塔吊是建筑工地上常(chang)用的一種(zhong)起(qi)重設備 又名(ming)”塔式起(qi)重機“，以(yi)一節一節的接長（高）（簡稱“標準節”），用(yong)(yong)來(lai)吊(diao)施工用(yong)(yong)的(de)鋼(gang)筋(jin)、木楞、混凝土、鋼(gang)管等施工的(de)原材料。塔吊(diao)是工地上一種必不可(ke)少的(de)設備。
塔(ta)吊（tower crane）尖(jian)的(de)(de)(de)功能是(shi)承受臂(bei)(bei)架(jia)拉(la)繩及平衡(heng)臂(bei)(bei)拉(la)繩傳(chuan)來的(de)(de)(de)上(shang)部(bu)荷(he)載，并通過回轉(zhuan)塔(ta)架(jia)、轉(zhuan)臺、承座等的(de)(de)(de)結構(gou)(gou)部(bu)件(jian)式(shi)直接通過轉(zhuan)臺傳(chuan)遞給塔(ta)身結構(gou)(gou)。自升塔(ta)頂有截錐柱式(shi)、前傾或(huo)后(hou)傾截錐柱式(shi)、人(ren)字架(jia)式(shi)及斜(xie)撐架(jia)式(shi)。 凡是(shi)上(shang)回轉(zhuan)塔(ta)機(ji)均需設(she)平衡(heng)重(zhong)(zhong)(zhong)(zhong)，其功能是(shi)支承平衡(heng)重(zhong)(zhong)(zhong)(zhong)，用(yong)以(yi)構(gou)(gou)成設(she)計上(shang)所(suo)要(yao)求的(de)(de)(de)作用(yong)方面與(yu)起(qi)(qi)重(zhong)(zhong)(zhong)(zhong)力(li)矩(ju)方向(xiang)相反的(de)(de)(de)平衡(heng)力(li)矩(ju)。除(chu)平衡(heng)重(zhong)(zhong)(zhong)(zhong)外(wai)，還常在(zai)其尾部(bu)裝設(she)起(qi)(qi)升機(ji)構(gou)(gou)。起(qi)(qi)升機(ji)構(gou)(gou)之所(suo)以(yi)同平衡(heng)重(zhong)(zhong)(zhong)(zhong)一起(qi)(qi)安(an)放在(zai)平衡(heng)臂(bei)(bei)尾端，一則可發(fa)揮(hui)部(bu)分(fen)配重(zhong)(zhong)(zhong)(zhong)作用(yong)，二則增大(da)繩卷筒與(yu)塔(ta)尖(jian)導(dao)輪間(jian)的(de)(de)(de)距(ju)離，以(yi)利鋼絲繩的(de)(de)(de)排繞并避(bi)免發(fa)生亂繩現象。平衡(heng)重(zhong)(zhong)(zhong)(zhong)的(de)(de)(de)用(yong)量與(yu)平衡(heng)臂(bei)(bei)的(de)(de)(de)長度(du)(du)成反比(bi)(bi)關(guan)系，而平衡(heng)臂(bei)(bei)長度(du)(du)與(yu)起(qi)(qi)重(zhong)(zhong)(zhong)(zhong)臂(bei)(bei)長度(du)(du)之間(jian)又存在(zai)一定(ding)比(bi)(bi)例關(guan)系。平衡(heng)重(zhong)(zhong)(zhong)(zhong)量相當可觀，輕(qing)型(xing)塔(ta)機(ji)一般至(zhi)少要(yao)3～4t，重(zhong)(zhong)(zhong)(zhong)型(xing)的(de)(de)(de)要(yao)近(jin)30t。
