Hitachi EX120-2 EX120LC-2 Excavator Swing Motor Assembly Slewing Motor 4241171 4334356 Complete Hydraulic Swing Device Replacement
Welcome to our heavy machinery hydraulic supply center. We specialize in providing the complete EX120-2 / EX120LC-2 excavator swing motor assembly (Part No. 4241171 / 4334356), precision-manufactured as a heavy-duty aftermarket replacement part compatible with Hitachi large engineering machinery equipment. Engineered to restore original slewing torque and turning speed, this complete swing device ensures high efficiency and durability on demanding jobsites.
Key Technical Specifications & Parameters
- Product Name: Swing Motor Assembly / Slewing Motor Device / Swing Reduction Gearbox
- Applicable Machine Models: Fit for Hitachi EX120-2, EX120LC-2, EX120-2m Excavators
- Reference Part Number / OEM: 4241171 / 4334356 / 4330219
- Key Internal Components: Swashplate axial piston motor, integrated swing relief valve, precision planetary reduction gears
- Condition: 100% Brand New Aftermarket / Direct OEM Fit Replacement
- Quality Assurance & Warranty: 100% Factory Hydraulic Pressure Tested, 6–12 months warranty included
EX120-2 Excavator Swing Motor Common Faults & Solutions
If your 12-ton excavator is experiencing rotation power loss, replacing your worn unit with our complete EX120-2 swing motor assembly directly resolves these critical operational issues:
1. Weak Swing Torque / Slow Rotation (回转无力)
Cause: Severe wear on cylinder block/pistons or pressure loss across relief valve seats.
Fix: Replacing the complete assembly restores original working hydraulic pressure and fast 360-degree rotation speed.
2. Abnormal Noise & Heavy Vibration (抖动异响)
Cause: Chipped planetary gear teeth, damaged pinion gear splines, or worn bearings.
Fix: Full assembly replacement eliminates gear grinding and chatter, protecting your excavator’s main slewing ring gear.
3. Hydraulic Oil Leakage from Shaft Seal (回转漏油)
Cause: Aged or blown main shaft oil seals due to high pressure spikes.
Fix: Japanese high-pressure oil seals are built-in to prevent oil contamination and maintain fluid system integrity.
4. Swing Sticking / Jerky Rotation (回转卡顿)
Cause: Contaminated hydraulic oil or sticking swing brake valve spools.
Fix: Precision-machined spool clearances ensure smooth start/stop slewing response without sudden braking shocks.
5. Overheating Swing Gearbox (回转高温)
Cause: Friction buildup caused by damaged internal bearings or bad gear oil circulation.
Fix: Optimized lubrication channels and hardened alloy gears keep operational temperatures low under continuous work.
Worksite Applications & Operating Scenarios
Engineered for versatile medium-class excavation tasks, this swing motor assembly suitable for Hitachi EX120-2 excels in:
- General Construction & Earthmoving: Delivers continuous, reliable turning torque for excavating and loading trucks.
- Trenching & Pipeline Installation: Smooth brake valve control allows exact placement of heavy pipes and shoring.
- Demolition & Site Clearance: Durable casing resists radial forces and vibration under hydraulic breaker operation.
Frequently Asked Questions (FAQ)
Q: Where can I buy a replacement swing motor assembly compatible with Hitachi EX120-2?
A: You can purchase brand-new aftermarket EX120-2 swing motor assemblies directly from us. We stock fully assembled, ready-to-install units designed to original factory specifications.
Q: What is the OEM part number for the Hitachi EX120-2 swing motor?
A: Common OEM reference numbers for the EX120-2 swing device include 4241171, 4334356, and 4330219. Please verify your old motor nameplate or contact us for confirmation.
Q: Is this EX120-2 swing motor a direct bolt-on replacement?
A: Yes, it features exact original mounting bolt hole dimensions, spline teeth, and hose threads for direct drop-in replacement without modifications.
