Trying to recall the name of it..
Plate loaded machines (some models similar to Hammer Strength design) that allowed you to overload the negative portion of the rep. For example, on the preacher curl you could load 100 lbs* on it and curl with 60lbs of weight on the positive portion, but the negative portion would be the full 100 lbs. Anyone remember the line?
*100 lbs is just an example for the 15" pipe cleaners that are prominent in the gyms today.