起重机:CraneAcraneisaliftingmachineequippedwithawinder(alsocalledwireropedrum),wireropesorchainsandsheavesthatcanbeusedbothtoliftandlowermaterialsandtomovethemhorizontally.Itusesoneormoresimplemachinestocreatemechanicaladvantageandthusmoveloadsbeyondthenormalcapabilityofahuman.Cranesarecommonlyemployedinthetransportindustryfortheloadingandunloadingoffreight;intheconstructionindustryforthemovementofmaterials;andinthemanufacturingindustryfortheassemblingofheavyequipment.起重机是一个装备了络纱机(也称钢丝绳鼓),用钢丝或铁链与滑轮来升降和平移材料的,用来举重物的机器。起重机的优点在于它是由一个或更多的简单机械组成的,因而具有在远超与人力的移动装载能力。起重机在运输工业常常作为装货和卸载货物的工具;在建筑业作为运输材料的工具;并且在制造工业用来聚集重物的设备.