Vibratory applications, such as vibrating screens or exciters, induce accelerations of rollers and cages in the bearings. This puts extra demands on the bearing design. SKF spherical roller bearings for vibratory applications can withstand considerably faster accelerations than corresponding standard bearings. The permissible acceleration depends on the lubricant and the mode of acceleration.
1, Mode 1
The SKF bearing is subjected to a rotating outer ring load in combination with a rotating acceleration field, or an internally induced angular acceleration field due to rapid speed variations. These accelerations cause the unloaded rollers to generate cyclic loads on the cages.
2, Mode 2
The SKF bearing is subjected to impact loads, which generate a linear acceleration in a constant radial direction, causing the unloaded rollers to “hammer” the cage pockets.
Typical examples for mode 1 are vibrating screens, planetary gears and general arrangements subjected to rapid starts or rapid speed variations. A typical example for mode 2 is the acceleration generated when rail wheels roll over rail joints. Road rollers, where the roller is vibrating against a relatively hard surface, are subjected to a combination of mode 1 and 2 acceleration.