Spring pull to the linkage to fully open the throttle. Governor arm pulls against the spring to pull throttle to idle. Its a balancing act from there. If the spring wasn't present and the governor is working correctly it would only idle.
Okay picture 2 (mower_10.jpeg) shown the engine running at fully throttle and you saying lost control of the revs it sounds like you have the static governor adjustment off or the governor/oil slinger has failed.
First try doing a static governor adjustment. Base the deck image the head is located forward. If so the adjustment is located on the right side close to tank in the image. Loosen the retainer screw and while the throttle is held at full turn the shaft CW to stop and tighten the screw back. Then test run if things are okay it should now govern the engine; otherwise, it would indicate a fail governor. The only wayto know for sure then is to go in and check the governor/oil slinger assembly.
