How to Check Bearings
The checking of bearings should be carried out during their operational phase to detect any anomalies in noise levels, the temperature reached, or vibrations produced. Using appropriate equipment (stethoscope and thermocouple), it is possible to quickly identify deviations in noise and temperature, which can help detect potentially harmful situations that should be addressed promptly.
Bearings on Moving Parts and Grease
In cases where the bearing is mounted on a moving part and it is not possible to check noise or temperature using the devices briefly mentioned above, it is still possible to perform periodic inspections, apply fresh grease, and observe its operation.
Regarding grease, it should be noted that—although lubricant is essential for the proper functioning of bearings—it is not necessary to use excessive amounts to ensure good usability. The amount of lubricant will depend on the type of bearing, its size, the number of revolutions, operating conditions, and other specific characteristics indicated in the user manuals. Also, the frequency of lubricant application and replenishment depends on the type of grease: some types require longer lubrication intervals than others.
As for oil lubrication, it is advisable to maintain an oil level equal to that of the housing indicator: if the quantity is below the expected level, simply refill it. Periodically, it is also necessary to consider replacing the oil: the frequency of this operation depends on the operating conditions and, in particular, on the temperature at which these components are used.
Disassembly and Replacement
If during these inspection phases the bearing shows anomalies that warrant further checks, it will be necessary to proceed with the disassembly of the element. We will discuss bearing disassembly in a dedicated article. For now, it is sufficient to remember that if disassembly reveals damage, spalling, or other impairments to this component, it may be advisable to proceed with its replacement.
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- AB-TOOLS Hand Tools for the Maintenance Technician
- Spherical Roller Bearings: Heavy-Load Applications Explained
- Angular Contact Bearings: When and Why to Use Them in 2026
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Building a Maintenance Programme That Actually Sticks
A bearing maintenance programme that survives the first audit cycle does three things consistently. First, it ties every inspection to a measurable trigger — operating hours, kilometres travelled, batches produced, or temperature thresholds — rather than to a vague calendar slot that drifts under production pressure. Second, it assigns clear ownership: the technician who walks the line knows which bearings are theirs, and the maintenance planner knows which signatures they need before the next shift. Third, it captures evidence — a photograph of the seal, a temperature reading, a vibration spectrum — that builds a longitudinal record. After eighteen months, that record is what separates a guess from a forecast, and it is the foundation of every meaningful condition-based or predictive-maintenance step that follows.
The Four Pillars: Lubrication, Sealing, Alignment, Temperature
Field studies on industrial bearing failures repeatedly attribute the majority of premature removals to four root causes that are entirely controllable. Inadequate lubrication — wrong grease, wrong quantity, wrong interval — accounts for roughly a third of cases. Contamination through degraded seals is a close second, especially in food processing, mining, and outdoor agricultural equipment. Shaft misalignment is the silent killer, generating uneven load distribution that fatigues the raceway long before any audible symptom appears. Thermal excursions complete the quartet, and they are usually the visible symptom of one of the other three problems rather than a primary fault. A maintenance plan that treats these four pillars with equal seriousness will halve unplanned removals within a single fiscal year on most installations.
Inspection Cadences for Different Operating Conditions
There is no universal cadence, but useful baselines exist. For continuously running motors and conveyors operating in clean environments at moderate speed and load, monthly visual checks and quarterly vibration measurements are typical. Heavy industry — steel, cement, paper, mining — moves the visual check to weekly and adds a monthly thermography sweep. Food and pharmaceutical lines with washdown cycles need to verify seal integrity after every clean-in-place sequence because that is when ingress is most likely. Mobile equipment such as agricultural tractors and forklifts should be inspected at the end of each operating season, not at calendar intervals, because their duty cycles are seasonal rather than uniform. The right cadence is the one that catches the third-stage symptoms before the fourth-stage failure.
When to Replace, When to Re-lubricate, When to Wait
The decision between replacement, re-lubrication, and continued observation is where maintenance budgets are won or lost. A bearing showing the first signs of grease degradation — colour shift, slight separation, mild noise increase — is almost always a candidate for re-lubrication rather than replacement, provided the housing is sealed and the temperature has not exceeded 30 °C above ambient for sustained periods. A bearing exhibiting raceway pitting visible on a borescope, audible high-frequency squeal, or vibration spectra showing characteristic ball-pass frequencies should be scheduled for replacement at the next maintenance window. A bearing that is hot but quiet, with no measurable vibration anomaly, may simply be under-greased and merits a single relubrication and a re-check two shifts later before any harder decision is made. Document each decision so the next technician inherits the reasoning, not just the result.
Related Resources from Eurobearing
For technicians who want to go deeper into bearing maintenance, our editorial team has produced dedicated guides on adjacent topics. Each of the following articles complements the framework above with concrete examples, photographs, and selection tables built around real distribution scenarios:
- SKF Bearing Maintenance and Lubrication: A Complete Guide
- Bearings: The Importance of Preventive Inspections
- Bearing Lubrication Intervals: A Practical Calculation Method
- How to Address Bearing Overheating
- Industrial IoT Sensors for Bearings: 2026 Buyers Guide
Common Maintenance Mistakes That Quietly Shorten Bearing Life
Three mistakes recur across every industry we serve. The first is over-greasing: more grease is not more protection. Filling the housing beyond the recommended fraction (typically one-third to one-half of free volume) raises operating temperature, which accelerates oxidation of the grease itself and degrades the seal. The second is mixing incompatible greases without flushing — lithium-based and polyurea-based greases, for example, can separate when blended and turn the housing into an abrasive paste within weeks. The third is dry-installing a bearing onto a tight shaft and beating it home with a hammer through the outer ring, transferring impact loads to the rolling elements and creating brinell marks that will surface as vibration months later.
None of these mistakes is caught by routine paperwork. They are caught only by direct observation and by a maintenance culture that treats bearing installation as a discipline rather than a chore. Training a single line technician to use an induction heater and a calibrated torque wrench typically returns its investment in three to six months on a moderately busy plant.
The corollary is that maintenance metrics matter. A facility that tracks mean time between bearing replacements, distinguishes premature from end-of-life failures, and feeds that data back into procurement decisions will steadily improve its uptime without dramatic intervention.
Eurobearing maintains technical documentation, cross-references and supply for the full catalogue of major bearing brands — SKF, FAG, INA, NSK, NTN, NMB, Schaeffler and dozens of secondary suppliers. If you need a second opinion on a bearing maintenance question your team is wrestling with, our engineering desk is reachable by email and replies typically within one business day.
Need help with bearing selection?
Eurobearing is a European bearing and power-transmission distributor based in Northern Italy serving OEMs, MRO buyers, and industrial resellers across more than 40 countries. Our technical desk can help you cross-reference legacy part numbers, identify the correct dynamic load rating, choose the right cage material or seal type, and align lubricant intervals to your duty cycle. If you are evaluating bearing maintenance for a specific machine — whether it is a continuous-process line, a packaging station, an agricultural drivetrain, or a marine winch — we are happy to review specs and propose qualified options from brands like SKF, FAG, INA, NSK, NTN, NMB, and Schaeffler. Contact the Eurobearing technical team for a free consultation, share the application photograph and the failed reference, and we will return a recommendation within one business day.