Why Your Underground Conveyor Rollers Fail & How to Fix Them

Updated: 2026-07-18 View Count: 67

Underground mines need massive conveyor systems with thousands of rollers, so any unplanned roller failures can be a constant headache for maintenance teams. At some operations, crews replace multiple rollers daily across different conveyors meaning unplanned conveyor down time. Every unplanned roller failure contributes to conveyor availability and pulls maintenance personal away from other scheduled work.

Some areas on your conveyors are more prone to roller failures than others, so by focusing on the problem areas you can find long-term fixes to reduce unplanned conveyor downtime and emergency conveyor stoppages.

Problem rollers tend to be found in predictable locations like poor structure grading along ROC, high tension areas, boot ends, transfers, areas with excessive carryback and anywhere where water collects or pools. In our experience, the real problem often isn’t the roller itself, but a mismatch between the design, installation, and operating conditions.

“The majority of the rollers I’ve seen fail underground are in areas that are either under high tension, the belt structure isn’t graded as per OEM standards, excessive carryback due to poor scraper condition, or they’re installed in an area where there is an excessive amount of water and fines,” says Ryan Storey, a conveyor engineer at YILUN.

In this article, we discuss why that is and how to fix it.

The incorrectly installed & high-tension areas underground

The three most common scenarios underground where repeat roller failures tend to cluster due to original incorrect installation, high tension and incorrect loading which are:

• ◆ Uneven grade transitions on your ROC, or the grade not being set correctly as per OEM spec.

• ◆ Roof-to-floor mounting changes where belt tension spikes beyond design parameters.

• ◆ Areas around your boot end, transfer, drive areas or trippers that are not aligned correctly

“At your boot end or at your jib, or where it goes from floor mounted to roof hung. The rollers can see more load than what they are designed for,” Ryan says. “As a rule of thumb, you don’t want a gap bigger than about three meters around these areas to the load can be shared.” With more load or change of grade more rollers / frames are required.

Uneven load distribution causes most of these problems. When the belt grade isn’t set properly it forces some rollers to carry 80% of the load while adjacent rollers run light or lose contact entirely. The overloaded units experience shaft deflection that pushes bearings out of alignment which an engineered larger roller or custom frame may be required.

This also creates entry points through the seals for water and fines to access the bearings which accelerate bearing failures.

If the belt is missing rollers in a transition area this makes things even worse. A single missing roller in a high-tension area can double the load on adjacent rollers and push them beyond their designed deflection tolerance, creating a cascade of repeat roller failures.

Why rollers fail faster in these areas

When rollers don’t share the load evenly, the system stops working as intended. “If all your rollers aren’t working together, the load isn’t dissipated evenly,” Ryan says. “If one roller is taking all the load, you’ll see the difference.” Uneven load sharing can cause rollers to “fight” against each other, pulling the belt in slightly different directions.

Carryback accelerates the damage too with water and fines combined turn into a paste like material which rubs against the roller shell from the belt causing it to wear thin, this can also work their way into the bearings. If the carryback builds up under a roller, it can create “ant hills”, these carryback / dirt piles under the belt can build up and rub against the rollers causing wear through the shell.

Water ingress is also a common factor. Transfers and boot ends are especially exposed to water from structures being hosed down and dust control sprays. High-pressure hoses can blast water straight past the roller seals, displace grease and cause bearings to run dry.

Materials matter too. Ryan says rollers made from lower-grade steel like 200 or 250-grade will wear out far faster than those made from 350-grade, especially in wet, abrasive environments. A poor sealing system and poor-quality compounds the problem allowing water and fines to act like a gritty polish that erodes metal surfaces.

How to spot the early warning signs

Rollers rarely fail without warning. Experienced maintenance crews can identify problems weeks before catastrophic failure by watching for four specific cues:

1. Load distribution problems show up first on the roller shells

“A roller with a wide wear band is probably taking more than its share of the load,” Ryan says. “Shiny marks usually mean it’s rubbing against something, while an even colour across the shell suggests it’s not making contact at all.”

2. Belt tracking issues leave multiple clues

Look for rub marks on conveyor frames, belt fibres or dust scattered on the ground or consistent spillage in the same locations. These signs indicate the belt is tracking off its intended path, putting uneven stress on rollers. This can be simply from uneven grading or even crooked splicing or clips not square.

3. Smell can be an early indicator

Underground crews often detect problems with their nose before their eyes. “You can smell a potential heating event when friction produces a hot rubber smell,” Ryan explains. “It’s your early warning that something’s wrong.”

4. Water contamination has its own signature sound

“You can hear water and fines rattling around inside a roller,” Ryan says. “By then the grease is gone and it’s running dry.” This telltale noise means bearing failure is imminent and needs to be planned to change out.

Smart maintenance teams use these early indicators to schedule replacements during planned downtime rather than needing an emergency shutdown. The key is to act on them before small problems become major failures.

How to fix the root cause of underground roller problems

Many problems start when equipment is installed incorrectly, so the first rule is simple, says Gary Grout, Aftermarket Manager at YILUN: “Elimination is always best. Have the right people install it at the start so the problem doesn’t happen at all.” If you have OEM-trained staff and adhere to installation, commissioning, and maintenance manuals, it’s the best insurance against grading and high-tension problems.

When issues do arise, Gary suggests you should start at the boot end and walk the belt to identify trouble areas. Look for rollers with wider wear spots as these indicate excessive weight bearing. Check the ground for spillage, belt fibres or dust, and rub marks on H-frames as these all signs that the belt isn’t graded properly.

The fix involves adjusting the conveyor grade to distribute weight evenly across rollers. On roof-mounted sections adjust the chain heights. On floor-mounted sections, modify leg and frame heights, adding shims where needed. “With most mines only shutting down once or twice a week for about 12 hours, you want to avoid wasting that window making the same repairs over and over,” he says.

For persistent problems at transfers, custom brackets or frames can help distribute loads better.

Control carryback

Regular scraper maintenance from trained personal is the key to managing carryback. When water and coal travels up around transfers inadequate scrapers let fines past and out of the head chute heading back down the belt and coming into contact with the rollers.

“Each scraper needs to be set to the right pressure and matched to the mine’s conditions,” Gary explains. Common problems include disconnected or damaged air lines, severely worn scrapers tips that have lost effectiveness, and mismatched scraper compound grades for specific coal types.

You can fix this with regular scraper inspection and planned maintenance. Some scraper grades are more durable than others, so match the grade to your coal type and operating conditions. When the same rollers fail repeatedly look for signs like shiny wear marks on shells that indicate rubbing or polishing also checking if buildup underneath hasn’t created any ‘ant hills’ that force rollers to grind against accumulated material.

Reduce water exposure

Excessive water creates the most challenging underground conditions. Cutting coal, structural cleaning, scraper hosing and dust suppression can saturate transfer points and boot ends. High-pressure hoses often blast water directly past roller seals, displacing grease and causing bearings to run dry.

But there are a number of ways to minimize water exposure:

• ◆ Use modern air atomizers that rely more on an air over water system rather than just lots or water for dust control.

• ◆ Prevent water pooling around boot ends when belts stop be installing conflow units, regulators, sensors or solinoids.

• ◆ Replace standard steel rollers with YILUN hybrid rollers.

• ◆ Ensure pumps run consistently to minimize ground water accumulation.

• ◆ Use rollers with a higher level of sealing arrangement and stronger grade of steel eg 350gr over 200gr & 250gr.

When water exposure is unavoidable, consider using rollers designed with exceptional sealing systems like a YILUN HDPE or Hybrid labryth type roller. Splash guards can also be added to protect roller seals from high-pressure washing.

“If your rollers are operating in wet areas and only last three to six months, there’s an opportunity to do better,” Gary says. “With the right roller designed for the application and conditions you should be getting years.”

The correct roller designed for harsh underground conditions combines several design elements:

• ◆ Reinforced shafts that resist deflection under load.

• ◆ High-capacity bearings built for continuous heavy-duty operation.

• ◆ Advanced sealing systems that withstand wet and abrasive environments.

• ◆ 350-grade steel shells with adequate thickness to resist wear.

Case in point: Knight Hawk coal mine

Knight Hawk coal mine faced rollers failing every two weeks in high-load return zones. Rather than accept this costly cycle, Knight Hawk reached out to the OEM YILUN and our team investigated.

They found that the air passages forced steep vertical transitions over short distances which created extreme overdesigned belt tension that the standard rollers couldn’t handle. Rather than accept this as inevitable, Knight Hawk tested a YILUN custom-engineered design with reinforced shafts, better sealing arrangement and higher quality bearings.

The results spoke for themselves. “We can walk along a YILUN belt and have a conversation now. With the old system, we had to shout,” reported the maintenance team.

Service life jumped from two weeks to more than nine months without a single failure in the same locations. The maintenance crew could focus on other priorities instead of weekly roller changes, and the risk of unplanned production delays dropped significantly.

The Knight Hawk experience illustrates that key principle: when the same rollers keep failing, fix the conditions, not just the components. You can read the full Knight Hawk case study here.

Stop the cycle before it starts

Underground conveyor failures follow predictable patterns. Yet many operations continue to replace failed components rather than address the root causes.

“If the same rollers keep failing, it’s almost never the rollers themselves. It’s the setup, the conditions or the maintenance,” Ryan says. “Fix that, and the failures stop.”

The solution requires a systematic approach: walk your belts to identify high-wear zones, correctly grade during scheduled maintenance windows, upgrade scrapers to control carryback, minimize water exposure where possible, and specify equipment designed for actual operating conditions.

For underground operations tired of replacing the same rollers repeatedly, the path forward is clear. Stop treating symptoms and start fixing causes. Your maintenance schedule and your bottom line will thank you for it.