Troughing idler is a belt idler having two or more rolls arranged to turn up the edges of the belt so as to form the belt into a trough. Most commonly used troughing idler is made with concentrator rollers set at 20°, 35°, or 45° angles to the center roller. This idler is a standard 6-inch steel shell roll running in anti-friction bearings. A troughing idler of an enclosed belt conveyor has a horizontal shaft that is supported by antifriction bearings mounted outside of the sidewalls of the trunking and carries a medial roller.