Classification of Hoisting Mechanism

The classification of KPK cranes and their mechanisms according to the standards STN ISO 4301 and FEM (Federation Europeenne de la Manutention) specifies the group into which the crane and its mechanisms are classified.

It serves:

  1. for commercial and technical negotiations between buyer and crane manufacturer for determination of required crane performance
  2. as a bases for the designer to prepare the analyses of crane and its mechanisms.

The crane and its mechanisms classification class is specified on the base of assumed kind of operation (light, medium, heavy, very heavy) and of the operation cycles number. The correct classification ensures the correct dimensioning of the equipment. The high classification classis, for example FEM 3m(M6), FEM 4(M7) and A6-A8 (J3-J6) are typical for cranes with high operating speeds and cranes loaded with loads corresponding to the crane carrying capacity, or for cranes operating in automatic mode.

The KPK specialists are always ready to provide help by classifying the crane according to the above standards.

The following table shows several examples of classification for cranes and their mechanisms depending on crane application.

 

Group classification

Application

of hoisting mechanism according to FEM 9.511 (STN ISO 4301) of crane as a complete unit according to STN ISO 4301 (STN 270103)
Maintenance and assembly cranes for occasional use 1Bm
(M3)
A3 till A4 (J1 till J2)
Assembly cranes for regular use 1Am
(M4)
A3 till A5 (J2 till J3)
Workshop use 1Bm till 1Am (M3 to M4) A3 till A5 (J2 till J3)
Warehouse cranes 2m till 3m (M5 to M6) A4 till A6 (J2 till J3)
Magnet cranes 3m till 4m (M6 to M7) A6 till A8 (J3 till J6)
Automatic and special cranes 4m till 5m (M7 to M8) A6 till A8 (J3 till J6)

By selection of hoist type (hoisting mechanism) it is important besides the specification of hoist carrying capacity according to the maximum weight of transporting load also the correct classification of hoisting mechanism.

The classification of hoisting mechanism depends on the average daily operating time Tm and on the load spectrum (rate of loading).

Tab.2- Determination of hoisting mechanism classification according to load spectrum and average daily operating time Tm

Klasifikácia 1

Tab.3 – Relation between the classification according to FEM , ISO and GOST.

ISO
4301-1
M1 M2 M3 M4 M5 M6 M7 M8
FEM
9.511
1Dm 1Cm 1Bm 1Am 2m 3m 4m 5m
GOST     1M 2M 3M 4M 5M  
% ED     25 30 40 50 60  
c/h 90 120 150 180 240 300 360 360
Klasifikácia 3 Klasifikácia 3

Intermittent Rating (%ED), Max.Number of Starts Per Hour

%ED = [ (t1 + t3) / (t1 + t2 + t3 + t4 ) ] * 100

Average daily operating time Tm

Depends on operation time per day.It is calculated according to the following formula:

Tm = ( 2 * H * C * T ) / ( 60 * V ) [ hour / day ]
Average hook path H [m]

H – Average hook path [ m ]

C – number of cycles per hour [ – ]

T – working hours per day [ hour ]

V – hoisting speed [ m/min ]

 

Mechanism load spectrum

Classification - Light – occasional lifting of maximum load
– medium load from suspension means, for example from traverse-beam
Classification - Medium – occasional lifting of maximum load
– regular lifting of low weight load
– medium load from suspension means, for example from traverse-beam
Classification - Heavy – frequent lifting of maximum load
– regular lifting of load with medium weight
– big load from suspension means, for example from traverse-beam
Classification - Very heavy – regular lifting of maximum load
– very big load from suspension means, for example from traverse-beam

 

Example of classification calculation

1.1 Input data

  • maximum weight of transported load Q = 5 000 kg
  • average hook path H = 4 m
  • number of cycles per hour C = 20
  • required lifting speed V = 8 m/min
  • working hours lifting mechanism T = 8 hours per day
  • medium 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.

Comparison of two identical cranes with different classification of lifting mechanism