How to Identify Bearings by Bearing Number – Calculation and Nomenclature

The friction force is a factor that usually affects objects’ movement and must be overcome to move the object. For moving mechanisms, such as machines, several types of bearings are employed to reduce this friction force. Depending on the size of the shaft and the needs of the application, many types of bearing sizes are available. They are required for a wide range of application sizes, from vehicle wheels to oil drills, due to their use in various kinds of industries. How are the sizes of these bearings determined?

If you are familiar with the Bearing nomenclature process and its easy calculations, you can quickly identify and decode Bearing features from their Bearing number. As one of India’s leading bearing suppliers, we see the necessity to inform non-technical people who need bearings as well. Buying Industrial Equipment Online will feel easier with EMM

This article will explain how to identify bearings solely based on their bearing number, enabling you to handle a variety of bearing tasks with ease.

Bearings Nomenclature

Although those components used for sliding surfaces are often known as bearings, the word bearing comes from the fact that it supports a rotating axle or shaft. Rolling bearings, also known as “rolling components,” employ balls or rollers.

A bearing’s code can have any or all of the following three components: the basic code, prefixes, and suffixes. Basic codes refer to bore diameter (the size of the inner ring), prefixes to basic bearing parts, and suffixes to any unique features or designs.

Bearing Standards

The American Bearing Manufacturers Association (ABMA) standard outlines how to calculate the bearing number in the inch system for tapered roller bearings. New designs types of bearing can use the ABMA method of defining types of bearing numbers. However, the majority of bearing producers use the ISO-15 identification scheme.

The same bearing numbers, which have been used and recognized for a long time, will be used to identify tapered roller bearings that utilize the inch system. As a result, a bearing from one manufacturer may be recognized by its ABMA code and linked to another bearing made by the same manufacturer using that code. TIMKEN designates new bearing designs with ABMA bearing numbers, even though many of these bearing numbers do not follow ABMA regulations.

Type of Bearing: First digit identification of bearing:

The following is the breakdown of a bearing number.

Eg: 7 2 10 ZZ

Type of bearing Bearing Series Bore Size/ Diameter Bearing Shield
7 2 15 ZZ

Type of Bearing

The first Number 7 says about the type of bearing, here 7 means it is a Single- Row Angular Contact Bearing

Bearing Codes Types of Bearings
1 Self-aligning Ball Bearing
2 Spherical Roller Bearing
3 Double Row Angular Contact Ball Bearing
4 Double Row Ball Bearing
5 Thrust Ball Bearing
6 Single- Row Deep Groove Ball Bearing
7 Single-Row Angular Contact Bearing
32/T Tapered Roller Bearing
R Inch Bearing
N Cylindrical Roller Bearing
NN Double –Row Roller Bearing
NA Needle Roller Bearing
BK Needle Roller Bearing with Closed ends
(Drawn Cups)
HK Needle Roller Bearings with Open ends
(Drawn Cups)

Basic Code: Second digit identification of bearing

Bearing Series and Code

The second digit indicates the bearing’s robustness; in this case, 2 indicates that it may be utilized for light-duty applications.

Series Code Bearing Series
0 Extra Light
1 Extra Light Thrust
2 Light
3 Medium
4 Heavy
8 Extra thin section
9 Very thin section

Bore size/diameter: Third and fourth digit identification of bearing:

The bearing’s bore size. The bearing size is determined by the appropriate dimension. It has a millimetre scale. The bearing’s inner diameter is indicated by the third and fourth digits. I.e.In this case, 1 states that the bearing’s inner diameter is 50 mm while 5 states that the inner diameter is 25 mm.

Bearing Code Bore Size/ Diameter (in mm)
0 10
1 12
2 15
3 17
4 20
5(X5) 25
6(X5) 30
7(X5) Hereafter, Bore size= Code x 5

(Bore Size and Corresponding Bearing Code)

Bearing Shielding: The bearings last Letter identification

The used type of enclosure is indicated by the last digit. It indicates whether shielding or sealing is available or unavailable, what kind it is, and any additional bearing-specific information. The many kinds of indicators include:

Types of Shielding(Last Letter) Description
Z One Side Shielded
ZZ Both Sides Shielded
RS One Side Sealed
2RS Both Sides Sealed
V One side Non-Contact Seal
VV Both Sides Non-Contact Seal
DDU Both sides Contact Seals

Buying Industrial Products Online

The bearing numbers are simple to understand. The difference in form, size, hardness, etc. is indicated by the bearing numbers. It will assist you in selecting and accurately determining the needed bearing. A bearing number generally consists of 6 characters (4 digits 2 alphabets). The first letter stands for the types of bearing, the second number for the bearing series, the third and fourth numbers for the bore size, and the final two alphabets for the seal/shielding/no-sealing markers.

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