Build a slewing bearing lubrication plan around raceway grease, gear lubricant, operating duty, environment, purge condition and inspection evidence.
Lubrication in a slewing bearing has three jobs: separate rolling contacts, protect raceways from corrosion and support the sealing barrier. A schedule based only on calendar time misses the conditions that consume grease fastest, including water, dust, high temperature, shock load, frequent oscillation and long idle periods.
The correct plan distinguishes raceway grease from open-gear lubricant and follows the approved bearing and equipment instructions. This article describes the decisions and records that make a lubrication program auditable without inventing one universal interval for every machine.
Select raceway grease from the complete operating condition
Confirm base oil viscosity, thickener, consistency, extreme-pressure performance, temperature range, water resistance and compatibility with seals and existing grease. A product with a familiar NLGI grade is not automatically interchangeable because different base oils and additive systems can behave differently under slow, heavily loaded rolling contact.
When changing grease, obtain written compatibility guidance from the lubricant and bearing suppliers. Incompatible thickeners can soften, harden or separate, leaving an uncertain mixture in the raceway. Extreme cold, high ambient temperature, food processing, marine exposure or automatic pumping may require a special product and delivery-system review.
Relubricate the full circumference, not one convenient sector
All specified grease points must remain accessible. Introduce grease while slowly rotating or adequately oscillating the bearing so fresh lubricant reaches the loaded circumference. Continue according to the approved procedure until the expected purge condition is visible at the seals. A blocked line, damaged nipple or hard grease pocket can make one sector appear serviced while another remains dry.
Inspect the purged grease. Water, rust color, metal particles, hard debris or a burned odor are maintenance evidence, not waste to discard unnoticed. Record which point produced the observation and preserve a sample when condition analysis is required. Remove excess external grease in a way that does not damage seal lips or trap water around the bearing gap.
- Label every grease point and confirm flow before commissioning.
- Rotate or oscillate safely during relubrication when the procedure requires it.
- Observe purge condition around the full circumference.
- Keep lubricant batch and service records traceable.
- Escalate water, metal or repeated blocked-line findings.
Set intervals from duty and evidence
Start with the equipment or bearing manufacturer interval, then shorten it for severe water exposure, abrasive contamination, high cycle rates, heavy load, vibration or temperature. A machine that slews continuously distributes grease differently from one that repeats a small angle. Long idle periods also need preservation because condensation and stationary contact zones can develop corrosion.
Use inspections to refine the plan. Trend grease condition, seal purge, operating torque, noise, temperature and wear measurements. If grease repeatedly emerges contaminated before the planned interval, the answer may be shorter service frequency, improved sealing or a corrected washdown practice. Adding more grease cannot compensate for a damaged seal or an open path for abrasive material.
Treat gear lubrication as a separate system
Open gear teeth need a lubricant formulated for adhesion, tooth-root coverage and sliding contact. The product and application method may differ from raceway grease. Clean and inspect the tooth flanks before applying fresh lubricant so cracks, pitting and abnormal contact patterns are not hidden under a new layer.
Lubricate the complete gear circumference and confirm pinion access, guarding and overspray control. Monitor backlash and tooth contact at defined positions. The gear tooth failure guide explains how lubrication evidence supports diagnosis when pitting or wear appears.
Build a service record that supports decisions
Record date, operating hours, grease name and batch, quantity by point, machine condition, purge observations, seal condition and technician. Link the record to periodic clearance measurements described in the clearance and wear trending guide. Consistent records allow maintenance teams to identify deterioration before a single alarm forces an unplanned shutdown.
FAQ
How often should a slewing bearing be greased?
Use the approved manufacturer interval and adjust it from duty, environment and inspection evidence. There is no safe universal interval.
Can raceway grease be used on the gear teeth?
Only if the approved lubrication specification permits it. Raceway and open-gear contacts often need different products.
What does contaminated purge grease mean?
It may indicate water, debris, wear or degraded lubricant and should trigger inspection rather than routine disposal.
Engineering references
For a drawing-based review, send MERYDOM the application, load cases, dimensions and required documentation. Final selection and service instructions must follow the approved drawing and equipment manufacturer requirements.