I have that feature on a MF 2660 81 horse tractor. Pure pain in the butt and of no real value. Something to add complexity and haunt you eventually. First off, it just allows a gravity dump if you have a heavy bucket load to go faster than it would under power. Whoopeee. Apparently the feature was intended for commercial users of larger tractors where time equals money and someone probably lobbied for the feature (or more likely the foolish marketing people THOUGHT someone wanted it.) In any case the primary result is a more complex and expensive loader valve which is finicky to adjust and more prone to failure. I have been so P.O.'d at that loader valve ... long story involving not only a bad original from the factory but another bad one from AGCO depot parts via a dealer. Would not allow forcing the bucket tip down in curl. Eventually fixed it myself using a kit from the valve manufacturer (Nimco.) Over the next 3yrs the loader valve developed complete slowdown and "won't work at all" until the oil gets hot. That is cause for a new set of seals which a dealer says will cure the issue. In my book the BEST loader valve is the simplest one, typical of small to medium sized farm tractors that has NO special features, NO fast dump and just does what it is told to do. I'm literally ready to throw this $1100 loader valve away and put on a simple one if the new seals don't solve the problems.