Craig, The systems will vary, as will the opinions of how they work best, but the way I see it...The handle, locks the plate in the optimum position for a properly trimed ride. The down pedal..will slow the boat down by droping the hull deeper in the water, acting sorta like a brake at the same time, allowing better control thru the turns,(as in circle racing flats), and the up pedal..After setting the handle for the conditions of the water etc. the plate is held up by the spring tension on the control arm link, (long one from the handle/pedals to the back), But the down pedal must be able to overcome the spring to lower the plate, as a result, some conditions will suck the plate down when you don't want it down, So the UP pedal allows the driver to raise the plate away from this unwanted suction. Once the boat is truly set up with the correct spring pressure, meaning enough to keep the plate up, but still allow the driver to overcome the spring (without having weight lifter thighs and calfs) to lower the plate when it is needed.. I'm sure others here can explain it better, but that's my .02 and I hope it answered your question...Moneypitt