Komatsu PC120-6 Swing Gearbox 1St Planetary Carrier Spider With Sun Gear Assy

Komatsu PC120‑6 Swing Gearbox 1St Planetary Carrier Spider With Sun Gear Assy For 203‑26‑61120 203‑26‑61150 203‑26‑61160

Product Overview

This complete first‑stage planetary carrier spider and sun gear assembly serves as the core primary reduction component fitted inside the swing reducer of Komatsu PC120‑6 12‑ton midi excavator. It receives torque input directly from the swing motor output shaft, executes initial speed reduction and torque amplification, and transfers driving power to the secondary planetary group to drive upper house rotation. This machine is widely deployed for municipal engineering, pipeline excavation, residential lot earth‑moving, road repair and small‑scale quarry operations. Under frequent forward‑reverse slewing impact loads, aging seals or degraded gear lubricant allow metal fines and construction dust to invade the gearbox cavity, triggering spline wear, gear tooth pitting, carrier spider deformation and pin‑hole ovalization. Typical failure symptoms include harsh metallic grinding noise within swing gearbox, jerky and discontinuous cabin rotation, insufficient swing torque, abnormal high temperature on reducer housing, and metallic sediment observed during swing gear oil change. Manufactured strictly following original forging drawings and gear engagement parameters, this aftermarket assembly supports direct drop‑in replacement, effectively prevents cascading damage to other costly internal gearbox components.

Technical Specification

Core Advantages

1. Forged alloy construction adapted for midi‑excavator frequent swing impact load Carrier spider and sun gear are forged from premium alloy steel blanks. After carburizing quenching treatment, gear teeth and internal splines obtain high surface hardness while retaining good core toughness. The component can withstand frequent instant impact torque generated during swing start‑stop and compound digging‑slew actions, lowering risks of tooth chipping, spline abrasion and carrier distortion under dusty site working conditions.
2. Pre‑inspected gear meshing tolerance delivers smooth slewing performance Every finished assembly goes through tooth profile inspection and backlash measurement before shipment. Tightly controlled meshing clearance minimizes transmission vibration and frictional grinding noise. When the excavator performs coordinated boom‑arm‑bucket plus swing operations, it maintains stable power transfer and avoids cabin stutter or jerky rotation caused by poor gear fitting accuracy.
3. Original replicated mounting structure cuts overhaul downtime for midi‑size machines Critical dimensions including carrier outer contour, sun‑gear spline specification, pin‑shaft hole layout and depth fully match OEM specifications. Field maintenance technicians can finish component swap directly without modifying gearbox housing or adjusting internal fitting gaps. For equipment rental fleets and local repair workshops, it shortens machine stand‑still hours and reduces economic loss caused by project suspension from swing system breakdown.
4. Stress‑relief annealing eliminates forging residual stress Stress‑relief annealing removes internal residual stress generated during hot forging, improving long‑term structural stability under cyclic shock loads. Combined with high‑precision machining for pin shaft holes and bearing seats, it slows premature wear of mating planetary gears and bearings, extending the overall service life of the complete swing reduction unit.
5. Budget‑friendly partial overhaul alternative for midi excavator fleets Instead of purchasing a full‑set expensive swing reducer unit, individually replacing the worn first‑stage planetary carrier and sun‑gear assembly helps customers control overhaul expenditure. It is highly suitable for machinery repair shops, construction equipment operators and global Komatsu midi‑excavator spare‑parts wholesalers.

Manufacturing & Quality Control

Our production workshop specializes in planetary transmission spare parts for Komatsu 10‑14 ton class excavator swing gearboxes. Full‑process quality supervision covers raw‑material composition verification, forging appearance inspection, heat‑treatment hardness testing, gear‑tooth precision detection, spline dimension validation and sample no‑load running‑in test. Only fully inspected‑qualified products move to packaging workflow. Finished assemblies are coated with anti‑rust preservation oil, wrapped with shock‑absorbing cushion materials and packed in export‑compliant fumigated wooden cases to prevent collision deformation and rust corrosion in long‑distance sea‑land logistics. We support bulk wholesale, stable batch supply, small trial orders are acceptable for worldwide purchasers.

Frequently Asked Questions

Q1: What abnormal phenomena indicate inspection or replacement of 1st planetary carrier and sun‑gear assembly? A: If your Komatsu PC120‑6 excavator produces loud grinding noise inside swing gearbox, cabin rotates jerkily, swing power drops obviously, reducer housing overheats, or metal particles are found in swing gear oil during oil‑drain maintenance, you should disassemble swing reducer for internal inspection promptly.

Q2: Will this assembly fit other excavator models? A: This component is engineered for Komatsu PC120‑6 swing gearbox. Though PC100‑6 and partial PC130‑7 look similar in appearance, internal gearbox configurations may differ. Please double‑verify OEM part numbers 203‑26‑61120, 203‑26‑61150, 203‑26‑61160 before placing order to avoid installation mismatch.

Q3: What essential installation notes during gearbox overhaul? A: Completely clear all metal debris and old gear‑oil residue inside swing gearbox housing prior to installation. Meanwhile inspect wear condition of planetary gears, bearings and oil seals. After assembly completion, refill qualified swing gear oil, execute low‑speed no‑load swing running‑in test before putting machine into formal construction work.

Q4: Warranty scope explanation A: Our warranty covers defects caused by raw‑material and manufacturing flaws. Damage resulting from foreign‑object intrusion, insufficient gear‑oil lubrication, severe overload impact and improper disassembly‑installation will not be included under warranty coverage. Please strictly comply with Komatsu official service manual for swing gearbox overhaul procedures.