The Mechanical Handling and Storing of Material

PUSH-PLATE OR SCRAPER CONVEYORS 67 24 in. apart, running at 48 ft. per minute, would deliver about 20 tons of coke per hour. Table giving Approximate Capacities of Rectangular Troughed Push-Plate Conveyors for Coal in Tons per Hour at a. Speed of 100 Feet per Minute Width of Scraper. Height of Scraper. For Horizontal Conveyors. Pitch of Scraper Blades. For Conveyors with Blades 24 in. pitch and inclined at Inches. 10 12 12 15 18 18 20 24 24 Inches. 4 4 5 5 6 8 8 8 10 16 in. 17 22 26 35 18 in. 15 19 •23 31 40 60 ... 24 in. 11 14 17 23 30 45 52 67 86 10° 9 12 14 •20 25 36 42 60 75 •20° 7 9 11 16 '20 28 33 48 60 30° 5 6 8 11 15 24 28 36 45 Capacities for other speeds in proportion. Power Required to Drive Push-Plate Conveyors.—This must depend on the nature of the material to be conveyed and on the condition of the trough. For instance, cement clinker and coke would take more power to convey than coal; but as this type of conveyor is altogether unsuited for hard and cutting substances on account of the great wear and tear, no examples are here given of a conveyor for such materials, the following figures being for coal conveying. A push-plate conveyor, 100 ft. long, conveying coal at the rate of 50 tons per hour, will require a driving power of 12 H.P. Timber Conveyors.—A conveyor on the same underlying principle, but of a much more substantial design, is frequently used in the lumber trade of North America. T his conveyor will handle large baulks of timber. The chains of the conveyor are very strong, and are fitted at regular intervals with jagged or dog links, which lay bold of the timber or tree and drag it on a suitable support for long distances. The timber is often transported in rafts on the rivers, or the single stems are floated to an incline on the bank where these conveyors are erected, the lower terminal reaching sometimes a few yards below the water level. A man stands on the floating tree or trunk and directs one end on to the conveyor, which drags it out of the water direct to the saw-mills. Figs. 82 and 83 show two such conveyors, the former for light loads, the latter for logs up to 4 ft. in diameter. Push-Plate Conveyors with Double Chains. —In this case the chains are attached to the two sides of the push-plates, preferably protected by being concealed in lecesses in the sides of the trough. Such conveyors are to be recommended when it is desirable to have the trough unimpeded by chains above the plates. This form of construction has also the advantage that the chains are attached at a central position, which is most effective. Belonging to this category is the hot coke conveyor (Figs. 206 to 209), the plates of which are sometimes in the form of rakes, and sometimes in the form of plain iron bars. 1 his latter design is quite admissible for coke when in large pieces, and theiefore as efficiently pushed by a bar as by a plate, whilst the rake is more 1 See pages 153 and J 54.