Thanks for your interest Klaus. The roller is used in forming sheet metal. Therefore, it is imperative that both ends are adjustable. In practice, the left end is adjusted up or down as required for a variety of thicknesses and bend radii. This up or down adjustment is constantly measured electrically with a 10 turn potentiometer mounted on the left end. The right end follows at a slight delay - according to the potentiometer reading on the left. An identical potentiometer is also mounted on the right end. Right end adjustment is confirmed and matched by the resultant measurement. So the lefthand pot senses direction and amount of movement first. The circuit then uses that information to instruct the direction of movement on the right end. The reading obtained from the righthand pot is used to measure and confirm stopping point. In a sense, the system actually does the leveling on the right end by moving to the appropriate level to match the left. When this operates properly, the balance and level is maintained.