Excavators naturally produce substantial mechanical noise during operation. However, when a fault occurs, it may also cause abnormal sounds—which can be easily confused with regular machine noise by inexperienced operators. This often complicates fault detection and delay necessary repairs.
Recently, the owner of a Kobelco excavator encountered such an issue. During operation, he clearly heard excessive noise from the gear pump, accompanied by noticeable vibrations in the cab. Let’s take a closer look at the full diagnostic and repair process.
Fault Analysis
Since gear pump noise and vibration can stem from various causes, the technician conducted a step-by-step inspection, starting from the most common and easily resolved possibilities:
1. Contaminated Hydraulic OilThe most frequent cause of abnormal noise is foreign particles or impurities in the hydraulic oil, which can scratch or damage the gear’s precision surfaces.
Solution: Replace the hydraulic oil and filters, and thoroughly clean the internal components. If damage is severe, replacing the gear pump is often more cost-effective than repairing it.
2. Internal Component DamageDefective gear tooth profiles, poor contact surfaces, or rough machining can cause abnormal mechanical wear and lead to vibration and unusual sounds during operation.
Similarly, issues like damaged bearing cages, worn shafts, or needle bearings can impede smooth rotation and generate mechanical noise.
Solution: Disassemble the gear pump to inspect and replace damaged needle bearings or other worn parts.
3. Assembly Issues & Improper TolerancesIf assembly clearances are too tight, or burrs are left unpolished before installation, gear teeth can get scratched during high-speed operation, leading to internal leakage and gear scoring.
Solution: Skilled technicians can disassemble the pump, grind and polish the components, and remove burrs without beveling the gear teeth. When regrinding the end cover, adjustments must be made to compensate for changes in the relief groove depth.
Takeaway for Excavator Owners
This case serves as a reminder to all operators: Excavator health is 30% repair and 70% maintenance—but 100% attention to detail.
Unusual sounds may blend in with normal machine noise, but they should never be ignored. Early detection and prompt action can prevent costly breakdowns and minimize downtime, helping you stay on schedule and protect your investment.
