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When a motor shaft system experiences axial loads, these forces are typically handled by the locating bearing on the shaft. If you're using a deep groove ball bearing as the locating bearing, you might run into limitations; its axial load capacity isn't designed for heavy lifting. So, what's the solution for systems needing to withstand significant axial forces? That's where angular contact ball bearings come into play as the locating bearing!
A single-row angular contact ball bearing can only handle axial loads in one direction. This means that for motors, you'll typically see paired angular contact ball bearings arranged in either a face-to-face or back-to-back configuration at the locating end.
Let's look at a common setup: a shaft system configured with face-to-face paired angular contact ball bearings and a deep groove ball bearing.
In this configuration, the right (shaft extension) end uses the face-to-face paired angular contact ball bearings as the locating bearing. The left (non-shaft extension) end utilizes a deep groove ball bearing as the non-locating bearing. In this arrangement, the paired angular contact ball bearings at the locating end are responsible for handling both the axial loads and radial loads of the shaft system. Meanwhile, the deep groove ball bearing at the non-locating end supports the radial loads.
What if your shaft system faces very heavy radial loads? A deep groove ball bearing might not be enough to meet the demand. In such cases, you can easily replace the deep groove ball bearing with a cylindrical roller bearing to handle those higher radial forces. Pretty versatile, isn't it?
When using this bearing configuration, it's crucial that the inner and outer rings of the paired angular contact ball bearings at the locating end are axially locked on both sides.
Here's a critical point: you absolutely must use matched paired angular contact ball bearings, not just any two single-row angular contact ball bearings you pick up. Why is this so important? Because the internal preload after clamping is adjusted by the precise dimensions of the bearings' end faces. Paired angular contact ball bearings are specifically manufactured and treated to ensure that when clamped, they achieve the necessary bearing preload.
Bearing suppliers can provide universally matched angular contact ball bearings or pre-paired angular contact ball bearings. Universally matched bearings mean you can pair any two angular contact ball bearings without special treatment. However, pre-paired bearings are typically supplied as a set and have specific marks on their matching faces. When installing these, it's vital not to separate the pair and to ensure the matching faces are installed according to the marks. Failing to do so can lead to an incorrect internal preload, significantly impacting the bearing's service life. You wouldn't want to shorten your bearing's life, would you?
There are two common configurations for paired angular contact ball bearings: face-to-face and back-to-back. While both bearing sets offer similar load-carrying capabilities, there are key differences:
Face-to-face paired bearings generally have better resistance to tilting moments and offer superior support rigidity.
However, for applications that require greater flexibility or compliance, a back-to-back configuration of angular contact ball bearings might be a better choice. It all depends on your specific needs!
Just like with other bearing arrangements, the non-locating bearing in a setup with angular contact ball bearings at the locating end needs to allow for the shaft's axial expansion and contraction when it heats up. This is absorbed by the non-locating end's ability to move freely in the axial direction.
For instance, in the configuration shown previously (with a deep groove ball bearing), the deep groove ball bearing's outer ring needs to be loosened on both sides, and there should be a relatively loose fit between the outer ring and the bearing housing. To help reduce noise, you can even apply a preload to the deep groove ball bearing using a spring.
What if you're using a cylindrical roller bearing as the non-locating (floating) end? Cylindrical roller bearings are excellent because they allow for good axial movement within the bearing itself. This means you don't need to loosen the outer ring or worry about axial movement when choosing the fit between the outer ring and the bearing housing. You can select a standard or even a tight fit based on your actual requirements. Pretty convenient, right?
For most motor manufacturers, the combination of paired angular contact ball bearings and a radial bearing (like a deep groove ball bearing or cylindrical roller bearing) is a straightforward and easy-to-implement configuration.
However, in some specialized fields, a cross-locating arrangement can be used, where a single angular contact ball bearing is placed at each end of the shaft to handle the axial load. But beware! This structure is typically more complex and requires careful calculation and verification of installation dimensions for the cross-locating angular contact ball bearings. Installation also involves specific adjustments. Because of this complexity, this type of structure is more commonly found in intricate designs like gearboxes, and is less frequently used in general motor shafts.
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