Really, a pretty simple device. You've already mentioned one of the important parts, but another is the water heater on the inside bottom of the washer. At least here in the U.S. you'll see a tube running around the inside bottom which provides firaly high water temperature and the heat to dry the dishes at the end of the cycle. What you can't see is under the outside bottom, which is the pump or pumps, depending on the make. The pump pushes the water through the spray arms at fairly high pressure and also evacuates the used water from inside. About only thing left is the timing devices for various cycles...