門(men)式(shi)(shi)(shi)起重(zhong)(zhong)機(ji)(ji)(又稱龍門(men)起重(zhong)(zhong)機(ji)(ji))是橋架(jia)通過(guo)兩側(ce)支(zhi)(zhi)腿(tui)支(zhi)(zhi)撐在(zai)地(di)面軌道上的橋架(jia)型起重(zhong)(zhong)機(ji)(ji)。在(zai)結構上由門(men)架(jia)、大(da)車運行機(ji)(ji)構、起重(zhong)(zhong)小車和電(dian)氣部分等組(zu)成。有(you)的門(men)式(shi)(shi)(shi)起重(zhong)(zhong)機(ji)(ji)只在(zai)一側(ce)有(you)支(zhi)(zhi)腿(tui)，另一側(ce)支(zhi)(zhi)撐在(zai)廠房或棧橋上運行，稱作半門(men)式(shi)(shi)(shi)起重(zhong)(zhong)機(ji)(ji)。門(men)式(shi)(shi)(shi)起重(zhong)(zhong)機(ji)(ji)的門(men)架(jia)上部橋架(jia)(含主梁(liang)(liang)(liang)(liang)和端梁(liang)(liang)(liang)(liang))、支(zhi)(zhi)腿(tui)、下橫梁(liang)(liang)(liang)(liang)等部分構成。為了擴(kuo)大(da)起重(zhong)(zhong)機(ji)(ji)作業范圍(wei)，主梁(liang)(liang)(liang)(liang)可以向一側(ce)或兩側(ce)伸出(chu)支(zhi)(zhi)腿(tui)以外(wai)，形成懸臂。也(ye)可采用(yong)帶(dai)臂架(jia)的起重(zhong)(zhong)小車，通過(guo)臂架(jia)的俯仰和旋轉擴(kuo)大(da)起重(zhong)(zhong)機(ji)(ji)作業范圍(wei)。