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What does the FEM class or ISO standard for lifting equipment entail?

Posted on 29-4-2020 by Nicky

What does the FEM class or ISO standard for lifting equipment entail?

The FEM class classification for hoist consist of: 1Dm, 1Cm, 1Bm, 1Am, 2m, 3m, 4m, and 5m. The classification according to ISO consists of M1, M2, M3, M4, M5, M6, M7, and M8. FEM and ISO are organizations that publish standards among other things. FEM and ISO are equivalent (1Dm=1, 1Cm=2, 1Bm=3 and more) The FEM/ISO classification has a goal to ensure and guarantee a certain lifespan of hoists.

The lifespan depends on the nature of the load (load spectrum) of the hoist, lifting speed, lifting height, and duty cycle. 5M, 8M is for heavier application than 1Bm; M3. S.W.P. (Safe Working Period) has to do with the theoretical lifespan of hoists depending on the load, this theoretical lifespan is shown in the chart below.

The duty cycle of electric hoists

The duty cycle (E.D. in %) is the ratio between the operating time and the operating plus standstill time. The duty cycle depends on the permitted heating of the motor. The standard rule, the maximum operating temperature is achieved with continuous use for a period calculated as follows: Time maximum operating temperature =% E.D. x 60 minutes.

After reaching the maximum operating temperature, an operating cycle of 10 minutes is maintained, with the duty cycle being the number of minutes of operating time. After that, a rest time of 10 minutes minus the operating time applies.


duty cycle = 25%
The maximum operating temperature is reached after 0.25 x 60 minutes = 15 minutes of continuous use. After that, the operating cycle is 2.5 minutes of operating time and 7.5 minutes of rest.

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