KOMATSU Excavator PC800 / PC850 Undercarriage Track Roller Assembly (P/N: 209-30-00310, DF Type) – Professional Manufacturer and Supplier of Custom Heavy -Duty Crawler Undercarriage Parts for Mining Applications. Manufactured by CQCTRACK

On a 75-tonne to 85-tonne class mining excavator such as the KOMATSU PC800 or PC850, the track lower rollers—also called bottom rollers or track roller assemblies—form the primary structural and load-bearing interface between the machine’s superstructure and the pit floor. Each roller must support the full working weight of the excavator while rolling continuously over fragmented rock, abrasive ore, and uneven, debris-laden ground. For the KOMATSU PC800, PC800SE, PC850, and PC850SE series, the Track Roller Assembly with part number 209-30-00310 is the specified double-flange (DF) configuration, designed to maintain precise chain alignment and resist lateral displacement under heavy side loading. CQC Track, a professional manufacturer specializing in custom heavy-duty crawler undercarriage parts for mining applications, directly supplies a premium, OEM-caliber replacement Track Roller Assembly, precisely interchangeable with this KOMATSU genuine part number. Manufactured inside the same active OEM production facility that serves multiple global equipment brands and refined through two decades of continuous field feedback, this roller is purpose-built for the severe demands of open-pit mining and large-scale quarry operations. Authored by Jack, with dedicated international support from Philip and Haily, this technical overview explains why KOMATSU PC800 and PC850 fleet operators worldwide rely on CQC Track for custom, consistent, and application-engineered undercarriage solutions.

1. Manufacturer Strength: Specialized OEM Production for Custom Mining Undercarriage Applications

CQC Track is not a general aftermarket parts supplier; we are a focused, specialized manufacturer dedicated to the production of custom heavy-duty crawler undercarriage components for the most demanding applications, including mining, quarrying, and heavy earthmoving. Our production facility operates as a certified OEM manufacturing base for the global heavy equipment industry, currently supplying complete track assemblies, rollers, idlers, and sprockets to Hitachi, Kobelco, LiuGong, XCMG, and SDLG. We also serve as an OEM and ODM partner for KOMATSU-compatible undercarriage solutions. This embedded OEM production reality means the KOMATSU PC800/PC850 Track Roller Assembly (P/N: 209-30-00310) is manufactured on the identical forging presses, heat-treatment furnaces, and CNC machining centers that serve Japanese, Korean, and Chinese assembly lines. The material certifications, process controls, and final quality gating applied to this roller are exactly those mandated by the world’s most rigorous equipment manufacturers.

What distinguishes CQC Track as a custom manufacturer is our engineering flexibility. The KOMATSU PC800 and PC850 series encompasses multiple generations—PC800-6, PC800-7, PC800-8, PC850-8, and their SE and LC variants—each with specific track frame configurations and roller mounting interfaces. Our engineering team maintains comprehensive dimensional data for the full PC800/PC850 platform range, enabling us to produce rollers that achieve exact OEM fitment across all applicable machine serial numbers. Furthermore, we actively support application-specific customization: whether a mine requires modified flange geometry for high side-load conditions, alternative grease specifications for extreme climates, or reverse-engineered replacements for obsolete part numbers, CQC Track delivers a tailored solution built to the same disciplined manufacturing standard as our OEM production.

2. Technical Architecture: Forged, Heat-Treated, and Sealed for Custom Mining Duty

A track roller on a KOMATSU PC800 or PC850 must combine immense structural integrity with an impermeable sealing environment and an exceptionally wear-resistant tread. The CQC Track 209-30-00310 Track Roller Assembly is constructed through a deliberately sequenced, high-integrity manufacturing process where every step is designed for repeatability and dimensional precision.

• Forged Alloy Round Steel Wheel Body: The roller shell originates as a solid billet of high-grade alloy round steel. Through controlled hot forging, the internal grain flow is aligned circumferentially around the load-bearing axis. This forging process eliminates the internal porosity, voids, and microstructural inconsistencies inherent in cast alternatives, delivering a monolithic structure with exceptional and consistent resistance to rolling-contact fatigue, spalling, and impact cracking under the massive static and dynamic loads of 80-tonne class mining excavators. Industry-standard material selections for this application include high-strength alloys such as 40Mn2 or 50Mn, which are specifically chosen for their balance of core toughness and surface hardenability. The double-flange (DF) profile provides lateral guidance to the track chain, maintaining alignment and reducing side wear on both the chain links and the roller flanges.
• Spheroidal Graphite Cast Iron Side Covers (Ductile Iron, Ball-Milled Casting): The sealing side covers are manufactured through a precision spheroidal graphite (ductile iron) casting process. This material is deliberately selected for its excellent machinability, superior dimensional stability, and ability to provide a flawlessly smooth, hard mating surface for the sealing system, ensuring uniform seal compression and absolute leak-free integrity over the roller’s entire service life.
• Shaft with Dual Seal Grooves and Top-Tier Floating Oil Seal System: The stationary shaft is CNC-ground with a precision dual seal groove profile, forming an inner labyrinth that accommodates a top-tier duo-cone floating oil seal set. This face-to-face metal sealing technology is the global benchmark for the absolute exclusion of water, mud, fine silica dust, and abrasive mining slurry from the internal bearing cavity. The fully sealed cavity is factory-filled with a specially formulated low-temperature-resistant anti-freeze grease, guaranteeing immediate full-film lubrication at every startup and continuous corrosion protection from Arctic deep-freeze to tropical monsoonal humidity. Each track roller assembly for the PC800/PC850 platform requires approximately 420–480 cc of oil for proper internal lubrication, a specification we verify during assembly.
• Advanced Thermal Treatment Protocol:
  • Integral Quench and Temper: The entire forged wheel body first undergoes a rigorous through quenching and tempering cycle. This integral heat treatment uniformly refines the core microstructure into tempered martensite, providing an optimal combination of high tensile strength and essential toughness across every production batch.
  • Rough and Finish Machining: Following thermal refinement, the roller undergoes precision rough machining to near-net geometry, followed by CNC finish machining to achieve exact KOMATSU OEM dimensional tolerances for the PC800 and PC850 track frame platforms.
  • Induction Hardening (55–62 HRC): The roller tread and flange wear faces are selectively hardened through a controlled medium-frequency induction hardening process. This creates a deep, wear-resistant case with a surface hardness consistently maintained between 55 and 62 HRC, dramatically enhancing wear resistance in the harsh, high-abrasion environment of hard-rock mining. The hardened case significantly resists abrasive grooving and surface-initiated spalling from the continuous rolling contact with the heavily loaded track chain. The ductile, tempered core beneath the hardened layer continues to absorb severe dynamic impact without crack propagation. This comprehensive thermal engineering ensures maximum durability and resistance to deformation, even in the most severe mining applications. For reference, the assembled weight of the PC800/PC850 series single-flange track roller assembly is approximately 140 kg, and the roller mounting bolts (part number SEN01056-01) are torqued to 137.2 ± 98 Nm {140 ± 10 kgm} during installation.

3. Two Decades of Continuous Process Refinement, Validated in Global Extreme Mining

The CQC Track 209-30-00310 Track Roller Assembly is the direct product of a 20-year continuous engineering improvement cycle, driven entirely by failure mode analysis and wear data harvested from the planet’s most demanding extraction environments. Our track rollers have been systematically tested, analyzed, and incrementally refined through sustained operation in the deep-level gold and platinum mines of South Africa, the high-altitude copper and silver pits of Peru and Ecuador, the frozen iron ore basins of Russia, the abrasive hard-rock quarry and demolition sites of South Korea, the large-scale infrastructure and mining projects of India, and the tropical laterite and basalt operations of Vietnam. Every design parameter—from optimizing the tempering curve to eliminate residual stress concentrations, to precisely calibrating the induction hardening scan speed for a flawless hardness gradient, to validating the long-term pumpability of the anti-freeze grease across extreme temperature swings—has been engineered directly back into our production standard. The quality stability and operational reliability of today’s track roller are not catalog promises; they are field-verified attributes proven over millions of machine operating hours on every continent.

4. A Complete, Matched Undercarriage Component Ecosystem with Customization Support

A track roller does not function in isolation. Installing a premium-grade bottom roller alongside worn track chains, marginal carrier rollers, or a fatigued idler creates a costly mismatch in component life that rapidly accelerates system-wide undercarriage deterioration. As a specialist manufacturer of complete tracked chassis solutions, CQC Track eliminates this risk by producing a comprehensive, in-house suite of related undercarriage parts for the KOMATSU PC800 and PC850 series. Our production program includes matched track link assemblies with induction-hardened pins and bushings, carrier roller assemblies, front idler wheel assemblies, and final drive sprocket assemblies, all manufactured within a unified metallurgical and thermal processing envelope. This integrated approach ensures consistent wear rates and predictable life cycles across all undercarriage components. Furthermore, our engineering team actively supports non-standard customization for unique machine configurations, obsolete part replacements, or application-specific modifications—whether reverse-engineered from a customer sample or built to specific drawings. The CQC International business team—comprising Philip, Jack, and Haily—is structured to deliver these components as synchronized, kit-based shipments and to manage custom projects from initial technical evaluation through to final global dispatch.

5. Global Direct Supply to Quality-Conscious Mining Markets

CQC Track heavy-duty mining undercarriage components are directly supplied and exported with full confidence into markets that enforce the most stringent import quality and performance standards. Our KOMATSU PC800/PC850 track roller assemblies and complete undercarriage kits are actively supporting 80-tonne class excavator fleets across South America (Ecuador, Peru), Southern Africa, the Russian Federation, South Korea, and high-end application segments in India. Our international direct supply network further extends to the South Pacific island nations, Vietnam, Kazakhstan and the broader Central Asian corridor, Turkey, and North America. This sustained and widespread global acceptance—spanning equatorial heat, arid desert dust, and continental deep-freeze conditions—confirms that CQC Track’s heat-treatment repeatability, dimensional precision, anti-corrosion packaging, and customization responsiveness meet the universal requirements of the KOMATSU PC800 and PC850 mining excavator class worldwide.

When you specify a CQC Track Track Roller Assembly for your KOMATSU PC800 or PC850—using compatible part number 209-30-00310 and applicable to PC700, PC800, PC800SE, PC850, and PC850SE platforms—you are engaging a component forged within the same OEM ecosystem that supplies the globe’s leading equipment manufacturers. Direct from our factory to your mine site, this roller represents a 20-year engineering commitment to custom heavy-duty undercarriage manufacturing, delivering consistent quality and application-specific engineering to keep 80-tonne class mining excavators productive, shift after demanding shift.

This article was authored by Jack of the CQC International Business Team, with sincere appreciation to Philip and Haily for their dedicated support of our global KOMATSU mining excavator undercarriage customers.