Screen Eccentric Shaft Bearing

Function

The eccentric shaft bearings sustain the full cyclic vibratory force — which may be several times the static screen weight — that drives aggregate classification efficiency. A deteriorating bearing causes vibration amplitude to diminish, reducing the screen's capacity and separation sharpness. Catastrophic bearing failure seizes the eccentric shaft, immediately stopping screening and — in the failure event itself — generating shock loads capable of fracturing the housing or cracking the screen box side-plate, converting a routine bearing replacement into a major structural repair.

Construction & quality

Self-aligning spherical roller bearing (ISO 22200 series or equivalent) selected specifically for high radial load capacity and self-aligning function to accommodate the shaft deflection inherent in vibrating-screen service. Dynamic load rating Cr in the range 400–1800 kN depending on screen size and exciter mass. Internal clearance C4 (greater than standard C3) to compensate for thermal expansion at operating temperature and the additional clearance lost under continuous radial loading. Sealing: double-lip contact seal plus labyrinth relief groove to resist fine-dust ingress under centrifugal action. Relief-valve grease nipple prevents dangerous pressure build-up from over-greasing while under centrifugal rotation. Grease: NLGI 2–3 polyurea or lithium-complex high-temperature formulation.

When to replace

• Bearing housing surface temperature above 90 °C measured at normal ambient conditions
• Audible change in vibration signature — from a smooth steady hum to a rough rattle, growl, or periodic knock
• Grease purging from bearing seals that contains metallic wear particles or has turned dark grey or black
• Measurable reduction in screen vibration amplitude at the side-plate pick-up point
• Cracking of the screen box side-plate adjacent to the bearing housing, indicating advanced bearing failure and shock loading