📋 Case Study

Case Study: Chronic Belt Tracking Failure on Case IH Axial-Flow 140 Combine Feederhouse Drive

Belt walking off pulley after 15–20 hrs despite repeated re-tensioning and alignment checks

🏗️ Project Overview

Western Canada grain farm, 2023 harvest

🎯 Challenge

Belt walking off pulley after 15–20 hrs despite repeated re-tensioning and alignment checks

🔧 Design Approach

Laser alignment + dynamic runout measurement identified 0.012″ shaft runout at input pulley bearing; root cause confirmed as worn tapered roller bearing preload loss

📐 Key Calculations

Tracking Deviation Rate

Lateral Movement / Operating Hours

Result: 0.042 in/hr

Correlated with bearing preload decay curve

Runout-Induced Belt Force

Tension × sin(Runout Angle)

Result: 89 lbf lateral force

Exceeded belt’s lateral stability threshold

📊 Results

Bearing replacement + preload torque verification extended tracking stability to full season (>320 hrs); reduced adjustment labor by 75%

💡 Lessons Learned

•Tracking issues are rarely belt-related — always verify shaft integrity first
•Dynamic runout > static alignment
•Preload degradation follows predictable logarithmic decay

✅ Key Takeaways

1Tracking issues are rarely belt-related — always verify shaft integrity first
2Dynamic runout > static alignment
3Preload degradation follows predictable logarithmic decay