An Introduction to Radial Bearing

Posted on May 1, 2021

Radial Bearing

Rolling element bearings work with low rolling friction, making them suitable for axles. They are categorized into a type of rolling-element bearing that is mainly utilized to support radial loads.

What Is a Radial Bearing?

A radial bearing is a type of rolling-element bearing that is mainly utilized to support radial loads. Some classic types of radial bearings include deep groove ball bearings, needle bearings, and cylindrical type roller bearings. What is the rolling element bearing? Rolling element bearings can be subdivided into radial bearings, angular contact bearings, or thrust bearings depending on the load type that the bearing is going to support. 

Rolling element bearings work with low rolling friction, making them suitable for axles. When carrying relatively light loads like bicycles, ball bearings are widely used. On the other hand, when intending for supporting heavier loads or the loads might be significantly affected during cornering, tapered rolling bearing is preferred to use, for example, in a truck. As for carrying axial loads like vertical shafts applications, thrust bearings are the preferred bearings. Some classic styles of thrust bearings include thrust ball bearings, cylindrical roller thrust bearings, spherical roller thrust bearings, and tapered roller thrust bearings. 

In some heavy-duty applications that low friction is required, hydrostatic and magnetic bearings, which have no rolling element in the structure, are also popular to be used. Although in some conditions radial bearings have the ability to carry limited thrust loads, the main use of radial bearing, as the name implies, is for radial applications.


What to Consider When Using Radial Bearings?

As mentioned, radial bearings create low friction during operations. These radial bearings accomplish their mission with nominal maximum loads and high performance. To have as long lifespans as possible, bearings should be appropriately lubricated with lubricants such as oil and grease. 

The proper lubricants should at least have minimum dynamic viscosity that is suitable for particular radial bearings. The lubrication can be incorporated with oils, which have benefits including allowing higher loads than nominal maximum loads. However, the oil should be maintained in bearings in different methods otherwise radial bearing’s operation generally tends to run out of this type of lubricant. 

Using oil as the lubrication element is suitable for applications that perform the mechanical operations at a relatively lower temperatures, where the oil will not become hotter than 50 °C, and in the conditions, the oil should be regularly replaced once a year. In applications where the oil becomes hotter than 50 °C but cooler than 100 °C, oil should be replaced four times every year. Also, in the engines of vehicles, the lubricants become 100 °C, so the engine is equipped with an oil filter to keep the quality of the oil, by the help of the accessory, the oil can be replaced less frequently than oils in radial bearings.

In the case that the radial bearing is utilized under oscillation, oil is an ideal choice for lubrication. When grease is required for lubrication, it is recommended to use grease with higher bleeding speed and lower base oil viscosity. In addition, when applying grease lubrication, the composition should be suitable for the parameters that are created in the operation.

:: Read more: What Are the Types of Bearing?


Different Types of Radial Bearings

Radial bearings can be basically divided into three kinds of rolling element bearings, including deep groove ball bearings, needle bearings, and cylindrical type roller bearings. Rolling bearings can support and carry a large variety of light to high loads by placing balls or rollers between the bearing rings. The bearing rings are also called races. The relative motions between the bearing rings lead to the rolling of balls or rollers with little resistance.


● Deep Groove Ball Bearing:

Deep groove design of radial bearings is the most common and classic style of radial bearings. Ball bearings utilize balls to keep the separation between the rings. The bearings can be made from a wide variety of materials, for instance, stainless steel, silicon nitride, chrome steel, and so on. Most ball bearings have relatively lower load capacity due to the size and the smaller contacting area between the rolling element and the races than other rolling bearings. However, they are capable of tolerating misalignment of the inner and outer rings. 

In deep groove ball radial bearings, the dimensions of the bearing rings are very similar to that of the balls that work in them. Deep groove ball bearings allow heavier loads than a shallower groove type, and they can be used for both radial and axial loads just like the angular contact bearings. However, the deep groove style of radial bearings is the lacks the choice in the contact angle of the load capacity. 

Deep groove ball bearings can reduce rotational friction effectively. One race will be stationary while another will be attached to the shaft or hub. The balls provide much lower resistance than the arrangement where surfaces sliding against each other.


● Cylindrical Roller Bearings:

Roller bearings typically utilize cylinders that are greater in dimensions than the diameters. Most roller bearings tend to have higher load capacity than the ball-type rolling bearings for the radial load. However, under axial loads, they have relatively high friction and low load capacity. 

The capacity of this type of radial bearing typically reduces quickly whenever the inner and outer bearing rings are misaligned. Like all kinds of radial bearings, the outer load will be consistently refreshed and distributed among the cylindrical rollers. In general, less than half of the rollers support a considerable load portion.


● Needle Roller Bearings:

As for the third type of radial bearings, the needle roller bearing, they are a special style of roller bearings. In the structure of needle roller bearing, there are long and significantly thin cylindrical rollers working. In general roller types of bearings, the cylindrical rollers only slightly longer the diameter. However, in this type of radial bearing, the needle rollers are at least 4 times longer than the diameter. They are also effective to reduce the rotational friction of the surface and greatly suitable for radial loads.


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