an oil skimmer of the endless belt type which is transportable as a unit is disclosed . the unit has an adjustment for adjusting the location of the axis of head pulley rotation and a floating tail pulley to assure accurate tracking of the belts on the pulleys and consistent and appropriate tension on the belt . the tail pulley features l - shaped spokes having legs that provide limited pulley - to - belt contact , minimizing oil transfer from the belt to the tail pulley , and also providing a mechanism for forcing oil against a descending belt reach to provide enhanced oil pick - up .