>> P.26
A23BearingloadsincaseofbeltorchaintransmissionWhenpoweristransmittedbyabeltorchain,theloadactingonthepulleyorsprocketwheelisobtainedfromthefollowingequations:T=9550000 ……………………………(11)Kt= ……………………………………(12)where,T:orqueactingonpulleyorsprocketwheel,N-mm Kt:Effectivetransmittingforceofbeltorchain,N H:Transmittingpower,kW n:Rotationalspeed,min-1 R Effectiveradiusofpulleyorsprocketwheel,mmForbelttransmission,theloadKractingonthepulleyshaftisobtainedfromthefollowingequation,multiply-ingtheeffectivetransmittingforceKtbythebeltfactorfbshowninTable7.Kr=fbKt ………………………………………(13)Table7BeltfactorV-beltsTimingbeltsPlainbelts(withtensionpulley)Plainbelts2〜2.51.3〜22.5〜34〜5TypeofbeltfbInthecaseofchaintransmission,avalueof1.2to1.5istakenasthechainfactorcorrespondingtofb.Theloadactingonthesprocketwheelshaftisobtainedfromequation(13)inthesamemannerasthebelttransmission.BearingloadsincaseofgeartransmissionWhenpoweristransmittedbygears,theforceactingonthegearsvariesaccordingtothetypeofgear.Spurgearsproduceradialloadsonly,buthelicalgears,bevelgearsandwormgearsproduceaxialloadsinadditiontoradialloads.Takingthesimplestcaseofspurgearsasanexample,thebearingloadisobtainedfromthefollowingequations:T=9550000 ……………………………(14)Kt= ……………………………………(15)Ks=Kttanθ ………………………………(16)Kc= Kt+Ks=Ktsecθ…………………(17) where, T:Torqueappliedtogear,N-mm Kt:Tangentialforceactingongear,N Ks:Radialforceactingongear,N Kc:Resultantnormalforceongeartoothsurface,N H:Transmittingpower,kW n:Rotationalspeed,min-1 R:Pitchcircleradiusofdrivegear,mm θ:Pressureangleofgear,deg.KtKsRFig.6Inthiscase,theresultantnormalforceonthetoothsurfaceactsastheradialforcetotheshaftandthemagnitudeofvibrationorshocksvariesdependingontheaccuracyandsurfacefinishofthegear.Therefore,theradialloadKrappliedtotheshaftisobtainedfromthefollowingequation,multiplyingtheresultantnormalforceKcongeartoothsurfacebythegearfactorfzshowninTable8.Kr=fzKc……………………………………(18)Table8GearfactorPrecisiongears(Pitcherrorandformerror:Lessthan0.02mm)1.05〜1.1Ordinarymachinedgears(Pitcherrorandformerror:0.02〜0.1mm)1.1〜1.3TypeofgearfzHnTRHnTR22
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