ring and two outer ring "halves" that clamp together axially. Slewing bearings are often made with gear teeth integral with the inner or outer race, used to drive the platform relative to the base.

Different types of slewing bearing

1. Light slewing bearing

The light slewing bearing has the same structure with four point contact ball slewing bearing, but the weight is light and could be used for some light type machinery applications. It could save some cost if the load capacity is low. The materials of the light load slewing ring are mainly 50Mn, 42CrMo and C45. The light duty slewing ring is low profile and has an excellent performance. With the open center, slewing bearings become ideal structural components.

2. Flange slewing bearing

Flange bearing is a special slewing ring bearing, it can have one flange in the outer ring, or one flanged bearing in the inner ring, even it can have one flange in both inner ring and outer ring.Flange slewing bearings are widely used on tow trucks, and other applications are the same as trailer bearing, such as lifting & transport machinery, mining machinery, construction machinery, excavator, concrete machine, paper machine, plastic and rubber machine and steel plant.

3. Four point contact ball bearing

Four-point contact bearings are single-row angular contact ball bearings and therefore require significantly less space in an axial direction than double-row designs.

The bearings comprise solid outer rings, split inner rings and ball and cage assemblies with brass or polyamide cages. The two-piece inner rings enable a large complement of balls to be accommodated. The inner ring halves are matched to the particular bearing and must not be interchanged with those of other bearings of the same size. The outer ring with the ball and cage assembly can be mounted separately from the two inner ring halves.

4. Double row ball slewing bearing

The double row ball slewing bearing has two row steel balls for structure, it has bigger load capacity comparing to single row type slewing bearing and better safety factor, and it could bear axial load, radial load and tilting moment at the same time. Double row ball slewing ring has three seat rings, the steel ball and the spacing block can be directly arranged into the upper and lower races.

5. Three row roller slewing bearing

The three row roller slewing bearing has three row raceway, the rolling element is steel roller. This structure could bear the heaviest load comparing to other structure bearing type. Usually the triple row roller slew bearing is used for some heavy duty machinery. Three-Row Roller Slewing Ring is equipped with seat-rings, upper orbit. Neither orbit and radial orbit is separated individually, it makes the load of each row of the rollers can be confirmed.

Application of slewing bearing

Large diameter slewing ring bearings are critical components in many applications. Military applications include tank turrets, missile launchers, communication antennae, precision radar antennas, and gun mounts. Common commercial applications include aerial lifts, hydraulic excavators, boom cranes, and tunnel boring machinery. 

In lifting equipment, the large diameter bearing serves as a joint between the upper structure and the undercarriage, providing a means of 360-degree rotation. Lifting devices typically have a complex load spectrum: the slewing ring bearing can simultaneously handle all combinations of thrust, radial, and tilting moment loading. The use of a slewing ring bearing provides yet another benefit: its shaftless design eliminates the need for a spindle or kingpost. The center of the bearing remains open to allow passage of various hydraulic and control components.

The short passage introduces briefly what slewing bearings are. It is an essential part in many machines, and usually used for large equipment. There are so many types of slewing rings. Sometimes people would cost so much time when selecting suitable and high-quality slewing bearings. So the article will surely help you. If you have any other questions, you can contact with us anytime.