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Slew Ring Bearings: How Do They Work?

Slew ring bearings, also referred to as slewing bearings, slewing rings, or turntable bearings, are forms of bearings designed to allow rotational motion between several components. They are commonly used in industrial, agricultural, and heavy-duty forestry equipment. Other areas of application include robotics, material handling equipment, and mining rigs. So, how exactly do slewing ring bearings work?

The Mechanics of Slew Ring Bearings

A slew ring is designed to work in a system of balls, caging, raceways, and mounting. It features two rings on the main structure or the turntable bearing. The ring on the outer side lies flat on a motionless surface and is fitted using screws. Then, the inner ring is fixed on a turning object using a sort of adapter or bracket. It runs in a rotational manner as the outer ring remains fitted on the mounting face. Think of it the way a crane turns without changing position.

The motion between the upper and lower rings is facilitated by sliding or rolling elements. If the slew ring is designed to work on ball bearings, it comes with additional parts, such as load plugs and seals that facilitate greasing. Notably, slew rings that use ball bearings create very low friction.

However, slew rings that use sliding movement rely on replaceable liners (plastic) that are installed between them. Again, slew rings that use plastic linings are recommended for flat horizontal applications. For equipment designed for vertical motion, the ball-based bearings will be a better option.

To facilitate applications with slew ring bearings, they feature gears on the outer ring. Then, they can be moved by using any of the following methods:

  • Worm gears.
  • External gear.
  • Drive plate coupling.
  • External belt.

Insulation when Using Slew Ring Bearings

If you are using slew ring bearings with plastic liners, they are electrically insulating. Therefore, no additional insulation is needed. This means that you can run cables at the center of the slewing without the need of additional polymers or grounding. However, slew rings that use ball bearings will require additional polymer lining to prevent current from running to the rings from the cables.

How to Select the Right Slew Ring Bearings

Now that you know how slew ring bearings work, how do you select the best? Here are some useful tips to consider:

  • Look for the slew ring bearings designed with high-quality materials.
  • Follow the recommended slew ring bearings for your equipment.
  • Go for the bearing that can handle the maximum load. Ensure to include static and dynamic loads exerted on the bearing.
  • Only buy the bearings designed by top brands for quality assurance.

This post has demonstrated that, like all other bearings, the slew ring bearings serve connections between two structures to support movement and load transmission. Although they were traditionally thought to be very large types of bearings, the truth is that they are not. Because they are available even with very small bore sizes of 50 mm, they can be an excellent pick for a lot of applications in your facility, including robotics. Remember always to maintain them in top condition, especially ensuring they are greased correctly.