The most important factor determining the life of bearings and bushings in crushers is lubrication. In cone crushers in particular, the eccentric bushing, countershaft bushings, spherical bearing and gears run on an oil film of clean oil at the right temperature and sufficient flow supplied by a lubrication unit. A lubrication unit typically consists of a lubrication pump, oil filter, oil cooler, tank and heater, breather filter, pressure and temperature sensors, and protective switches.
In this guide we cover in detail the function of each lubrication unit component, the parameters to monitor, how to interpret oil analysis, the maintenance schedule, common mistakes and spare part selection. For general cone crusher operation, see our cone crusher guide.
Components of the Lubrication Unit
| Component | Function | What to monitor |
|---|---|---|
| Lubrication pump | Pumps oil to the bearings | Pressure, flow, noise, leakage |
| Oil filter | Captures particles | Differential pressure indicator |
| Oil cooler (air/water) | Controls oil temperature | Inlet/outlet temperatures, fin cleanliness |
| Tank and heater | Stores oil and heats it in cold weather | Level, temperature, sludge |
| Breather filter | Prevents dust and moisture entering the tank | Clogging, saturation |
| Sensors and switches | Pressure/flow/temperature protection | Calibration and function test |
| Return line and magnetic plug | Returns oil to the tank and catches metal particles | Flow, amount of particles on the plug |
Which Parameters Should Be Monitored?
- Oil supply pressure: A drop may indicate pump wear, air on the suction side or internal leakage; a rise may indicate a clogged filter or passage.
- Oil return temperature: The best indicator of friction inside the crusher. An increasing difference between return and tank temperature is a warning of internal problems.
- Tank temperature: Minimum values for cold starting and maximum values for operation are specified by the manufacturer.
- Filter differential pressure: Shows that the filter is filling; change it before the alarm.
- Flow / return flow: Seeing flow in the return line confirms that oil is reaching the inside of the crusher.
How to Interpret Oil Analysis
| Finding | Possible meaning |
|---|---|
| Rising copper, tin, lead | Wear of bronze bushings or the socket liner |
| Rising iron and chromium | Gear, shaft or bearing wear |
| Rising silicon | Dust ingress; dust seal or breather filter problem |
| Water | Condensation, cooler leak or washing water ingress |
| Change in viscosity | Oil degradation or a different oil being added |
| Rising particle count | Insufficient filter performance or a source of contamination |
The trend across successive samples matters more than a single sample. Samples should always be taken from the same point, with the crusher running or immediately after it stops. For a predictive maintenance approach, see our predictive maintenance guide.
Maintenance Schedule
| Task | Interval |
|---|---|
| Pressure, temperature and return flow check | Every shift |
| Tank level and leak check | Daily |
| Cooler fin cleaning | Weekly in dusty environments |
| Breather filter check | Weekly to monthly |
| Oil analysis | Every 250–500 hours |
| Filter element change | At differential pressure warning or manufacturer’s interval |
| Oil change | According to the manufacturer’s interval and analysis results |
| Sensor and switch function test | Every 3–6 months |
Lubrication Pump Maintenance and Replacement
Crusher lubrication units usually use gear pumps or screw pumps. As the pump wears, internal leakage increases and pressure drops.
- The cause of a pressure drop is first separated from the filter, suction line and oil level.
- Pump noise (cavitation noise), coupling condition and motor current are checked.
- For replacement, the unit is stopped, lines are closed and the pump is removed with its coupling.
- The new pump is aligned and installed; confirm that the suction line is not drawing air.
- The pump is primed at the first start (if required) and pressure/flow are checked.
How to Change Filters Correctly
- Clean the filter housing and its surroundings before changing.
- With duplex filters, you can switch to the standby filter while the crusher is running.
- The filtration rating (micron value) of the new element must be the same as the original.
- The old filter element can be cut open and examined; the particles inside give information about failures.
Cold and Hot Weather Conditions
- In cold weather: The crusher should not be loaded until the tank heater has brought the oil to the minimum temperature specified by the manufacturer; viscous oil does not reach the bearing surfaces adequately.
- In hot weather: Cooler capacity becomes critical; if the fins are covered with dust the oil heats up quickly. Additional cooling capacity should be considered if necessary.
Common Mistakes
- Adding new oil with dirty containers.
- Waiting until the filter alarm or running in bypass.
- Mixing different oils.
- Neglecting the breather filter: Dust goes straight into the tank.
- Not cleaning the cooler fins.
- Bypassing protective switches: Running without oil can cause bushing seizure within minutes.
Troubleshooting Table
| Symptom | Possible cause | Solution |
|---|---|---|
| Low pressure | Pump wear, air on suction, low level, hot/thin oil | Check level and suction line, check the pump |
| High pressure | Clogged filter/passage, cold oil | Change the filter, heat the oil |
| High return temperature | Dirty cooler, increased internal friction, overload | Clean the cooler, oil analysis, load control |
| Water in the oil | Condensation, cooler leak | Find the source and change the oil |
| Excessive particles on the magnetic plug | Gear/bearing wear | Oil analysis and overhaul plan |
An Example from the Field
At a limestone plant, the oil temperature of a cone crusher started giving alarms every summer. The fins of the air cooler were coated with fine dust and oil mist; although they looked clean from outside, the gaps between the fins were almost completely blocked. The fins were cleaned with a suitable cleaner, a dust shield was added to the cooler and weekly cleaning was added to the maintenance list. Oil temperatures returned to the normal range and the forced stoppages in the summer months ended.
Spare Part Selection
- Pump: Flow, pressure, speed and connection dimensions; coupling and motor compatibility.
- Filter elements: Micron rating, dirt holding capacity and housing compatibility.
- Cooler: Heat transfer capacity and connection dimensions.
- Heater, sensors and switches: Electrical ratings and measuring range.
- Oil: The viscosity grade and additive package recommended by the manufacturer.
CSP Mühendislik supplies lubrication pumps, filter elements, coolers, heaters, sensors and seal kits as part of its cone crusher spare parts range. You can also see our detailed guides on the eccentric bushing and countershaft bushings, which are often affected by lubrication problems.
Pre-Purchase Checklist
- Have the make/model of the lubrication unit and the pump nameplate details been obtained?
- Are the filter element part number and micron rating known?
- Have the cooler type (air/water) and capacity been determined?
- Are the type and viscosity of the oil in use recorded?
Safety
- Hot oil can cause serious burns; use protective equipment when changing oil and taking samples.
- Before working on the electric heater and pump motor, cut and lock out the power.
- Spilled oil is a slipping and fire hazard; clean it up immediately.
Frequently Asked Questions
How long can the crusher run if the lubrication pump fails?
It should not run. When oil pressure or flow is lost, the protection system must stop the crusher; running without oil causes severe damage to bushings and bearings in a short time.
How often should the oil be changed?
The manufacturer’s recommended interval and oil analysis results should be considered together. Oil that is kept clean and monitored by analysis can be used for longer.
Is a finer filter always better?
No. A filter finer than necessary can cause high differential pressure and bypass with cold oil. Use the filtration rating recommended by the manufacturer.
Are the hydraulic oil filter and the lubrication oil filter the same?
No. The hydraulic system and the lubrication system are usually separate circuits; their filters and oils may be different.
Spare Parts and Service for the Lubrication Unit
CSP Mühendislik supplies pumps, filters, coolers and sensors for the lubrication systems of cone crushers and other crushers as part of its cone crusher spare parts range, and supports lubrication unit overhauls, oil analysis interpretation and troubleshooting with our service team. Share your unit’s nameplate details on WhatsApp for a quick quote.
