Bearing clearance

Bearing clearance refers to the free space or play between the various components of a rolling bearing, such as the balls or rollers and the surrounding races. This clearance or play is necessary to ensure that the bearing functions smoothly and can expand and contract properly during operation. Bearing clearance has a direct effect on the operation and performance of the bearing.

There are different types of internal clearance, which can vary depending on the application and design:

• Preloaded bearings: In these bearings, the internal clearance is deliberately reduced to create a certain preload that increases the rigidity and precision of the bearing. This is often required in applications with high precision and low clearance.
• Standard internal clearance: This is the normal internal clearance specified by the manufacturer. It provides sufficient clearance for proper operation of the bearing and a certain tolerance to thermal expansion and loads.
• Increased internal clearance: In some cases, it may be necessary to increase the internal clearance, for example to compensate for thermal expansion or axial loads. This may be necessary in applications with high temperatures or strong vibrations.

The bearing clearance classes, also known as tolerance classes, are normally specified by the manufacturers of rolling bearings and are used to define the accuracy and clearance of the bearings. Here are some common bearing clearance classes:

• C0 (standard clearance): This is the normal internal clearance provided by the manufacturer. It provides sufficient clearance for proper operation of the bearing and a certain tolerance to thermal expansion and loads.
• CN (normal internal clearance): Similar to C0, but with a slightly lower tolerance. This is often used for applications with less stringent accuracy and rigidity requirements.
• C2 (small internal clearance): This class has a smaller internal clearance than C0 and offers greater rigidity and precision. It is often used in applications with very low clearance or high precision.
• C3 (Larger internal clearance): This class has a larger internal clearance than C0 and is often used for applications with higher temperatures or stronger vibrations to compensate for thermal expansions or axial loads.
• C4 (Larger internal clearance than C3): This class has an even larger internal clearance than C3 and is used for applications with extreme conditions such as very high temperatures or strong vibrations.
• C5 (Larger internal clearance than C4): This class provides the largest internal clearance and is used for applications with extreme conditions where maximum tolerance to thermal expansion or loads is required.

The selection of the correct internal clearance class depends on various factors, including the type of load, the operating environment, precision and rigidity requirements and the manufacturer's recommendations. It is important to select the correct internal clearance class according to the requirements of the application and the manufacturer's recommendations to ensure optimum performance and service life of the bearing.