A fork truck is basically a ratio & proportion machine. Therefore , I don't see the formula you offer working very well. It can reasonable be said that each time you double the Load Center the capacity is reduced by about 50%. This is not perfect, but, it is close enough for rough calculations. One must also take into consideration the extra weight of any special forks or attachment above the weight of normal forks. As said above, this is not perfect but it will help you from making a gross capacity error.
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