塔吊是(shi)建筑工地上常用(yong)的一(yi)種(zhong)起重設備(bei) 又名”塔式(shi)起重機“，以一節一節的接(jie)長（高）（簡(jian)稱“標準節”），用來吊施工(gong)用的鋼(gang)筋、木(mu)楞(leng)、混凝(ning)土、鋼(gang)管等施工(gong)的原(yuan)材料。塔(ta)吊是工(gong)地上一種必不可少(shao)的設備。
塔(ta)(ta)吊(diao)（tower crane）尖的功能(neng)是(shi)承(cheng)受臂架拉(la)(la)繩(sheng)及(ji)平(ping)(ping)衡(heng)(heng)(heng)(heng)臂拉(la)(la)繩(sheng)傳來的上部(bu)(bu)荷載，并通過(guo)回轉(zhuan)(zhuan)塔(ta)(ta)架、轉(zhuan)(zhuan)臺、承(cheng)座等的結構部(bu)(bu)件(jian)式(shi)直接(jie)通過(guo)轉(zhuan)(zhuan)臺傳遞(di)給塔(ta)(ta)身結構。自升塔(ta)(ta)頂有截(jie)錐柱式(shi)、前傾或后傾截(jie)錐柱式(shi)、人字架式(shi)及(ji)斜撐架式(shi)。 凡是(shi)上回轉(zhuan)(zhuan)塔(ta)(ta)機均需設平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)，其功能(neng)是(shi)支承(cheng)平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)，用以構成設計上所(suo)(suo)要(yao)求的作用方面與(yu)起(qi)重(zhong)(zhong)力(li)(li)矩(ju)方向相(xiang)反的平(ping)(ping)衡(heng)(heng)(heng)(heng)力(li)(li)矩(ju)。除(chu)平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)外，還常在其尾部(bu)(bu)裝設起(qi)升機構。起(qi)升機構之所(suo)(suo)以同平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)一起(qi)安放在平(ping)(ping)衡(heng)(heng)(heng)(heng)臂尾端，一則(ze)可發揮部(bu)(bu)分配重(zhong)(zhong)作用，二則(ze)增(zeng)大繩(sheng)卷筒與(yu)塔(ta)(ta)尖導輪間(jian)(jian)的距離，以利鋼絲(si)繩(sheng)的排繞并避免發生亂繩(sheng)現象。平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)的用量與(yu)平(ping)(ping)衡(heng)(heng)(heng)(heng)臂的長度成反比(bi)關系，而平(ping)(ping)衡(heng)(heng)(heng)(heng)臂長度與(yu)起(qi)重(zhong)(zhong)臂長度之間(jian)(jian)又存在一定比(bi)例關系。平(ping)(ping)衡(heng)(heng)(heng)(heng)重(zhong)(zhong)量相(xiang)當可觀，輕型塔(ta)(ta)機一般至少(shao)要(yao)3～4t，重(zhong)(zhong)型的要(yao)近30t。
