^Troughing sets 3.2 - Choice of troughing sets When choosing the troughing sets and their arrangements during the project phase of the construction of a belt conveyor the following factors must be considered: - total load capacity in tons/hour of conveyed material - belt speed - belt, single directional or reversible - lump size of material and its angle of repose - temperature and environmental challenge - characteristics of load, humidity and material abrasiveness - type, flexibility and weight of rubber belt. The development of detail concerning the above considerations is contained in chapter 1 - technical information. Defining the belt width, in relation to the flow of conveyed material and establishing the speed, allows the choice to be made of the type of transom support and the correct roller series, matching the working conditions. Above all when the rollers are subjected to a corrosive environment or materials (salt, chemical substances, etc.) very careful attention should be paid in their choice. In the same way the transoms that carry the rollers must be protected with a suitable galvanised treatment. The weight of the material determines the dynamic load which the troughing set has to sustain and also defines the pitch of the sets in the upper carrying sections of the belt. In practice the type of troughing set is chosen that meets the criteria of load together with the use of the minimum rubber belt width to provide the most economic solution. The choice of the return sets is also important, in that they take account of the belt centralising and cleaning conditions. In fact on the return sets the rollers are in contact with the dirty side of the belt and thus face a variety of problems.

The residual material remains attached to the return section of the belt and may deposit onto the rollers in a non uniform way that promotes belt drifting and premature wear. This material may act to abrade the roller shell in a serious way and place a critically high demand on the protection qualities of the sealing system of the roller bearings. Therefore the solution must be to put in place the very best belt cleaning system, utilising the auto centralising system (self centralising troughing sets) and in the use of rollers with rubber rings that permits residual material to fall freely to...