SAE TECHNICAL PAPER SERIES Study on the Change of Friction Characteristics with Use in the Wet Clutch of Automatic Transmission Kohei Matsuo and Shin Saeki Japan Energy Corp. Reprinted from: Lubricants for Passenger Car and Heavy Duty Diesel Engines (SP-1304) OCT t.9 5 OYYl The Engineering Society *A =For Advancing Mobility -iand sea ~ir and space. INTERNATIONAL International Fall Fuels & Lubricants Meeting & Exposition Tulsa, Oklahoma October 13-16.1997 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (412)776-4841 Fax:(412)776-5760 Downloaded from SAE International by University of Leeds, Monday, September 24, 2018., - MA01923foroo~ingbeyondthat~edby~l070r1080fthe~.~.'~opy1ight Law. Th*;mnsent~note~endtodherkindsofcopyingsuchaswpyingforgeneral ~n,fwadve~ngorpromoBonalpuforwo,or for resale. SAE routinely stocks printed papers for a period of three years following date ofpublication. Directyourordersto SAE CusbmerSalesandSalisfaction Depament A// SAEpapes, standards. andseleded tmAsare~andhMm~SAE G!QM~~. P~and~~m~6paperaremoSeofh~s)andnot~ thoseof SAE The~rissolehrreswmibleforWcontentoftheDawr. AD~~SS~S available by which chscussiw hil de tinted with the woer if it dublist& in SAE TransactM . . &. For permission to publihmii paper in kllbr in pa& contact the SAE -om. P~~to&mRpapeffiWbe~cedforp~n~prM'~m~ SAEshwldsendthe manuscript ora300wordabstractof a~mwsedmanuscriptto: Downloaded from SAE International by University of Leeds, Monday, September 24, 2018Study on the Change of Friction Characteristics with Use in the Wet Clutch of Automatic Transmission Kohei Matsuo and Shin Saeki Japan Energy Corp. Copyright 1997 Society of Automotive Engineers, Inc. ABSTRACT The friction characteristics of wet clutches in an automatic transmission (AT) change with use, due to both deterioration of the clutch friction plates and automatic transmission fluid (ATF). In this study, we have tried to separate the change of the friction characteristics of wet clutches with use into two components: one, the deterioration of the clutch friction plates, and two, the deterioration of ATF. We used an SAE No. 2 clutch friction test machine and an engine stand to evaluate the contribution of each component to the overall change in the friction characteristics of two ATFs. INTRODUCTION The friction characteristics of wet clutches in an automatic transmission (AT) change with use. Normally these systems exhibit decreased dynamic friction coefficient( p d) and increased static-dynamic ratio(@ O/@ d)') with increasing mileage. The effects of deteriorated wet clutch friction plates and automatic transmission fluids (ATF), respectively, on the friction characteristics of the wet clutch have been reportedz4). For clutch friction plates, carbonization of paper friction materials2) and plugged pores3' cause the decrease in dynamic friction. For the ATF, on the other hand, decreased viscosity, increased total acid number, and decreased total base number have been reported'). As for the effects on the friction characteristics, there is a repoe) which estimated increases in /L 01 fi d due to thermal and oxidative deterioration and friction modifier(FM) consumption. Much remains unclear however. There has been no investigation that has attempted to divide the change of friction characteristics of wet clutches with use into the effects of the deterioration of the clutch friction plates and that of ATF. In order to improve the friction durability characteristics of wet clutches, these two effects need to be investigated . separately. In this study, we used an SAE No. 2 clutch friction test machine and an engine test stand to evaluate the difference in the two components of wet clutch friction characteristics using two ATFs. CHANGE OF FRICTION CHARACTERISTICS OF WET CLUTCHES WITH USE CONCEPT - According to references 1-4, the change of friction coefficient with use is as fol