Overhead gantry crane installation site and the work conditions is vary greatly, the use of lifting capacity and working frequency are also different. In order to use the crane economically and reasonably, it is necessary to choose the appropriate working level according to the working condition of the crane. The working level of the bridge crane is divided into A1 ~ A8, according to the level of the crane and the load state, that is, according to the frequency and load degree of the crane through the calculation to determine.
The crane has a certain number of working cycles during its useful life. A working cycle of a travelling gantry crane is to start the process of loading the goods from the beginning to the next. The total number of working cycles represent the utilization of cranes. In order to facilitate the calculation, the total number of working cycles can be divided into 10 categories.