21N-27-00140 / 21N-27-00130 Final Drive Assembly for Komatsu PC1250LC-8

The 21N-27-00140 and 21N-27-00130 Final Drive Units are heavy-duty planetary reduction assemblies engineered for the Komatsu PC1250LC-8 hydraulic excavator, operating in the 120-130 ton machine class. Each unit integrates a high-displacement axial piston hydraulic motor with a reinforced multi-stage planetary gear train housed in a thick-wall ductile iron casing, delivering exceptional swing and track drive torque for demanding excavation, mining, and heavy construction applications in large-scale earthmoving operations.

Komatsu PC1250LC-8 excavators are deployed across diverse global worksites, and our final drives are specifically optimized for regional conditions:

• North America Oil Sands & Heavy Clay Operations: Features deep-case carburized planetary gears and induction-hardened bearing races to resist abrasive wear from silica-laden overburden and sticky clay formations
• Australia & Indonesia Coal and Mineral Mining: Equipped with upgraded tungsten carbide floating seal faces and heavy-duty dust wiper rings to prevent fine mineral dust ingress during extended high-cycle loading operations
• Chile & Peru High-Altitude Copper Mines: Incorporates cold-weather seal compounds and modified breather valve assemblies to withstand pressure differentials and thermal stress at elevations exceeding 4,000 meters

• Enhanced Gear Train Durability: Precision-ground helical planetary gears with optimized tooth profile modifications distribute torque loads evenly across multiple contact points, minimizing noise, vibration, and localized stress concentrations under peak digging forces
• True Direct Fit Replacement: All mounting bolt patterns, pilot register diameters, dowel pin positions, and hydraulic port thread configurations exactly match original Komatsu specifications for seamless bolt-on installation requiring zero modifications
• Superior Structural Rigidity: Heavy-wall ductile iron housing with integrated reinforcing webs resists housing deflection and maintains gear alignment integrity under severe side-load conditions during trenching and benching operations
• Advanced Contamination Protection: Dual-cone floating seals with secondary dust lip barriers provide superior protection against abrasive silica, clay slurry, and moisture ingress in the harshest undercarriage environments

• Case Drain Line Verification: Confirm the motor case drain line is routed independently to the hydraulic tank with minimal back pressure. Elevated case pressure above 15 psi will accelerate rotary seal wear and potentially cause internal leakage. Perform quarterly oil sampling to monitor wear particle concentration trends.
• Gear Oil Change Protocol: Replace planetary gear oil every 250 hours for initial break-in, followed by 500-hour intervals thereafter. Use extreme pressure gear oil SAE 80W-140 meeting Komatsu specifications. Inspect drained oil for copper content indicating bushing wear and ferrous debris indicating gear or bearing distress.
• Track Frame Mounting Bolt Care: Always install new mounting bolts with manufacturer-approved thread locking compound upon reassembly. Clean bolt threads and blind holes thoroughly with compressed air and solvent. Torque in three progressive stages using a cross pattern to final specification of 1,500 ± 100 N*m.
• Pre-Start Motor Priming Procedure: Before first operation after installation or extended downtime, fill the motor housing completely with filtered hydraulic oil through the uppermost port until oil steadily flows from the case drain opening. Slowly rotate the final drive at low engine RPM for several minutes to purge trapped air pockets, preventing cavitation damage and ensuring immediate bearing and piston lubrication at startup.

Guangzhou Tieqi Construction Machinery Co., Ltd. (IRON CAVALRY) is strategically located in Guangzhou's Huangpu District. With nearly 15 years of experience, we specialize in engineering machinery hydraulics and are committed to delivering practical solutions and upholding our responsibilities.

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Our efficient execution and rigorous manufacturing approach ensure our products meet over 95% of original performance specifications. This commitment has built widespread trust in the industry.

We maintain a ready inventory of over 500 assembly types, providing access to more than 6,000 different parts. Hydraulic pump, control valve, travel, and swing assemblies are our core products, with particular expertise in large mining excavator components and hard-to-find items.

For large items, we use sturdy plywood crates secured with metal fasteners. Products are cushioned with bubble wrap and secured with wooden braces, with special attention given to protecting vulnerable parts. External reinforcement includes high-strength PET plastic strapping and waterproof wrapping.

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