Methodology to Derive RLD Based Durability Test Schedule for Gearbox Oil Seals 2021-26-0461

Oil seal leakage is one of the major failure mode in gearbox / transaxle. Oil seal failures can be due to various reasons like high temperature, insufficient lubrication, failure due to external environment, incorrect fitment etc. Major reason for oil seal failure is insufficient oil flow inside gearbox when vehicle is running on gradient for long duration. When vehicle is running in hilly region, transmission will get incline leading to oil deficiency at one half of the transmission. Oil seal in this location will not get sufficient lubrication and will run dry. Also, there will be rise in local temperature at seal lip to shaft interface leading to failure of oil seal lip. Subsequently, oil leakage from transmission will start from this location when vehicle is running in different terrain. Due to continuous seepage, oil quantity in the transmission will get reduced and may lead to gear failure or seizure of bearing.

Some OEM use transmission with transparent housing for lubrication study to get vital information on sufficiency of lubrication at critical parts at different inclinations of transmission (simulating driving of vehicle in different terrain). Such study does not provide clear idea about endurance life of oil seals and other parts under certain extreme / critical driving conditions.

This paper discusses the test schedule & methodology developed to simulate oil flow inside gearbox as per real world driving scenarios on test bench and to evaluate endurance life of oil seal under such conditions. To develop the test procedure rigorous road load data need to be done at vehicle level. During this vehicle need to be driven in various road mix conditions like mines, rough road, hilly terrain in forward and reverse gear for few hundred kilometers and vehicle level and powertrain level data is recorded with help of commercially available sensors and data loggers. Test procedure need to be derived after data analysis to have test schedule for simulating real world condition on test bench. Process briefed in this paper will help to reduce development time & cost.