Here is something thats probably what you have herd of.

http://www.gebrueder-fruehauf.de/bilder/bilderneu05/sus1.jpg

It looks as if the sear engages the hammer at the top so it gets a better leavarage and reduces the
power that is needed to disengage it. And it seems as if the safe grips where the "ordinary" sear grips on the hammer, i think anyway.