The Mechanical Handling and Storing of Material

.56 THE MECHANICAL HANDLING OF MATERIAL To the four inner sides of this tube are attached oblique blades, forming an unbroken •sequence of oblique channels on each side for the whole length of the conveyor. These blades do not extend across the whole sides of the tube, but are only half as wide as the sides, and leave a longitudinal channel quite unobstructed by blades in each of the four •corners of the tube. For example, a 12-in. tube (inside measurement) has blades on each side 6 in. wide, leaving a space of 3 by 3 in. in each corner the whole length of the conveyor. When at work the action is as follows : Supposing the whole of the material in the conveyor rest;all along one of the corners, and as this corner slowly moves upwards the underside of the tube changes .its horizontal position for a slanting one, and as soon as the angle is sufficiently steep, the whole of the contents of the corner is forced by the law of gravity to slide across the oblique channels into the next corner, and in doing this it travels forward by the pitch of the channels or blades. This process repeats itself four times in every revolution. The very considerable slope of 45 degrees can be given to the blades, so that with each quarter revolution in a 12-in. tube the material moves theoretically 6 in. forward, or 2 ft. with every revolution. This is practically equal to a 12-in. worm with a 24-in. pitch, if it were possible to make such a worm of the ordinary continuous type, which it is not, on account of the difficulty and expense of bending the blades to such a pitch, and for that reason a square tube like the Suess has a much larger capacity than a cylinder of the same size. With the Suess conveyor a single internal screw formed of four blades would not give a very positive result, as only part of the material would follow the oblique path, and in order to get the highest efficiency the oblique blades are placed at such a distance apart as to form a five-fold or five threaded screw, so that practically every particle is forced forward in its appointed channel. The conveyor is made in lengths of from 15 to 20 ft., and joined together with flanges. These are turned on the face and periphery, and are used at the same time as supports for the conveyor, resting on a series of pairs of rollers. The rollers are provided with flanges to prevent end movement.There is also a flexible packing- ring between each pair of couplings, so that a slight variation from the straight line in the erection is not detrimental.