Bearing numbers provide important information about the size and design of a bearing. Understanding bearing numbers can help maintenance engineers, purchasing teams, and machine operators identify replacement bearings more accurately.
A bearing designation may indicate information such as the bearing type, series, bore size, internal clearance, sealing arrangement, or other design characteristics.
However, bearing numbering systems can vary between bearing types and manufacturers. Therefore, a bearing number should always be interpreted according to the relevant manufacturer’s designation system.
Why Are Bearing Numbers Important?
Industrial machinery may contain hundreds of different bearing sizes and configurations.
Two bearings can look similar while having different:
- Bore diameters
- Outer diameters
- Widths
- Load capacities
- Internal clearances
- Sealing arrangements
- Lubrication requirements
- Speed capabilities
The bearing number provides a standardized way to identify the required configuration.
For maintenance teams, correctly identifying the bearing number can reduce the risk of ordering an unsuitable replacement.
Understanding Bearing Series
Bearing series often provide information about the dimensional characteristics and design of the bearing.
For example, the 1200 Series is associated with self-aligning ball bearings.
Raseen Trading’s 1200 Series includes self-aligning ball bearings designed to accommodate minor shaft and housing misalignment.
You can view the 1200 Series bearings on the Raseen Trading website. Other bearing families may be designed for different applications and load conditions.
Therefore, the series number should not be interpreted independently from the complete bearing designation.
Understanding Bore Size
The bore is the internal diameter of the bearing and determines the shaft size with which the bearing is designed to work.
For many standardized metric bearings, the final digits of the bearing designation can provide information about the bore diameter.
However, the exact interpretation depends on the bearing numbering system.
For example, some common standardized bearing designations use a bore code where the last two digits are multiplied by a standard factor to determine the bore diameter.
There are also exceptions, particularly for smaller bore sizes and special bearing designs.
For this reason, engineers should always confirm the manufacturer’s dimensional table before ordering.
Bearing Dimensions
Three basic dimensions are particularly important:
Bore Diameter
The inside diameter of the bearing.
Outside Diameter
The external diameter of the bearing.
Width
The axial width of the bearing.
All three dimensions should be checked when replacing a bearing.
A bearing with the correct bore but an incorrect outside diameter may not fit the housing.
Similarly, a bearing with the correct bore and outside diameter but a different width may not be suitable for the machine.
Bearing Type
The bearing designation can also identify the bearing type.
Common types include:
- Deep groove ball bearings
- Self-aligning ball bearings
- Tapered roller bearings
- Cylindrical roller bearings
- Spherical roller bearings
- Thrust bearings
Each type has different load and application characteristics.
For example, self-aligning ball bearings are designed to accommodate minor angular misalignment, while roller bearings are often selected for applications requiring higher radial load capacity.
Seals and Shields
Many bearings are available with different sealing or shielding configurations.
These may be represented by additional letters or numbers in the designation.
Sealed bearings can provide protection against contamination and can retain lubricant inside the bearing.
Shielded bearings may be used where reduced friction and protection from larger particles are required.
The appropriate configuration depends on the application environment.
Internal Clearance
Bearing internal clearance refers to the amount of movement between the bearing’s rings and rolling elements before installation and under defined conditions.
Different applications may require different clearance classes.
Temperature, shaft fit, housing fit, speed, and operating conditions can affect the appropriate internal clearance.
Therefore, replacing a bearing with a different clearance specification simply because the dimensions appear identical may not always be appropriate.
Why You Should Not Choose a Bearing by Number Alone
A bearing number is an important identification tool, but it should not be the only factor considered during replacement.
Before ordering a replacement bearing, confirm:
- Bearing type
- Bore diameter
- Outside diameter
- Width
- Load requirements
- Speed
- Sealing
- Internal clearance
- Lubrication
- Operating temperature
- Manufacturer requirements
The original bearing number should also be checked against the machine manufacturer’s documentation whenever possible.
What If the Bearing Number Is Not Visible?
Sometimes the number is difficult to read because of wear, corrosion, contamination, or installation conditions.
In this situation, measurements can help identify possible replacements.
Measure:
- Shaft or bearing bore diameter
- Bearing outside diameter
- Bearing width
These measurements can then be compared with bearing catalogs and manufacturer specifications.
However, dimensions alone may not identify the exact bearing configuration. Load, speed, seals, clearance, and application should also be considered.
Frequently Asked Questions
Can I identify a bearing only by its dimensions?
Dimensions can narrow down the possibilities, but they may not identify the exact bearing configuration.
Does the bearing number indicate the bore size?
In many standardized bearing systems, part of the designation provides bore information, but the exact interpretation depends on the bearing series and designation system.
What does the 1200 Series mean?
The 1200 Series on the Raseen Trading website refers to self-aligning ball bearings designed for applications where minor shaft or housing misalignment may occur.
Should I replace a bearing with exactly the same number?
If the original bearing is still appropriate for the application, matching the complete designation is generally the starting point. However, changes in machine load, speed, temperature, or operating conditions should also be evaluated.