320C Swing Gearbox 2nd Planetary Carrier Spider With Sun Gear Assy For Excavator Parts

320C Swing Gearbox 2nd Planetary Carrier Spider With Sun Gear Assy For Excavator Parts

Product Overview

This complete second‑stage planetary carrier spider and sun gear assembly serves as the secondary reduction core component fitted inside the swing reducer of 320C classic 20‑ton crawler excavator. It receives torque transferred from the first‑stage planetary assembly, executes secondary speed reduction and torque amplification, and delivers powerful output to drive upper house rotation. The 320C is one of the most widely recognized medium excavator models worldwide, extensively deployed in earthmoving, quarry loading, highway construction, site grading and general demolition projects. Under long‑duration cyclic forward‑reverse slewing impact loads, ageing oil seals and degraded gear lubricant allow metal wear particles and construction dust to invade the gearbox cavity, triggering spline galling, gear tooth pitting, carrier spider deformation and pin‑hole ovalization. Typical failure symptoms include harsh metallic grinding noise within swing gearbox, jerky and discontinuous cab rotation, insufficient swing torque, abnormal high temperature on reducer housing, and metallic sediment found during swing gear oil change. Manufactured strictly following original forging drawings and gear meshing standards, this aftermarket assembly supports direct drop‑in replacement and effectively prevents cascading damage to other expensive internal gearbox components.

Technical Specification

Core Advantages

1. Forged alloy construction built for 20‑ton excavator sustained swing impact load Carrier spider and matching sun gear are hot forged from premium alloy steel blanks. After carburizing quenching heat treatment, gear tooth surfaces and internal splines obtain high surface hardness while retaining reliable core toughness. The assembly can withstand frequent instant impact torque generated during swing start‑stop and compound digging‑slew actions on quarry and earthmoving sites, lowering risks of tooth chipping, spline abrasion and carrier spider distortion.
2. Pre‑inspected gear meshing tolerance ensures smooth and stable slewing performance Every finished assembly passes tooth profile inspection and backlash measurement before shipment. Tightly controlled meshing clearance minimizes transmission vibration and frictional grinding noise. When the 320C performs coordinated boom‑arm‑bucket plus swing compound movements, it maintains steady secondary power transfer and avoids cabin stutter or jerky rotation caused by poor gear fitting accuracy.
3. OEM‑matched mounting dimensions shorten on‑site repair downtime Critical dimensions including carrier outer contour, sun‑gear spline specification, pin‑shaft hole layout and depth fully comply with original specifications. Field service technicians can finish component replacement directly without modifying gearbox housing or adjusting internal fitting gaps. For equipment rental fleets and local repair workshops supporting the large installed base of 320C machines, it reduces machine stand‑still hours and economic loss from project suspension.
4. Stress‑relief annealing eliminates residual stress from hot forging Stress‑relief annealing removes internal residual stress generated in hot‑forging procedures, improving long‑term structural stability under repeated 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. Cost‑effective partial overhaul solution for legacy fleets Instead of purchasing a whole expensive swing reducer unit, individually replacing the worn second‑stage planetary carrier and sun‑gear assembly helps customers control maintenance costs. It is highly suitable for machinery repair shops, equipment operators and global spare‑parts wholesalers serving the widespread 320C installed base.

Manufacturing & Quality Control

Our production workshop specializes in planetary transmission spare parts for medium 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 enter the 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 and stable batch supply; small trial orders are acceptable for worldwide purchasers.

Frequently Asked Questions

Q1: What abnormal phenomena indicate inspection or replacement of 2nd planetary carrier and sun‑gear assembly? A: If your 320C excavator produces loud grinding noise inside swing gearbox, cabin rotates jerkily and intermittently, 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 the 320C swing gearbox. Though some models look similar externally, internal gearbox configurations may differ. Please double‑verify relevant OEM part numbers 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 before installation. Meanwhile inspect wear condition of planetary gears, bearings and oil seals. After assembly completion, refill qualified swing gear oil, carry out 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 flaws and manufacturing errors. Damage resulting from foreign‑object intrusion, insufficient gear‑oil lubrication, severe overload impact and improper disassembly‑installation will not be covered under warranty. Please strictly comply with official service manual for swing gearbox overhaul procedures.