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. Belt conveyors play a critical role in coal mine transportation and handling – bearings are essential components of coal mining mechanical equipment. Coal conveyor lines often require 24-hour continuous operation, and any unexpected shutdown can become a production 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.

 

A US coal mine has conveyor head pulleys that operate for around 18 hours per day, with unplanned downtime at this trapped bearing location typically requiring about 1 day. Hatfield Colliery in the UK faced long downtime every time they replaced bearings on their underground coal handling conveyors. The main belt conveyor drive drum at Xishan Coal Electricity Group Dongqu Coal Mine had traditional bearing defects causing difficult replacement and frequent failures. The auxiliary shaft hoist bearing system at Huoerxinhe Coal Mine suffered frequent failures.

 

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. Direct-coupled hoist motor-end solid bearings are large and difficult to replace with high operational risk.

 

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. When seals fail, dust penetrates bearings and mixes with grease to form abrasive paste, accelerating wear.

 

High worker safety risks – 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. Split bearings are specially designed and manufactured based on solid bearings, with low resistance and smooth operation.

 

More critically – NMT split bearings can be replaced without removing drive motors, gearboxes, couplings, without moving shaft systems, without using heavy lifting equipment. The biggest advantage of split bearings is that they can be installed quickly and conveniently without removing other coaxial components. 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. Split bearings can operate at temperatures up to 180°C, making them ideal for low-speed, heavy-load, high-impact, poor-sealing conditions found in coal mines.

 

▸ 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. No changes to shaft alignment or driveline are required.

 

▸ 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.

 

▸ 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. 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.

 

▸ 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.

 

▸ 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. Split bearings can operate at temperatures up to 180°C.

 

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%.

 

Specific Case Data:

 

US Coal Mine: Conveyor head pulleys operate approximately 18 hours per 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.

 

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. Compared to solid bearings, downtime was cut by up to 90%.

 

Xishan Coal Electricity Group Dongqu Coal Mine: After retrofitting the +973 level main belt conveyor drive drum with split bearings, operation became stable and reliable, bearing failures were reduced, and transport efficiency improved.

 

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.

 

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

 

Coal 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%.

 

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, 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. 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.

 

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.

 

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.

 

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 – Sealed split bearings outperform traditional bearings in heavy contamination conditions.

 

Improved worker safety – Simplified installation reduces exposure time at repair sites – reducing safety risks.

 

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“.