In bearing terminology, what does the term "preload" refer to?

In bearing terminology, "preload" refers to the initial tension applied to a bearing assembly. This tension is used to control the clearance within the bearing and eliminate any internal play, thereby increasing the stiffness of the bearing arrangement. By applying preload, it enhances the bearing's overall performance, reduces the chances of vibration and noise, and improves the load distribution across the bearing surfaces.

Preloading is particularly important in applications where precise alignment and low levels of movement are critical for the reliability and lifespan of mechanical systems. Proper preload can also help in achieving optimal contact between the rolling elements and the raceways, thereby enhancing the overall efficiency of the bearing in its operational environment.

While grease and lubrication are important for the functionality of bearings, they do not define preload. Clearance between races also plays a role in how bearings operate but is distinct from the concept of preload itself. Interference fit can be related to how bearings fit into housings, yet it does not capture the essence of the tension and internal forces in a bearing assembly that preload specifically denotes.