ToolFusion
📋 Case Study

Case Study: New Holland TW Series Tractor PTO Gearbox Overheating & Viscosity Breakdown

PTO gearbox oil temperature exceeded 120°C; viscosity dropped from ISO VG 80 to VG 32; bearing spalling observed

🏗️ Project Overview

Large-scale dairy farm in Wisconsin, 24/7 manure spreader duty cycle

🎯 Challenge

PTO gearbox oil temperature exceeded 120°C; viscosity dropped from ISO VG 80 to VG 32; bearing spalling observed

🔧 Design Approach

Applied Thermal Degradation Limits Framework; substituted SAE 80W-90 GL-5 with NH FLD-1 (ISO VG 46, synthetic PAO, TBN 8.5, RPVOT >500 min)

📐 Design Diagram

PTO Gearbox\nOverheating\n>120°CNH FLD-1\nISO VG 46\nRPVOT >500 minViscosity Loss\n60% (VG 80→VG 32)RPVOT Margin\n+215 minChallengeSolution Metric

AI-generated project design illustration

📐 Key Calculations

Viscosity Loss %

(Initial KV@100°C – Current KV@100°C) / Initial KV@100°C × 100
Result: 60%
Confirms severe thermal shearing

RPVOT Margin

RPVOT test result – OEM minimum requirement
Result: 215 min
Margin above NH minimum of 285 min ensures longevity under thermal stress

📊 Results

Peak oil temp stabilized at 92°C; PTO gearbox MTBF increased from 1,100 to 3,800 hrs; eliminated 32 annual service interventions

💡 Lessons Learned

  • •SAE multigrade gear oils lack thermal stability for continuous-load PTO applications
  • •RPVOT >450 min is non-negotiable for >10,000 annual PTO hours
  • •TBN monitoring is essential—FLD-1 requires <25% TBN depletion before change

✅ Key Takeaways

  • 1SAE multigrade gear oils lack thermal stability for continuous-load PTO applications
  • 2RPVOT >450 min is non-negotiable for >10,000 annual PTO hours
  • 3TBN monitoring is essential—FLD-1 requires <25% TBN depletion before change