Materials Behavior & Characterizatio: Case study- Effect of Axle Oil characteristics on High Cycle Fatigue Bench Test of Crown Wheel Pinion Gear set

The primary function of Axle Oil is to provide the proper lubrication by maintaining the thin oil film at the teeth interface which reduces the friction between the Crown wheels Pinion Teeth & extract the heat generated during rubbing action. In this particular case- 3 numbers of Heavy Truck drive Rear axles having hypoid gear ratio 6.17R are validated for High Cycle Gear set Fatigue Bench test at 30000Nm Torque. The Axle Oil SAE 85W140 is considered for this study & oil confirms to SAE J2360 specification. The oil samples before & after bench test is collected & analyzed for oil characteristics Viscosity, Wear Elements, Additive Elements. The gear set fractured at 80000 Ring Gear cycles & test suspended. The fractured gear teeth examined shows No imperfection like scoring, wear, friction marks that evident Oil is not the cause for the fracture. The Oil analysis comparison before & after shows, Increase in Oil Viscosity 4 to 6% indicates oil has become thicker than the original. Decrease in Additive elements 9 to 11% , Increase in Wear elements 89% Observed. This deterioration in Axle oil Quality captured when Gear set achieves life 80000 Ring Gear Cycles. The axles are confirmed the cleanliness specification before the bench test. The Oil deterioration is marginal because the oil film did not rupture as evident by the fracture mode & tooth surface. Typically the oil quality from the field samples are seen much poorer than this bench test study. This case study helps us to understand when the Ger set Fatigue bench validation carried out for a Particular gear ratio , at particular torque & Gear set Fatigue life meets 80000 RG Cycles, then the Quality of axle oil deteriorates to some extent particularly the viscosity, Additive elements & the wear elements.