Originally Posted by
OSAVIP
They provide an increased range of stab trim travel which is sometimes used to set takeoff trim with aft cg conditions. The signal also overrides or neutralizes (depending on model) any other conflicting trim inputs. Levers or switches are simple push-pull operation, spring loaded to neutral position.
Ah, spring loaded, I see now... thanks. Just looking at them I'd assumed that if you pulled it to a certain position that it would stay there. Good to know.