1. Core Pain Points of Coal Mining Bearing Replacement

Coal mining and processing are classic continuous heavy industries. Bearings in belt conveyors, mine hoists, bucket elevators, crushers and ball mills endure heavy impact loads, high-concentration coal dust and high humidity year-round. Coal conveyor lines often require 24-hour continuous operation, and any unexpected shutdown can become a production or operational accident.

 

Compounding the challenge – a large portion of coal mining equipment bearings are located in inaccessible or trapped positions. Conveyor head pulley bearings are wedged between the drive pulley and the gearbox or motor; mine hoist bearings are located at the top of the headframe, surrounded by gearboxes, motors and extensive equipment. Traditional solid bearing replacement requires disassembly of shafts, couplings, gearboxes and surrounding components – taking days or weeks, with downtime losses reaching millions. Installing and servicing bearings in conveyors or bucket elevators, especially between head pulleys and gearboxes or motors, can be very tricky, time-consuming and therefore costly.

 

Typical pain points of traditional solid bearings in coal mining:

 

Inaccessible equipment locations – Conveyor head pulley bearings are trapped between pulleys and gearboxes; hoist bearings are at the top of headframes. In these locations, lifting equipment cannot access, and maintenance personnel working space is extremely limited.

 

Enormous disassembly workload – Replacing one bearing requires disassembling couplings, motors, gearboxes, frames and numerous surrounding components. The drive roller position bearing units on coal conveyor lines are located between drive equipment and drums, making maintenance and repair time-consuming and labor-intensive.

 

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

 

High-concentration coal dust accelerates bearing wear – Coal mine environments are filled with coal dust and contaminants. Conventional bearings have average sealing effectiveness, and dust can easily enter the bearing interior, potentially causing premature failure.

 

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.

 

Long spare parts lead times – Lead times for extra-large bearings can be as long as 12 to 18 months – once unplanned downtime occurs, waiting for spare parts further compounds production losses.

 

2. NMT Split Bearings for Coal Mining: No-Shaft-Removal Quick Replacement

NMT split bearings for coal mining perfectly combine the core advantage of split bearings – “no-shaft-removal installation“ – with the special requirements of coal mining equipment. 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.

 

More critically – NMT split bearings can be replaced without removing drive motors, gearboxes, couplings, without moving shaft systems, without using heavy lifting equipment. Fully split housed bearing units adopt radial installation and disassembly, eliminating the need to disconnect and disassemble components around the bearing, such as motors, gearboxes and couplings. This is like installing a “service door“ on coal mining equipment, enabling true “online“ maintenance. Compared to traditional solid bearings, split bearings can reduce maintenance time by over 80%.

 

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

 

Every component of an NMT split bearing for coal mining 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. Split bearings disassemble into smaller components, easing lifting and handling tasks and making assembly or changeout simple even in the most cramped and inaccessible conditions.

 

In terms of materials, NMT offers a complete impact-resistant steel system for coal mining heavy-load, high-dust 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 coal 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 coal mining is – bearing replacement without moving the shaft, without removing drive motors and couplings, without using heavy lifting equipment. This means for conveyor head pulley bearing replacement, no drive coupling or cantilevered drive disassembly is required. For mine hoist bearing replacement, the motor stays in place, couplings stay in place, gearboxes stay in place. For bucket elevator bearing replacement, no drive disassembly is required.

 

Fully split housed bearing units are suitable for situations where bearing installation and removal are limited, perfectly fitting coal conveyor line drive roller applications. Installation requires no movement of surrounding equipment or machinery. 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 coal mining are designed with full interchangeability with standard heavy-duty solid bearings in mind. 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 coal mining operations can directly replace existing solid bearings in their equipment with NMT split bearings without any machining modifications to bearing housings.

 

3. Product Series

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

 

▸ Coal Mining Split Spherical Roller Bearings

 

Split spherical roller bearings are the most widely used split bearing type in coal mining, providing high load capacity and shock load resistance. NMT split spherical roller bearings are specifically designed for mine hoists, belt conveyors, crushers, ball mills 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. Sealed split bearings perform reliably in coal-dust-filled mining environments.

 

Schaeffler offers rich solutions for key equipment in the coal mining chain, including hoists, belt conveyors, large ventilation equipment and bucket wheel excavators. Split spherical roller bearings are typically used in shaft diameters from 240mm to 450mm for conveyor and stacker/reclaimer applications. By resisting the effects of contamination, split spherical roller bearings extend the working life of conveyors.

 

▸ Coal Mining Split Cylindrical Roller Bearings

 

Split cylindrical roller bearings are mainly used for bearing arrangements in inaccessible or restricted locations. Using 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, crusher drive shafts and more.

 

▸ Coal Mining Split Tapered Roller Bearings

 

NMT split tapered roller bearings feature two rows of opposed tapered rollers, capable of simultaneously bearing radial and bidirectional axial loads. Suitable for mine hoists, crushers and other fixed-end bearing positions requiring combined loads.

 

▸ Split Housed Bearing Units

 

Fully split housed bearing units are suitable for situations where bearing installation and removal are limited, perfectly fitting coal conveyor line drive roller applications. Using radial installation and disassembly without disconnecting and disassembling components around the bearing, such as motors, gearboxes and couplings. The unique design of the cylindrical roller bearing core and outer spherical bearing housing ensures balance between centering function and excellent axial floating capability. Housings are available in steel, gray cast iron or ductile iron to suit different application requirements.

 

4. Specialized Sealing and Lubrication Systems

Coal mining equipment operates year-round under harsh conditions of high coal dust, high impact and high humidity. NMT split bearings for coal mining feature customized sealing and lubrication systems:

 

▸ Heavy-Duty Labyrinth Seal Structure – Non-contact design using centrifugal force from rotation to expel coal dust, particulates and contaminants. Maintains reliable sealing even in coal-dust-filled mining environments.

 

▸ Three-Barrier Sealing – For extreme environments, NMT provides three sealing barriers: the first is the precision-machined seal itself, the second is a V-ring seal mounted directly on the bearing, and the third is grease surrounding the bearing. These three barriers effectively exclude contaminants, further extending bearing service life. SKF Taconite seals are a global solution for split housings in mining, mineral and metal processing industries where the ingress of contaminants poses a challenge to bearing service life.

 

▸ Sealed Split Bearings – 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. In fine dust environments around conveyors, sealed split bearings effectively prevent contaminant intrusion.

 

▸ Split Seals – Seals are also split for installation without shaft threading, assembled simultaneously with the bearing.

 

▸ Heavy-Duty Grease – 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.

 

5. Installation Efficiency Comparison

Traditional solid bearing: Shutdown → disassemble couplings, motors, gearboxes → move shaft → slide bearing on → realign → reassemble → recommission. Time: days to weeks.

 

NMT split bearing: Shutdown → open housing → remove old halves → install new halves → tighten bolts → complete. Time: hours to days.

 

Industry data shows that mining equipment using split bearings achieves a 55% reduction in average maintenance intervals, compressing single bearing replacement from the traditional 9 days to 4 days. Split bearings can reduce installation downtime by up to 90%. SKF Cooper split spherical bearings can reduce mean time to repair (MTTR) for conveyor pulley bearings by 70%. Schaeffler split bearings can reduce maintenance time by 67%.

 

Specific Case Data:

 

Colorado Mine, USA: 16km conveyor through snowy mountains – traditional 9-day downtime shortened to 4 days with SKF Cooper split spherical bearings, well within the 6-day stockpile limit. Future split bearing installation is estimated at approximately 18 hours. MTTR shortened by 55%. Because the pulley remained in place, there was no need to run in the belt after installation.

 

US Coal Mine: Conveyor head pulleys operate approximately 18 hours per day. Unplanned downtime at trapped bearing positions is typically around one day. Replacing traditional bearings with SKF Cooper sealed split spherical roller bearings – without changing shaft alignment or disturbing the driveline – saved over 10 hours of downtime and avoided over $100,000 in lost production.

 

BHP Billiton Australia Mine: Main ore conveyor head pulley drive end bearing (380mm bore, 650mm OD, 200mm width). Schaeffler replaced the 23180K solid spherical roller bearing with a FAG.231SM380MA split spherical roller bearing during the scheduled shutdown window – with no additional equipment downtime. No shaft-mounted gearbox removal required, no realignment needed, no special tools such as hydraulic nuts required. The entire drive system had not been touched for over twelve years, which could have significantly added to the difficulty.

 

Pilbara Iron (Rio Tinto Group), Dampier Port: Bucket wheel excavator drive bearing replacement – traditional solid bearing took 72 hours, with downtime cost of 1,110 euros ($2,000 AUD) per hour. FAG split spherical roller bearings reduced downtime by 36 hours, saving 40,000 euros ($72,000 AUD). Solid bearing cost 2,780 euros, split bearing 16,670 euros – minimum savings per bearing change: 27,514 euros ($49,520 AUD).

 

Hatfield Colliery, UK: Underground coal handling conveyors using Revolvo SRB split bearing units – Heavy Duty 240mm units on main pulleys, Medium Series 110mm units on tail pulleys. Split bearing fitting time is just 10%-15% of the time required to fit a typical solid bearing. Compared to solid bearings, downtime was cut by up to 90%.

 

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. In September 2021, the mine successfully converted solid rolling bearings to split bearings.

 

Beiminghe Iron Mine: The IKM-3.5×6ZⅢ hoist was successfully converted from solid rolling bearings to split rolling bearings. This technology can be promoted and applied in similar products as a cost-effective retrofit approach.

 

Huoerxinhe Coal Mine: The auxiliary shaft hoist bearing system suffered frequent failures. After retrofitting with split rolling bearings, the bearings operated normally with no damage, effectively ensuring normal hoist operation.

 

Mine Screw Conveyor: After adopting split bearings, equipment failure rate dropped by 67%, fault warnings were provided 7-15 days in advance, and 10-year total cost of ownership was reduced by 28.6%.

 

Large-Scale Mine Equipment: After replacing with heavy-duty split bearings, equipment bearing maintenance no longer required disassembly of bucket wheel bodies, gearboxes or conveyor frames – single overhaul time reduced from the original 2-3 days to within 2 hours, and unplanned downtime rate dropped by over 70%.

 

6. Quality Control

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

 

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

 

High-strength locking system – High-strength steel clamp rings and multiple bolts ensure split surfaces remain secure during operation.

 

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

Common split spherical roller bearings, split cylindrical roller bearings and split tapered roller bearings kept in stock – covering over 80% of split bearing needs for coal conveyors, hoists, crushers and other applications. Emergency failures receive rapid response – minimizing unplanned downtime.

 

Lead times for extra-large bearings can be as long as 12 to 18 months – pre-stocking split bearing spares can dramatically shorten emergency downtime.

 

Custom solutions available: special bore/OD/width (standard range 55mm to 630mm, expandable), custom heavy-duty materials (carburized bearing steel/heat-resistant steel/stainless steel), special split configurations, custom sealing solutions (Taconite seals/three-barrier/labyrinth), custom clearance, split housed bearing units.

 

Rapid customization from samples or drawings. Cost-effective replacement for imported brands (SKF Cooper, FAG, Timken, NSK) with significant procurement savings.

 

8. Lifecycle Cost Optimization

Unplanned downtime in the coal mining industry often costs tens of millions or even hundreds of millions of yuan. A US coal mine using SKF Cooper split bearings saved over 10 hours of downtime and avoided over $100,000 in lost production. Hatfield Colliery in the UK cut downtime by up to 90% using split bearings. Pilbara Iron using FAG split bearings saved 40,000 euros per replacement. BHP Billiton Australia completed the replacement during scheduled downtime with no additional equipment downtime. A coal mine screw conveyor using split bearings achieved a 28.6% reduction in 10-year total cost of ownership.

 

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. Pilbara Iron loses 1,110 euros per hour of downtime.

 

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

 

Heavy lifting equipment rental costs are enormous.

 

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

 

Extra-large bearing lead times are 12 to 18 months – waiting for spares during unplanned downtime compounds losses.

 

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

 

Traditional bearing solutions constrain coal mining efficiency improvement and expose maintenance workers to safety threats for extended periods.

 

NMT split bearings for coal mining deliver “no motor removal, no shaft removal, quick bearing replacement without production stoppage“ in belt conveyors, mine hoists, bucket elevators, crushers and ball mills:

 

Downtime reduced by over 80% – From weeks to days/hours – annual unplanned downtime losses dramatically reduced. Traditional 9-day replacement compressed to 4 days.

 

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 coal mining conditions.

 

Superior sealing for high coal dust environments – Three-barrier sealing effectively protects against coal dust intrusion, extending bearing life.

 

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 coal mining operations, coal preparation plants and coal transport companies, the total cost of ownership with NMT split bearings for coal mining 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 production line“.