【英语翻译Inpassengercars,thefinaldriveusuallyconsistsmerelyofahypoidbevel-geardrive.Thegeometryofthebevel-drivepinionandofthecrownwheeldeterminesthefinal-driveratio(i0=2.24~4.93forstandard-productionvehicles)(Fig.3-1】

　　英语翻译

　　Inpassengercars,thefinaldriveusuallyconsistsmerelyofahypoidbevel-geardrive.Thegeometryofthebevel-drivepinionandofthecrownwheeldeterminesthefinal-driveratio(i0=2.24~4.93forstandard-productionvehicles)(Fig.3-18).Thehypoidgearisincommonusetodayduemainlytothefactthattheoffsetpinionallowsthepropellershafttobesetbelow(forcars),orabove(forcommercialvehicles)thecrownwheelcenter.Thisgiveseitherareductioninthepropellershafttunnel,whichcausesabumpinthevehiclefloor,orinthecaseofacommercialvehicleareductionintheanglethoughwhichtheuniversaljointhastooperate.

　　Incommercialvehicles,thenecessaryfinal-driveratiocanonlyrarelybeaccommodatedinonestage(bevel-geardrive).Forthisreason,useisusuallymadeofmoreelaboratefinal-drivesystems:

　　1)single-reductionaxle(uptoi0=7),

　　2)transmission-typeaxlewithfront-ortop-mountedbevel-geardrive,

　　3)double-reductionaxle(totaltransmissionratiouptoi0=9),

　　4)pinionaxle(spur-geardrivesinthewheelhubs),

　　5)planetary-hubreductionaxle(alsoshiftableinspecialcases).

　　Largecrownwheelsreducethegroundclearanceunderthedifferential.Inthecaseofpinionaxlesandplanetary-hubreductionaxles,thedifferentialandthehalf-shaftscanbemadesmallerbysplittingthereduction.Thismakesitpossible,eveninthecaseofhighpoweroutputs,toachievesufficientgroundclearanceofthevehicle.