TL;DR
A drive overload trip means the crusher was fed beyond its capacity or a tramp event occurred. Clear the chamber, check for uncrushables, and reduce feed rate before restarting.
What you might see
- crusher motor trips on overload
- feed material packing in the crushing chamber
- flywheel speed drop before trip
- high motor current alarm before shutdown
Likely causes
Feed rate too high for the current CSS setting packing the crushing chamber
Tramp metal or uncrushable object jamming the crushing zone
CSS too tight for the ore hardness causing choking
Drive belt slippage causing the crusher to run below rated speed before the overload
Required tools
- Air lance or bar for chamber clearing
- CSS measurement device
- LOTO kit
Safety first
- Never enter the crushing chamber for any reason without full drive and feed lockout and a confined-space entry permit.
- Dust explosion hazard with sulfide ores. No hot work near the crushing chamber.
- Falling material from the feed opening above the crushing zone. Wear hard hat and face shield.
Procedure
- 1
Stop the feed conveyor immediately. Do not attempt to restart the crusher against a packed chamber.
Warning: Do not enter the feed opening or crushing chamber without full lockout of the drive and feed system. - 2
Lock out the crusher drive and feed conveyors.
- 3
Inspect the crusher feed opening from above for visible tramp metal or an uncrushable object.
- 4
If the chamber is packed with feed material, use a bar or air lance to clear material from the feed zone. Never use a torch on the chamber, it can ignite sulfide ore dust.
Warning: Dust explosion hazard in sulfide ore. No ignition sources near the crushing chamber. - 5
Check the CSS setting. If it was set tighter than the recommended minimum for the ore hardness, open it by 5 mm and retest.[1]
- 6
Review the feed control system. If the feed conveyor has no load limiter, add a belt scale interlock to cap crusher feed rate.[1]
- 7
Check the V-belt or direct drive coupling for slip damage before restarting.
- 8
Restart the crusher at no load first, confirm normal current, then gradually introduce feed.
Sources
Metso Outotec Metso Nordberg C / HP / GP / Symons Crusher (Jaw / Cone / Gyratory) general technical documentation, Metso Outotec
Metso Outotec crusher operation and maintenance documentation, overload response and chamber clearing procedures (general)
More guides for Metso Outotec Metso Nordberg C / HP / GP / Symons
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A lube alarm means the crusher protection has tripped for a reason. Do not override. Check oil level, filter condition, and pump pressure before restarting.
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Coarsening product and a widening closed side setting mean the liners are worn out. Measure the CSS and compare against the minimum allowed setting before scheduling a liner change.
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