Komatsu 2083000320 20730K1200 81E520031 PC300-6 PC360-8 Track Carrier Roller / Upper Roller Assy / Professional Manufacturing EXC Undercarriage Part / CQC TRACK

Komatsu 2083000320, 20730K1200, 81E520031 PC300-6 PC360-8 Track Carrier Roller / Upper Roller Assembly: Professional Undercarriage Manufacturing Excellence by CQC TRACK

Author: Jack
Date: April 3, 2026

1. Technical Overview: The Critical Role of Carrier Rollers in Komatsu Undercarriage Systems

The carrier roller—also known as the top roller or upper roller—is an essential but often overlooked component of any crawler excavator’s undercarriage system. While bottom track rollers bear the machine’s full operating weight against the ground, carrier rollers perform a distinctly different but equally vital function: they guide and support the upper (return) section of the track chain as it travels from the front idler back to the drive sprocket. Without properly functioning carrier rollers, the track chain would sag, whip excessively during high-speed travel, and risk derailment—particularly during sharp turns or when traversing uneven terrain.

For operators of Komatsu PC300-6 and PC360-8 excavators—30–34 ton class machines widely deployed in mining, quarrying, heavy construction, and infrastructure development—the reliability of the carrier roller assembly directly affects track alignment, undercarriage component life, and overall machine uptime.

This publication delivers a comprehensive technical examination of three Komatsu OEM part numbers—2083000320, 20730K1200, and 81E520031—which represent critical track carrier roller assemblies for the PC300-6 and PC360-8 platforms. Particular focus is placed on CQC TRACK (HELI MACHINERY MANUFACTURING CO., LTD.), a vertically integrated manufacturer with over two decades of specialization in heavy-duty undercarriage components, and why its position as a source factory matters for global procurement professionals seeking OEM-quality chassis components.

2. Part Number Identification and Machine Compatibility

Understanding the relationship between Komatsu’s OEM part numbers and their corresponding machine applications is essential for accurate sourcing. Below is a detailed compatibility matrix based on verified supplier data, parts catalogs, and cross-reference documentation.

2.1 Primary Part Numbers and Their Applications

The 2083000320 part number has been documented as the OEM-spec top carrier roller assembly for the Komatsu PC300LC-6LC (long carriage variant), with each machine utilizing four such rollers—two per track side. For the PC360-8 platform, industry documentation indicates that excavators of this class typically use two carrier rollers per side to manage the upper track’s movement during sharp turns and high-speed travel.

2.2 Machine Platform Specifications

The target machines for these carrier roller assemblies operate in the 30–34 ton class, with the following verified specifications:

The PC360-8M1 variant, for which these carrier roller assemblies are compatible, features an operating weight of 34,160 kg, a maximum travel speed of 5.5 km/h, and is powered by the Komatsu SAA6D114E-3 engine with 8.27 L displacement.

2.3 Cross-Reference Compatibility

For procurement professionals managing mixed fleets, the following OEM cross-reference information is valuable:

3. Engineering Function and Mechanical Design of Carrier Rollers

3.1 Functional Responsibilities

The track carrier roller assembly performs three mission-critical functions that directly impact undercarriage longevity:

1. Upper Track Guidance: Carrier rollers guide the track chain’s return (upper) section as it travels from the front idler back to the drive sprocket. Proper guidance maintains track alignment, prevents lateral sway, and reduces wear on both the track chain and the sprocket teeth. The double-flange design of most Komatsu carrier rollers securely guides the track chain link, preventing lateral slippage and excessive whip during high-speed travel.
2. Dynamic Tension Management: While the front idler and track adjuster control static track tension, carrier rollers help manage dynamic tension fluctuations that occur as the machine accelerates, decelerates, or turns. This function is particularly important during sharp turns, where the upper track experiences significant lateral forces.
3. Contamination Barrier: Carrier rollers incorporate advanced sealing systems—multi-labyrinth seals combined with high-performance grease seals—to create a robust barrier against mud, sand, and moisture. This protects the internal tapered roller bearings and extends service life in abrasive mining and construction environments.

3.2 Component Architecture

A complete Komatsu carrier roller assembly consists of the following subcomponents:

4. Material Specifications and Heat Treatment Standards

4.1 Material Selection

Quality carrier rollers for Komatsu excavators are manufactured from high-grade alloy steels selected for their exceptional yield strength, toughness, and wear resistance. The most commonly specified materials include:

4.2 Heat Treatment Specifications

The performance of a track carrier roller depends critically on its heat treatment profile:

The core of durability lies in advanced metallurgy: the roller tread undergoes induction hardening or case carburizing processes, creating a deep, wear-resistant surface layer (typically 55–60 HRC) while maintaining a ductile, shock-absorbing core to prevent brittle fracture.

4.3 Load Capacity and Performance Metrics

Many modern carrier roller designs are lubrication-free (sealed-for-life) to reduce maintenance and contamination risk, with tapered roller bearings as standard for their excellent capacity to handle combined radial and axial loads.

5. CQC TRACK: A Specialized Manufacturer of Komatsu Undercarriage Components

5.1 Corporate Profile and Manufacturing Heritage

CQC TRACK, operating under HELI MACHINERY MANUFACTURING CO., LTD., is a vertically integrated manufacturer based in Quanzhou, China—a region recognized as a key supply cluster for global earthmoving equipment. With over 20 years of manufacturing experience, HELI has established itself as a specialized supplier of heavy-duty crawler excavator chassis components, serving Original Equipment Manufacturers (OEMs) of mining machines worldwide.

The brand name CQC TRACK symbolizes three foundational commitments: Crawler systems, Quality assurance, and Commitment to durability under the most abrasive and high-impact environments encountered in mining, quarrying, and major infrastructure projects.

5.2 Manufacturing Capabilities and Quality Control

CQC TRACK’s manufacturing strength rests on complete vertical integration and controlled sequential processes:

5.3 Komatsu Carrier Roller Product Portfolio

CQC TRACK manufactures a comprehensive range of undercarriage components for Komatsu excavators, including:

• Track carrier rollers (top/upper rollers) — For PC300-6, PC360-8, and compatible models
• Track bottom rollers (lower rollers) — Including part numbers 2073000510, 2073000511, and KM1429 for PC300-7/8 and PC360-7/8 series
• Track front idler assemblies
• Drive sprockets and sprocket segments
• Track chains and track link assemblies
• Track adjuster and recoil assemblies

CQC TRACK has documented cross-reference compatibility for its undercarriage components across multiple brands, including Komatsu, Caterpillar, Hitachi, Kobelco, Sumitomo, Doosan, Hyundai, and Volvo, confirming the broad applicability of their manufacturing standards.

5.4 OEM and ODM Service Model

CQC TRACK operates a dual service model that accommodates both standardized replacement parts and customized engineering solutions:

• OEM Manufacturing: Production of components to exact client specifications, drawings, and quality standards. The factory is equipped for seamless integration into global supply chains, providing reliable volume production of rollers, idlers, sprockets, and track links.
• ODM Engineering: Collaborative development, design, and validation of 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.

5.5 Quality Assurance and Warranty

CQC TRACK’s undercarriage components are manufactured under ISO 9001-2015 quality management systems. The company combines design and engineering expertise with advanced manufacturing technologies to develop innovative, reliable, and competitive products that meet the highest quality standards. Warranty coverage typically extends to 12 months or 2,000 operating hours, depending on component grade and application severity.

6. Factory-Direct Sourcing: Competitive Advantages

6.1 Supply Chain Value Proposition

Sourcing Komatsu PC300-6 and PC360-8 carrier roller assemblies directly from a source factory and manufacturer such as CQC TRACK offers distinct advantages over multi-tier distribution channels:

6.2 Lead Times and Logistics

For Komatsu carrier roller assemblies, typical factory-direct lead times are:

• Stocked items: 5–10 business days (ready stock)
• Manufactured to order: 20–25 days after contract confirmation
• Express delivery: Available for urgent requirements

Standard shipping is FOB from Xiamen port, China, with door-to-door logistics available through established freight forwarding partnerships.

6.3 Cost Comparison

7. Installation, Maintenance, and Service Life Optimization

7.1 Pre-Installation Verification

Before installing a new track carrier roller assembly, verify the following critical parameters:

1. Mounting pattern compatibility — Confirm bolt hole spacing and diameter match the track frame bracket
2. Roller width and diameter — Verify dimensions match the track chain link spacing and upper track clearance
3. Flange configuration — Confirm double-flange or single-flange design matches OEM specification
4. Track chain condition — Measure chain pitch elongation; if exceeding 3%, chain replacement should precede roller installation

7.2 Installation Procedure Summary

1. Securely support the machine with the track chain relieved of tension
2. Remove the existing carrier roller mounting bolts using appropriate torque tools
3. Clean the mounting bracket surface and inspect for damage
4. Position the new carrier roller assembly and install mounting bolts
5. Torque bolts to specification (consult machine workshop manual for exact values; typically 250–350 N·m for PC300/PC360 class)
6. Re-tension the track chain to manufacturer-specified sag (typically 30–40 mm between the track and track frame at the midpoint)
7. Operate the machine at low speed and inspect for proper roller rotation and seal integrity

7.3 Maintenance Schedule

7.4 Failure Modes and Troubleshooting

8. The Importance of Proper Carrier Roller Selection

Carrier rollers are often the most neglected components in an excavator undercarriage system. Unlike bottom rollers, which show obvious signs of wear through reduced ground clearance or visible flat spots, carrier rollers can fail gradually without immediate operational symptoms. However, a failed carrier roller can cause catastrophic track derailment, particularly during high-speed travel or sharp turns, leading to extensive undercarriage damage and costly downtime.

For Komatsu PC300-6 and PC360-8 excavators operating in mining and heavy construction, selecting high-quality carrier rollers with proper heat treatment, robust sealing systems, and precision machining is essential. CQC TRACK’s carrier rollers incorporate advanced sealing technology—multi-layered seal systems combining radial seals, O-rings, and dust lips—providing a robust barrier against contamination and significantly extending service life and re-lubrication intervals.

9. Conclusion

For operators of Komatsu PC300-6 and PC360-8 excavators deployed in mining, quarrying, heavy construction, and infrastructure projects, the track carrier roller assembly represented by part numbers 2083000320, 20730K1200, and 81E520031 is a mission-critical component whose reliability directly affects track alignment, undercarriage component life, and machine uptime.

CQC TRACK distinguishes itself as a specialized manufacturer that combines over two decades of metallurgical expertise, vertical integration of forging and heat treatment processes, and a dual OEM/ODM service model to deliver undercarriage components that perform reliably under the most demanding conditions. With material options ranging from standard 50Mn alloy steel to premium 60Si2Mn and SAE 1055/1060 grades, heat treatment achieving HRC 50–58 surface hardness with 6–12 mm case depth, and advanced multi-labyrinth sealing systems, CQC TRACK provides fleet owners and procurement professionals with engineered solutions that meet or exceed OEM specifications.

By sourcing Komatsu carrier roller assemblies directly from the factory, mining and construction operations gain access to consistent quality, direct technical support, competitive pricing (30–40% savings versus OEM), and transparent supply chain logistics—factors that collectively optimize total cost of ownership and maximize machine uptime in the world’s toughest operating environments.

Author: Jack
Specializing in heavy equipment undercarriage systems, mining machinery reliability, and global sourcing strategies for construction equipment fleets.

Disclaimer: This publication is original content created for informational and technical reference purposes. All product numbers, brand names, and manufacturer references are used for identification and cross-reference only. Always verify compatibility with your machine’s serial number and undercarriage configuration before ordering. Installation procedures summarized from industry standards are provided for reference; consult the complete original equipment documentation before performing any maintenance. Warranty information is representative and subject to confirmation with the manufacturer at the time of purchase.