In mechanical engineering, preload is an internal load applied to certain types of bearings during assembly to eliminate clearances and improve their performance and service life. Applying the correct preload is crucial for the optimal functioning of these bearings. The most common types of bearings that require preload are ball bearings, roller bearings, angular contact bearings, and tapered roller bearings. Continue to read and let’s learn more about them.
Ball Bearings
Ball bearings consist of inner and outer races with a set of balls that roll between them. In some applications, a specified preload is applied to the bearing by adjusting the internal clearance or using an external load. Preloading ball bearings eliminates internal clearances, improves stiffness, reduces noise and vibration, and allows higher speeds.
Our premium pillow block ball bearings use optimized preload levels to achieve precise and smooth rotation performance. We supply preloaded ball bearings for various critical applications including machine tools, robots, and semiconductor manufacturing equipment. Too much preload can cause overheating and premature failure while too little preload will not properly eliminate clearances.
Common methods for preloading ball bearings include spring preload, curvature preload from residual stresses, and direct mechanical preload from bolts or hydraulics. Our top-quality deep groove ball bearings are often preloaded using spring washers or lock nuts in high-precision motor applications requiring quiet and vibration-free operation.
Roller Bearings
Roller bearings like cylindrical, needle, and tapered types use rollers between the inner and outer races rather than balls. These bearings also often require preloading to remove internal clearances. The rollers have a line or point contact which allows them to support heavier radial loads than ball bearings.
However, the high stresses require proper lubrication and preload management to prevent surface damage and ensure a reasonable service life. Preloaded roller bearings exhibit less play and run more smoothly. Preload techniques include spring washers, lock nuts, mating housing fits, and hydraulic nuts. Our top-quality spherical roller bearings utilize preloading for reduced vibration in gearboxes and heavy machinery.
Angular Contact Bearings
Angular contact bearings have inner and outer race grooves that are offset at an angle allowing them to handle axial and radial loads simultaneously. Internal preloading improves their precision by tightly controlling internal clearances even under changing loads and temperatures.
Optimal preload levels also enhance stability, reduce noise, and increase axial and radial rigidity. Common preloading methods include spring pushers, Prevailing torque locknuts, tapered sleeves, diaphragm springs, and hydraulic techniques. These premium bearings excel in high-speed spindle applications once properly preloaded during installation.
Tapered Roller Bearings
Tapered roller bearings consist of inner and outer rings with tapered rollers spaced between them. These bearings are inherently preloaded because the shape of the rollers generates a radial load component that pushes them against the inner ring. However, additional preloading can optimize internal clearances and improve performance.
Common preload approaches include tightening the nut on the bearing until a specified torque level or axial displacement amount generates the desired preload. Our top-quality tapered roller bearings utilize optimized preloading to achieve superior operation in gearboxes, wheel hubs, transmissions, and other heavy machinery.
How to choose
While not all bearings require preloading, certain types like ball bearings, roller bearings, angular contact bearings, and tapered roller bearings function best when properly preloaded during installation. Applying optimal preload eliminates internal clearances, increases stiffness, reduces vibration and noise, accommodates higher speeds, and ultimately extends the service life through improved running accuracy.
Our premium bearing products use fine-tuned preloading techniques to deliver exceptional performance and longevity. Please contact NSAR for any questions on bearing preload requirements or to request a competitive quotation on our high-quality preloaded bearing solutions.