Worn and pitted gears
Tooth pitting, scoring, and spalling reworked when light, or new gears cut in house and matched to the original ratio when the damage is severe.
Houston, TX ยท Ball mill gearbox repair
Ball Mill Gearbox Repair
A ball mill turns slowly and carries an enormous load, so the drive gearbox lives a hard life. It takes the speed of the motor and reduces it down to the crawl the mill shell needs, while passing through some of the highest torque in the plant. When that gearbox starts to whine, run hot, or throw metal in the oil, the whole grinding circuit is on the clock. We are a family owned gear shop in Houston, established in 1998, and we rebuild ball mill gearboxes for mining and mineral processing and cement operations every week.
We rebuild ball mill drive gearboxes stronger than OEM at our Houston shop. That covers central reducers and pinion gearbox assemblies for mining and cement mills, with free shipping both ways, a free inspection, and up to a 24 month workmanship warranty.
We see two basic drive arrangements on these mills. The central drive uses a co-axial reducer, often a two stage planetary unit or a combination of a bevel helical stage feeding a planetary output, mounted in line between the motor and the mill trunnion. The other arrangement is the girth gear and pinion drive, where a pinion gearbox or pinion shaft assembly meshes with the big ring gear bolted around the mill shell. We repair both, and we rebuild them to run stronger than the original.
Everything we do happens in house. We tear the unit down, find the real root cause instead of just swapping the broken part, machine and cut what needs to be made new, reassemble to spec, and test before it ships back. Shipping is free both ways, the inspection is free, and we cover the work with up to a 24 month workmanship warranty.
How ball mill drive gearboxes are built
The job of the gearbox is brutal in its simplicity. The mill shell needs to turn slowly, often well under 20 rpm, while grinding tons of ore or clinker against a charge of steel balls. To get there the gearbox carries a very high reduction ratio and a very high torque, and the lower the speed the higher the torque the teeth and bearings have to hold.
On central drive mills the reducer is usually a multi stage unit. Smaller and medium duty mills run a two stage planetary box where each stage spreads the load across three planet wheels, which is why these units handle the torque in a compact case. Larger mills add a bevel helical or helical input stage ahead of the planetary stages, and the biggest central drives push into the thousands of kilonewton meters. All of that stacked reduction creates heavy thrust loads, which is why the shafts ride on high capacity tapered roller bearings.
On girth gear mills the pinion gearbox is a parallel shaft helical reducer, and its output pinion meshes directly with the ring or crown gear around the shell. Here the bearings, the shaft, and the pinion alignment have to be held tight, because the pinion is the small gear taking the full bite against a very large, through hardened girth gear.
Why ball mill gearboxes fail
Misalignment is the number one killer we find. When the pinion and the girth gear, or the input and output shafts of a central reducer, are even slightly off in parallelism, center distance, or runout, the load piles onto one end of the tooth face instead of spreading across it. That corner of the tooth wears fast while the rest barely carries load, and the box gets loud and hot long before it lets go.
- Tooth pitting and scoring. When the oil film gets too thin you get metal to metal contact, and the tooth surface starts to pit and spall. Caught early it can be ground and reworked. Left alone it eats the tooth.
- Abrasive wear from contamination. Cement dust and ore fines that get past the seals turn the oil into grinding paste and accelerate wear on gears and bearings alike.
- Bearing wear. Inadequate lubrication, contamination, and pinion misalignment overload the bearings. A failing pinion bearing shows up as vibration, heat, and changing gear mesh, and it drags the gears down with it.
- Torque overload. Uneven feed, a surge load, or a frozen charge can shock the teeth past their fatigue strength and crack or break them.
We diagnose the actual cause before we quote, because replacing a gear without fixing the alignment or the seal that killed it just buys you the same failure a few months later.
What our rebuild includes
When your gearbox lands at our Houston shop we strip it completely and inspect every component. We measure the gears for wear, pitting, and profile, check the shafts for runout and journal wear, and examine the bearings and bores.
- New gears cut in house when teeth are pitched too far gone to rework, matched to the original ratio and profile. See our gear cutting capability.
- Shaft and pinion repair, including journal buildup and regrind, or new shafts machined when the wear is past limits.
- Bearing replacement with matched high precision sets, with clearance and preload set to spec so the thrust loads are carried properly. We also handle standalone bearing repair.
- New seals and a thorough clean to keep dust out and keep the oil where it belongs.
- Full alignment of the gear axes and center distance, then assembly and load testing before it ships.
If your unit is a planetary central drive, our dedicated planetary gearbox repair work applies directly. We rebuild these to run stronger than OEM, not just back to worn out tolerances.
Free shipping both ways, so Houston is not a problem
Ball mills run all over the country, and a drive gearbox is heavy and awkward to move. That is exactly why we ship both ways for free and handle the crating and rigging. Distance from Houston does not add a freight bill to your repair.
For operations near us we offer free local pickup and delivery, since Houston is home base. Wherever you are, the inspection is free and we will tell you honestly what the box needs before you commit. We run a 24 hour line so a mill that goes down at night does not wait until morning to get moving.
What we repair and rebuild
What we fix.
Pinion shaft and pinion
Worn or scored pinions and pinion shafts repaired or remachined, with journals built up and reground to restore the mesh against the girth gear.
Bearing failure
Worn tapered roller and other bearings replaced with matched high precision sets, with clearance and preload set to spec to carry the high thrust loads.
Misalignment damage
Gear axes, parallelism, and center distance recalibrated so load spreads across the full tooth face instead of overloading one end.
Central reducer rebuild
Two stage planetary and combined bevel helical plus planetary central drives torn down, repaired, and rebuilt stronger than OEM.
Cracked or broken teeth
Torque overload damage from surge feed or a frozen charge addressed with new gears and a root cause review of the feed and load path.
Oil contamination and seal failure
Abrasive dust ingress and leaking seals corrected with new seals, a full clean, and a fresh start so the oil stays an oil and not a grinding paste.
Heat and vibration
Running hot, loud, or shaking diagnosed to the real source, whether bearing, alignment, or gear, then fixed and load tested before it ships.
Common questions
What plants ask us.
Do you repair both central drive and girth gear pinion gearboxes?
Yes. We rebuild central reducers, including two stage planetary and combined bevel helical plus planetary units, and we repair the pinion gearbox and pinion shaft assemblies that mesh with the girth gear. We handle both arrangements in house.
Can a pitted or worn ball mill gear be saved, or does it need replacing?
It depends on how far it has gone. Light pitting and surface wear can often be reworked. When the tooth profile is pitched too far or teeth are cracked, we cut new gears in house and match them to the original ratio and profile.
How do you keep distance from Houston from being a problem?
We ship both ways for free and handle crating and rigging, so freight does not add to your bill no matter where the mill runs. For operations near us we also offer free local pickup and delivery.
What kind of warranty do you offer on a rebuilt gearbox?
We offer up to a 24 month workmanship warranty. We rebuild these units stronger than OEM, and the free inspection up front means you know what the box needs before you commit to the work.
My mill went down overnight. Can I reach you?
Yes. We run a 24 hour line at 832 270 2009 so a mill that fails at night does not sit until morning. Our main number is 713 270 6000 during business hours.
Get your ball mill gearbox back in service
Free shipping both ways, free inspection, and an up to a 24 month warranty on every rebuild. Tell us about your unit and we reply fast, often the same day.
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