傳(chuan)動比(bi)是機構(gou)中(zhong)兩轉動構(gou)件角速(su)度(du)(du)的比(bi)值，也稱速(su)比(bi)。構(gou)件a和構(gou)件b的傳(chuan)動比(bi)為i=ωa/ ωb=na/nb，式(shi)中(zhong)ωa和 ωb分別為構(gou)件a和b的角速(su)度(du)(du)（弧度(du)(du)/秒）；na和nb分別為構(gou)件a和b的轉速(su)（轉/分）。

當式中(zhong)的(de)(de)角速度為瞬(shun)(shun)時(shi)(shi)值時(shi)(shi)，則求得的(de)(de)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)為瞬(shun)(shun)時(shi)(shi)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)。當式中(zhong)的(de)(de)角速度為平(ping)均值時(shi)(shi)，則求得的(de)(de)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)為平(ping)均傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)。理(li)論上對于大(da)多(duo)數(shu)漸開(kai)線(xian)齒(chi)廓正確的(de)(de)齒(chi)輪傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)，瞬(shun)(shun)時(shi)(shi)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)是(shi)(shi)不變的(de)(de)；對于鏈傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)和(he)摩(mo)(mo)擦輪傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)，瞬(shun)(shun)時(shi)(shi)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)是(shi)(shi)變化的(de)(de)。對于嚙(nie)合傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)，傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)可(ke)用a和(he)b輪的(de)(de)齒(chi)數(shu)Za和(he)Zb表示，i=Zb/Za；對于摩(mo)(mo)擦傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)，傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)比(bi)(bi)可(ke)用a和(he)b輪的(de)(de)直徑Da和(he)Db表示，i=Db/Da。

計算方法：

傳動(dong)比=使用扭矩÷9550÷電機(ji)功(gong)率(lv)×電機(ji)功(gong)率(lv)輸入轉數÷使用系數

傳動比=主(zhu)動輪轉速(su)除以(yi)從動輪轉速(su)的值=它們分(fen)度圓(yuan)直徑比值的倒(dao)數(shu)。即(ji)：i=n1/n2=D2/D1

i=n1/n2=z2/z1（齒(chi)輪(lun)的(de)）

對于多級齒輪傳動：1.每兩軸之間的(de)傳動比按照上面的(de)公式計算(suan)。 2.從第一軸到第n軸的(de)總傳動比等于各級傳動比之積(ji)