FEM SERVICE CLASS

To determine your crane duty group (according to FEM, Fédération Européene de la Manutention) you need following factors:

1) Load spectrum (Indicates the frequency of maximum and smaller loadings during examined time
period).

2) Class of utilization (This is determined according to number of hoisting cycles during lifetime of crane)

3) Combining these factors is how a duty group is selected.

Example of different load spectrums:

Calculate the Average Daily Operating Time

t = (2 x H x N x T) / (V x 60)

Where:

 H = average hoisting height (m or feet)
 N = number of work cycles per hour (cycle/hour)
 T = daily working time (h)
 V = hoisting speed (m/min or feet/min)

AISE SERVICE CLASS

AISE also provides for different service classes for cranes covered under AISE Technical Report No. 6, "Specifications for Electric Overhead Traveling Cranes for Steel Mill Service". Like CMAA, AISE also provides a numerical method for determining crane class based on the expected load spectrum. Without getting into the specifics of this method, AISE does generally describe the different service classes (load cycles) as follows:

1. Service Class 1 (N1): Less than 100,000 cycles

2. Service Class 2 (N2): 100,000 to 500,000 cycles

3. Service Class 3 (N3): 500,000 to 2,000,000 cycles

4. Service Class 4 (N4): Over 2,000,000 cycles

Further AISE describe the different Load Classes as

1. L1= Cranes which hoist the rated load exceptionally, and normally hoist very light loads

2. L2= Cranes which rarely hoist the rated load, and normally hoist loads about 1/3 the rated capacity

3. L3= Cranes which hoist the rated load fairly frequently, and normally hoist loads between 1/2 and 2/3 or the rated capacity

4. L4= Cranes which are regularly loaded close to the rated capacity

Based on the load classes and load cycles, the CMMA chart below helps determine the class of the crane.