塔吊(diao)是建筑工(gong)地(di)上常用(yong)的一種(zhong)起重(zhong)設備 又名”塔式(shi)起重(zhong)機(ji)“，以一節一節的(de)接長（高(gao)）（簡稱(cheng)“標準節”），用來吊(diao)施工用的鋼筋、木楞、混凝(ning)土、鋼管等施工的原材料。塔吊(diao)是(shi)工地上(shang)一種必不可(ke)少的設備(bei)。
塔(ta)(ta)吊（tower crane）尖的(de)(de)(de)功(gong)能(neng)是承(cheng)受(shou)臂(bei)架拉(la)繩(sheng)(sheng)及平(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)拉(la)繩(sheng)(sheng)傳來的(de)(de)(de)上(shang)(shang)部荷載，并(bing)通(tong)過回(hui)轉(zhuan)塔(ta)(ta)架、轉(zhuan)臺、承(cheng)座等的(de)(de)(de)結構(gou)(gou)部件(jian)式(shi)直接通(tong)過轉(zhuan)臺傳遞給塔(ta)(ta)身結構(gou)(gou)。自(zi)升塔(ta)(ta)頂有截錐(zhui)柱(zhu)式(shi)、前(qian)傾或(huo)后傾截錐(zhui)柱(zhu)式(shi)、人字架式(shi)及斜撐架式(shi)。 凡是上(shang)(shang)回(hui)轉(zhuan)塔(ta)(ta)機(ji)(ji)均需設(she)平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)，其(qi)功(gong)能(neng)是支承(cheng)平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)，用(yong)(yong)(yong)以(yi)構(gou)(gou)成設(she)計上(shang)(shang)所要求(qiu)的(de)(de)(de)作(zuo)用(yong)(yong)(yong)方面與(yu)起重(zhong)力矩(ju)方向相反的(de)(de)(de)平(ping)(ping)(ping)衡(heng)(heng)(heng)力矩(ju)。除(chu)平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)外，還常在(zai)其(qi)尾部裝設(she)起升機(ji)(ji)構(gou)(gou)。起升機(ji)(ji)構(gou)(gou)之(zhi)所以(yi)同(tong)平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)一起安放(fang)在(zai)平(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)尾端，一則可發揮(hui)部分(fen)配重(zhong)作(zuo)用(yong)(yong)(yong)，二(er)則增大繩(sheng)(sheng)卷筒與(yu)塔(ta)(ta)尖導輪(lun)間的(de)(de)(de)距離，以(yi)利鋼絲(si)繩(sheng)(sheng)的(de)(de)(de)排繞并(bing)避(bi)免發生亂繩(sheng)(sheng)現象。平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)的(de)(de)(de)用(yong)(yong)(yong)量與(yu)平(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)的(de)(de)(de)長(chang)度成反比(bi)關(guan)系，而平(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)長(chang)度與(yu)起重(zhong)臂(bei)長(chang)度之(zhi)間又存在(zai)一定比(bi)例(li)關(guan)系。平(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)量相當可觀，輕型(xing)塔(ta)(ta)機(ji)(ji)一般至少要3～4t，重(zhong)型(xing)的(de)(de)(de)要近30t。
