Crane duty classification is according to the grades of crane use (in the whole design life cycle total working cycles) and crane load condition, or to say, crane service classifications is that crane heavy degree of parameters, namely that the extent of the crane work on time and hoisting load parameters.
Crane duty classification is according to the grades of crane use and crane load condition. Classification principle is in the load, the frequency of different cases, have the same life of the crane at the same level.
Divide crane service class of purpose is not covered, manufacture and selection of users to provide reasonable and unified technical basis and the reference standard, in order to obtain better security, economic effect, make the working status of crane is an accurate reflection of.
It also can improve the generalization level of crane parts, achieve different lifting weight of crane components work in the same general level of the crane. crane classification is the important basis of crane parts, crane components and component design, is also a security check, accident analysis and scrap the basis of a standard to determine. In general, the duty classification is different, safety factor is different, scrap standard is also different.
To identify the duty classification of the types of overhead crane helps you to buy the most suitable overhead cranes for you application, which will be the most economical solution for your application. The right selection of the crane duty cycle or classification will ensure the durability of the overhead crane and components to withstand the loads and usage requirements. Therefore to buy overhead crane, the crane duty classification have to be confirmed.
Two cranes with different duty classifications but with identical capacity and span may vary in price very largely. For high duty classification requires specialized components, such as, electric hoist, end carriage, electric motors, bearings, and crane controls, etc., whereas, the lower duty classification cranes are more standardized and matched with more economical components and parts, which will lower expense to a large degree.
And also you may have a long term plan, that you may expand your production in the future, in this way, your crane capacity may be higher or the number of lifts per day may be increased. In this way, you may want to spec the crane out so that it can support the needs of your future growth.
To select the suitable crane duty class or service class for your crane is very important for it will affect your initial investment and your future maintenance cost required. How to select the crane duty classification for your overhead crane? The following factors should be considered:
Other factors
The following factors do not affect the overhead crane classification directly , but they may affect the crane designing and specifying, which also should be noted.
For different countries, the crane duty classifications may vary however they are basicly the same. In the following, the Crane duty classifications from China and USA is presented for your reference.
There are six (6) different classifications for overhead cranes, specified by the Crane Manufacturers Association of America (CMAA). Overhead crane duty classification were established so that the manufacturer and end-user could design the most economical crane for the application, based mostly on the average rated load that the crane will lift, and how often the crane will be performing lifts.
Below we’ll identify and define the six types of overhead crane classes and provide types of businesses or industries that match up the best with each overhead crane classification.
Duty Class A1 (STANDBY SERVICE)
This duty classification covers cranes where precise handling of valuable machinery at slow speeds with long idle periods between lifts is required. Rated loads may be handled for initial installation of machinery and for infrequent maintenance.
Cranes of this duty class are usually used in power houses, public utilities, turbine rooms, nuclear reactor buildings, motor rooms, nuclear fuel handling and transformer stations.
Duty Class A2 (INFREQUENT USE)
These cranes will be used in installations where the loads are relatively light, the speeds are slow, and a low degree of control accuracy is required. The loads may vary anywhere from no load to full rated load with a frequency of a few lifts per day or month.
Cranes of this duty class are usually used in small maintenance shops, pump rooms, testing laboratories, etc.
Duty Class B (LIGHT SERVICE)
This duty classification covers cranes where service requirements are light and the speed is slow and loads may vary from no load to occasional full rated loads.
Cranes of this duty class are usually used in repair shops, light assembly operations, service buildings, light warehousing, etc.
Duty Class C (MODERATE SERVICE)
This duty service class covers cranes where service requirements are deemed moderate.
Cranes of this duty service class are usually used in machine shops, paper mill machine rooms, etc.
Duty Class D (HEAVY SERVICE)
In this type of duty service class, heavy-duty production is required but with no specific cycle of operations.
Cranes of this duty class are usually used in heavy machine shops, foundries, fabricating plants, steel warehouses, container yards, lumber mills, etc., and standard duty bucket and magnet operations where heavy-duty production is required.
Duty Class E (SEVERE SERVICE)
Typical examples of this duty class are magnet, bucket, magnet / bucket combination cranes for scrap yards, cement mills, lumber mills, fertilizer plants, container handling, etc.
Crane use level shows that the crane used frequently during the entire design life, According to the design life period general work cycle number N is divided into ten levels (see table 1).
Table 1:
Crane use level |
general work cycle number N | annotation |
| U0 | 1.6*104 |
Not often use |
| U1 | 2.2*104 | |
| U2 | 3.3*104 | |
| U3 | 1.25*105 | |
| U4 | 2.5*105 |
Free to use |
| U5 | 5*105 |
Often secondary to use |
| U6 | 1*106 |
Don't always busy to use |
| U7 U8 U9 |
2*106 4*106 >4*106 |
Busy use |
Load condition indicates that the degree of the crane load, related to two factors, Namely the ratio of hoisting of the load and the rated load Pi/Pmax, and the ratio of the role of various hoisting load number and the general work cycles ni/N. Indicated the two relations of load spectrum factor and Kp calculated by type:
In the formula:
Kp—load spectrum factorand;
ni—the effect number of load Pi;
N—general work cycles, N= ;
Pi—the I hoisting load, i=1,2….n;
Pmax—max lifting load;
m—index, in here m=3.
Crane load condition according to nominal load spectrum coefficient is divided into four (see table 2)
Table 2:
| Crane load condition | nominal load spectrum coefficient (Kp) | Explain |
| Q1-light Q2-middle Q3-heavy Q4-extra heavy |
0.125 0.25 0.5 1.0 |
Rarely lifting load rating Sometimes lifting load rating Often lifting load rating frequently lifting load rating |
Crane duty classification is divided into A1-A8 level. If compare with crane work type China’s regulations in the past, roughly equivalent to: A1-A4 light; A5-A6 middle; A7 heavy; A8 extra heavy.
The following table is the common crane duty classification for overhead crane, gantry crane, jib crane and other Types of cranes, etc.
For different types of overhead crane, the duty classification is also very different. In the following table, the main ducty classificaiton of overhead crane are presented for your reference. If you need to buy overhead crane and to confirm your overhead crane duty classification or duty service classification, please contact loal expert or leave a message below.
| Crane type | duty classification | ||
| Overhead crane | Hook type | Power station installation and maintenance | A1-A3 |
| In workshop and factory | A3-A5 | ||
| Heavy work with workshop and warehouse | A6-A7 | ||
| Grab type | Discontinuous load and unload | A6-A7 | |
| Continuous load and unload | A8 | ||
| Metallurgy type | Used for Lifting work bin | A7-A8 | |
| feed in raw material | A8 | ||
| Used for casting | A6-A8 | ||
| Used for forging | A7-A8 | ||
| Used for quenching | A8 | ||
| Used for clamping | A8 | ||
| Used for De-cap | A7-A8 | ||
| Material rake | A8 | ||
| Electromagnet type | A7-A8 | ||
| Gantry crane | General use hook type | A5-A6 |
| Loading and unloading with the grab bucket | A7-A8 | |
| Power station with hook type | A2-A3 | |
| Shipbuilding mounting hook type | A4-A5 | |
| Used for container | A6-A8 |
Gantry crane
| Loading bridge crane | Yard handling with the grab bucket | A7-A8 |
| Port with the grab bucket | A8 | |
| Port loading and unloading of containers | A6-A8 |
Loading bridge crane
| Portal jib crane | Installation used hook type | A3-A5 |
| Hook type used for loading and unloading | A6-A7 | |
| Loading and unloading with the grab bucket | A7-A8 |
Portal jib crane
| Tower crane | General construction and installation | A2-A4 |
| With bucket loading and unloading of concrete | A4-A6 |
Tower crane
| Crawling crane truck crane | Hook type | A1-A4 |
| Grab bucket | A4-A6 |
Crawling crane truck crane
In order to give you suitable crane solution and specific crane price promptly, please help our crane engineer to confirm the following information as much as possible:
If you do not know about how to select the crane, please feel free to leave us a message or email to sales@cranesdq.com. The reply of our crane engineer will be given within 24 hours. Get your custom design crane.
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