- Technical documentation
- How to choose the operating mode of the crane
How to choose the operating mode of the crane
When forming the technical specification for the order of lifting equipment, in particular bridge cranes, cantilever cranes, gantry cranes, the customer must, in addition to the basic requirements, decide on the choice of the operating mode of the crane.
- What is the operating mode?
- How do I choose the most appropriate mode?
- Is there a need to select the operating mode "with a margin"?
So, let's try to figure it out
The operating mode determines, first of all, the intensity of the equipment, the frequency of its use and the degree of load. It is important that it is in the Customer's operating conditions that the cranes can be successfully operated throughout their entire service life.
It should be understood that the operating mode directly affects the complexity of manufacturing equipment, the cost of components, which certainly affects the final price. Therefore, you should not choose an increased mode of operation without an objective need. At the same time, it is also not worth trying to save money if the crane will be operated with high intensity. This will quickly wear out the mechanisms, increase downtime, frequency of repairs and, ultimately, shorten the service life of the equipment. The light mode is not applicable for frequent loads exceeding the rated load capacity.
How to determine the degree of activity of working with the equipment, if you purchase a crane for the first time?
If you do not have specific data on the nature of the loads and the purpose of the crane, you can choose the appropriate operating mode in accordance with the tables provided in the regulatory documents.
To select the operating mode, it is necessary to follow 3 parameters according to GOST 25835-83: class of use, class of loading, operating time of the mechanism, during which it is in motion.
The total operating time of the mechanism — its machine time Tmash is determined in hours by the formula
tc— the average daily operating time of the mechanism, at which it is in motion( action), h;
pd — the number of working days in a year, pd= 250-for two days off per week, for one and for continuous production;
tk— the service life of the mechanism in years before major repairs or before decommissioning, tK= 15-25 years.
Thus, provided that the crane is operated in the order of 5 hours per day, its machine time will be (for cranes with a service life of 25 years):
Based on the calculation data, you can select the use class (see Table 1 of GOST 25835-83)
In our case, the appropriate use class is C5
Next, you need to determine the loading class Q (Table 2 of GOST 25835-83)
Kr = ∑ (Qi / Q))3 Si / St ,
- Q-cargo weight, actual and nominal
- C — the number of cycles of operation of the crane with a load of actual weight, the number of cycles of operation of the crane over its service life
Suppose that the crane lifts a load weighing 3.0 tons with a load capacity of 5.0 tons for 1.5 * 104 hours during the service life, in this case K will be 0.103, which corresponds to the load class Q1
We select the operating mode group according to Table 3 of GOST 25835-83:
at the intersection of column Q1 and row C5, we get a group of 4K, which corresponds to the operation mode A4 according to ISO 4301-1-86.