Classification of cranes and mechanisms

The KPK crane and mechanism classification according to STN ISO 4301 and the FEM (European Crane Federation) standard specifies the classification groups for cranes and their mechanisms.

It is used in commercial and technical negotiations between the buyer and the crane manufacturer to determine the required crane performance and as a basis for the designer to prepare an analysis of the crane and its mechanism. Selecting the appropriate crane classification or crane duty cycle is important for customers who wish to balance the initial investment in a crane system with the required future maintenance costs.

To ensure your crane meets the correct duty cycle and classification, you need to determine the four most important requirements:

Rated load - an estimate of the load that can be lifted at or near maximum load.

Service - total hours worked per day

Lift - average number of lift, tram and bridge trips per hour

Distance - average distance per move

Other factors may not directly affect the classification of a crane, but should be considered when designing and specifying a crane:

Speed - How fast can the crane move materials or equipment? How many lifts per hour can it make?

Maintenance requirements

Operating environment

Future needs

Why should cranes be classified according to duty cycle or service class?

Crane service classification allows you to select and manufacture the most economical and safest crane for your lifting application.

KPK experts will help you classify your crane according to the above criteria.

Load spectrum classes Q1 to Q4

Q1 - The structure can carry a specifically rated load and is usually lightly loaded

Q2 - The structure is rarely loaded with the rated load, usually about 1/3 of the rated load

Q3 - The structure is usually loaded with the full rated load, usually 1/3 to 2/3 of the rated load

Q4 - The structure is often loaded with loads close to its rated load.

General classification of cranes according to ISO 4301/1 (classes A1 to A8)

When calculating the classification, it is assumed that the crane's operating cycle starts when it is ready to lift a load and ends when it is ready to lift the next load.

The following table shows some examples of classification of cranes and their mechanisms according to their purpose.

When selecting a hoist type, in addition to determining the hoist's load-bearing capacity based on the maximum weight of the goods being transported, the correct classification of the lifting mechanism is also important.

Classification of mechanisms, such as lifting, walking, etc.

The total working time of the mechanism is the theoretical time, which is used for the design of mechanical parts such as bearings, gears and shafts.

The operating time Tm is only regarded as the time when the mechanism is under load.

According to the ISO standard, the load state of the mechanism is L1 to L4 (1 to 4 by finite element method):

L1 (by finite element 1) The mechanism or mechanical element is subjected to the maximum frequency of use in special cases, but is usually rarely used.

L2 (by finite element analysis, 2) The mechanism or mechanical element is usually the most frequently used, but the frequency of use is usually low.

L3 (by finite element analysis, 3) The mechanism or mechanical element tends to be the most frequently used, but the frequency is usually average.

L4 (by finite element analysis, 4) The mechanism or mechanical element is frequently used at a frequency close to the maximum frequency of use.

Table 2 - Loading mechanism conditions based on ISO and FEA

Table 3 - Relationship between classification according to FEM, ISO and GOST.

Example of classification calculation

1.1 Input data

Maximum transport weight Q = 5 000 kg

Average hook path H = 4 m

Number of cycles per hour C = 20

Required lifting speed V = 8 m/min

Lifting mechanism operating time T = 8 hours per day

Medium-sized mechanism group

1.2 Calculation

Average daily operating time Tm:

Tm = ( 2 * H * C * T ) / ( 60 * V ) = ( 2 * 4 * 20 * 8 ) / (60 * 8) = 2,66 hours

According to Table 2 for medium operation is the lifting mechanism classification FEM – 2m (ISO -M5)

1.3 Choice of hoist

For lifting the load it is necessary to chose the hoist with carrying capacity 5000 kg, lifting speed 8 m/min and with classification according FEM 2m.