Why preload bearings

Excessive preload can cause increased heat, fatigue, and torque. Insufficient preload can allow resonant vibration causing fretting of the raceways. Left image: A bearing with no play, or an interference fit has all rolling elements loaded, wears and heats up excessively.

Center image: A bearing with standard play in the free state has low rigidity, and rolling elements can slide or skid instead of rotating. Right image: A standard bearing with proper preload applied will provide system rigidity, reduced vibration, and optimal bearing life. Preload can be applied using two standard methods, solid preload and spring preload. A solid preload is achieved by holding the inner and outer rings of the bearing in place with spacers or locking mechanisms while applying an axial load.

Figure two illustrates a solid preload applied mechanically to two radial ball bearings. A spring preload is created using a coil spring or a spring wave washer applying a constant axial load to the inner or outer rings. Spring preload is the most commonly used method because they are often simpler to assemble.

This constant contact is achieved through a bearing preload. For example, a preloaded radial bearing would be beneficial in a centrifuge with tricky mounting requirements and where precision is required while spinning, but reverse load could occur during filling or emptying the centrifuge. Adding a preload using a wavy washer, Belleville spring, or something similar would be helpful in preventing a reverse load from occurring. Preloading a bearing helps optimize the performance of a bearing.

Here are some specific benefits of bearing preload:. Most bearings, like our GMN angular contact bearings , have a factory preload already on the bearing when manufactured which activates when the bearings are installed.

Bearing Technical Calculation Tool. Basic Bearing Knowledge. Case studies. Bearing Trivia. Movie list. TOC of Basic Bearing Knowledge Front Page of Basic Bearing Knowledge Outline of bearing selection Selection of bearing type Selection of bearing arrangement Selection of bearing dimentions Bearing service life Calculation of service life Calculation of loads Dynamic equivalent load Basic static load rating and static equivalent load Allowable axial load for cylindrical roller bearings Applied calculation examples Boundary dimensions and bearing numbers Boundary dimensions Dimensions of snap ring grooves and locating snap rings Bearing number Bearing tolerances Tolerances and tolerance classes for bearings Tolerance measuring method Limiting speed Limiting speed Correction of limiting speed Limiting speed for sealed ball bearings Considerations for high speed Frictional coefficient refer.

With rotation, this looseness translates into wobble or non-repetitive runout. The application of axial preload forces the balls into contact with raceways, establishing a contact angle which causes the ball set to rotate in a uniform circumferential plane. Coil springs or wave spring washers are most commonly used, but a variety of spring types are available.

The spring is used to press the races together, or apart. Spring preloading uses a floating ring that reduces vibration levels transmitted from the bearings, making it a good choice in noise-sensitive applications.

However, these types of assemblies will have minimal stiffness. Usually, the spring is positioned to push against the non-rotating ring. This is commonly performed using the dead weight method. With dead weight preloading, adhesive is used to secure the rings in position while held in place with a weight equal to the specified preload amount.