汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)主要由(you)起(qi)(qi)(qi)(qi)(qi)升、變(bian)幅、回轉、起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)臂(bei)和(he)(he)汽(qi)(qi)(qi)(qi)(qi)車(che)(che)底盤組(zu)成。由(you)于液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)技術，電子工業，高強度鋼(gang)材(cai)和(he)(he)汽(qi)(qi)(qi)(qi)(qi)車(che)(che)工業的(de)發(fa)(fa)展(zhan)，促進(jin)了(le)汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)的(de)發(fa)(fa)展(zhan)。自重(zhong)(zhong)(zhong)(zhong)(zhong)大，工作(zuo)(zuo)準備時(shi)間長(chang)的(de)機(ji)(ji)(ji)械傳動(dong)(dong)式汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)已被液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)式汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)所代替。液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)的(de)液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)系統采用(yong)液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)泵、定(ding)量或(huo)變(bian)量馬達(da)(da)實(shi)現起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)起(qi)(qi)(qi)(qi)(qi)升回轉、變(bian)幅、起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)臂(bei)伸(shen)縮及支腿伸(shen)縮并可單獨或(huo)組(zu)合動(dong)(dong)作(zuo)(zuo)。馬達(da)(da)采用(yong)過熱保護，并有(you)防止(zhi)(zhi)錯誤操作(zuo)(zuo)的(de)安全裝(zhuang)置。大噸位(wei)的(de)液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)選用(yong)多(duo)聯齒(chi)輪泵，合流時(shi)還可實(shi)現上述各動(dong)(dong)作(zuo)(zuo)的(de)加速。在(zai)液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)系統中設有(you)自動(dong)(dong)超(chao)負荷安全閥、緩沖(chong)閥及液(ye)(ye)(ye)(ye)壓(ya)(ya)(ya)鎖等，以防止(zhi)(zhi)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)作(zuo)(zuo)業時(shi)過載或(huo)失速及油管突然po裂引起(qi)(qi)(qi)(qi)(qi)的(de)意外事故發(fa)(fa)生。汽(qi)(qi)(qi)(qi)(qi)車(che)(che)起(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)(zhong)(zhong)(zhong)機(ji)(ji)(ji)裝(zhuang)有(you)幅度指示器和(he)(he)高度限(xian)位(wei)器，防止(zhi)(zhi)超(chao)載或(huo)超(chao)伸(shen)距，卷筒和(he)(he)滑輪設有(you)防鋼(gang)絲繩跳槽(cao)的(de)裝(zhuang)置。

但起(qi)升速(su)(su)(su)(su)度(du)和回轉速(su)(su)(su)(su)度(du)必須根據以下幾(ji)點來考慮(lv)。 ① 考慮(lv)汽車(che)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)的(de)作業對(dui)象(xiang)。用于(yu)(yu)港口碼頭(tou)、車(che)站貨物進裝(zhuang)和搬運的(de)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)，一般要求工作速(su)(su)(su)(su)度(du)快，徐工汽車(che)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)修理站點，以提高作業效率(lv)，徐工汽車(che)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)售后保養，用于(yu)(yu)建筑安裝(zhuang)工程的(de)汽車(che)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)，則(ze)要求吊裝(zhuang)平(ping)穩(wen)性，對(dui)起(qi)升速(su)(su)(su)(su)度(du)和回轉速(su)(su)(su)(su)度(du)要求低些。 ② 考慮(lv)機(ji)型(xing)。大(da)型(xing)起(qi)重(zhong)(zhong)(zhong)(zhong)機(ji)，主要解決重(zhong)(zhong)(zhong)(zhong)件吊裝(zhuang)問題。重(zhong)(zhong)(zhong)(zhong)件的(de)流量小，工作速(su)(su)(su)(su)度(du)不(bu)是主要問題，應重(zhong)(zhong)(zhong)(zhong)點考慮(lv)工作平(ping)穩(wen)性、安全性，小型(xing)機(ji)則(ze)相反。

支腿型式

汽(qi)車起(qi)重機(ji)支腿，可(ke)分(fen)為手動(dong)和液(ye)壓(ya)(ya)操縱的兩類。目前，手動(dong)操縱的支腿已不多見(jian)，徐工汽(qi)車起(qi)重機(ji)維修服務站(zhan)，絕大多數汽(qi)車起(qi)重機(ji)都是采用液(ye)壓(ya)(ya)支腿。液(ye)壓(ya)(ya)支腿又可(ke)分(fen)為下列幾(ji)種型式。

（1）蛙式支腿

這種支(zhi)腿(tui)的活動支(zhi)腿(tui)鉸接(jie)在固定支(zhi)腿(tui)上，其展開動作(zuo)由液壓缸完成，威海徐工汽車起(qi)(qi)重機，特點是結構簡單(dan)、重量較輕(qing)，但支(zhi)腿(tui)跨度不大，只(zhi)適用于小噸(dun)位的起(qi)(qi)重機。

（2）H型支腿

這種(zhong)支(zhi)腿(tui)有兩個液壓缸(gang)。活(huo)動支(zhi)腿(tui)伸出后，工作時垂直腿(tui)撐(cheng)地，形如(ru)H而得名。特點是支(zhi)腿(tui)跨距較大，對場地適應性較好，目前已被(bei)廣(guang)泛采用。