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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.



LevelTotal number of working cycles NRemarks
U01.6﹡104not usually
U12.2﹡104
U23.3﹡104
U31.25﹡105
U42.5﹡105seldom
U55﹡105medium
U61﹡106Not frequently used
U7

U8

U9

2﹡106

4﹡106

﹥4﹡106

frequently used


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:

gongshi.jpg

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



load statusKpInstructions
Q1—light0.125Rising rated load rarely, generally lifting light loads
Q2—medium0.25Sometimes lifting rated load, usually lifting medium load
Q3—heavy0.5Rising rated load often, usually lifting heavier loads
Q4—Special weight1.0Frequent lifting rated load



1.3 crane working level diagonal list

Load status

Kp

level

U0

U1

U2

U3

U4

U5

U6

U7

U8

U9

Q1—light

0.125



A1

A2

A3

A4

A5

A6

A7

A8

Q2—medium

0.25


A1

A2

A3

A4

A5

A6

A7

A8


Q3—heavy

0.5

A1

A2

A3

A4

A5

A6

A7

A8



Q4—special heavy

1.0

A2

A3

A4

A5

A6

A7

A8




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

Crane type

Work duty

Overhead crane

Hook type

Power station installation and maintenance

A1~A3

Workshop and warehouse

A3~A5

Heavy work shop and warehouse

A6~A7

grab type

Intermittent handling

A6~A7

Continuous loading and unloading

A18

Metallurgy

For lifting boxes

A7~A8

Feeding

A8

Casting

A6~A8

Forging

A7~A8

Quenching

A8

Clamp, depilation

A8

Uncover

A7~A8

Electromagnet

A7~A8

Gantry crane

General purpose hook type

A5~A6

Grab bucket for loading and unloading

A7~A8

Power station hook

A2~A3

Shipbuilding installation hook type

A4~A5

For loading and unloading containers

A6~A8


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