Square lifting

Hello everyone!!
Well, I have been with a Renault engine (a K4M 804) and it turns out that in the camshaft cover I have seen a kind of valve that consisted of a little bit with a spring that attacked a square lite. I have left me intrigued what it could, so I have put myself in the Renault Modus workshop manual, and the manual calls it "square lifting" and has not taken me out of doubt from the mission that this gadget has,
does anyone know what Mission has?

It seems to me that, being in the escape tree, it makes the function of cushioning or maintain the position of the tree when the advance variator that it carries acts, but I do not know if I am right, because there is not much information on this 2 "courage pusher." Greetings!!