Collection: CN Clearance single row deep groove ball bearings
Depending on the application, choosing the right internal clearance for your deep groove ball bearings can be just as important as making sure that the bearing is the right size. So when exactly should you select a CN clearance bearing ?
What is a CN clearance bearing ?
CN internal clearance on a bearing relates to the space on the inside of the bearing between the steel balls and the outer race. Bearing clearances are defined from low to high and the available clearances are :
C1, C2, CN (This is the standard clearance that deep groove ball bearings are manufactured to), C3, C4, C5.
Within each of these clearance codes the are different variants for when more specific clearance requirements are needed. Using CN bearings as an example, you could have either a CNL, a CN, or a CNH. If your bearing is a CNL, then this means that the clearance is at the lower end of the tolerance allowed for a CN bearing. If your bearing is a CN bearing then the clearance can be anywhere within the full allowable clearance for a CN bearing and if your bearing has a CNH clearance then the internal clearance is limited to the upper end of the CN clearance range.
Bearing clearances are used on both metric and inch sized bearings so it doesn't matter which you have, the same clearance principles will follow.
How do i know what clearance my bearing is ?
The easiest way to find out what internal clearance your bearing you have is to check the laser markings on the bearing or the product markings on the bearing. Your bearing might for example say 6205-2RSC2. 6205 is the bearing series which we can ascertain the bearing dimensions from. -2RS tells us that the bearing has 2 rubber seals and then the CN tells us that the internal radial clearance of the bearing is to CN specification and tolerances.
A more difficult method of ascertaining the internal clearance of a bearing is to use what are known as feeler gauges which come in different thicknesses and if a gauge doesn't fit between the balls and outer race then the clearance is lower than what is stated on that gauge. The first gauge that passes through gives you the clearance of the bearing. This method needs to be treated with some caution as worn or damaged bearings won't necessarily have the same clearance as when the bearings were originally installed.
You can also refer back to the manufacturer. Many major bearing manufacturers these days have online parts catalogues and many of those include the international standard part numbers or ISO part numbers of the component parts meaning that the bearing codes are quite often listed in the catalogues. You could also contact their technical department if in any doubt for more information.
I currently have a CN clearance bearing
So if your application already has a CN clearance bearing then usually it makes sense to replace like for like. If the bearing has worked for a long time before failing or exceeded the manufacturers warranty period then this is a good indication that a CN clearance bearing is right for your application.
The manufacturer parts catalogue specifies a CN clearance bearing
If the manufacturer part catalogue specifies a CN bearing then it is doing so for a reason. CN bearings aren't particularly common and they are often used in gearboxes or where noise and vibrations aren't a problem.
More information about bearing internal clearances
In most cases, the internal clearance that a bearing is designed with is higher than the clearance that the bearing operates with and this is mostly due to the fact that bearings are usually mounted with an interference fit either between the shaft and the inner ring or between the housing and the outer ring. Depending on which way around this occurs then it will cause either the inner ring to expand and reduce the internal clearance or the outer ring of the bearing to compress and reduce the internal clearance.
Another reason why the clearance in operation will be lower than the initial designed clearance of the bearing is due to thermal expansion. Bearings generate heat during operation due to friction and this heat causes the steel within the bearings to expand.
| Typical Application | Clearance |
| Where there is significant shaft deflection. High impact applications such as construction equipment applications suit C5 bearings | C5 |
| C4 bearings are often used in gearboxes or in paper manufacturing equipment | C4 |
| C3 bearings are often used where some thermal expansion is in place such as high temperature applications including clutches. | C3 |
| CN bearings the industry standard and are suitable for applications where a balance is required between noise, vibration and thermal expansion. They are a good allrounder | CN |
| For applications where low noise and low vibrations are a requirement | C2 |
For more information on available internal radial clearances for deep groove ball bearings please follow the links below:
CN bearing clearance
C2 bearing clearance
C3 bearing clearance
C4 bearing clearance
C5 bearing clearance
C5L bearing clearance
C5H bearing clearance
Interested in learning more about deep groove ball bearings ?
We have information on different designs of deep groove ball bearings including, single row deep groove ball bearings including bearings with snap rings or snap ring grooves and double row deep groove ball bearings as well as on stainless steel deep groove ball bearings which can be suitable for use in corrosive environments. We give detailed information on the difference between open bearings, sealed bearings and shielded bearings.
If you have space constraints but need a bearing to take more load than a standard deep groove ball bearing then we have max load bearings with filling slots and we also have lots of useful information on deep groove ball bearings that have been designed for specific applications or with special uses in mind like, low noise bearings, bearings for the food industry and energy efficient bearings which are becoming increasingly necessary and popular due to rising energy costs and the need to protect the environment.