1. The “Underground Dilemma“ of Bearing Replacement in the Mining Industry

Mining is a classic heavy-load, continuous-operation, harsh-environment industrial scenario. Bearings in mine hoists, belt conveyors, bucket elevators, crushers, stacker-reclaimers and other equipment endure hundreds of tons of heavy impact loads, extreme dust and high humidity year-round. In the mining industry, conveyors are by far the most frequently problematic equipment type. Coal conveyor lines often require 24-hour continuous operation, and any unexpected shutdown can become a production or operational accident.

 

When bearings in these machines fail, maintenance teams face a far more complex “underground dilemma“ than ordinary industrial equipment – traditional solid bearing replacement requires disassembly of shafts, gears, couplings, gearboxes and numerous surrounding components, with confined working spaces (especially in underground tunnels) and massive component weights – the entire replacement cycle takes days or weeks, with downtime losses reaching tens of millions or even hundreds of millions of yuan.

 

Taking the main shaft multi-rope friction hoist at Jiangxi Copper‘s Wushan Copper Mine as an example: the hoist bearing is located at the top of the headframe, surrounded by gearboxes, couplings, motors and extensive equipment. Traditional solid bearing replacement required first disassembling couplings, motors, gearboxes and other surrounding components, and extracting the main shaft. The entire project was extremely time-consuming, with confined working space and difficult hoisting. By adopting split rolling bearings for the hoist bearing retrofit, the split bearing performed well in practice, effectively ensuring the normal operation of the hoist.

 

At a mine in Colorado, USA, there was a 16-kilometer conveyor belt running through snowy mountains. When the vibration monitoring system showed signs of pulley bearing damage, the traditional solution required taking down a wall, renting a crane for several days, and lifting the pulley out of the machine room – the entire process would take 9 days, exceeding the mine‘s 6-day stockpile buffer. After adopting split spherical roller bearings, replacement was completed in just 4 days. Future estimates indicate new split bearing installation will take approximately 18 hours, replacing the original 9-day shutdown. Mean time to repair (MTTR) was shortened by 55%.

 

Typical pain points of traditional solid bearings in the mining industry:

 

Enormous disassembly workload – Replacing one bearing requires disassembling couplings, gears, gearboxes, frames and numerous surrounding components. In mine hoists, the main shaft itself weighs several to tens of tons – disassembly alone is a major project.

 

Extremely confined working space – Underground tunnels have limited space where heavy lifting equipment cannot access – making hoisting and handling extremely difficult. Bearings between head pulleys and gearboxes or motors are often in “inaccessible or trapped positions,“ making replacement extremely difficult.

 

Dependence on heavy equipment – Bearings and surrounding components weigh several to tens of tons – requiring heavy lifting equipment, whose rental and scheduling is itself a challenge.

 

Downtime measured in days or even weeks – Traditional solid bearing replacement typically takes days or even weeks, while mine conveyor lines operate 24/7 – any extended downtime means enormous capacity losses.

 

Production losses measured in tens of millions – Days to weeks of unplanned downtime directly lose tens of millions or even hundreds of millions of yuan. At the Colorado mine, the traditional 9-day shutdown exceeded the 6-day stockpile buffer.

 

High worker safety risks – 43% of accidents in the mining and cement industry occur while workers perform maintenance or checks on conveyors. Complex disassembly, heavy lifting and confined space work all significantly increase safety risks.

 

2. NMT Split Bearings for the Mining Industry: Underground, No Shaft Removal, Quick Bearing Replacement

NMT split bearings for the mining industry perfectly combine the core advantage of split bearings – “no-shaft-removal installation“ – with the stringent requirements of mining heavy-duty applications. The inner ring, outer ring, rolling elements and cage are all split along the axial direction – installation requires no removal of shafts, gears, couplings or any other core components – assembly is completed directly on the shaft in situ. Unlike traditional sliding installation, split bearings are installed directly around the shaft – no need to slide the bearing on or off from the shaft end.

 

More critically – NMT split bearings can be replaced without removing drive motors, without moving shaft systems, without using heavy lifting equipment. This is like installing a “service door“ on mining heavy-duty equipment, enabling true “online“ maintenance. Industry data shows split bearings reduce average maintenance intervals by 55%, compressing single bearing replacement from 9 days to 4 days.

 

▸ Full Split + Heavy-Duty Construction: Every Piece Can “Go in Separately, Rotate Together“ – Withstanding Mining Impact

 

Every component of an NMT split bearing for the mining industry is split – split inner ring, split outer ring, split cage with rolling elements, split seals. During installation, these half-ring components are assembled sequentially around the shaft. After being locked with high-strength bolts, they form a precision transmission unit with performance fully equivalent to a solid bearing. Precision step-type mating or V-shaped split joint design at the split interfaces ensures load capacity and rotational precision equal to solid bearings. Split bearings enable rapid disassembly and replacement without dismantling shaft systems or integrated equipment.

 

In terms of materials, NMT offers a complete impact-resistant steel system for mining heavy-duty applications – carburized bearing steel with deep-case hardening achieves uniform surface hardness HRC60-64 while the core maintains sufficient toughness to absorb impact loads. For high-dust, high-humidity mining environments, stainless steel or special anti-corrosion coatings are available.

 

▸ No-Shaft-Removal Installation: No Motor Removal, No Coupling Removal, No Heavy Lifting Equipment

 

The core value of NMT split bearings for the mining industry is – bearing replacement without moving the shaft, without removing drive motors and couplings, without using heavy lifting equipment. This means for mine hoist bearing replacement, the motor stays in place, couplings stay in place, gearboxes stay in place. For conveyor pulley bearing replacement, no drive coupling or cantilevered drive disassembly is required. Maintenance personnel simply open the bearing housing, remove the old bearing halves, install the new bearing halves, and tighten the bolts – complete.

 

▸ Interchangeable with Standard Heavy-Duty Solid Bearings: Seamless Replacement, No Modifications

 

NMT split bearings for the mining industry are designed with full interchangeability with standard heavy-duty solid bearings in mind. The split bearing outer ring has the same external dimensions as a standard ISO spherical bearing outer ring. In most cases, the outer diameter and outer ring width of split bearings are identical to standard spherical roller bearings (222, 230, 231, 239, 240, 241 series). This means mining operations can directly replace existing solid bearings in their equipment with NMT split bearings without any machining modifications to bearing housings.

 

▸ Split Housed Bearing Units Option – NMT also offers split housed bearing units that integrate split bearings and housings as a complete assembly. These housed bearing units are particularly suitable for conveyor drive rollers, bucket elevators and other equipment, using radial installation and disassembly without disconnecting and disassembling components around the bearing, such as motors, gearboxes and couplings. They can bring considerable savings in operating costs. Housings are available in steel, gray cast iron or ductile iron to suit different application requirements.

 

3. Full Series Split Bearing Types for the Mining Industry

NMT offers a complete split bearing product system covering multiple mining applications:

 

▸ Mining Split Spherical Roller Bearings

 

Split spherical roller bearings are the most widely used split bearing type in the mining industry, providing high load capacity and shock load resistance. NMT split spherical roller bearings are specifically designed for mine hoists, conveyor pulleys, crushers and other heavy impact applications – inner rings, outer rings and cages with rollers are all split in half. Spherical outer ring raceways and barrel-shaped rollers provide self-aligning capability, effectively compensating for shaft deflection and installation errors. Excellent sealing characteristics ensure reliable operation in the dusty mining environment. Widely used in mine hoist main shafts, belt conveyor drive and bend pulleys, stacker-reclaimers, crushers, ball mills and other mining equipment. The split structure allows bearing replacement without removing drive systems. Wire-cut inner and outer ring manufacturing techniques ensure high precision in split surface alignment.

 

▸ Mining Split Cylindrical Roller Bearings

 

Split cylindrical roller bearings are mainly used for bearing arrangements in inaccessible or restricted locations. NMT split cylindrical roller bearings use cylindrical rollers to carry high radial loads – inner and outer rings each split in half, with one or two rows of cylindrical rollers in a split cage. Common applications include belt conveyor drive rollers, bucket elevator head and tail pulleys, stacker-reclaimer traveling wheels, crusher drive shafts and more. Widely used in coal, metal and non-metal mining conveying and hoisting systems. The split housed cylindrical roller bearing unit features a “half-half“ internal cylindrical roller bearing and a “half-half“ bearing box, perfectly fitting conveyor line drive roller applications.

 

▸ Mining Split Tapered Roller Bearings

 

NMT split tapered roller bearings feature two rows of opposed tapered rollers with tapered inner and outer ring raceways, specifically designed for combined loads. They can simultaneously bear radial and bidirectional axial loads, suitable for mine hoists, crushers and other fixed-end bearing positions requiring combined loads. Available in a complete range of specifications, widely used in the mining and metallurgical industry.

 

▸ Split Housed Bearing Units

 

NMT offers split housed bearing units that integrate split bearings and housings as a complete assembly. The core advantage of split housed bearing units is “radial installation and disassembly“ – no need to disconnect and disassemble components around the bearing, such as motors, gearboxes and couplings. High-performance and diverse sealing options provide tight protection for healthy bearing operation. The unique design of the cylindrical roller bearing core and outer spherical bearing housing ensures balance between centering function and excellent axial floating capability. Widely used in coal conveyor line drive rollers, bucket elevators, stacker-reclaimers, crushers and other equipment.

 

4. Specialized Sealing and Lubrication Systems – Adapting to High Dust, High Impact and High Humidity Environments

Mining equipment operates year-round in harsh conditions of high dust, high impact and high humidity. NMT split bearings for the mining industry feature customized sealing and lubrication systems:

 

▸ Heavy-Duty Labyrinth Seal Structure – Non-contact design using centrifugal force from rotation to expel dust, particulates and contaminants. Excellent sealing characteristics ensure reliable operation in the dusty mining environment. SNU500 series split housed bearing units are suitable for medium-speed and heavy-load applications, widely used in conveyors, fans, mining equipment and metallurgical machinery.

 

▸ Contact Seal Upgrade (Taconite Seals) – For high-dust, high-contamination environments, NMT offers heavy-duty sealing solutions such as Taconite seals. In extremely contaminated and wet applications, these seals help keep contaminants out of bearing arrangements. Sealed split bearings significantly extend service life through improved contamination resistance. Sealed split spherical roller bearings can operate in ambient temperatures from -40°C to 90°C.

 

▸ Three-Barrier Sealing Solution – For extreme environments, NMT can provide a three-barrier sealing solution – contaminants must pass through three barriers to reach the bearing. SKF Cooper split spherical bearings are equipped with V-ring seals as a second barrier, with grease surrounding the bearing as a third barrier. SNL split plummer block housings with TXL contacting lip seals offer excellent protection against heavy contamination in industries like mining, metals and agriculture.

 

▸ Heavy-Duty Grease and Solid Lubrication Solutions – Conventional grease is easily squeezed out under heavy impact conditions. NMT offers graded lubrication solutions: standard conditions use extreme-pressure heavy-duty grease; high-temperature conditions use high-temperature grease or solid lubrication solutions. Sealed split bearings reduce grease consumption.

 

5. Installation and Maintenance – An Efficiency Revolution from “Days/Weeks“ to “Hours“

Installation Time Comparison:

 

Traditional mining heavy-duty solid bearing: Shutdown → disassemble couplings, motors, gearboxes, frames → move shaft → slide bearing on → realign → reassemble → recommission. Typical time: days to weeks (typical conveyor pulley bearing replacement takes 9 days).

 

NMT split bearing: Shutdown → open bearing housing → remove old halves → install new halves → tighten bolts → complete. Typical time: just hours to 1-2 days (split bearing installation takes approximately 18 hours).

 

NMT split bearings for the mining industry can reduce bearing replacement downtime by 80-90%. Industry data shows split bearings reduce average maintenance intervals by 55%, compressing single bearing replacement from 9 days to 4 days. SKF Cooper split spherical bearings can reduce mean time to repair (MTTR) for conveyor pulley bearings by 70%. Traditional bearing replacement typically takes 24 hours, while split spherical bearings take just 8 hours. At the Colorado mine, the traditional 9-day shutdown was shortened to 4 days with split bearings. At a coal mine in Australia, split bearings reduced downtime by 36 hours, saving 40,000 euros (72,000 Australian dollars).

 

Specific Case Studies:

 

Jiangxi Copper Wushan Copper Mine: After adopting split rolling bearings for the main shaft multi-rope friction hoist, the split bearing performed well in practice, effectively ensuring normal hoist operation.

 

Colorado Mine: 16-kilometer conveyor belt through snowy mountains – traditional 9-day shutdown shortened to 4 days with SKF Cooper split spherical bearings, MTTR reduced by 55%.

 

Beiminghe Iron Mine: IKM-3.5×6ZⅢ hoist successfully converted from solid rolling bearings to split rolling bearings.

 

Huoerxinhe Coal Mine: Auxiliary shaft hoist bearing system retrofitted with split rolling bearings – bearings operated normally with no damage.

 

Maintenance Convenience:

 

No heavy lifting equipment required – Bearings are handled in sections – no large cranes needed.

 

No wall removal or structural modification – The Colorado mine‘s traditional solution required wall removal; split bearings require no structural modification.

 

Inspect anytime – Bearing housing can be opened for inspection without disassembly.

 

Split handling – Bearings can be disassembled into smaller components – assembly and replacement are simple even in confined and inaccessible spaces.

 

No on-site adjustment – Clearances are preset at the factory – no on-site adjustment or specialized tools required.

 

Improved worker safety – Simplified installation reduces safety risks from complex disassembly work.

 

6. Quality Control – Triple Assurance of Split Precision, Heavy-Duty Strength and Seal Reliability

NMT implements a strict quality control system for mining industry split bearings:

 

Heavy-duty material certification – Each batch of bearing steel undergoes impact load testing and hardness inspection to ensure performance meets mining heavy-duty requirements.

 

Precision split surface machining – High-precision wire cutting for inner and outer ring split surfaces, ensuring concentricity and strength after assembly. Wire-cut inner and outer rings ensure the two halves are geometrically precisely aligned, allowing rollers to transit from one half of the race to the other more smoothly. The outer ring features a “saw tooth“ joint design providing precise axial alignment.

 

High-strength locking system – High-strength steel clamp rings and multiple bolts ensure split surfaces remain secure during operation. Steel inner ring clamping rings permit split bearings to sustain higher axial loading than other forms of split bearings.

 

Seal performance verification – Each batch undergoes dust environment seal testing to ensure sealing effectiveness under high-contamination mining conditions.

 

Post-assembly precision inspection – Each split bearing is inspected for radial clearance, rotational accuracy and vibration after assembly – ensuring performance equivalent to solid bearings.

 

7. Stock Availability + Customization – Rapid Response to Mining Emergency Needs

Common mining split bearing models (split spherical roller bearings, split cylindrical roller bearings, split tapered roller bearings) kept in stock – Covering over 80% of split bearing needs for mine hoists, belt conveyors, bucket elevators, crushers, stacker-reclaimers and other applications. Emergency failures receive rapid response – minimizing unplanned downtime.

 

Custom solutions available – Special bore/OD/width (standard range 55mm to 630mm, expandable to 1850mm+), custom heavy-duty materials (carburized bearing steel/heat-resistant steel/stainless steel), special split configurations, custom sealing solutions (heavy-duty labyrinth/Taconite seals/three-barrier), custom clearance, split housed bearing units, compatibility with SNU/SNL/SMS/SAF/SDAF series split block housings.

 

Rapid customization from samples or drawings – Provide old bearing samples or equipment drawings – NMT completes surveying and custom production quickly. Cost-effective replacement for imported brands (SKF Cooper, FAG, Timken, NSK) with significant procurement savings.

 

8. Lifecycle Cost Optimization – No Motor Removal, No Shaft Removal, Save Millions in Downtime Losses

Unplanned downtime in the mining industry often costs tens of millions or even hundreds of millions of yuan. Taking the Colorado mine conveyor pulley bearing as an example: the traditional solid bearing solution required 9 days of downtime, exceeding the 6-day stockpile buffer; with the split bearing solution, replacement was completed in just 4 days, and future installation will take only 18 hours. FAG split spherical roller bearings reduced downtime by 36 hours, saving 40,000 euros (72,000 Australian dollars).

 

Hidden costs of cheap heavy-duty solid bearings:

 

Single replacement requires days to weeks of downtime – downtime losses are hundreds or even thousands of times the bearing price.

 

Disassembly of motors, couplings and surrounding components is time-consuming and may cause secondary damage.

 

Heavy lifting equipment rental costs are enormous.

 

43% of accidents occur during maintenance or inspections – high worker safety risks.

 

Standard heavy-duty bearings have limited life under extreme mining conditions – frequent replacement compounds the above losses.

 

NMT split bearings for the mining industry deliver “no motor removal, no shaft removal, quick bearing replacement without production stoppage“ in mine hoists, belt conveyors, bucket elevators, crushers and stacker-reclaimers:

 

Downtime reduced by 80-90% – From weeks to days/hours – annual unplanned downtime losses dramatically reduced.

 

No motor or coupling removal – Drive systems and surrounding components stay in place – avoiding secondary damage and realignment.

 

No heavy lifting equipment required – Bearings are handled in sections – no large cranes or wall removal.

 

Heavy-duty steel withstands high impact and harsh environments – Carburized bearing steel and deep hardening resist impact loads – adapting to extreme mining conditions.

 

Superior sealing for high-dust environments – Sealed split bearings outperform traditional bearings in heavy contamination conditions – reducing grease consumption.

 

Improved worker safety – Simplified installation reduces exposure time at repair sites – reducing the 43% accident risk.

 

Extended life of equipment (motors, gearboxes, couplings) – Fewer disassembly cycles – longer overall equipment overhaul intervals.

 

For underground mines, open-pit mines, mineral processing plants and material handling facilities, the total cost of ownership with NMT split bearings for the mining industry is significantly lower than the repeated disassembly and replacement costs of traditional heavy-duty solid bearings – what you save is not bearing price difference, but the enormous operational risk of “replacing one bearing, shutting down an entire line“ in mining equipment.