The Mechanical Handling and Storing of Material

CONVEYORS A. Appliances consisting of a Stationary Trough in which the Material is conveyed by Means of a Continuous Pushing Device. B. Appliances with a Stationary Trough in which the Material IS CONVEYED BY MEANS OF A RECIPROCATING PUSHING DEVICE. C. Appliances in which the Trough containing the Material Moves Bodily with the Material. D. Appliances in which the Material is conveyed by the Action of a Semi-Stationary Reciprocating Trough. CHAPTER 111 INTRODUCTORY REMARKS By the name conveyor is generally understood a machine for mechanically transporting materials in a horizontal or slightly inclined direction. In the following seven chapters conveyors of different types are dealt with. Before, however, entering into the various constructions of these appliances, their utility, peculiarity, capacity, and the driving- power required, it will be well to give a few introductory remarks as to the behaviour of different materials when being handled by these various machines. Conveyors of almost q,11 known forms of construction are more or less suitable for the mechanical handling of such materials as minerals, coal, coke, stone, clinker, gravel, seeds, cereals, oil seeds and nuts, but small materials such as cement, plaster of Paris, fine sand, and the powders produced by grinding or crushing the first named substances, as well as sugar, salt, and spices, are all more or less difficult to handle, and indeed only a limited number of types of conveyor can be used for this purpose, and even then often only with indifferent success. The reasons why fine material is so much more difficult to handle than coarse are various, and one of the principal is the production of dust at the slightest agitation, so that a conveyor which moves the material by a stirring, pulling, or pushing device must be enclosed, to prevent the escape of dust and consequent loss, as well as injury to the workmen. Even with conveyors which perform their functions without this agitation, and in which the material is carried as it is on a belt conveyor, the usual high speed at which these conveyors work will create dust by the resistance of the air to the passage of the material. There are also other difficulties, caused by the great difference in the consistency of fine materials. Some are of a lively nature and run through the fingers if an attempt is made to get a handful, and this class of stuff needs a close-fitting conveyor, say of the push-plate or worm type, for its handling, as on a belt conveyor there is a great tendency for it to run off, unless the belt is well troughed. Other fine materials are of 40