龙门吊也就是门式起重机工作级别A：它反映了起重机在载荷状态和利用繁忙程度两个方面的工作特性。

工作级别的划分是由起重机的利用等级U和载荷状态Q决定的。它们分为A1～A8八个级别。起重机工作级别，

也就是金属结构的工作级别，按起升机构确定，分为A1－A8级，若与中国规定的起重机工作类型对照，

大体上相当于：A1－A4－轻；A5－A6－中；A7－重，A8－特重。

Gantry crane is also known as gantry crane working level A: it reflects the working characteristics of the crane in terms of load status and busy utilization.

The classification of work levels is determined by the utilization level U and load state Q of the crane. They are divided into eight levels, A1 to A8. Crane working level,

The working level of the metal structure is determined by the lifting mechanism and divided into A1 to A8 levels. If compared with the crane working type specified in China,

Generally equivalent to: A1 A4 light; A5-A6 medium; A7 heavy, A8 extra heavy.