Q:What are the working duty and working duty analysis of the crane

The working duty of the crane is divided according to the crane utilization level and load status, or the crane working level is a parameter indicating the heavy workload of the crane, that is, indicating the busyness of the crane working in terms of time and the parameters of full load in terms of lifting weight.

The working level of the crane is also an important basis for the safety of the crane. It is the basis for safety inspections, accident analysis and calculation, and the determination of scrap standards for components. In general, different levels of work, different safety factors, scrap standards are also different.

Crane working level

The utilization level of the crane is used to characterize the use of the crane during the entire design life. It is divided into 10 levels of U0 to U9 according to the total number of work cycles during the design life. The load status of the crane is an index indicating the severity of the crane load. According to the nominal load spectrum factor, it is divided into light, medium, heavy and special weight. Considering the use of grades and load conditions comprehensively, according to the diagonal principle, the crane working level is divided into 8 levels of A1~A8.

1.1 Utilization level of cranes

 The use level is used to characterize the cranes' use frequency during the entire design life, and is divided into ten levels according to the total number of working cycles N during the design life span.

1.2 Load status of the crane

The load status indicates the severity of the load on the crane, which is related to two factors, namely the ratio Pi/Pmax of the lifted load to the rated load and the ratio of the number of interactions of each lifting load to the number of work cycles, ni/N. The load spectrum coefficient Kp representing the relationship between the two is calculated from the following equation:

Kp - load spectrum factor; ni - the number of times the load pi; N - the total number of engineering cycles;

Pi - the i-th lifting load; Pmax - the maximum lifting load; m - index, where m=3;

The load status of the crane is divided into four levels according to the nominal load spectrum factor

1.3 crane working level diagonal list

2. Crane agency working duty

Here, first of all, it should be pointed out that the crane working duty and crane lifting weight are two different concepts. The lifting weight refers to the quality of the hoisted material at a time, and the working duty is the comprehensive operating characteristic parameter of the crane. The lifting weight is large, the working level is not necessarily high; the lifting weight is small, and the working level may not be low. Even if the cranes of the same type are of the same weight, the safety factor of the parts will not be the same as long as the work level is different. If you only look at heavy tonnages and ignore the work level, and the cranes with low working levels are used frequently and at full capacity, you will expedite the use of vulnerable parts and components, cause frequent failures, and even cause accidents.

In addition, it should be noted that the working level of the crane and the metal structure is different from the working level of the organization. For the same crane, due to the inconsistent load and the unequal work performance of each working mechanism, even if the same crane, the working level of different agencies and the crane's working level is often inconsistent, which is in different parts of the organization. Pay special attention when scrapping and updating

3 Examples of common working levels for cranes