I want the details please. I know when the pushrod goes and the bottle starts letting brake fluid in then it returns. But how does the mechanism work. Is it that the pushrod pushs the rod blocking the bottle/tank full of brake fluid then when you press the brake and then when you let go the rod goes back to blocking it??
That bottle is the brake cylinder or servo. When it fills it does just what you say. But, when you release the brake the pressure of the fluid is released it is still in there but there is no longer anything to keep the pressure high and it needs to be returned to the reservoir. That is where the return spring comes in. It pulls the brake pads back to their original position and also forces the push rod back down.
