塔吊是建筑工(gong)地(di)上常用的一種起重(zhong)設備(bei) 又(you)名”塔式起重(zhong)機“，以一節(jie)一節(jie)的接長（高）（簡稱“標準節”），用(yong)來吊施工用(yong)的鋼(gang)筋(jin)、木楞、混凝土、鋼(gang)管(guan)等(deng)施工的原(yuan)材(cai)料。塔吊是工地上(shang)一種必不可少的設(she)備。
塔(ta)(ta)(ta)吊(diao)（tower crane）尖的功(gong)(gong)能(neng)是(shi)承受臂(bei)架(jia)拉(la)繩(sheng)(sheng)及平(ping)(ping)衡(heng)(heng)(heng)臂(bei)拉(la)繩(sheng)(sheng)傳(chuan)來(lai)的上(shang)部(bu)荷載，并(bing)通過回轉(zhuan)(zhuan)(zhuan)(zhuan)塔(ta)(ta)(ta)架(jia)、轉(zhuan)(zhuan)(zhuan)(zhuan)臺(tai)、承座等的結(jie)構部(bu)件式(shi)直(zhi)接通過轉(zhuan)(zhuan)(zhuan)(zhuan)臺(tai)傳(chuan)遞給塔(ta)(ta)(ta)身結(jie)構。自升(sheng)塔(ta)(ta)(ta)頂有(you)截錐(zhui)柱式(shi)、前傾(qing)或(huo)后傾(qing)截錐(zhui)柱式(shi)、人(ren)字架(jia)式(shi)及斜撐(cheng)架(jia)式(shi)。 凡是(shi)上(shang)回轉(zhuan)(zhuan)(zhuan)(zhuan)塔(ta)(ta)(ta)機(ji)(ji)均需(xu)設(she)平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)，其功(gong)(gong)能(neng)是(shi)支承平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)，用(yong)以(yi)構成設(she)計上(shang)所(suo)要(yao)求的作用(yong)方面與起(qi)重(zhong)(zhong)(zhong)(zhong)力矩方向相反(fan)的平(ping)(ping)衡(heng)(heng)(heng)力矩。除(chu)平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)外，還常在其尾部(bu)裝設(she)起(qi)升(sheng)機(ji)(ji)構。起(qi)升(sheng)機(ji)(ji)構之所(suo)以(yi)同平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)一(yi)起(qi)安放在平(ping)(ping)衡(heng)(heng)(heng)臂(bei)尾端，一(yi)則可(ke)發揮(hui)部(bu)分(fen)配(pei)重(zhong)(zhong)(zhong)(zhong)作用(yong)，二則增(zeng)大(da)繩(sheng)(sheng)卷筒(tong)與塔(ta)(ta)(ta)尖導輪間的距離，以(yi)利鋼絲繩(sheng)(sheng)的排繞并(bing)避免發生亂繩(sheng)(sheng)現象。平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)的用(yong)量與平(ping)(ping)衡(heng)(heng)(heng)臂(bei)的長度(du)(du)成反(fan)比關(guan)系(xi)，而平(ping)(ping)衡(heng)(heng)(heng)臂(bei)長度(du)(du)與起(qi)重(zhong)(zhong)(zhong)(zhong)臂(bei)長度(du)(du)之間又(you)存在一(yi)定比例關(guan)系(xi)。平(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)(zhong)量相當可(ke)觀，輕型塔(ta)(ta)(ta)機(ji)(ji)一(yi)般至少要(yao)3～4t，重(zhong)(zhong)(zhong)(zhong)型的要(yao)近30t。
