Example:

Cantilever Beam is carrying a uniformly distributed load ‘UDL’ of 0.8 kilo Newton/meter at a distance of 1.5 meters from the free end and also a point load of 2 kilo Newton at a distance of 1.5 meters from the free end. Now, due to the specific downward acting rule, the reaction is RA at point A and we have to find out this reaction. As per shear force diagram calculations, upward forces are set negative, while downward forces are set positive.