門(men)(men)式(shi)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)(又稱(cheng)(cheng)龍門(men)(men)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji))是橋架通(tong)(tong)過(guo)兩(liang)(liang)側支(zhi)(zhi)(zhi)腿(tui)(tui)(tui)支(zhi)(zhi)(zhi)撐在地(di)面軌道上的(de)橋架型起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)。在結構上由門(men)(men)架、大(da)(da)車(che)運行機(ji)(ji)(ji)構、起(qi)(qi)(qi)(qi)重(zhong)(zhong)小車(che)和(he)電氣部(bu)分等(deng)組成。有的(de)門(men)(men)式(shi)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)只在一(yi)側有支(zhi)(zhi)(zhi)腿(tui)(tui)(tui)，另(ling)一(yi)側支(zhi)(zhi)(zhi)撐在廠房或棧(zhan)橋上運行，稱(cheng)(cheng)作半門(men)(men)式(shi)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)。門(men)(men)式(shi)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)的(de)門(men)(men)架上部(bu)橋架(含主梁(liang)和(he)端梁(liang))、支(zhi)(zhi)(zhi)腿(tui)(tui)(tui)、下橫梁(liang)等(deng)部(bu)分構成。為了(le)擴大(da)(da)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)作業(ye)范圍，主梁(liang)可以(yi)向一(yi)側或兩(liang)(liang)側伸出支(zhi)(zhi)(zhi)腿(tui)(tui)(tui)以(yi)外，形成懸(xuan)臂(bei)。也可采(cai)用帶臂(bei)架的(de)起(qi)(qi)(qi)(qi)重(zhong)(zhong)小車(che)，通(tong)(tong)過(guo)臂(bei)架的(de)俯仰和(he)旋轉擴大(da)(da)起(qi)(qi)(qi)(qi)重(zhong)(zhong)機(ji)(ji)(ji)作業(ye)范圍。