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This paper takes a review of fretting phenomenon on splines of the engaging gears and corresponding splines on shaft of automotive transmission and how it leads to failure of other components in the gearbox. Fretting is a special wear process which occurs at the contact area of two mating metal surfaces when subject to minute relative oscillating motion under vibration. In automotive gearbox, which is subjected to torsional vibrations of the powertrain, the splines of engaging gears and corresponding shaft may experience fretting, especially when the subject gear pair is not engaged. The wear debris formed under fretting process when oxidizes becomes very hard and more abrasive than base metal. These oxidized wear particles when comes in mesh contact with nearby components like bearings, gears etc. may damage these parts during operation and eventually lead to failure.

Single plate dry clutch is one of the most abuse components in the vehicle. With the growing population of traffic in cities, useful life of clutch is affected drastically which is evident from the rise in complaints on clutch from metropolitan cities. The governing design parameter, which affects the life of clutch, is the energy dissipated in clutch per unit area of friction lining of clutch disc. The life of clutch is affected by many factors like vehicle weight, engine torque, driveline ratios, friction lining, size of clutch, which are taken into consideration during design stage of the clutch. Apart from these factors, one more factor, engine calibration, affects the clutch life drastically. However, it is not taken into consideration during design stage owing to its inherent nature as it gets matured over the vehicle development program.

Clutch engagement judder is a phenomenon wherein the driver experiences vibrations on seat during the clutch engagement process for the vehicle launch. Clutch engagement judder is one of the critical vehicle attributes as a part of overall vehicle NHV. Torsional oscillations, specifically originating from clutch in the driveline during clutch engagement, are referred as clutch engagement judder. Judder is a phenomenon wherein friction induced torsional vibrations are generated in the driveline because of sliding contact between clutch and flywheel, during engagement. These resulting oscillations inherit the first resonance frequency of the driveline. The engagement judder not only affects the dynamics of transmission system but also the vehicle, because of excitations being transferred to body via suspensions and mounts. Passengers experience these oscillations as vibrations during vehicle launch. If excitation level is high then it may cause discomfort to passengers.

Drive components of live axle undergoes different loading conditions during field usage depending upon terrain conditions, vehicle loading and traffic conditions etc. During vehicle running, drive components of axle experiences variable torque levels, which results in the fatigue damage of the components. Testing of these drive components of axle on test rig for endurance life is an imperative part of axle development, owing to limitations of vehicle testing because of time and cost involved. Similarly, correlating field failures with rig testing is equally critical. In such situation, if a test cycle is derived correlating the field usage, rig testing can be effectively used for accelerated life testing and reliability prediction of these components. An approach is presented in the paper wherein test cycle is derived based on the data collected on vehicle in the field under service road and loading conditions.

During every clutch engagement energy is dissipated in clutch assembly because of relative slippage of clutch disc w.r.t. flywheel and pressure plate. Energy dissipated in clutch is governed by many design parameters like driveline configuration of the vehicle vis-a-vis vehicle mass, and operational parameters like road conditions, traffic conditions. Clutch burning failure, which is the major failure mode of clutch assembly, is governed by energy dissipation phenomenon during clutch engagement. Clutch undergoes different duty cycles during usage in city traffic, highways or hilly regions during its lifetime. A test schedule was derived using energy dissipated during every clutch engagement event as a base and using road load data collected on the vehicle. Road load data was collected in different road mix conditions comprised of city traffic, highway, hilly region, rough road for few hundred kilometers.

During every clutch engagement energy is dissipated in clutch assembly because of relative slippage of clutch disc w.r.t. flywheel and pressure plate. Energy dissipated in clutch is governed by many design parameters like driveline configuration of the vehicle vis-a-vis vehicle mass, and operational parameters like road conditions, traffic conditions. Clutch burning failure, which is the major failure mode of clutch assembly, is governed by energy dissipation phenomenon during clutch engagement. Clutch undergoes different duty cycles during usage in city traffic, highways or hilly regions during its lifetime. A test schedule was derived using energy dissipated during every clutch engagement event as a base and using road load data collected on the vehicle. Road load data was collected in different road mix conditions comprised of city traffic, highway, hilly region, rough road for few hundred kilometers.

Interdependency of automotive transmission aggregates on electrical/ electronics systems is increasing day by day, offering more comfort and features. For a system integrator, it becomes very much important while selecting/designing any such component to take into consideration the relationship between such interdependent components from performance as well as endurance point of view. DMF failures due to inadequate starting system, is a major stumbling block in development of DMF for a particular vehicle application. The interface of DMF and starting system of a vehicle makes it essential to consider the effect of one on another. The study shows that the majority of DMF failures happen because of resonance phenomenon in the DMF during engine starting. The improper selection of starter motor makes the DMF more vulnerable for such failures.