Kobelco 2404N271 2404N416 2404N254 SK100 Track Sprocket Wheel Assembly – Mini Excavator Undercarriage Parts Sprocket

Manufactured by CQC TRACK – Professional Undercarriage Component Manufacturer Based in Quanzhou, China

Technical Abstract

This technical publication provides comprehensive engineering documentation for three interconnected Kobelco drive sprocket assemblies—OEM cross-reference part numbers 2404N271, 2404N416, and 2404N254—engineered for the Kobelco SK100 series hydraulic crawler excavators. The 2404N271 and 2404N416 part numbers represent identical drive sprocket components with cross-brand compatibility across Kobelco and New Holland equipment lines, while 2404N254 serves as an additional OEM reference for the SK100 undercarriage system.

Within the 10-ton excavator undercarriage architecture, the drive sprocket serves as the primary power transmission component—the cogwheel that engages the track chain to enable machine movement. Unlike passive undercarriage components such as idlers or rollers which rotate freely, the drive sprocket is an active, driven component connected directly to the output shaft of the final drive travel gearbox. The gearbox receives torque from the hydraulic motor and transmits it to the excavator’s tracks through the sprocket and chain assembly, propelling the machine forward or backward.

The Kobelco SK100 series is a 10-ton class excavator manufactured from 1992 to 1996 with a 10.5-ton operating weight, 500 mm track width, Isuzu 4 BD engine delivering 56 kW, and 0.45 m³ bucket capacity. For these machines—widely deployed in urban construction, utility work, site development, and light infrastructure projects across South America, Australia, Europe, Russia, and Central Asia—the engineering integrity of the drive sprocket assembly is fundamental to machine mobility, operational productivity, and total cost of ownership.

This analysis examines these sprocket assemblies through multiple technical lenses: functional engineering principles of torque transmission and track engagement, metallurgical composition with detailed material grade specifications including 50Mn, 40SiMnTi, and high-manganese steel, advanced manufacturing process engineering featuring closed-die hot forging and precision CNC machining, comprehensive heat treatment protocols including induction hardening achieving HRC 48–58 surface hardness, detailed dimensional specifications (21 teeth, 324 mm inner diameter, 601 mm outer diameter), rigorous quality assurance protocols including ISO 9001:2015 certification, comprehensive installation and final drive removal/replacement procedures, wear diagnosis and replacement criteria, regional market analysis for key global markets, and strategic sourcing considerations for procurement professionals managing Kobelco mini excavator fleets worldwide.

CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.) operates as a vertically integrated OEM and ODM manufacturer with over two decades of specialization in crawler excavator undercarriage components. The company has established itself as one of the top three undercarriage component manufacturers in the Quanzhou region, a premier industrial cluster for global earthmoving equipment manufacturing located in Fujian Province, China. With state-owned land and factory facilities, and fully integrated production lines encompassing forging, casting, and complete undercarriage component production, CQC TRACK represents a vertically integrated source manufacturer of OEM-quality heavy-duty crawler excavator undercarriage parts. The company’s strategic position in Quanzhou provides exceptional access to major international ports including Xiamen and Fuzhou, enabling efficient export logistics to global construction equipment markets.

The company manufactures a full range of Kobelco-compatible undercarriage parts spanning from 10-ton mini excavators to ultra-class machines, including track sprockets, idlers, track rollers, carrier rollers, track chains, and track shoes—all manufactured to meet OEM replacement standards ensuring reliable fit, durability, and stable performance.

CQC TRACK warmly welcomes you to build cooperation and generate a brilliant long-term partnership together.

1. Product Identification and Application Coverage

1.1 Component Nomenclature and Functional Overview

A drive sprocket assembly—technically designated as a driving sprocket, final drive sprocket rim, track drive wheel, or cogwheel—is the primary active propulsion component of the excavator’s undercarriage system. Located at the rear of the undercarriage, this sprocket is the primary power transmission component. Unlike passive components such as idlers or rollers, which rotate freely, the drive sprocket is an active, driven component that engages directly with the track chain’s bushings to propel the machine.

The primary functional responsibilities of the drive sprocket include:

• Torque-to-Traction Conversion: The sprocket transmits torque from the final drive gearbox to the track chain, converting rotational hydraulic motor power into linear pulling force that moves the 10-ton machine forward or backward.
• Precision Chain Engagement: The sprocket engages with track links to generate motion, with teeth engineered for precise chain engagement to ensure smooth, consistent power transmission without skipping or binding.
• Load Distribution: Designed to withstand high stress and continuous load, the sprocket distributes driving load evenly across multiple teeth and bushings to prevent concentrated stress points that would cause premature wear or failure.
• Optimal Weight Distribution: Positioned at the rear for optimal weight distribution, the sprocket works in concert with the front idler and track rollers to maintain proper track chain alignment during forward travel, reverse travel, and turning operations.

The sprocket is a critical cogwheel component in tracked vehicles, responsible for engaging and driving the track chain to enable movement. In the Kobelco SK100 excavator, sprockets are essential parts of the undercarriage system, ensuring reliable power transmission, track tension, and smooth operation across rugged terrains.

1.2 OEM Part Numbers and Compatible Excavator Models

The three drive sprocket assemblies documented in this analysis correspond to precise Kobelco OEM engineering specifications. The 2404N271 and 2404N416 part numbers are directly interchangeable and serve the same function across multiple equipment brands. The table below provides comprehensive cross-reference data:

2404N271 Compatibility: The driving sprocket with OEM number 2404N271 is applicable to an extensive range of Kobelco excavator models including K904-2, K904L-2, MD140C, SK100, SK100-3, SK100L, SK115SRDZ, SK115SRDZ-1E, SK135SRLC-1E, SK120-3, SK120-5, SK120LC-3, SK120LC-5, SK135SR, SK135SR-1E, SK135SRL, SK135SRL-1E, and SK135SRLC. The sprocket features 21 teeth, an inside diameter of 324 mm, an outside diameter of 601 mm, and 15 screw holes. Additional compatible models include K904-2, K904L-2, MD140C, and various SK100 and SK120 variants with specific serial number ranges documented in OEM parts catalogs.

2404N416 Compatibility: The track sprocket with OEM number 2404N416 is compatible with Kobelco excavators including K904 (II), K904LC (II), SK100 (4), SK100-3, SK100-III (II), SK100-IV (II), SK115-SR (II), SK115DZ-IV (II), SK115SR-1ES (II), SK115SRDZ-1E (II), SK115SRDZ-1E LC (II), SK120 (4), SK120-3, SK120-III (II), SK120-IV (II), SK120-V (II), SK120LC-III (II), SK120LC-IV (II), SK120LC-V (II), SK130-IV (II), SK130LC-IV (II), SK135SR (II), SK135SRLC (II), and SK135SRLC-2 (II). It also replaces Kobelco OEM number 2404N271 and New Holland OEM number 2404N416. This sprocket shares identical dimensional specifications: inside diameter 324 mm, outside diameter 601 mm, 21 teeth. Cross-brand compatibility extends to New Holland excavators including E130, E130 (LC SR), E130SRLC, EH130LC, and New Holland mini excavator E18SR.

2404N254 Compatibility: This part number serves as an additional OEM reference for the SK100 drive sprocket assembly, applicable to the same SK100 series excavator models. It represents an alternative OEM numbering within the Kobelco parts catalog system for the same functional component.

The comprehensive cross-platform compatibility of these sprocket assemblies makes them valuable inventory items for fleet operators managing multiple Kobelco model generations and even cross-brand New Holland equipment.

1.3 Kobelco SK100 Excavator Specifications and Undercarriage Parameters

The Kobelco SK100 series represents the 10-ton class in the Kobelco product line, offering substantial digging performance in a compact package suitable for confined job sites. The table below provides comprehensive technical specifications:

Data sources:

The SK100-III model offers a 500 mm track width, which provides stability for the 10.5-ton operating weight across various ground conditions. The Isuzu 4 BD engine delivers 56 kW of power, enabling the machine to tackle demanding excavation tasks efficiently.

The SK100MSR-7 represents a newer generation with enhanced features including a short radius design allowing operators to work in tight spaces, a 10″ color monitor with jog-dial operation, an eagle-eye camera for 270-degree vision, Kobelco Geoscan Excavator Remote Monitoring System, and the iNDr Cooling System for optimum low noise and dust reduction.

1.4 Component Architecture and Assembly Composition

A complete Kobelco drive sprocket assembly consists of multiple precision-engineered subcomponents, each manufactured to exacting tolerances for the 10-ton excavator undercarriage format:

• Sprocket Rim (Tooth Ring): The toothed outer component that directly engages with the track chain bushings. The teeth feature precise involute geometry designed to mesh with the chain’s cylindrical bushings. For 10-ton excavator applications, the sprocket features 21 teeth with an outside diameter of 601 mm.
• Hub (Mounting Interface): The central portion of the sprocket that bolts directly to the final drive motor’s output hub flange. The hub incorporates precisely drilled bolt holes (15 screw holes) with hardened seating surfaces. Splined or bolted mounting to the output planetary carrier provides solid, non-slip torque transmission.
• Mounting Hardware: High-strength bolts, hardened washers, and lock nuts (typically grade 10.9 or higher) that secure the sprocket rim to the final drive hub. For the 10-ton class, bolt torque specifications typically range from 300–500 Nm depending on the specific fastener size.
• Final Drive Interface: The sprocket interfaces with the multi-stage planetary gear reduction final drive, which houses planetary gear reduction stages that dramatically increase output torque for propulsion. To remove the final drive from an excavator, the track must be removed and the sprocket bolts loosened—it is much easier to loosen the sprocket bolts before removing the final drive.

The final drive consists of a hydraulic motor including gearbox and is offered completely as a plug & play solution, allowing the old traction motor to be replaced and put into operation immediately.

1.5 Final Drive System Overview

The travel gearbox is located within the undercarriage of the excavator and is responsible for the machine’s movement. When the hydraulic motor rotates, it transfers power to the gearbox, which then converts the power into torque and drives the track drive sprockets, which in turn move the tracks and propel the excavator forward or backward. The final drive for the SK100L consists of a hydraulic motor including gearbox and is offered completely as a plug & play solution.

Final drives in high-class original equipment quality (OEM) are manufactured to provide high durability, high reliability, and a fair price-to-performance ratio. Before delivery, an acceptance test is carried out on a test bench specially designed for this purpose to verify functionality.

2. Metallurgical Composition and Forging Engineering

2.1 Material Grade Specifications

CQC TRACK manufactures Kobelco cross-reference drive sprockets using premium alloy steel grades selected for their specific mechanical properties in 10-ton excavator undercarriage applications. The primary material grades employed include:

50Mn Alloy Steel: A premium-grade manganese steel offering superior wear resistance and surface hardness characteristics. 50Mn steel is widely used in manufacturing crawler machine parts that work under heavy loads, providing excellent wear resistance and impact toughness. After undergoing heat treatment, 50Mn achieves a surface hardness of HRC 48–58 with a hardened depth of 4–6 mm (reaching HRC 45 at this depth), enabling it to deliver exceptional impact resistance and wear resistance even under harsh working conditions. Industry sources confirm that Kobelco SK100 mini excavator track drive sprockets are manufactured with 50Mn material and heat treatment achieving HRC 48–54.

40SiMnTi Alloy Steel: A silicon-manganese-titanium alloy steel offering excellent hardenability and wear resistance. Industry sources list 40硅锰钛 (40SiMnTi) as a primary material for SK100 sprockets, with manufacturing techniques including forging, casting, machining, heat treatment, and assembly processes.

High-Manganese Steel: High-manganese steel provides exceptional work-hardening properties—the more impact the material receives during operation, the harder its surface becomes. This self-hardening characteristic is particularly valuable for drive sprockets in heavy-duty excavator applications. Industry sources list high manganese steel as a material option for SK100 sprocket rims, achieving surface hardness of HRC 45–55.

40Mn/SCMn3A Cast Steel: For related undercarriage components, 40Mn and SCMn3A materials are used for idler bodies, achieving HRC 52–58 surface hardness.

The material grade selection directly determines the sprocket‘s service life in high-abrasion environments. For steel parts like sprockets, the quality difference between OEM and aftermarket is largely about material grade and heat treatment. These can be measured and verified with hardness tests and metallurgical analysis.

2.2 Forging Technology: The Manufacturing Foundation

Kobelco drive sprockets are manufactured using advanced closed-die hot forging techniques. Forging is a manufacturing process that shapes metal using localized compressive forces, typically delivered by a hammer or press. Industry sources confirm that forging and casting are the primary manufacturing techniques for SK100 sprockets, with forging representing the premium manufacturing method for high-stress applications.

Grain Flow Alignment: The forging process aligns the material grain structure with the sprocket geometry, with grain boundaries oriented to resist the principal tensile and compressive stresses encountered during operation. This grain flow orientation is particularly important at the tooth root radii where stress concentrations are highest. The forging process creates a superior grain structure essential for handling shock loads.

Porosity Elimination: The high compressive forces of forging eliminate internal voids and porosity that would otherwise act as crack initiation sites under cyclic loading. Cast components may contain internal porosity or inclusions that can serve as crack initiation sites under repeated loading cycles.

Material Consolidation: The forging process increases material density, resulting in superior mechanical properties compared to cast components of equivalent alloy composition. The dense, uniform microstructure of forged steel provides consistent performance across the entire component cross-section.

Surface Integrity: The forged surface exhibits superior fatigue resistance due to the absence of casting defects and the compressive residual stresses imparted by the forging process.

2.3 Precision CNC Machining

All critical surfaces of Kobelco cross-reference drive sprockets are machined using modern CNC lathes, milling machines, and drilling centers that perform rough and finish machining operations to ISO 2768-mK dimensional accuracy standards. Key machining operations include:

• Tooth Profile Machining: Precision machining of the sprocket tooth profile to ensure exact pressure angle and pitch for non-slip engagement with track bushings. The 21-tooth configuration requires precise tooth spacing and profile geometry.
• Bore Machining: Precision boring of the central mounting bore to achieve exact hub interface specifications—324 mm inside diameter.
• Bolt Hole Drilling: Precision drilling of 15 mounting bolt holes with exact positional tolerances.
• Mounting Surface Machining: Precision surfacing of the hub mounting interface for optimal load transfer.
• Outer Diameter Machining: Precision turning of the 601 mm outside diameter to exact specifications.

Utilizing specialized hardening and tempering techniques ensures products possess outstanding mechanical characteristics, exceptional durability, and enhanced resistance to deformation and fracture.

3. Heat Treatment Engineering

3.1 Metallurgical Principles for Sprocket Applications

Heat treatment is the single most critical manufacturing operation determining drive sprocket service life in heavy construction applications. The heat treatment process—primarily quenching and tempering—transforms steel at the molecular level, achieving a precise balance between hardness and toughness. For undercarriage components, this balance determines how long a part can endure before fatigue or deformation occurs.

The quenching process is where steel‘s real strength begins. The component is heated to a critical temperature (typically around 850–900°C), where its crystalline structure transforms into austenite. It is then rapidly cooled—usually by immersion in water or oil. This sudden temperature drop locks carbon atoms in place, forming a very hard but brittle microstructure known as martensite. This creates the hard, wear-resistant surface essential for sprocket teeth.

While quenching provides hardness, it also introduces brittleness. Tempering is the crucial follow-up step that relieves internal stresses and restores ductility. The component is reheated to a lower, controlled temperature (typically between 150–500°C) and held for a specific period before slow cooling. This process slightly reduces extreme hardness but significantly improves toughness, impact resistance, and flexibility. The result is an ideal combination—a hardened, wear-resistant surface and a strong, flexible core—perfect for sprockets that must withstand dynamic loads and shocks.

3.2 Induction Hardening Specifications

Kobelco drive sprockets employ induction hardening heat treatment to achieve the required hardness profile on the tooth surfaces. The sprocket teeth are induction hardened to create a wear-resistant surface while maintaining a tough, ductile core.

The specific heat treatment parameters for Kobelco SK100 drive sprockets are as follows:

Industry sources confirm that Kobelco SK100 mini excavator track drive sprockets are manufactured with heat treatment achieving HRC 48–54. SK100 sprocket rims achieve surface hardness of HRC 45–55. For related undercarriage components, body hardness reaches HRC 52–58 with shaft hardness of HRC 52–58.

External tooth profiles are induction hardened to more than 50 RC for heavy-duty excavator sprockets, ensuring extended wear life even in abrasive operating conditions. Forged and through-hardened components provide extended wear life compared to cast alternatives.

3.3 Quality Control and Consistency

Effective heat treatment demands strict quality control. Manufacturers must continuously monitor temperature uniformity, soaking time, cooling rate, and metallographic structure to ensure the process meets performance requirements. Ignoring these parameters—or relying on inconsistent heat treatment—can drastically shorten component lifespan. Even minor temperature deviations during quenching or tempering can lead to uneven hardness, causing premature wear, cracking, or dimensional instability.

Components produced with advanced alloys and heat treatments undergo rigorous testing to ensure uniform hardness, impact resistance, and fatigue strength. Before a final drive is delivered, an acceptance test is carried out on a test bench specially designed for this purpose to verify functionality. This level of quality reduces the likelihood of unexpected failures and ensures machines operate at peak performance for longer periods.

4. Dimensional Specifications

4.1 Sprocket Dimensional Data

The 2404N271 / 2404N416 drive sprocket assembly is engineered to precise dimensional specifications for direct fitment to the Kobelco SK100/SK120 track frame and final drive system:

Data sources:

These dimensional specifications apply to both the 2404N271 and 2404N416 part numbers, confirming that they are identical components with different OEM numbering across Kobelco and New Holland parts catalogs.

4.2 Undercarriage Fitment Parameters

For the Kobelco SK100-III, the undercarriage features:

• Track Width: 500 mm, providing stability for the 10.5-ton operating weight
• Track Chain Pitch: Industry standard pitch sizes for 10-ton class excavators typically range from 135 mm to 152.4 mm depending on configuration
• Number of Track Rollers per Side: Typically 7 per side for the SK100 undercarriage
• Number of Carrier Rollers per Side: Typically 2 per side
• Sprocket Mounting: Bolted connection to final drive output hub with 15 bolts

4.3 Sprocket Mounting Configuration

The Kobelco SK100 undercarriage features a robust final drive system that incorporates:

• Final Drive Travel Gearbox: Located within the undercarriage of the excavator, connected to the hydraulic motor and the track drive sprockets. The gearbox then converts the power into torque and drives the track drive sprockets, which in turn move the tracks and propel the excavator.
• Sprocket Mounting Interface: The sprocket mounts to the output planetary carrier via 15 bolted connections, providing solid, non-slip torque transmission.
• Sealing System: Floating face seal with labyrinth pre-seals prevents contamination ingress and lubricant leakage.

5. Installation and Final Drive Removal Procedures

5.1 Final Drive Removal Procedure

Proper removal of the final drive is often required when replacing a drive sprocket. The following procedure is recommended based on industry best practices:

Step 1: Remove the Track and Loosen Sprocket Bolts: It is much easier to loosen the sprocket bolts before removing the final drive.

Step 2: Remove the Track Motor Cover Plate: Remove the track motor cover plate from inside the undercarriage frame.

Step 3: Sling the Final Drive and Take the Weight: Final drives can be very heavy—use appropriate lifting equipment.

Step 4: Mark Hydraulic Hoses: Mark the hydraulic hoses so you can later identify them.

Step 5: Remove Hoses and Cap Ports: Remove the hoses and cap them, plug the ports on the track motor. It is very important to seal all hydraulic hoses and ports to prevent contamination of the hydraulic system.

Step 6: Remove Final Drive Bolts: From inside the track frame, remove the bolts securing the final drive to the frame.

Step 7: Swing Out the Final Drive: If the final drive is tight in the track frame, do not hit the travel motor in an attempt to free it—this will damage the motor. Lever the final drive out from outside of the track frame.

5.2 Fitting a New Final Drive and Sprocket

Fitting a new final drive is the reverse of removal but pay special attention when connecting the pipes as incorrect fitting can cause an immediate failure of the travel motor. The final drive for SK100L consists of a hydraulic motor including gearbox and is offered completely as a plug & play solution, so that the old traction motor can be replaced and put into operation immediately.

5.3 Bolt Torque Specifications

Refer to manufacturer bolt torque settings when tightening bolts. For 10-ton class excavators:

• Mounting Hardware Grade: Class 10.9 or higher for heavy-duty applications
• Bolt Torque Range: 300–500 Nm depending on bolt size and configuration
• Torque Pattern: Staggered (criss-cross) pattern applied in three progressive stages
• Anti-Seize Compound: Apply high-quality anti-seize compound to bolt threads before installation
• Re-Torque Requirement: After 2–4 hours of operation, re-torque the sprocket mounting bolts to the specified value

5.4 Hydraulic Pipe Connections

Refer to travel port motor identification to safely identify the appropriate connections for your machine. All piston-type hydraulic motors leak oil from the barrel and piston assembly (rotating group assembly) into the motor casing, requiring proper case drain connections.

5.5 Track Tension Adjustment Procedure

After sprocket installation, proper track tension must be established according to Kobelco SK100 specifications:

Step 1: Preparation: Perform check and adjustment on level and firm ground. Run the engine at low idle, then move the machine forward for a distance equal to the track length on ground, and slowly stop the machine.

Step 2: Measurement: Measure the track sag as the vertical distance between the top of the track chain and the top of the track frame at the midpoint between the front idler and the first track roller.

Step 3: Standard Range Verification: For 10-ton class excavators, the proper track sag is typically 15–35 mm. If the deflection is out of the standard range, adjust it accordingly.

Step 4: Adjusting Track Tension: To increase track tension, pump grease through the track adjuster grease fitting using a manual grease pump.

Step 5: Verification: After adjustment, run the engine at low idle, move the machine slowly forward, then check the track tension again. If the tension is not correct, adjust it again.

5.6 Critical Tensioning Considerations

• Underfoot Conditions: Adjust track tension based on the underfoot conditions. Added track tension increases both the load and the wear on all mating components of the undercarriage.
• Wear Consequences: Improperly adjusted track can result in problems and wear on other components. Tight track increases loads, which advances wear on rollers, idlers, sprockets, and chain bushings.
• Regular Monitoring: The wear of pins and bushings of the undercarriage depends on the working condition and soil condition. Check the track tension occasionally and keep it in the standard range.

6. Quality Assurance and Testing Protocols

6.1 ISO 9001:2015 Certified Manufacturing

CQC TRACK operates under ISO 9001:2015 certified quality management systems, with components traceable from raw material receipt through finished assembly. The quality management system encompasses all production stages:

• Material Certification: Incoming raw material certification verifying alloy composition and mechanical properties against industry standards, including mill test certificates for 50Mn, 40SiMnTi, and high-manganese steels
• Dimensional Verification: Inspection of all critical dimensions using calibrated measurement equipment, including CMM and precision gauging
• Heat Treatment Validation: Verification of hardness profiles and case depth using calibrated Rockwell hardness testers and metallographic examination
• Final Testing: Dynamic testing and quality verification

6.2 Final Drive Acceptance Testing

Before a final drive is delivered, an acceptance test is carried out on a test bench specially designed for this purpose. In this process step, the functionality of the traction motor is checked once again. This is very important to ensure the reliability of the final drive. Only a traction motor that has passed the test is approved for delivery.

6.3 Warranty and Service Life Expectations

Industry-standard warranty coverage for aftermarket drive sprockets typically ranges from 12 to 24 months depending on the manufacturer and application. Industry sources indicate that SK100 sprocket rims are offered with a 2,000 working hours warranty. For Kobelco 2404N271 driving sprockets, FridayParts offers a 1-year warranty and 90-day hassle-free return policy.

Expected service life for SK100 sprockets in heavy construction applications typically ranges from 3,000 to 6,000 operating hours depending on ground conditions, operator practices, and maintenance schedules.

6.4 Anti-Corrosion Protection and Packaging

The sprocket surface is coated with anti-corrosion industrial paint, available in black, yellow, or customized colors to meet customer specifications. Industry sources indicate that sprocket rims are available in yellow or black and customized colors. The coating protects the sprocket from rust and harsh environmental exposure during storage and field operations.

Finished sprockets are wrapped in anti-rust film and packed into pallets or fumigated wooden crates suitable for international ocean freight. Standard packaging includes exported wooden pallets. Packaging meets international shipping standards for seafreight export from Chinese ports (Xiamen, Fuzhou) to destinations worldwide, with fumigated wooden crates complying with ISPM 15 phytosanitary regulations. Fast delivery is available within 7–30 days depending on order volume and destination.

6.5 EPR Compliance and Sustainability

Kobelco undercarriage parts are designed to comply with European environmental regulations and are certified with EPR France and Germany packing standards, meeting stringent environmental regulations for waste management and recycling. Stable production processes are analyzed and further developed at regular intervals to ensure high product quality and sustainability.

7. Wear Diagnosis and Replacement Criteria

7.1 Primary Wear Indicators

For equipment dealers, rental fleet operators, and end users managing Kobelco SK100 excavators, early identification of drive sprocket wear is essential to prevent secondary damage to track chains, rollers, and final drive systems. The following wear indicators should be monitored:

Tooth Thickness Reduction: Teeth worn to less than 70% of original thickness indicates immediate replacement is required. Measurable using calibrated calipers or dedicated tooth wear gauges.

Hook Formation: When the driving face of the sprocket tooth develops a characteristic “hook” or undercut shape, this indicates significant wear has progressed beyond acceptable limits. Hook formation reduces driving efficiency and accelerates chain bushing wear.

Cracked Root Areas: Visual inspection of the tooth root radii should be performed regularly. Cracks in the root area indicate stress fatigue and can lead to catastrophic tooth failure if not addressed promptly. Regular inspection of all sprockets for signs of tooth wear, cracks, or misalignment is essential.

Bolt Hole Elongation: Elongation or deformation of the mounting bolt holes indicates that the sprocket has been operating with loose bolts or that excessive torque has been applied. This condition compromises the sprocket’s secure mounting to the final drive hub.

Uneven Tooth Wear Pattern: If some teeth show significantly more wear than others, this may indicate misalignment between the sprocket and the track chain or issues with the final drive output shaft concentricity.

7.2 Signs That Travel Gearbox Needs Replacement

Industry sources identify the following signs that the travel gearbox may need replacement:

• Unusual noises coming from the gearbox
• Reduced speed or power of the excavator
• Leaking oil from the gearbox
• The excavator tracks are not moving evenly
• The gearbox is damaged or worn beyond repair

7.3 Replacement Interval Planning

A well-maintained sprocket directly reduces long-term operational costs. When replacing the track chain, always inspect and likely replace the sprockets for balanced wear. The economic rationale is straightforward: installing a new track chain on a worn sprocket will accelerate wear on the new chain’s bushings, significantly reducing overall system life. Conversely, installing a new sprocket on a worn chain will cause accelerated tooth wear and premature sprocket failure.

For fleet operators, the recommended replacement strategy is to replace the sprocket and track chain as a matched set whenever either component reaches the end of its service life. Proper track tension and lubrication can significantly extend the life of both the sprockets and the track chain, reducing downtime and maintenance costs.

7.4 Travel Gearbox Maintenance Best Practices

To extend the lifespan of the travel gearbox (final drive), industry best practices recommend:

• Regular Lubrication and Oil Changes: Proper lubrication is essential for gearbox function
• Avoid Overloading: Do not overload the excavator or expose it to extreme temperatures beyond design limits
• Regular Inspections and Maintenance: Conduct periodic inspections to identify issues early
• Replace Damaged Components Promptly: Address worn or damaged components immediately
• Use High-Quality Lubricants and Replacement Parts: Use API GL-5 Extreme Pressure (EP) hypoid gear oil

8. Regional Market Applications

8.1 South America: Brazilian Construction and Chilean Infrastructure

The South American construction market presents significant demand for 10-ton class excavator components, with operations concentrated in Brazilian infrastructure projects (São Paulo, Rio de Janeiro, Belo Horizonte), Chilean urban development (Santiago, Valparaíso, Concepción), Peruvian construction markets (Lima, Arequipa), and Argentinean infrastructure development (Buenos Aires, Córdoba). Kobelco SK100 excavators are extensively deployed across these operations for utility work, residential construction, site preparation, and light infrastructure projects.

For South American customers, CQC TRACK’s Kobelco cross-reference drive sprockets offer OEM-equivalent quality at competitive pricing, with efficient logistics to Latin American destinations including Brazil (Santos, Rio de Janeiro ports), Chile (Valparaíso, San Antonio ports), Peru (Callao port), Colombia (Buenaventura, Cartagena ports), and Mexico (Veracruz, Manzanillo ports).

8.2 Australia: Residential Construction, Rental Fleet, and Infrastructure

The Australian construction and rental equipment market demands aftermarket components that meet or exceed OEM performance standards, with consistent supply availability. Australian operators seek parts fit for purpose, of OEM-equivalent quality or higher, with reliable supply chains and documented quality certifications. The Australian market—including applications in Sydney, Melbourne, Brisbane, Perth, Adelaide, and regional centers—utilizes Kobelco SK100 excavators for residential construction, utility trenching, landscaping, and site preparation.

Industry sources confirm that VemaTrack keeps a stock of undercarriage parts such as sprockets, idlers, and rubber tracks for Kobelco machines, with robust and wear-resistant aftermarket undercarriage products available. Kobelco SK100 machine undercarriage components including rubber tracks, chains, idlers, bottom rollers, and top rollers are readily available.

8.3 Europe: German Quarrying, French Infrastructure, and UK Construction

The European market requires undercarriage components to comply with relevant EU directives and safety standards. EN 474-12:2006/A1:2008 applies to cable excavators and their undercarriage systems, establishing essential health and safety requirements that CE marking confirms. Germany‘s construction and quarrying industry (Berlin, Munich, Hamburg, Rhineland), France’s infrastructure sector (Paris, Lyon, Marseille, Lille), the United Kingdom‘s utility and residential construction markets (London, Manchester, Birmingham, Glasgow), and Scandinavia’s construction industry (Stockholm, Oslo, Copenhagen, Helsinki) represent major application zones for Kobelco SK100 excavators.

Aftermarket excavator spares including undercarriage parts (track rollers, idlers, sprockets) are available for Kobelco models including the SK135SR, SK210LC, SK250, and SK350. CQC TRACK maintains technical documentation and quality records that support CE compliance declarations for European customers.

8.4 Russia and Central Asia: Growing Compact Equipment Market

Following the realignment of global supply chains, Russian and Central Asian construction operators increasingly source heavy equipment components from Chinese manufacturers. Russia‘s urban development projects (Moscow, St. Petersburg, Kazan, Yekaterinburg, Novosibirsk), Kazakhstan’s infrastructure growth (Astana, Almaty, Shymkent, Karaganda), Uzbekistan‘s construction sector (Tashkent, Samarkand, Bukhara), and Mongolia’s construction and mining support operations (Ulaanbaatar, Darkhan, Erdenet) represent growing markets for Kobelco compact excavator components.

For customers in Russia, Kazakhstan, Uzbekistan, and Mongolia, CQC TRACK provides reliable supply through established export channels, with packaging suitable for rail and overland transport across Central Asian routes. The company’s manufacturing capacity supports volume orders for fleet operations requiring regular undercarriage replacement schedules.

8.5 Service Center Network Strategy

CQC TRACK‘s strategic objective is to establish, directly or through authorized distributors, a well-integrated network of service centers in major construction equipment markets worldwide that provide complete specialized undercarriage maintenance service. These service centers employ properly trained professionals with the right expertise and tools, backed by the best parts availability to enable machines to be up and running quickly and reliably.

The company warmly welcomes you to build cooperation and generate a brilliant long-term partnership together. With a full range of Kobelco-compatible excavator spare parts including track sprockets, idlers, track rollers, carrier rollers, track chains, and track shoes, all manufactured to meet OEM replacement standards ensuring reliable fit, durability, and stable performance, CQC TRACK serves customers across South America, Australia, Europe, Russia, and Central Asia.

9. Sourcing Considerations for Procurement Professionals

9.1 Cross-Reference Verification

Before purchasing aftermarket undercarriage components, procurement professionals should verify compatibility using the machine’s serial number and the specific OEM part number from the Kobelco parts catalog. The part numbers documented in this analysis—2404N271, 2404N416, and 2404N254—serve as primary OEM references for direct cross-reference ordering.

The 2404N271 sprocket is applicable to Kobelco SK100, SK100-3, SK100L, SK120-3, SK120-5, SK120LC-3, SK120LC-5, K904-2, K904L-2, SK115SRDZ, SK135SR, SK135SRLC, and additional models. The 2404N416 sprocket is compatible with New Holland E130 series excavators and cross-references to the same Kobelco models. The 2404N254 part number serves as an alternate OEM reference for SK100 applications.

9.2 Quality Documentation Requirements

When sourcing drive sprockets for construction applications, request supplier quality documentation including:

• ISO 9001:2015 certification
• Dimensional inspection reports (verifying 324mm ID, 601mm OD, 21 teeth)
• Metallurgical test certifications (material grade verification: 50Mn, 40SiMnTi, or high-manganese steel)
• Heat treatment records (hardness profiles: HRC 48–58, case depth: 4–6 mm)
• Mill test certificates for raw material
• Bolt grade certification (grade 10.9 or higher)
• Warranty documentation (12–24 months or 2,000 working hours typical)
• EPR compliance certifications (for European customers)

Reputable manufacturers maintain full traceability from raw material to finished assembly, enabling verification of material grade, heat treatment parameters, and dimensional compliance.

9.3 Supply Chain and Lead Times

CQC TRACK maintains finished goods inventory for high-demand part numbers including the 2404N271, 2404N416, and 2404N254 sprocket assemblies, with lead times of 7–30 days depending on order volume and destination. Industry sources indicate supply ability of 100 pieces per day for SK100 sprocket rims. Minimum order quantities are negotiable, with sample quantities available for qualification testing. Payment terms include T/T and L/C. Fast delivery is available within 7–30 days after contract confirmation.

9.4 Cost Optimization Through Aftermarket Sourcing

Undercarriage components can account for up to 50% of a machine‘s operating costs over its service life. For construction companies, rental fleet operators, and equipment dealers managing fleets of Kobelco SK100 excavators, sourcing OEM-equivalent aftermarket sprockets from specialized manufacturers like CQC TRACK provides significant cost savings without compromising quality or reliability. The company’s vertically integrated manufacturing—encompassing material sourcing, heat treatment, machining, and assembly—eliminates multiple supply chain markups, enabling competitive pricing for volume buyers.

The shift toward aftermarket components is driven by several factors: rising machinery costs and budget pressures have made aftermarket parts a smart investment; durability and performance have improved dramatically in the aftermarket sector; manufacturers now use advanced forging, CNC machining, and heat treatment processes to produce components that match OEM specifications; reinforced steel, precision-ground components, and heat-treated tooth profiles ensure long service life and reliable operation under extreme conditions.

9.5 OEM and ODM Service Models

CQC TRACK operates two primary service models for international customers:

OEM Manufacturing: The company produces components to exact client specifications, drawings, and quality standards. The factory is adept at seamless integration into global supply chains, providing reliable volume production of sprockets, idlers, rollers, track links, and complete undercarriage systems for brands including Kobelco, Hitachi, Komatsu, Caterpillar, Volvo, Doosan, Hyundai, SANY, and others.

ODM Engineering: Leveraging extensive field experience, CQC TRACK collaborates with clients to develop, design, and validate improved or fully customized undercarriage solutions. The engineering team proactively addresses common failure modes, offering value-optimized designs that enhance performance and reduce total cost of ownership. If customers don‘t have drawings, they can offer the main dimensions for comparison with ready products and drawing creation for customer checking.

10. Frequently Asked Questions for Equipment Dealers and Fleet Operators

Q1: What is the function of a drive sprocket on a Kobelco SK100 excavator?

A drive sprocket (also called a driving sprocket, final drive sprocket rim, or track drive wheel) is a critical cogwheel component responsible for engaging and driving the track chain to enable machine movement. It transmits torque from the final drive gearbox to the track chain, propelling the excavator forward or backward. The sprocket is designed to withstand high stress and continuous load.

Q2: What is the difference between 2404N271 and 2404N416?

2404N271 and 2404N416 are identical drive sprocket components with different OEM numbering across Kobelco and New Holland parts catalogs. Both have 21 teeth, 324mm inside diameter, and 601mm outside diameter. 2404N416 replaces Kobelco OEM number 2404N271.

Q3: How do I verify which sprocket part number my Kobelco excavator requires?

Verify using the machine‘s serial number and the specific OEM part number from the Kobelco parts catalog. The part numbers covered in this analysis—2404N271, 2404N416, and 2404N254—cover the SK100, SK100-3, SK100L, SK120-3, SK120-5, and related models.

Q4: What materials are used in CQC TRACK sprockets for Kobelco excavators?

CQC TRACK uses premium 50Mn, 40SiMnTi, and high-manganese alloy steel, induction-hardened to HRC 48–58 with case depth of 4–6 mm for optimal wear resistance. Forging and casting manufacturing techniques are employed depending on the application.

Q5: What are the dimensional specifications of the 2404N271 sprocket?

The 2404N271 sprocket has 21 teeth, an inside diameter of 324 mm, an outside diameter of 601 mm, and 15 screw/bolt holes.

Q6: Is the 2404N416 sprocket compatible with New Holland excavators?

Yes, the 2404N416 sprocket is compatible with New Holland excavators including E130, E130 (LC SR), E130SRLC, EH130LC, and New Holland mini excavator E18SR.

Q7: What quality certifications does CQC TRACK hold?

CQC TRACK operates under ISO 9001:2015 certified quality management systems with full component traceability from raw material through finished assembly.

Q8: What is the typical service life of a drive sprocket in 10-ton excavator applications?

Drive sprocket service life in SK100 applications typically ranges from 3,000 to 6,000 operating hours, depending on ground conditions, operator practices, and maintenance schedules.

Q9: What warranty is provided with these sprockets?

Industry-standard warranty coverage typically ranges from 12 to 24 months depending on the manufacturer and application. Industry sources indicate SK100 sprocket rims are offered with a 2,000 working hours warranty, with 1-year warranty and 90-day return policy also available.

Q10: What is the correct track sag specification for Kobelco SK100 excavators?

Proper track sag for 10-ton class excavators is typically 15–35 mm measured as the vertical distance between the top of the track chain and the top of the track frame at the midpoint between the front idler and the first track roller.

Q11: What is the lead time for volume orders of Kobelco sprockets?

Lead times for volume orders of Kobelco drive sprockets typically range from 7–30 days depending on order volume and destination, with supply ability of 100 pieces per day.

Q12: How do I remove the final drive from an excavator?

Remove the track and loosen the sprocket bolts—it is much easier to loosen the sprocket bolts before removing the final drive. Remove the track motor cover plate from inside the undercarriage frame, sling the final drive and take the weight, mark and remove hydraulic hoses, and then remove the bolts securing the final drive to the frame.

Q13: What are the signs that the travel gearbox needs replacement?

Signs include unusual noises coming from the gearbox, reduced speed or power, leaking oil from the gearbox, tracks not moving evenly, or the gearbox being damaged or worn beyond repair.

Q14: What maintenance practices extend travel gearbox life?

Regular lubrication and oil changes, avoiding overloading, regular inspections and maintenance, replacing damaged components promptly, and using high-quality lubricants (API GL-5 EP hypoid gear oil) and replacement parts.

Q15: How can I extend the life of both sprockets and track chains?

Proper track tension and lubrication can significantly extend the life of both the sprockets and the track chain. Regular inspection for signs of tooth wear, cracks, or misalignment is crucial.

11. Manufacturing Capability Overview: CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.)

11.1 Corporate Profile

CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.) has established itself as one of the top three undercarriage component manufacturers in the Quanzhou region, a premier supply cluster for global earthmoving equipment. Rooted in the industrial hub of Quanzhou, Fujian Province—a region renowned for its concentration of mechanical manufacturing expertise and strategic access to major international ports including Xiamen and Fuzhou—the company serves the global market as a proficient OEM (Original Equipment Manufacturer) and ODM (Original Design Manufacturer) partner.

With over two decades of specialized experience, state-owned land and factory facilities, and fully integrated production lines encompassing forging, casting, and complete undercarriage component production, CQC TRACK represents a vertically integrated source manufacturer of OEM-quality heavy-duty crawler excavator undercarriage parts. The company’s evolution from a specialized parts workshop in the late 1990s to its current status as a vertically integrated manufacturing powerhouse reflects a steadfast focus on the undercarriage niche, investing in advanced manufacturing assets and cultivating deep technical expertise in metallurgy and tribology specific to track systems.

CQC TRACK manufactures a comprehensive range of undercarriage components spanning the entire spectrum of crawler excavator applications, from 5-ton mini excavators to 300-ton ultra-class machines. The product range includes track sprockets, idlers, track rollers, carrier rollers, track chains, and track shoes for all major brands including Kobelco, Hitachi, Komatsu, Caterpillar, Volvo, Doosan, Hyundai, SANY, and others.

11.2 OEM and ODM Service Models

CQC TRACK operates two primary service models for international customers:

OEM Manufacturing: The company produces components to exact client specifications, drawings, and quality standards. The factory is adept at seamless integration into global supply chains, providing reliable volume production of sprockets, idlers, rollers, track links, and complete undercarriage systems for brands including Kobelco, Hitachi, Komatsu, Caterpillar, Volvo, Doosan, Hyundai, SANY, and others.

ODM Engineering: Leveraging extensive field experience, CQC TRACK collaborates with clients to develop, design, and validate improved or fully customized undercarriage solutions. The engineering team proactively addresses common failure modes, offering value-optimized designs that enhance performance and reduce total cost of ownership.

11.3 Integrated Production Workflow

The company‘s manufacturing prowess is built on complete vertical integration and controlled sequential processes:

• Material Sourcing: Utilization of premium 50Mn, 40SiMnTi, and high-manganese alloy steels through strategic supply partnerships, with full material certification and traceability
• Forging and Casting Capabilities: Advanced closed-die hot forging processes ensuring optimal grain flow and material density; forging process creates superior grain structure essential for handling shock loads
• CNC Machining Centers: Precision machining of all critical surfaces to ISO 2768-mK tolerances, including precision-machined tooth profiles and mounting surfaces
• Advanced Heat Treatment Lines: Computer-controlled induction hardening and tempering furnaces achieving deep, uniform case hardness profiles; induction hardened tooth profiles achieving HRC 48–58 surface hardness
• Assembly and Testing: Dust-free assembly environments with dynamic testing on every finished component; acceptance testing on test benches before delivery
• Anti-Corrosion Coating: Industrial-grade painting systems providing long-term rust protection, available in black, yellow, or customized colors to meet customer specifications
• Packaging and Logistics: Anti-rust film wrapping with pallet or fumigated wooden crate packing for international ocean freight, complying with ISPM 15 phytosanitary regulations

11.4 Quality and Value Proposition

World-class quality with factory direct pricing, extensive experience in excavator undercarriage parts manufacturing, flexible payment terms including T/T and L/C, and fast delivery within 7–30 days after contract confirmation. The company warmly welcomes you to build cooperation and generate a brilliant long-term partnership together.

The company’s focused specialization enables CQC TRACK to deliver components that not only meet but often exceed OEM performance standards. With a full range of Kobelco-compatible excavator spare parts including track sprockets, idlers, track rollers, carrier rollers, track chains, and track shoes, all manufactured to meet OEM replacement standards ensuring reliable fit, durability, and stable performance, CQC TRACK serves customers across South America, Australia, Europe, Russia, and Central Asia.

CQC TRACK warmly welcomes you to build cooperation and generate a brilliant long-term partnership together.

12. Conclusion

The three Kobelco OEM cross-reference drive sprocket assemblies documented in this analysis—2404N271, 2404N416, and 2404N254—represent essential power transmission components for SK100 series hydraulic crawler excavators deployed in construction sites, utility work, site development, and light infrastructure projects worldwide. As the primary active propulsion component at the rear of the undercarriage, the drive sprocket converts final drive torque into linear traction, playing a critical role in machine mobility, operational productivity, and undercarriage system longevity.

The Kobelco SK100 series is a 10-ton class excavator manufactured from 1992 to 1996 with a 10.5-ton operating weight, 500 mm track width, Isuzu 4 BD engine delivering 56 kW, and 0.45 m³ bucket capacity. For these machines, the drive sprocket must provide reliable power transmission under demanding conditions—including high torque loads, abrasive ground contact, and continuous cyclic operation—while maintaining precise 21-tooth engagement with the track chain.

The 2404N271 and 2404N416 part numbers represent identical drive sprocket components with 21 teeth, 324 mm inside diameter, and 601 mm outside diameter, with cross-brand compatibility across Kobelco and New Holland equipment lines. The 2404N254 part number serves as an additional OEM reference for the SK100 undercarriage system.

CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.) manufactures these sprockets to meet or exceed OEM specifications through advanced closed-die hot forging technology, precision CNC machining, computer-controlled induction heat treatment achieving HRC 48–58 surface hardness with 4–6 mm case depth, and rigorous quality assurance protocols. The company’s ISO 9001:2015 certified manufacturing processes, comprehensive testing protocols, and strategic position as one of the top three undercarriage component manufacturers in Quanzhou‘s heavy machinery industrial cluster enable consistent supply to global construction markets.

For equipment dealers, rental fleet operators, and end users throughout South America (Brazil, Chile, Peru, Argentina, Colombia), Australia (Sydney, Melbourne, Brisbane, Perth, Adelaide), Europe (Germany, France, United Kingdom, Scandinavia), and Russia/Central Asia (Moscow, St. Petersburg, Astana, Almaty, Tashkent, Ulaanbaatar), these drive sprockets provide a reliable, cost-effective alternative to OEM parts without compromising on material quality, manufacturing precision, or service life.

For fleet managers and maintenance supervisors, implementing a proactive sprocket inspection and replacement schedule—including regular tooth wear measurement, root crack inspection, bolt torque verification, proper track tension adjustment to 15–35 mm sag, and coordinated sprocket-and-chain replacement—represents the most effective strategy for maximizing undercarriage system life and minimizing unplanned downtime in mini excavator operations. The sprocket is a critical cogwheel component in tracked vehicles, responsible for engaging and driving the track chain to enable movement.

CQC TRACK warmly welcomes you to build cooperation and generate a brilliant long-term partnership together.

This technical publication is intended for engineering and procurement professionals in the construction, rental, and light infrastructure industries. All specifications are subject to verification against current OEM documentation. Original spare part numbers are for comparison purposes only. For current pricing, lead times, and technical support, contact CQC TRACK directly.