門式起重機(又稱龍門起重機)是橋架通過兩側支腿支撐在地麵軌道上的橋架型起重機。在結構上由門架、大車運行機構
、起qi重zhong小xiao車che和he電dian氣qi部bu分fen等deng組zu成cheng。有you的de門men式shi起qi重zhong機ji隻zhi在zai一yi側ce有you支zhi腿tui
，另ling一yi側ce支zhi撐cheng在zai廠chang房fang或huo棧zhan橋qiao上shang運yun行xing
，稱cheng作zuo半ban門men式shi起qi重zhong機ji。門men式shi起qi重zhong機ji的de門men架jia上shang部bu橋qiao架jia(含主梁和端梁)、支腿、下xia橫heng梁liang等deng部bu分fen構gou成cheng。為wei了le擴kuo大da起qi重zhong機ji作zuo業ye範fan圍wei，主zhu梁liang可ke以yi向xiang一yi側ce或huo兩liang側ce伸shen出chu支zhi腿tui以yi外wai，形xing成cheng懸xuan臂bi。也ye可ke采cai用yong帶dai臂bi架jia的de起qi重zhong小xiao車che，通tong過guo臂bi架jia的de俯fu仰yang和he旋xuan轉zhuan擴kuo大da起qi重zhong機ji作zuo業ye範fan圍wei