Figure I - When there is no pressure on the arm, or pressure is released, the trem will be at/return to what is know as the Zero Point. This is the point at which the pull of the strings and springs equal each other and the angle the trem rests at.
Figure II - When the arm is pushed down, the trem will tilt forward, the strings will relax, and the springs will be stretched.
Figure III- When the arm is pulled, the trem is tilted back/down, the strings are stretched, and the springs are relaxed.
The tension on the strings, whether they are stretched or relaxed, will raise and lower the pitch respectively. This is how the Floyd-type trem actually changes the pitch of notes.