When a cone crusher operates, problems such as the moving head stopping its gyrating motion, failing to move normally, or causing the machine to shut down shortly after startup may be related to chamber blockage, lubrication failure, damage to the eccentric assembly, or excessive operating loads.
A stuck moving head may result from temporary material blockage or severe wear, overheating, or seizure of internal bearings and bushings. These conditions require different corrective actions. The cause should be identified by checking operating records, lubrication conditions, and the mechanical components.
Material-related problems causing chamber blockage
Oversized feed or uneven feeding
Every cone crusher has a specified maximum feed size. When material larger than the permitted size enters the crushing chamber, it may become stuck at the feed opening or inside the chamber, restricting the normal movement of the moving head.
Uneven feed distribution can also cause material buildup and concentrated loading in certain areas of the chamber. If the feed is consistently off-center or poorly distributed, the crusher may become overloaded and stop operating.
Wet, sticky material or excessive fines
When the feed has high moisture content or strong adhesive properties, material may stick to the chamber surfaces, mantle, and concave, gradually forming a buildup.
Excessive fines in the feed can also interfere with material movement and discharge. Material packing may increase the load inside the chamber, making it difficult for the moving head to operate normally. Severe blockage can eventually cause the motor overload protection to trip.
Lubrication system failures affecting the eccentric assembly
Insufficient lubricant or incorrect oil specification
The eccentric bushing, main shaft mating surfaces, and thrust support components require proper lubrication.
If the oil level is too low, the viscosity is unsuitable, or the lubricant has oxidized and deteriorated, the affected friction surfaces may not maintain an adequate oil film. Continued operation under these conditions can increase friction, raise operating temperatures, and accelerate wear. Severe cases may result in metal-to-metal contact and seizure of the moving head.
Oil pump failure or blocked lubrication lines
The lubrication pump supplies oil to critical internal components. If the pump fails, the oil flow becomes insufficient, or a filter or pipeline becomes blocked, some components may no longer receive adequate lubrication.
Prolonged lubrication failure can cause abnormal wear or burnout of the eccentric bushing and related bearings. In severe cases, the crusher may become mechanically locked.
When checking the lubrication system, inspect the supply pressure, oil flow, oil temperature, filter condition, and return oil rather than relying on the oil tank level alone.
Contaminated lubricating oil
Dust, moisture, and metal particles from the mining environment can enter the lubrication system. When seals or filtration components fail, contaminants circulate with the oil and accelerate wear on bearing and bushing surfaces.
For example, abnormal eccentric bushing wear may release bronze particles into the return oil filtration system. If unusual metal particles are found in the filter together with rising oil temperature or increased operating resistance, eccentric bushing burnout or other internal bearing problems should be investigated.
Metso recommends monitoring the return oil screen, lubrication oil temperature and pressure, and conducting regular oil analysis to assess the wear condition of internal cone crusher components. <Cite refs={["turn545594view1","turn545594view0"]}/>
Mechanical component damage or assembly problems
Worn or burned eccentric bushing
The eccentric bushing is an important component of the cone crusher eccentric assembly. Its condition directly affects the movement of the moving head.
Insufficient lubrication, interrupted oil supply, or severe oil contamination can increase friction between the eccentric bushing and the associated shaft surfaces. This may lead to higher operating temperatures, abnormal fitting clearances, and eventually bushing burnout or seizure.
When the eccentric bushing becomes severely seized against the shaft, the moving head may no longer move. This is one of the major mechanical causes of a locked cone crusher.
Main shaft or bearing damage
The main shaft and its supporting components carry substantial loads during operation. Cracks or severe deformation in the shaft, or damage to the thrust bearing, support bearings, and related mating components, can interfere with the normal movement of the moving head.
Bearing burnout, broken internal components, or abnormal shaft clearances may cause increased rotational resistance, abnormal vibration, or complete mechanical seizure.
These failures generally require disassembly and inspection of the affected components. Repairs or replacements should be determined according to the extent of the damage.
Loose or damaged mantle and concave
The mantle and concave are the main wear components of a cone crusher. If the liners are not properly secured, incorrectly installed, or severely damaged, the actual crushing chamber configuration may change, resulting in abnormal contact and concentrated loading.
Loose liners or trapped foreign material can also contribute to chamber blockage and interfere with normal moving head operation. Inspect the liner fastening bolts, contact conditions, and wear profiles to confirm that the crushing chamber is properly configured.
Abnormal counterweight or balancing components
Some cone crushers use eccentric assemblies and counterweights to balance inertial loads during operation. If a counterweight becomes loose, damaged, or incorrectly positioned, the crusher may develop excessive vibration and unstable operation.
However, a fault in the balancing arrangement does not necessarily mean that the moving head is mechanically seized. The eccentric assembly, bearings, and other moving components must also be inspected to determine whether mechanical interference or abnormal fitting conditions are present.
Prolonged overloading and drive system faults
Extended operation under excessive loads
If a cone crusher operates beyond its rated processing capacity for extended periods, or if the crushing chamber configuration does not match the feed material, the internal mechanical load may remain excessively high.
For example, an excessively small closed side setting (CSS), off-center feeding, and excessive fines in the feed can increase the load on the eccentric bushing and related support components. Prolonged operation under these conditions may accelerate wear and eventually lead to bushing burnout and a locked moving head.
Motor or electrical control system faults
Faults in the electric motor, variable frequency drive, starter, or protection system may prevent the cone crusher from starting or cause it to stop during operation.
However, an electrical shutdown is not necessarily evidence of mechanical seizure. The motor current, protection alarms, drive system, and mechanical movement should be checked to identify the actual cause.
If the motor overload protection has tripped because of excessive mechanical load, further inspection is needed to determine whether the crushing chamber is blocked, the eccentric assembly is seized, or a bearing has failed.
Troubleshooting a stuck moving head in a cone crusher
When the moving head becomes stuck, do not repeatedly restart the motor or attempt to force the head to rotate. Stop the feed, follow the equipment shutdown procedure, isolate the power supply, and apply lockout/tagout (LOTO) procedures to prevent unexpected startup.
The following areas should then be inspected:
Check the crushing chamber for oversized material, tramp metal, or accumulated wet and sticky feed to determine whether the problem is caused by material blockage.
Check the lubrication oil level, supply pressure, flow rate, temperature, and filter condition. Verify that the oil pump and pipelines are operating correctly.
Inspect the return oil screen for abnormal metal particles, particularly bronze wear debris.
Check the eccentric bushing, main shaft, thrust bearing, and other support components for wear, overheating, burnout, or seizure.
Inspect the mantle, concave, and eccentric assembly for looseness, damage, or abnormal contact.
If the problem is caused by chamber blockage, use the approved chamber-clearing procedure and equipment specified by the manufacturer. If eccentric bushing burnout or bearing seizure is suspected, qualified maintenance personnel should dismantle the affected assembly, measure the relevant fitting dimensions, and determine whether repair or replacement is necessary.
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