780097 ToyotaFour-Speed Automatic Transmission withOverdrive AkioNumazawa, SeitokuKubo, andYoshioShindo ToyotaMotorCo.,Ltd.(Japan) ShuzoMoroto AisinWarner,Ltd.(Japan) CongressandExposition CoboHall,Detroit February27-March 3,1978 Downloaded from SAE International by University of British Columbia, Sunday, September 23, 2018Theappearance ofthecodeatthebottomofthefirstpageofthispaperindicatesSAE's consentthatcopiesofthepapermaybemadeforpersonalorinternaluse,orfortheper sonalorinternaluseofspecificclients.Thisconsent isgivenonthecondition, however, thatthecopierpaythestatedperarticlecopyfeethroughtheCopyright Clearance Cen ter,Inc.,OneParkAvenue,NewYork,NewYork10016,forcopyingbeyondthatpermit tedbySections107or108oftheU.S.Copyright Law.Thisconsentdoesnotextendto otherkindsofcopyingsuchascopyingforgeneraldistribution, foradvertising orpromo tionalpurposes, forcreatingnewcollective works,orforresale. Paperspublished priorto1978mayalsobecopiedataperpaperfeeof$2.50underthe abovestatedconditions. SAEroutinely stocksprintedpapersforaperiodofthreeyearsfollowing dateofpub lication.DirectyourorderstoSAEOrderDepartment. Toobtainquantityreprintrates,permission toreprintatechnicalpaperorpermission tousecopyrighted SAEpublications inotherworks,contacttheSAEPublications Division. ISSN0148-7191 Copyright ©1978SocietyofAutomotive Engineers, Inc. Downloaded from SAE International by University of British Columbia, Sunday, September 23, 2018780097 ToyotaFour-Speed Automatic Transmission withOverdrive AkioNumazawa, SeitokuKubo, andYoshioShindo ToyotaMotorCo.,Ltd.(Japan) ShuzoMoroto AisinWarner,Ltd.(Japan) THISPAPERDESCRIBES anewfour-speedautomatic transmission withoverdrive (A40Dmodeltransmission), which Toyota MotorCo.,Ltd.hasdesigned, developed andputintoproduction in cooperation withAisinWarnerLtd.forimproving fueleconomy andsimul taneously reducing enginenoise(Fig.l).Inordertoachieve thebest fueleconomy andahighleveloftrans missiondurability, lotsofconsiderationanddetermination weremadein theprocess ofthetransmission devel opment. First,geartrainarrangement wascarefully investigated andevaluatedfromvarious kindsofaspects toturn outalightweight, compact, efficient,durable, andinexpensive transmission (Fig.2). Specialattention wasdevotedtotheconstruction andlubrication of theoverdrive unitsothatitmight standsevereusage. Next,computer simulations wereusedtoprovide designdirectionforoptimum overdrive gearratioandshiftpointsbetweenthirdandover drivegearsconsidering fueleconomy, exhaust emissions, andvehicleperfor manceandalsosmoothshiftfeelcon -ABSTRACT Anewfour-speed automatictransmission withoverdrive hasbeen developed andputintoproduction for thepurpose oftheimprovement offuel economy andthereduction ofenginenoise. Thetransmission hasthe following characteristics: Geartrainarrangement havingoverdrive unitbetweenthetorqueconverter andthethree-speedauxiliary transmission Highoverdrive gearratioShiftfeelcontrols forclutch to-clutch shiftingOptimumshiftpointsbetweenthirdandoverdrive gearson fueleconomy, driveability and exhaust emissions Lockout systemofoverdrive gearThispaperdescribes the designfeatures andconfirmation testingsconsidered toassurethereliabilityanddurability ofthetransmission.Italsoreferstoeffects onfueleconomy andnoiseofthetransmission inthevehicle. 0148-7191/78/0227-0097$02.50 Copyright ©1978SocietyofAutomotive Engineers, Inc. Downloaded from SAE International by University of British Columbia, Sunday, September 23, 20182 troisforclutch-to-clutch shifting between second andthirdgears. Thethirdphase,development anddurability testing wasnewlypro grammedspecifically fortheA40Dtransmission andcarried outbothinthe laboratory andinvehicles toqualify thedurability ofthetransmission,especially thedurability ofoverdriveplanetary gearsetandfriction clutchesandthereliability ofshiftcontrol system.Finally, vehicle performancetestwascarried outtoconfirm the substantial effect oftheA40Dtrans mission infueleconomy andengine noisereduction. TheA4OD