Vibrating Screen Bearing and Spring Maintenance

Vibrating screen bearing and spring maintenance is the job most often postponed on a crushing and screening line and the one that costs most when it is. When the screen stops, the crushers behind it stop too, yet the failure itself is rarely sudden. A warming bearing, a spring losing height or a distorted motion path signals its condition weeks ahead. Reading those signals turns an unplanned stoppage into a planned change-out.

Why a screen wears itself out

A screen body is a steel structure working under continuous, directed vibration. Eccentric weights accelerate and decelerate the body many times a second, and that acceleration is what makes material bounce along the deck and separate. The same acceleration fatigues the bearing housings, the welds, the bolts and the springs. The machine behaves as one system: when a spring collapses the body tilts, the tilted body changes bearing load, and the changed load heats the bearing. Maintenance that looks at a single part therefore never holds.

From symptom to cause

Reading bearing temperature

Screen bearings run hotter than bearings of the same size in other machinery, and that is normal. What matters is not an absolute figure but the baseline of that particular machine. In practice a housing above 70 °C goes on close watch, while around 90 °C is widely treated as an alarm threshold. The binding value is always the one printed in the manufacturer's manual.

Three causes account for most temperature rises. The first is lubrication: too much grease increases churning friction, too little prevents a film forming, and both heat the bearing. The second is sealing and dust: silica-bearing dust that reaches the raceway behaves like an abrasive paste. The third is alignment and clearance, where an incorrect mounted clearance or a tilted body loads the rolling elements in a direction they were not designed for. Readings must always be taken at the same point under the same duty; two figures from different points cannot be compared.

Stroke and g-force: is the screen really working

A screen that turns is not necessarily a screen that works. Separation performance is governed by amplitude and speed, which together set the acceleration the body experiences. Amplitude is measured with a stroke card, which also shows whether the motion is circular, elliptical or linear and whether all four corners behave alike.

These are typical bands; each machine's own design figure governs. Because acceleration follows both amplitude and speed, adjustment runs along two routes: changing eccentric weight plates or changing drive speed. Speed affects acceleration faster than amplitude does, so it is altered in small steps and always with a measurement afterwards. Keeping those adjustments inside the maker's limits protects the design life of a conventional vibrating screen body.

Springs: quiet but decisive

Coil springs isolate the body from the support structure. A fatigued spring first loses height and then cracks. The loss of height tilts the body and therefore disturbs material flow, bearing load and motion path at the same time. The check is simple: with the machine stopped, measure spring height at all four corners and record the difference between opposing corners; level the body with a spirit level; look for cracks, deformation and corrosion in the coils. Springs are replaced as a set, since renewing one spring only worsens the load distribution. On machines with rubber mounts, hardening and tearing remove the same function.

Vibrating screen bearing and spring maintenance intervals

Intervals are worthless without records. A temperature taken at the same point, a spring height measured at the same corner and a stroke read with the same card only reveal a trend when compared over time. That trend is the only way to move a maintenance and wear plan from the calendar to the actual condition of the machine.

Frequently asked questions

Should grease be added when a bearing runs hot

Usually not. Excess grease is itself a cause of heating. Check the lubrication record, the grease type and the seal condition first; if needed, purge the housing and refill with the correct quantity.

How is a collapsed spring recognised

By comparing free length with installed height and looking at the difference between opposing corners. A visibly low side, or material drifting to one side of the discharge, is a strong indicator.

How often should stroke be measured

At the monthly inspection and whenever the product curve is questioned. A new reference reading is also taken after any change of media type, feed rate or eccentric weight setting.