NSK´s EVB series of spherical roller bearings have been developed for vibratory operations on equipment such as screens, feeders and compactors. Benefiting from a design with fewer bearing components, the EVB series is perfectly suited to the high radial loads, higher than normal temperatures (up to 2000C) and vibration frequencies encountered in these type of applications.
The major component in the EVB series design is a one- piece brass cage, which ensures accurate guidance of the rollers and also minimises resonance from the induced vibrations. Because the cage is roller-centred as opposed to ring riding higher speeds are possible together with a reduced lubrication requirement for the bearing.
The EVB design employs heat stabilised bearing rings that facilitate continuous bearing operation at 200o C without any effect on bearing performance. The inner rings are equipped with two external ribs that provide supplementary roller guidance under exceptional load conditions. The ribs also ensure maximum bearing/shaft abutment contact, and help provide a uniform stress to the inner ring after fitting.
In manufacture, the radial internal clearance of the EVB series is controlled to the upper 2/3rds of the ISO clearance tolerance. This ensures improved running control and reduces the inertia effects experienced by the bearing under induced vibrations. In addition, both the bore and outside diameter tolerances of the EVB units are reduced to suit vibratory conditions, a feature which also allows total bearing interchangeability.
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