Komatsu Mini Track Excavator PC75 Sprocket Wheel Group – OEM Cross-Reference Part Numbers 22E2711111, 21W2741110, 21W2731110, 21W2731112

Source OEM Manufacturer – CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.) – Based in Quanzhou, China

Technical Abstract

This technical publication provides comprehensive engineering documentation for the Komatsu PC75 track sprocket wheel group—comprising OEM cross-reference part numbers 22E-27-11111, 21W-27-41110, 21W-27-31110, 21W-27-31112—engineered for the Komatsu PC75 series hydraulic crawler excavators. These sprocket assemblies, alternatively designated as final drive sprocket groups, drive sprockets, or track sprocket wheels, represent the primary power transmission component within the undercarriage system of the 7–8 ton mini excavator class.

Within the PC75 undercarriage architecture, the drive sprocket serves as the active propulsion component, converting hydraulic motor torque into linear pulling force that moves the track chain and propels the entire machine. For Komatsu PC75 excavators—machines widely deployed in construction sites, utility work, landscaping, residential development, and light infrastructure projects across South America, Australia, Europe, Russia, and Central Asia—the engineering integrity of the sprocket assembly is fundamental to machine mobility, operational productivity, and total cost of ownership.

This analysis examines the PC75 sprocket group through multiple technical lenses: functional engineering principles of torque transmission and track engagement, metallurgical composition with detailed material grade specifications including 50Mn and 42CrMo alloy steels, advanced manufacturing process engineering featuring closed-die hot forging and precision CNC machining, comprehensive heat treatment protocols including induction hardening achieving HRC 52–58 surface hardness, dimensional specifications for PC75 undercarriage fitment, rigorous quality assurance protocols including ISO 9001:2015 certification, comprehensive installation procedures, wear diagnosis and replacement criteria, regional market analysis for key global markets, and strategic sourcing considerations for procurement professionals managing Komatsu mini excavator fleets worldwide.

The Komatsu PC75 is a versatile and reliable compact hydraulic excavator designed for a wide range of construction, landscaping, and utility tasks, known for its durability and efficiency. The PC75UU-3 is an upgraded version of the UU series with enhanced hydraulics, improved engine performance, and better fuel economy. For tight urban jobs, zero-tail swing models like the PC75UU series are prioritized.

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 undercarriage component manufacturers in the Quanzhou region, a premier industrial cluster for global earthmoving equipment manufacturing located in Fujian Province, China. 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. 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.

CQC TRACK warmly welcomes you to build cooperation and generate a brilliant long-term partnership together. The company manufactures a full range of Komatsu-compatible undercarriage parts spanning the entire spectrum from 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.

1. Product Identification and Application Coverage

1.1 Component Nomenclature and Functional Overview

A drive sprocket assembly—technically designated as a final drive sprocket group, track sprocket wheel, or sprocket wheel assembly—is the primary active propulsion component of the excavator‘s undercarriage system, mounted at the rear of the track frame and connected directly to the output shaft of the final drive travel gearbox. 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: Converting the rotational torque generated by the hydraulic travel motor via the final drive gearbox into linear pulling force that moves the track chain and, consequently, the 7–8 ton machine.
• Precision Chain Engagement: Engaging with the track chain bushings with exact tooth geometry to ensure smooth, consistent power transmission without skipping, binding, or excessive friction.
• Load Distribution: Distributing the driving load evenly across multiple teeth and bushings to prevent concentrated stress points that would cause premature wear or failure.
• Directional Control: Working in concert with the front idler and track rollers to maintain proper track chain alignment during forward travel, reverse travel, and turning operations.

The final drive 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.

1.2 OEM Part Numbers and Compatible Excavator Models

The four sprocket assemblies documented in this analysis correspond to precise Komatsu OEM engineering specifications, offering direct interchangeability across multiple PC75 variants and related Komatsu models. The table below provides comprehensive cross-reference data:

The 22E-27-11111 sprocket is documented for Komatsu PC60/75UU-7 applications, confirming direct compatibility with the PC75UU-7 variant. Industry sources indicate that the KOMATSU 21W-27-11111 is a PC60/75UU-7 SPROCKET, manufactured to Komatsu‘s OEM specifications.

The 21W-27-31112 sprocket is specifically documented for Komatsu PC78US-5, PC75UU-3, and PC70FR-1 excavators, as well as Yanmar VIO80, VIO75, VIO70, VIO70-2, B7-3, and VIO82 mini excavators. This demonstrates broad cross-brand compatibility between Komatsu and Yanmar undercarriage systems in the 7–8 ton class.

The 21W-27-41110 sprocket is documented for Komatsu PC78US-6, PC78US-8, PC78US-10, PC78UU-6, PC78MR-6, PC88MR-6, PC88MR-8, and PC88MR-10 excavators, as well as Volvo ECR88 mini excavators. This confirms cross-brand compatibility between Komatsu and Volvo undercarriage systems.

The comprehensive cross-platform compatibility of these sprocket assemblies makes them valuable inventory items for fleet operators managing multiple Komatsu model generations and even cross-brand equipment from Yanmar and Volvo.

1.3 Komatsu PC75 Excavator Specifications and Undercarriage Parameters

The Komatsu PC75 series represents the 7–8 ton class in the Komatsu product line, offering substantial digging performance in a compact package suitable for confined job sites. The PC75 is a versatile and reliable compact hydraulic excavator widely used in construction, landscaping, and utility projects.

The table below provides comprehensive technical specifications for the PC75 series based on multiple authoritative sources:

Data sources:

The PC75R-2 crawler midi excavators are specifically designed to work in tight spaces and hard-to-reach areas, with special features and options, multipurpose machines equipped with a swing offset boom and can be supplied in customized configurations.

The PC75UU-3 is a reliable and powerful excavator that offers impressive specifications and performance. From its robust engine to its compact dimensions, this machine is designed to tackle various tasks with ease. The PC75UU-3 is an upgraded version of the UU series with enhanced hydraulics, improved engine performance, and better fuel economy.

The PC75-1 is equipped with a 68.4 hp engine and a hydraulic pump flow capacity of 44.2 gpm, ensuring efficient and reliable operation on the job site.

1.4 Undercarriage Component Configuration

The Komatsu PC75 undercarriage is engineered for durability and stability. Key undercarriage parameters include:

• Track Shoe Width: 450 mm (standard for PC75-1)
• Track Gauge: 1,650 mm
• Length of Track on Ground: 2,160 mm (7.09 ft)
• Ground Clearance: 400 mm
• Rubber Track Sizes: 450 mm width, 76 mm pitch, 80 links for rubber track configurations

A quick rule for part identification: a part number identifies the component, while a machine serial number confirms the correct fitment range (serial breaks, options, revisions). This principle is essential for accurate parts procurement.

1.5 Component Architecture and Assembly Composition

A complete Komatsu PC75 drive sprocket assembly consists of multiple precision-engineered subcomponents, each manufactured to exacting tolerances for the mini 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 without causing excessive friction or wear. For the PC75 class, the sprocket typically features 20–21 teeth with an outer diameter of approximately 474 mm. A sprocket is defined as a profiled wheel with teeth or cogs that mesh with a chain, track, or other perforated or indented materials.
• Hub (Mounting Interface): The central portion of the sprocket that bolts directly to the final drive motor‘s output hub flange or mounts via splined connection to the output planetary carrier. The hub incorporates precisely drilled bolt 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 7–8 ton class, bolt torque specifications typically range from 250–450 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.
• Tooth Configuration: The PC75 class sprocket typically features 20–21 teeth (varies by model year), with industry references indicating 20–21 holes and an outer diameter of approximately 474 mm for this class of sprockets.

2. Metallurgical Composition and Forging Engineering

2.1 Material Grade Specifications

CQC TRACK manufactures Komatsu cross-reference drive sprockets using premium alloy steel grades selected for their specific mechanical properties in 7–8 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.

42CrMo Alloy Steel (Premium Grade): A chromium-molybdenum forged alloy steel offering exceptional strength, deep hardenability, and superior impact resistance. 42CrMo is a medium carbon alloy structural steel with high strength, high toughness, good hardenability, and excellent fatigue resistance. For demanding applications where extended service life is critical, forged 42CrMo provides the highest level of performance. After quenching and tempering, 42CrMo achieves hardness of HRC 48–52, and with induction quenching and tempering, hardness reaches HRC 54–60.

40Mn2 Alloy Steel: A chromium-manganese alloy offering an optimal balance of surface hardenability, core toughness, and cost-effectiveness for mini excavator applications. This material responds well to induction heat treatment, achieving uniform case hardness profiles with minimal distortion.

High-Strength Alloy Steel: Sprockets are manufactured using high-strength alloy steel construction, enabling components to withstand extreme stress and harsh environmental conditions common in heavy machinery operations.

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

Komatsu PC75 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. The forging process provides several critical advantages over cast alternatives:

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. The core sprocket wheel is typically forged from chromium-molybdenum alloy steel (e.g., 42CrMo, 50Mn). This forging process aligns the metal‘s grain flow with the component’s shape, resulting in superior tensile strength and impact resistance compared to cast alternatives.

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.

Closed-Die Hot Forging Process: The sprocket undergoes a multi-stage hot forging process that includes primary hot forging for initial volume distribution, secondary hot forging for establishing core structural geometry, tertiary hot forging for achieving final dimensional accuracy, and trimming-piercing for eliminating flash and forming any necessary through-holes.

2.3 Precision CNC Machining

All critical surfaces of Komatsu 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 20–21 tooth configuration requires precise tooth spacing and profile geometry.
• Bore Machining: Precision boring of the central mounting bore to achieve exact hub interface specifications.
• Bolt Hole Drilling: Precision drilling of 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 outer diameter to exact specifications (approximately 474 mm for the PC75 class).

State-of-the-art CNC gear hobbing and turning centers are employed to achieve micron-level accuracy in tooth profile, pitch, and mounting bore dimensions. This guarantees perfect alignment and reduces vibration during operation. Utilizing specialized hardening and tempering techniques ensures products possess outstanding mechanical characteristics, exceptional durability, and enhanced resistance to deformation and fracture.

2.4 Integrated Production Workflow

CQC TRACK‘s manufacturing prowess is built on complete vertical integration and controlled sequential processes:

• Material Sourcing: Utilization of premium 50Mn, 42CrMo, and 40Mn2 alloy steels through strategic supply partnerships, with full material certification and traceability
• Forging Capabilities: Advanced closed-die hot forging processes ensuring optimal grain flow and material density
• 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
• Assembly and Testing: Dust-free assembly environments with dynamic testing on every finished sprocket
• Anti-Corrosion Coating: Industrial-grade painting systems providing long-term rust protection, available in black, yellow, or customized colors to meet customer specifications

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 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

Komatsu PC75 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 Komatsu PC75 drive sprockets are as follows:

The sprocket teeth undergo computer-controlled induction hardening. This process creates a deep, consistent case hardness (typically 55-62 HRC) on the tooth flanks and roots—the areas of highest contact stress and wear. The core remains tough and ductile, providing structural resilience against shock loads.

Heat treatment is adopted to ensure better hardness and crack resistance in working time, significantly extending the service life of the sprocket in demanding applications.

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. 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 Komatsu PC75 sprocket group is engineered to precise dimensional specifications for direct fitment to the PC75 track frame and final drive system. Industry sources provide the following dimensional reference for sprockets in this class:

Industry sources indicate that sprockets suitable for KOMATSU and CATERPILLAR applications in this class typically feature 20–21 holes, an outer diameter of 474 mm, and an approximate weight of 36 kg. These specifications align with the PC75 class of mini excavators.

4.2 Undercarriage Fitment Parameters

For the Komatsu PC75-1, the undercarriage features:

• Track Width: 450 mm
• Track Gauge: 1,650 mm (5.42 ft)
• Length of Track on Ground: 2,160 mm (7.09 ft)
• Ground Clearance: 400 mm
• Ground Pressure: 32.41 kPa (4.7 psi)
• Max Travel Speed: 5.1 km/h (3.17 mph)

4.3 Sprocket Mounting Configuration

The Komatsu PC75 undercarriage features a robust final drive system that incorporates:

• Final Drive Travel Gearbox: Located within the undercarriage, connected to the hydraulic motor and the track drive sprockets. The gearbox converts hydraulic power into torque and drives the track drive sprockets.
• Sprocket Mounting Interface: The sprocket mounts to the output planetary carrier via bolted connection (20–21 bolt holes), providing solid, non-slip torque transmission.
• Sealing System: Floating face seal with labyrinth pre-seals prevents contamination ingress and lubricant leakage.

5. Quality Assurance and Testing Protocols

5.1 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, 42CrMo, and 40Mn2 steels
• Dimensional Verification: Inspection of all critical dimensions using calibrated measurement equipment, including CMM (Coordinate Measuring Machine) 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

5.2 Komatsu Undercarriage Parts Quality Standards

Komatsu excavator undercarriage parts are engineered for heavy-duty performance in construction machinery. Designed to enhance durability and operational efficiency, these components are manufactured to meet OEM replacement standards. Key quality features include:

• High-Strength Material Technology: Components utilize high-strength alloy steel construction
• Precision-Engineered Design: Precision-machined sprocket teeth ensure smooth track engagement
• Heavy-Duty Performance: Robust load-bearing capacity handles up to 8 tons of continuous operation in rugged terrains
• Finish Machining: Finish machining makes the sprocket have smooth surface and accurate precision

5.3 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. For Komatsu PC75 sprockets manufactured by CQC TRACK, warranty periods are aligned with customer requirements and application severity. Expected service life for PC75 sprockets in construction applications typically ranges from 3,000 to 6,000 operating hours depending on ground conditions, operator practices, and maintenance schedules.

5.4 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. 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. Each package is labeled with part number, dimensions, and quantity for easy handling and identification at destination ports and warehouses. 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. Installation and Track Tensioning Procedures

6.1 Pre-Installation Preparation

Proper installation of a drive sprocket assembly on a Komatsu PC75 excavator is critical to achieving expected service life. The following procedures should be followed:

1. Site Preparation: Park the machine on level and firm ground. Engage the parking brake. Block the tracks securely to prevent unintended movement.
2. Component Inspection: Before installation, inspect the final drive output hub for spline wear, corrosion, or damage. Clean all mounting surfaces thoroughly, removing all debris, old gasket material, and corrosion.
3. Sprocket Assembly Inspection: Inspect the new sprocket assembly for any shipping damage. Verify that the mounting holes are clean and free of debris.
4. Hardware Inspection: Inspect all mounting bolts for thread damage or stretching. For heavy-duty applications, use new bolts and washers of grade 10.9 or higher specification.
5. Final Drive Interface: Ensure that the sprocket mounting interface is properly aligned with the final drive output planetary carrier. Install the sprocket mounting hardware to specified torque values using a calibrated torque wrench.
6. Track Chain Engagement: After sprocket installation, ensure proper track chain engagement with the sprocket teeth before operating the machine.

6.2 Bolt Torque Specifications

For the Komatsu PC75 class excavator, the following torque specifications apply:

• Mounting Hardware Grade: Class 10.9 or higher for heavy-duty applications
• Bolt Torque Range: 250–450 Nm depending on bolt size and configuration (consult Komatsu service manual for model-specific specifications)
• 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 to prevent galling and ensure accurate torque readings
• Re-Torque Requirement: After 2–4 hours of operation, re-torque the sprocket mounting bolts to the specified value to account for initial seating and thermal expansion

6.3 Track Tension Adjustment Procedure

After sprocket installation, proper track tension must be established according to Komatsu PC75 specifications. The general procedure for 7–8 ton excavators is as follows:

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 7–8 ton class excavators, the proper track sag is typically 15–30 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 by an amount equal to the length of track on ground, then check the track tension again. If the tension is not correct, adjust it again.

6.4 Critical Tensioning Considerations

The following operational considerations are essential for maximizing undercarriage component life:

• Underfoot Conditions: Adjust track tension based on the underfoot conditions in which the machine is working. 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.
• Post-Installation Verification: After 2–4 hours of operation, re-check track tension and re-torque any mounting hardware as specified in the Komatsu service manual to account for initial seating and thermal expansion.

7. Wear Diagnosis and Replacement Criteria

7.1 Primary Wear Indicators

For equipment dealers, rental fleet operators, and end users managing Komatsu PC75 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. Heat treatment is adopted to ensure better crack resistance in working time.

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.

Signs That Your Travel Gearbox Needs 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, or the gearbox is damaged or worn beyond repair.

7.2 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. Industry best practices recommend replacing wear parts in sets to ensure even wear and prevent premature failure. For PC75 mini excavators in construction applications, planned undercarriage replacement intervals typically range from 3,000 to 6,000 operating hours depending on ground conditions and maintenance practices.

7.3 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, Chilean Infrastructure, and Argentine Development

The South American construction market presents significant demand for 7–8 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). Komatsu PC75 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 Komatsu 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 Komatsu PC75 excavators for residential construction, utility trenching, landscaping, and site preparation.

Industry sources confirm that VemaTrack has a wide range of undercarriage components for Komatsu PC75 machines, including rubber tracks, idlers, and sprockets. Australian parts suppliers maintain extensive inventory for Komatsu undercarriage components, with large inventory holdings of genuine new parts, new replacement parts, used, and reconditioned parts and components.

CQC TRACK’s manufacturing processes align with Australian requirements through ISO 9001:2015 certification, comprehensive testing protocols, and full component traceability.

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

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 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 Komatsu PC75 excavators.

For tight urban jobs, zero-tail swing models like the PC75UU series are prioritized, making the PC75 a popular choice for European urban construction applications where space is constrained.

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 Komatsu 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 Komatsu-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 Komatsu parts catalog. The part numbers documented in this analysis—22E-27-11111, 21W-27-41110, 21W-27-31110, and 21W-27-31112—serve as primary OEM references for direct cross-reference ordering.

Use the part number to identify the component, and use the machine serial number to confirm the correct fitment range (serial breaks, options, revisions). This two-step verification process ensures accurate parts procurement.

The 22E-27-11111 sprocket is documented for Komatsu PC60/75UU-7 applications. The 21W-27-31112 sprocket is compatible with Komatsu PC78US-5, PC75UU-3, and PC70FR-1 excavators, as well as Yanmar VIO80, VIO75, VIO70, VIO70-2, B7-3, and VIO82 mini excavators. The 21W-27-41110 sprocket is compatible with Komatsu PC78US-6, PC78US-8, PC78US-10, PC78UU-6, PC78MR-6, PC88MR-6, PC88MR-8, and PC88MR-10 excavators, as well as Volvo ECR88 mini excavators.

9.2 Quality Documentation Requirements

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

• ISO 9001:2015 certification
• Dimensional inspection reports
• Metallurgical test certifications (material grade verification: 50Mn, 42CrMo, or 40Mn2)
• 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 typical)

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 PC75 sprocket assemblies, with lead times of 7–30 days depending on order volume and destination. 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 Komatsu PC75 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 Komatsu, Hitachi, Caterpillar, Volvo, Kobelco, 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 Komatsu PC75 excavator?

A drive sprocket (also called a final drive sprocket group or track sprocket wheel) is a profiled wheel with teeth or cogs that mesh with the track chain. It converts the rotational torque from the hydraulic travel motor via the final drive gearbox into linear pulling force that moves the track chain, propelling the 7–8 ton excavator forward or backward.

Q2: How do I verify which sprocket part number my Komatsu PC75 excavator requires?

Verify using the machine‘s serial number and the specific OEM part number from the Komatsu parts catalog. A part number identifies the component, and a machine serial number confirms the correct fitment range (serial breaks, options, revisions). The part numbers covered in this analysis—22E-27-11111, 21W-27-41110, 21W-27-31110, and 21W-27-31112—cover the PC75 series and related models.

Q3: What is the difference between the 21W-27-31110 and 21W-27-31112 part numbers?

21W-27-31110 and 21W-27-31112 are both drive sprocket assemblies for the PC75UU-3, PC78US-5, and PC70FR-1 models. The 21W-27-31112 sprocket also offers cross-brand compatibility with Yanmar VIO80, VIO75, VIO70, VIO70-2, B7-3, and VIO82 mini excavators.

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

CQC TRACK uses premium 50Mn, 42CrMo, and 40Mn2 alloy steel, induction-hardened to HRC 48–58 with case depth of 4–6 mm for optimal wear resistance. The forging process aligns the metal‘s grain flow with the component’s shape, resulting in superior tensile strength and impact resistance compared to cast alternatives.

Q5: What are the dimensional specifications of the PC75 sprocket group?

Industry references indicate that sprockets suitable for Komatsu and Caterpillar applications in this class feature an outer diameter of approximately 474 mm, weight of approximately 36 kg, and 20–21 holes.

Q6: Are these sprockets direct replacements for Komatsu OEM parts?

Yes, all drive sprockets manufactured by CQC TRACK are direct OEM cross-reference replacements, manufactured to Komatsu‘s original engineering specifications for dimensional accuracy and mechanical properties. Original spare part numbers are for comparison purposes only.

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 PC75 applications?

Drive sprocket service life in PC75 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 for aftermarket drive sprockets typically ranges from 12 to 24 months depending on the manufacturer and application.

Q10: What is the correct track sag specification for Komatsu PC75 excavators?

Proper track sag for 7–8 ton class excavators is typically 15–30 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. Always consult the Komatsu service manual for model-specific specifications.

Q11: What is the lead time for volume orders of Komatsu PC75 sprockets?

Lead times for volume orders of Komatsu PC75 drive sprockets typically range from 7–30 days depending on order volume and destination, with fast delivery within 30 days after contract confirmation.

Q12: What are the signs that the travel gearbox needs replacement?

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

Q13: 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. Adjust track tension based on underfoot conditions—added track tension increases both the load and the wear on all mating components of the undercarriage.

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 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.

HELI Machinery Manufacturing Co., Ltd., operating under the CQC TRACK brand, is a vertically integrated producer of critical power transmission components for heavy-duty crawler excavators. 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.

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 Komatsu, Hitachi, Caterpillar, Volvo, Kobelco, 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 Komatsu, Hitachi, Caterpillar, Volvo, Kobelco, 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.

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, 42CrMo, and 40Mn2 alloy steels through strategic supply partnerships, with full material certification and traceability
• Forging 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 55–62 HRC surface hardness on tooth flanks and roots
• Assembly and Testing: Dust-free assembly environments with dynamic testing on every finished component
• 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 Komatsu-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 four Komatsu OEM cross-reference drive sprocket assemblies documented in this analysis—22E-27-11111, 21W-27-41110, 21W-27-31110, and 21W-27-31112—represent essential power transmission components for PC75 series hydraulic crawler excavators deployed in construction sites, utility work, landscaping, residential 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 Komatsu PC75 is a versatile and reliable compact hydraulic excavator designed for a wide range of construction, landscaping, and utility tasks, known for its durability and efficiency. The PC75R-2 crawler midi excavators are specifically designed to work in tight spaces and hard-to-reach areas. The PC75UU-3 is an upgraded version of the UU series with enhanced hydraulics, improved engine performance, and better fuel economy. For tight urban jobs, zero-tail swing models like the PC75UU series are prioritized. For these machines, the drive sprocket must provide reliable power transmission under demanding conditions—including torque loads, abrasive ground contact, and continuous cyclic operation—while maintaining precise tooth engagement with the track chain.

The 22E-27-11111 and 21W-27-31112 part numbers demonstrate cross-platform compatibility across Komatsu PC75 variants and cross-brand compatibility with Yanmar and Volvo mini excavators, making these sprocket groups valuable inventory items for fleet operators managing mixed equipment fleets.

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 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 15–30 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.

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.