ZBrushCentral

Gouge brush behaves unpredictable

Hi,

how exactly is the gouge brush in Z3.5r3 supposed to behave?
I get a kind of inconsistent outcome. Sometimes it fades out, sometimes it produces a long deep stroke without any fade. Sometimes it fades very fast, sometimes more slowly. Neither speed nor pressure or direction of the stroke seem to explain those jumps in behaviour. So from which values is it derived?
As I read it is supposed to keep the form of the mesh and that seems to explain that the stroke is not actually fading but sinking into the surface and rising again on the other side of an elevation. (Be it the curvature of a sphere or the edge of cube. Almost mirrorlike or as if there was a plane running underneath. ) But even then, it sometimes will go all around the edge or curvature. As you see, I didn’t really understand the point and working of that brush but would like to. The Icon of that brush leaves me even more confused since it seems to show some kind of excavation.
I couldn’t find any documentation and my installation of r3 seems to be missing the helpfiles except the pdf’s for the new features. I remember being able to download helpfiles for 3.1 . Is there something similar for 3.5.r3?