吊车是起重机的俗称，起重机(Crane)是起重机械的一种，是一种作循环、间歇运动的机械。一个工作循环包括：取物装置从取物地把物品提起，然后水平移动到指定地点降下物品，接着进行反向运动，使取物装置返回原位，以便进行下一次循环。如固定式回转起重机、塔式起重机、汽车起重机、轮胎、履带起重机等。
Crane is the common name of crane, crane is a kind of lifting machinery, is a kind of cycle, intermittent movement machinery. A working cycle includes: the retrieval device lifts the object from the retrieval place, then moves horizontally to the designated place to lower the object, and then makes the reverse movement to return the object to its original position for the next cycle. Such as fixed slewing crane, tower crane, truck crane, tire, crawler crane, etc.
在一定范围内垂直提升和水平搬运重物的多动作起重机械。又称吊车。属于物料搬运机械。起重机的工作特点是做间歇性运动，即在一个工作循环中取料、运移、卸载等动作的相应机构是交替工作的。
It is a multi action lifting machine with vertical lifting and horizontal handling of heavy objects within a certain range. Also known as crane. It belongs to material handling machinery. The working characteristic of crane is intermittent movement, that is to say, in a working cycle, the corresponding mechanism of reclaiming, moving and unloading works alternately.