Bearings for vibratory applications

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 higher accelerations than corresponding standard bearings. The permissible acceleration depends on the lubricant and the type of acceleration - rotating or linear acceleration.

Rotating acceleration

The bearing is subjected to a rotating outer ring load and a rotating acceleration field. This generates cyclic loads on the cages from the unloaded rollers. Typical examples are vibrating screens and planetary gears. Road rollers are subject to a mix of rotating and linear accelerations (fig 1).
Individual values for the permissible rotating accelerations are provided in the product table and are valid for oil lubricated bearings. The values are expressed in m/s2, where 28 g stands for 28 × 9,81 = 275 m/s2 for example.

Linear acceleration

The bearing is subjected to impact loads and thus linear accelerations. This causes hammering in the cage pockets by the unloaded rollers. A typical linear acceleration is generated when rail wheels are rolling over rail joints (fig 2). An analogous application using bearings for vibrating applications is a road roller where the roller is vibrating against a relatively hard surface.
Individual values for the permissible linear accelerations are provided in the product table and are valid for oil lubricated bearings. The values are expressed in m/s2, where 90 g stands for 90 × 9,81 = 883 m/s2 for example.

Bearing design

SKF spherical roller bearings for vibratory applications have the same dimensions and performance values as bearings in the 223 series but have a C4 radial internal clearance as standard. They are available with either a cylindrical or tapered bore. To facilitate efficient lubrication all bearings are provided with an annular groove and three lubrication holes in the outer ring.
SKF spherical roller bearings for vibratory applications are, depending on their size, available in one of the designs described below.

E/VA405 (bearings with d ≤ 65 mm)

Two surface hardened window-type steel cages, flangeless inner ring and guide ring centred on the inner ring.

E/VA 405 (bearings with d > 65 mm)

Two surface hardened window-type steel cages, flangeless inner ring and guide ring centred on the cages (fig 3).

EJA/VA405 and CCJA/W33VA405

Two surface hardened window-type steel cages for bearings of EJA design (fig 4) or CCJA design (fig 5), flangeless inner ring and guide ring centred on the outer ring raceway.

EJA/VA406 and CCJA/W33VA406

These bearings have a PTFE coated cylindrical bore and the same features as a VA405 design bearing. These bearings are intended for the non-locating bearing position in vibratory applications to prevent fretting corrosion between the shaft and the bore of the bearing. Shafts do not require special heat treatments or coatings.

System solutions for vibrating screens

In addition to single bearings for vibrating screens, SKF has developed fault detection and bearing systems that can extend performance, reduce maintenance and monitor machine condition in vibratory equipment.