The Mechanical Handling and Storing of Material

BAND CONVEYORS a case the position of the carriage when not in use is immaterial, as the grain can proceed through this third outlet uninterruptedly. Band conveyors can be fed without any difficulty; but it has been found necessary to slide the grain upon them from the feeding hopper through a shoot rather less than half the breadth of the band and set at an incline of 42J degrees to the horizontal, to give the grain falling upon the band a horizontal velocity nearly equal to that of the band. It is very important to regulate the feed of the band, if only to minimise wear as much as possible, especially when conveying coal and other sharp-edged material. The material should not strike the band vertically, whilst the height from which it falls must be reduced as much as possible to allow of a gentle drop. As the flow by gravity of grain of various kinds and in varying condition through a spout differs considerably, it is advisable to place a pair of oblique side rollers at the point where the grain falls upon the band as already mentioned, for the purpose of preventing the tendency of the grain to spread. In passing heavy quantities of grain along the band for a considerable distance it has also been found expedient to apply Fig. 107. Non-adjustable Type of Throw-off Carriage. at intervals pairs of these oblique side rollers, which are carried in movable frames which can be set at any required spot. All conveyors which are intended for intermediate delivery by means of an adjustable throw-off carriage must be fitted with tightening gears as shown in Figs. 102 and 103, because the use of such throw-off carriages necessitates additional length of conveyor band, which must be disposed of whenever the carriage is out of use. These tightening arrangements provide suitable accommodation for such extra length of band. As there is sometimes a tendency for the band to make a side movement on its rollers, so that the centre of the band is not in the centre of its supports, the employment of one or more pairs of small rollers placed against the edge of the belt is sometimes resorted to to prevent this, but this should not be necessary if the belt is well made, and if the idlers are all parallel and true. Belt conveyors require no particularly rigid structure, and are, therefore, very suitable for temporary or contractors’ work, provided that the conveyor is of itself suitable for the work. 1 he belt conveyor is now a very popular means of conveying both heavy and light materials. When first introduced, about 1868, by Mr George Fosbery Lyster, engineer to the Mersey Dock and Harbour Board, it was used for conveying cereals and seeds only, but between the years 1885 and 1890 a number of more or less experimental plants were erected for minerals, and the credit for this extension of the utility of band