1. Core Pain Points of Coal Conveying & Hoisting Equipment Bearing Replacement

Coal mining and processing are classic continuous heavy industries. Bearings in belt conveyors, mine hoists, bucket elevators and crushers 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 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 conveying & hoisting equipment:

 

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. 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. Unplanned downtime at trapped bearing positions in a US coal mine is typically around one day.

 

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. Coal dust is hygroscopic – it absorbs lubricating oil from bearing grease, forming an abrasive paste of contaminated grease and coal dust that rapidly destroys bearings.

 

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. Split bearings are specially designed and manufactured based on solid bearings, enabling quick and convenient installation without removing other coaxial components.

 

More critically – NMT split bearings can be replaced without removing drive motors, gearboxes, couplings, without moving shaft systems, without using heavy lifting equipment. There is no 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. 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 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. 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). Schaeffler split spherical roller bearings offer greater versatility without requiring special self-aligning bearing housings – when replacing solid cylindrical bore bearings, no additional tolerance or clearance adjustments are needed. 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 conveying and hoisting equipment applications:

 

▸ Coal Belt Conveyor Split Spherical Roller Bearings

 

Split spherical roller bearings are the most widely used split bearing type for coal belt conveyors. After retrofitting the +973 level main belt conveyor drive drum at Xishan Coal Electricity Group Dongqu Coal Mine with split bearings, operation became stable and reliable, bearing failures were reduced, and transport efficiency improved. NMT split spherical roller bearings are specifically designed for belt conveyor drive pulleys, bend pulleys, stacker-reclaimers and other heavy-load applications – inner rings, outer rings and cages with rollers are all split in half. The 231 series of split spherical roller bearings, available in shaft diameters of 240-450mm, is typically used in mining conveyor and stacker/reclaimer applications. 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.

 

▸ Coal Mine Hoist Split Spherical Roller Bearings

 

Mine hoist bearings are located at the top of headframes – replacing traditional solid bearings requires disassembly of numerous surrounding components. The auxiliary shaft hoist bearing system at Huoerxinhe Coal Mine suffered frequent failures. After retrofitting with split rolling bearings, the bearings operated normally with no damage, effectively ensuring normal hoist operation. The IKM-3.5×6ZⅢ hoist at Beiminghe Iron Mine was successfully converted from solid rolling bearings to split rolling bearings – this technology can be promoted and applied in similar products. NMT split spherical roller bearings are specifically designed for mine hoists and other heavy impact applications – the split structure allows bearing replacement without removing drive systems, dramatically shortening maintenance time.

 

▸ Coal Bucket Elevator and Stacker-Reclaimer Split Bearings

 

Bucket elevator bearings are located in the enclosed spaces of the elevator head and boot, making replacement extremely difficult. NMT split spherical roller bearings can be used on bucket elevator head and tail pulleys. Underground coal handling conveyors at Hatfield Colliery in the UK are equipped with Revolvo SRB split bearing units – Heavy Duty 240mm units on the main pulleys, with Medium Series 110mm units on the tail pulleys. Split bearing fitting time is just 10%-15% of the time required to fit a typical solid bearing.

 

▸ Split Housed Bearing Units

 

NMT offers fully split housed bearing units 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.

 

4. Specialized Sealing and Lubrication Systems

Coal mining equipment operates year-round under harsh conditions of high coal dust, high impact and high humidity. Coal dust is hygroscopic – it absorbs lubricating oil from bearing grease, forming an abrasive paste of contaminated grease and coal dust that rapidly destroys bearings. 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. By resisting the effects of contamination, sealed split bearings extend the working life of conveyors.

 

▸ 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.

 

▸ 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. After replacing traditional bearings with SKF Cooper sealed split spherical roller bearings in a US coal mine, vibration and temperature levels ran exactly where the customer wanted them.

 

▸ 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 split bearings can reduce installation downtime by up to 90%. Split bearing fitting time is just 10%-15% of the time required to fit a typical solid bearing. 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:

 

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. At a downtime cost of USD 10,000 per hour, the customer avoided over USD 100,000 in lost production. After replacement, vibration and temperature levels ran exactly where the customer wanted them.

 

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%. Split bearings can be easily maintained in cramped underground conditions, and labyrinth seals perform exceptionally well in harsh operating environments.

 

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.

 

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. Xishan Coal Dongqu Coal Mine achieved improved transport efficiency after adopting split bearings. The hoist bearing retrofits at Huoerxinhe Coal Mine and Beiminghe Iron Mine both achieved excellent results.

 

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.

 

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

 

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. US coal mine saved over 10 hours, Hatfield Colliery cut downtime by up to 90%.

 

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 – Labyrinth seals and three-barrier sealing effectively protect 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“.