Bearings
Roller bearings
What are roller bearings?
Roller bearings, which are closely related to ball bearings, have the main function of carrying loads with as little friction as possible. Although both types of bearings are aimed at reducing resistance while moving machine parts, roller bearings are distinguished by their unique form of construction. Instead of round balls that ball bearings use, roller bearings are fitted with cylindrical rollers.
Roller bearings are equipped with single or double rows of rollers, with the double rows offering especially significant increases in radial load-carrying capacity. The versatility in shapes and sizes of these bearings allows them to facilitate efficient transfer of both radial and axial loads, resulting in reduced friction during operations.
What does a roller bearing consist of?
Roller bearings normally consist of an inner and outer ring. Between these rings are the rolling elements (roller bodies). Common rolling elements are cylinders, barrels, cones, diabolos and needles. To ensure that the rolling elements are evenly distributed and do not touch each other, they are contained in a cage. In removable bearings, the cage also ensures that the roller elements do not fall out of the bearing.
Why use roller bearings?
Roller bearings are an essential choice for many industrial applications, primarily because of their ability to reduce friction. This results in multiple operational benefits:
- Cost savings: The use of roller bearings significantly reduces maintenance and service costs.
- Ease of use: The removable design of roller bearings facilitates easy assembly and disassembly, saving users time and increasing efficiency.
- Flexibility of use: Roller bearings facilitate the change of direction of movement without the need for technical adjustments.
- Axial displacement: They allow for axial displacement, providing additional versatility in various applications.
Bearing load
Radial and axial loads are important loads in rolling bearings. When a force acts perpendicular to a shaft, we speak of a radial load. When a force acts in the longitudinal direction of the shaft, we speak of an axial load.
We distinguish the bearing loads into three categories:
- Low bearing load
- Medium bearing load
- Heavy bearing load
Lifespan
Roller bearings feature a line contact. As a result, they will eventually fail due to exhaustion. Standard formulas are available to calculate the lifespan of a roller bearing. However, the environment in which a rolling bearing is located can also play a large role on its life.
More than 90% of roller bearings are lubricated with grease or liquid lubrication is used. For low-load bearings, spray lubrication is also used in some cases.
In doing so, the lubrication film thickness must have a minimum value to achieve the usual life of the rolling bearing. However, because these are precision materials, the lubrication film thickness can remain extremely thin. In many cases, less than 1/50ste part of a human hair.
Water and moisture have an adverse effect on the service life of a rolling bearing. In the event of premature bearing failure, corrosion caused by water is the cause. Water resistance and corrosion protection are therefore an important part of many lubricant specifications.
Dirt, however small the particles, can also significantly shorten the life of a rolling bearing. Not infrequently, a rolling bearing comes into contact with dirt particles because the lubricant was not clean. Grease lubrication should therefore always be done with a new and clean lubricant.
Tapered roller bearings
Tapered roller bearings differ from other types of rolling bearings in that they can support high radial as well as high unilateral axial loads. The cup, cone and rollers of tapered roller bearings have a tapered surface. Their tapered surfaces convert to a single point on the centerline of the bearing.
Tapered roller bearings are suitable for high-load or impact-load applications. These bearings are available in metric series and inch sizes. The metric series are suitable for a bore diameter of 15mm - 200mm. The inch series are suitable for a bore diameter of 15.875mm - 200,000mm.
Tapered roller bearings can take combined loads in one direction. Because radial load generates an axial force, two bearings in an X arrangement, or two or more paired bearings, are used.
There are standard, medium and very conical types. These are distinguished by the contact angle. Medium-conical and metric series are designated by the additional code "C. This code is listed as a suffix after the bearing number.
Tapered roller bearings whose width, smallest inner diameter and cup contact angle are designed according to ISO 355 are indicated by the additional code 'J'. The cones and cups of these tapered roller bearings are interchangeable with other brands when the numbers of these bearings are the same.
When the code 'J' is listed as a prefix, the tapered roller bearing has not been designed according to ISO 355 but has been produced to special tolerances.
Product line
The range of rolling bearings supplied by Neita consists of the following categories:
- 1-row cylindrical roller bearings
- 2-row cylindrical roller bearings
- Multi-row Cylindrical Roller Bearings
- 2-row spherical roller bearings
- 1-row tapered roller bearings
- 2-row tapered roller bearings
- Multi-row tapered roller bearings
- Cup for 1-row tapered roller bearings
- Cone for 1-row tapered roller bearings
