Bearing Preloading: Principles, Methods, and Application Gui

Publication Time：2025-12-27 08:45 [ From：Andge Bearing ] Author：Bearing Website

Bearing preloading is a critical technique used to enhance the performance and precision of rolling bearings, particularly in high-precision and high-speed applications. Preloading involves applying a slight axial load to the bearing before operation, eliminating internal clearance and ensuring that rolling elements make consistent contact with the raceways. This article explains the principles of bearing preloading, the main preloading methods, and provides guidelines for selecting and implementing preloading in various applications.

The primary principle of bearing preloading is to eliminate internal clearance (the radial or axial play between rolling elements and raceways) in the bearing. Internal clearance is necessary to accommodate thermal expansion during operation, but excessive clearance can lead to vibration, noise, reduced precision, and uneven load distribution. By applying a preload, the rolling elements are pressed firmly against the raceways, creating a slight elastic deformation that eliminates clearance. This ensures that the bearing operates with high rigidity, improved rotational accuracy, and reduced vibration.

There are three main methods of bearing preloading: fixed preloading, constant preloading, and adjustable preloading. Fixed preloading (also known as rigid preloading) is achieved by installing the bearing with a predefined axial dimension, such as using shims or spacers of a specific thickness. This method provides a constant preload that does not change during operation, making it suitable for high-precision applications such as machine tool spindles. However, fixed preloading is sensitive to temperature changes, as thermal expansion can increase the preload, leading to excessive heat generation.

Constant preloading (also known as spring preloading) uses a spring to apply a constant axial load to the bearing. The spring compensates for thermal expansion and contraction, maintaining a consistent preload throughout the operating temperature range. This method is suitable for applications with varying temperatures or high-speed operations, such as electric motors and turbochargers. Common spring types used for constant preloading include coil springs, wave springs, and Belleville washers.

Adjustable preloading allows for the preload to be adjusted manually or during operation. This method is typically used in applications where the preload needs to be optimized for specific operating conditions, such as in some industrial gearboxes or precision measuring equipment. Adjustable preloading can be achieved using threaded nuts, hydraulic systems, or other adjustable mechanisms.

When selecting a preloading method and determining the preload magnitude, several factors must be considered, including bearing type, size, operating speed, temperature, load, and precision requirements. The preload magnitude should be sufficient to eliminate internal clearance and ensure rigidity, but not so high that it causes excessive friction, heat generation, or premature wear. For high-speed bearings, a lighter preload is typically recommended to minimize heat generation, while high-precision applications require a heavier preload to maximize rigidity.

Common applications of preloaded bearings include machine tool spindles (requiring high precision and rigidity), electric motors (high speed and low vibration), automotive steering systems (precision and reliability), and aerospace components (high performance and durability). In each of these applications, preloading enhances bearing performance, improves system accuracy, and extends service life.

In conclusion, bearing preloading is a valuable technique for optimizing the performance of rolling bearings in high-precision and high-speed applications. By understanding the principles of preloading, selecting the appropriate preloading method, and determining the correct preload magnitude, engineers can significantly improve bearing rigidity, rotational accuracy, and reliability. Proper preloading also reduces vibration and noise, extending the service life of both the bearing and the overall system.

【Andge Bearing】WuXi Andge Bearing Co.,Ltd. delivers reliable bearing solutions for industrial, automotive and mechanical applications.

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Bearing Preloading: Principles, Methods, and Application Gui

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