Effective Grade (Static Force)
Rolling resistance is combined with the grade of a slope to determine the effective grade (or static force applied to the truck).
In up-hill calculations:
the effective grade (resistance)% = grade% + rolling resistance%
Conversely, for down-hill calculations:
the effective grade% = grade% - rolling resistance
Example Effective Grade:
Taking a loaded truck of 376t (GVM) as an example, on a uphill ramp of 8% grade and a rolling resistance of 2%, the effective grade will be 10% and the static force on the truck will be 376 x 0.1 = 37.6tf (or 37,600 kgf).
Note: This isn't quite the maths, this has been simplified to avoid learning too much physics. Your static force will be around 1% less than this, if you're interested in static force calculations, as a starting point, please visit: