Cov yam ntxwv tseem ceeb ntawm cov iav muaj xws li kev sib kis tau zoo, kev siv ntau yam, kev sib kis tau zoo, kev ua haujlwm ruaj khov thiab lub neej ntev. Gear kis tau tus mob yog qhov tseeb thiab tsis tu ncua, haum rau ntau yam kev thov los ntawm lub zog qis mus rau lub zog siab, thiab muaj lub zog sib kis tau dav heev, los ntawm {{0}}.001W txog 60000kW. Kev ua haujlwm ntawm cov iav kis tau zoo yog qhov siab, feem ntau 0.94 ~ 0.99, tab sis nws muaj cov kev xav tau siab hauv kev tsim khoom thiab kev teeb tsa, thiab tus nqi kuj tseem siab. Tsis tas li ntawd, iav kis tau tus mob yog tsim rau kis tau tus mob ntawm parallel axes, intersecting axes thiab staggered axes, uas yog ib qho nyuaj rau ua tiav nrog rau lwm yam kis tau tus mob txoj kev. cov
Kev faib tawm ntawm cov iav yog nyob ntawm cov yam ntxwv xws li kev teeb tsa ntawm cov axes, cov kev taw qhia ntawm cov kab hniav txheeb ze rau cov iav generatrix, cov hniav profile nkhaus thiab hardness ntawm cov hniav. Cov txheej txheem kev faib ua feem ntau suav nrog:
Los ntawm kev npaj ntawm axes: parallel axis iav kis tau tus mob, kev sib tshuam axis iav kis tau tus mob, staggered axis iav kis tau tus mob.
Los ntawm cov kev taw qhia ntawm cov hniav kab txheeb ze rau cov iav generatrix: cov hniav ncaj, helical hniav, herringbone hniav, nkhaus hniav.
Raws li cov hniav profile nkhaus: involute hniav, cycloid hniav, arc hniav.
According to the tooth surface hardness: soft tooth surface (≤350HB), hard tooth surface (>350 HB).
Cov keeb kwm keeb kwm ntawm cov iav tuaj yeem taug qab mus rau lub sijhawm qub. Thaum ntxov li 350 BC, tus kws tshawb fawb Greek thaum ub Aristotle tau sau cov phiaj xwm hauv cov ntaub ntawv. Ancient Tuam Tshoj kuj tau pib siv zog los ntawm 400 mus rau 200 BC. Tom qab European Industrial Revolution nyob rau hauv lub xyoo pua 18th, daim ntawv thov ntawm iav kis tau tus mob tau nce zuj zus, thiab niaj hnub iav tshuab tau txuas ntxiv txhim kho, mus txog ib theem ntawm kev ua haujlwm siab thiab siab precision.