Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/708006
32 AGGREGATES MANAGER / July 2016 EQUIPMENT MANAGEMENT ile materials may degrade at loading and discharge points, as well as when moved over idlers. Therefore, these types of materials should also be con- veyed at lower speeds. As stated previously, belt capaci- ty increases with the increase of belt width. It is important to know the tons per hour of material an end user ex- pects to move with a conveyor. If there is uniform feed to the conveyor, a cross section of the material loaded on the belt is used in calculating the capac- ity of a conveyor. The cross section of material must meet the following two conditions: - The material does not extend beyond the belt edge or the distance recom- mended by the Conveyor Equipment Manufacturers Association, and - The top of the load does not exceed the surcharge angle of loading. Idler selection All belt conveyor idlers have the same purpose. They provide shape and support for the belt and minimize the power needed to transport material. Idler spacing affects both the shape and support of the conveyor belt. Idlers placed too far apart will not properly support the belt or enable it to maintain the desired profi le. Idlers that are placed too close together will provide the necessary support and profi le, but may add a prodigal expense to the conveyor. The main infl uences in idler selection are belt weight, material weight, idler load rating, belt sag, idler life, belt rating, and belt tension. Proper idler roll diameter and size of bearing and shaft selection is based on load carried, belt speed, and operating conditions. Pulley and shaft selection The standardization of pulleys lends itself to the ease of choosing the correct pulley for a given application. The most commonly used pulley is the standard steel pulley. Plain steel drum pulleys are best used in dry clean environments where traction is not critical and when no foreign material is present on the return belt. Conveyor pulleys may also be covered with rubber, fabric, or other material. This is referred to as lagging. Lagging on a drive pulley provides an increase in the friction between the belt and the pulley. Lagging is also used to reduce abrasive wear to the face of the pulley and to create a self-cleaning The pile under this conveyor was partially caused by carryback, which stuck to the bottom side of the conveyor belt. A combination of primary and secondary belt cleaners is used to ensure carryback ejects at the conveyor's discharge point.