The importance of the load centre can be seen in the diagram above. It is necessary to look at it from the point of view of the person designing the forklift. In order to calculate how much weight to put on the rear end of the truck to keep it stable, the designer does a series of calculations. The dimension on the right-hand side shown by a series question marks is used in these calculations.
The reason for the question marks is that, on the face of it, the truck designer would not know this dimension. It can be worked out however because the dimension from the front wheel centreline to the front face of the forks is within the control of the designer. To this is added the 500 mm load centre which the designer knows is standard.
Providing nothing is done by the operator to increase the load centre the calculations will work but the minute the operator causes the load centre to increase then the calculations fail.
It should also be noted that just because a smaller load centre is used it does not follow that the truck can lift any extra capacity. This is not due to stability but mechanical reasons such as component strengths etc.