State of loading for the crane as a whole.
| State of loading | Nominal load spectrum factor, Km | Descriptive definition |
| L1 Light | 0.5 | Mechanisms subjected very rarely and normally light loads |
| L2 Modarate | 0.63 | Mechanisms occasionally subjected to their maximum load, but normally to rather light loads |
| L3 Heavy | 0.8 | Mechanisms frequently subjected to their maximum load and normally to loads of medium magnitude
|
| L4 Very Heavy | 1 | Mechanisms regularly subjected to their maximum load
|
Load spectrum factor can be calculated using the following method.
P1 - load corresponding to operating time t1
Pmax - rated load
t1 , t2 , etc. - operating time for individual loads P1 ,P2 , etc.
T - total operating time
Step 1: Select Class of utilisation
Classes of utilisation of mechanisms
| Class of utilisation | Service life hours | Assumed average daily utilisation time in hours | Remarks |
| T1 | 400 | ≤ 0.25 | Irregular use |
| T2 | 800 | > 0.25 & ≤ 0.5
| Irregular use
|
| T3 | 1600 | > 0.5 & ≤ 1
| Irregular use
|
| T4 | 3200 | > 1 & ≤ 2 | Regular light use
|
| T5 | 6300 | > 2 & ≤ 4 | Regular intermittent use
|
| T6 | 12000 | > 4 & ≤ 8
| Regular intensive use
|
| T7 | 25000 | > 8 & ≤ 16
| Continuous intensive use |
| T8 | 50000 | > 16
| Continuous intensive use
|
| T9 | 50000 | > 16
| Continuous intensive use
|
Step 2: Find the crane mechanism classification based on the class of utilisation (T1 - T8) and Km factor (0.5 - 1).
Group classification of crane mechanism
| State of loading | Km | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 |
| L1 Light | 0.5 | M3 | M3
| M3
| M3
| M4 | M5 | M6 | M7 | M8 |
| L2 Moderate | 0.63 | M3
| M3
| M3
| M4
| M5
| M6
| M7
| M8
| M8
|
| L3 Heavy | 0.8 | M3
| M3
| M4
| M5
| M6
| M7
| M8
| M8
| M8
|
| L4 Very Heavy | 1 | M3
| M4
| M5
| M6
| M7
| M8
| M8
| M8
| M8
|
Crane mechanism classification
