113-2907 Excavator Idler Roller E320/E200B The function of an idler is to guide the track links into running smoothly and to prevent dislocation,idlers also carry some weight and therefore increasing groud pressure.there is also an arm in the center which supports the track link and guides the two sides.the smaller the distance between the idler and track roller,the better the orientation. Our products are according to the standard of OEM to manufacture.