傳(chuan)動(dong)比是(shi)機構(gou)中兩轉(zhuan)動(dong)構(gou)件(jian)(jian)角(jiao)(jiao)速度的比值，也稱速比。構(gou)件(jian)(jian)a和構(gou)件(jian)(jian)b的傳(chuan)動(dong)比為i=ωa/ ωb=na/nb，式中ωa和 ωb分別為構(gou)件(jian)(jian)a和b的角(jiao)(jiao)速度（弧度/秒）；na和nb分別為構(gou)件(jian)(jian)a和b的轉(zhuan)速（轉(zhuan)/分）。

當式(shi)(shi)中(zhong)的(de)角速(su)度(du)為(wei)瞬(shun)時值(zhi)時，則求(qiu)得的(de)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比為(wei)瞬(shun)時傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比。當式(shi)(shi)中(zhong)的(de)角速(su)度(du)為(wei)平均(jun)值(zhi)時，則求(qiu)得的(de)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比為(wei)平均(jun)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比。理(li)論上對(dui)于(yu)(yu)大多數漸開線(xian)齒廓正確的(de)齒輪(lun)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)，瞬(shun)時傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比是不變的(de)；對(dui)于(yu)(yu)鏈(lian)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)和(he)(he)摩擦輪(lun)傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)，瞬(shun)時傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比是變化的(de)。對(dui)于(yu)(yu)嚙合傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)，傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比可用(yong)a和(he)(he)b輪(lun)的(de)齒數Za和(he)(he)Zb表示，i=Zb/Za；對(dui)于(yu)(yu)摩擦傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)，傳(chuan)(chuan)(chuan)(chuan)動(dong)(dong)(dong)(dong)(dong)比可用(yong)a和(he)(he)b輪(lun)的(de)直徑(jing)Da和(he)(he)Db表示，i=Db/Da。

計算方法：

傳動(dong)比=使用扭矩÷9550÷電機(ji)功率×電機(ji)功率輸(shu)入轉數÷使用系數

傳(chuan)動(dong)(dong)比=主動(dong)(dong)輪轉速除以從動(dong)(dong)輪轉速的值=它(ta)們(men)分度圓直徑比值的倒(dao)數。即：i=n1/n2=D2/D1

i=n1/n2=z2/z1（齒輪的(de)）

對于多級齒(chi)輪傳(chuan)(chuan)動(dong)：1.每兩軸(zhou)之間的傳(chuan)(chuan)動(dong)比(bi)按照上面(mian)的公(gong)式計算。 2.從第一軸(zhou)到第n軸(zhou)的總傳(chuan)(chuan)動(dong)比(bi)等于各(ge)級傳(chuan)(chuan)動(dong)比(bi)之積