塔(ta)吊是建筑工(gong)地上常用的(de)一種起重(zhong)設(she)備 又(you)名”塔式起重(zhong)機“，以一節一節的(de)接長(chang)（高）（簡稱(cheng)“標準節”），用(yong)來吊施工(gong)用(yong)的鋼(gang)筋、木楞、混凝土、鋼(gang)管等施工(gong)的原材料。塔吊是工(gong)地(di)上一種(zhong)必不可少(shao)的設(she)備。
塔(ta)吊（tower crane）尖的(de)(de)(de)功能是承受臂(bei)(bei)架(jia)拉繩及平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)(bei)拉繩傳(chuan)來(lai)的(de)(de)(de)上(shang)部荷載，并通過回(hui)轉塔(ta)架(jia)、轉臺、承座等的(de)(de)(de)結構(gou)(gou)部件式(shi)直(zhi)接通過轉臺傳(chuan)遞給塔(ta)身結構(gou)(gou)。自升塔(ta)頂有截錐柱(zhu)式(shi)、前傾或后(hou)傾截錐柱(zhu)式(shi)、人字架(jia)式(shi)及斜撐(cheng)架(jia)式(shi)。 凡是上(shang)回(hui)轉塔(ta)機均需設(she)(she)平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)，其功能是支(zhi)承平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)，用以構(gou)(gou)成設(she)(she)計上(shang)所(suo)要求的(de)(de)(de)作用方面與起(qi)(qi)重(zhong)(zhong)(zhong)力矩方向相反的(de)(de)(de)平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)力矩。除平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)外，還常在其尾部裝設(she)(she)起(qi)(qi)升機構(gou)(gou)。起(qi)(qi)升機構(gou)(gou)之所(suo)以同(tong)平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)一起(qi)(qi)安放在平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)(bei)尾端，一則(ze)可發揮部分配重(zhong)(zhong)(zhong)作用，二則(ze)增大(da)繩卷筒(tong)與塔(ta)尖導(dao)輪間(jian)的(de)(de)(de)距離，以利鋼絲(si)繩的(de)(de)(de)排(pai)繞并避免(mian)發生亂繩現象。平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)的(de)(de)(de)用量與平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)(bei)的(de)(de)(de)長度成反比關(guan)系，而(er)平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)臂(bei)(bei)長度與起(qi)(qi)重(zhong)(zhong)(zhong)臂(bei)(bei)長度之間(jian)又存在一定比例關(guan)系。平(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)重(zhong)(zhong)(zhong)量相當可觀，輕型塔(ta)機一般至少要3～4t，重(zhong)(zhong)(zhong)型的(de)(de)(de)要近30t。
