The Mechanical Handling and Storing of Material

696 THE MECHANICAL HANDLING OF MATERIAL all fed from this hopper. After weighing, each machine discharges itself automatically into sacks, which are then ready to be loaded into barges or railway trucks. The four installations are all on exactly the same lines as the one described. Each pair of granaries is provided with one common sack conveyor band which is 308 ft. in length, so that the full sacks can be carried to the railway trucks as soon as they can be got ready by twelve men in connection with each weighing shed, ihere is one gas engine for driving each of the two sack bands. These sack bands are so arranged that the speed can be either slow, to take sacks, or it may be higher for the purpose of conveying grain in bulk for loading barges or bulk grain cars. The silos are generally fed by a fleet of twenty-six of Philip s patent self-discharging lighters.1 These lighters are charged from ocean-going steamers at Tilbury, and towed by special steam tugs to the transit silos. Previous to the installation of these important granaries the grain had to be unloaded and weighed by means of a floating hopper which was exposed to all weathers, and the motion of the unloading elevator was not conducive to accurate weighing; but with the new machinery it is now possible to discharge at the rate of 100 tons of grain per hour from each hatch by means of the derrick elevator described on page 469. And whereas the lightermen had formerly to be at work night and day, it is now possible to make all deliveries to receivers by daylight. The arrange- ments are so perfect that the grain which is loaded at Tilbury into the lighters can be delivered to rail or private craft from the transit silos in six hours. The whole installation is driven by fourteen gas engines, three being employed for each silo-house and two for the sack bands. The gas engine for the intake or barge elevator is one of 20 H.P., the one for the inside elevator 36 H.P., the one for turning over and delivering the grain 28 H.P., and the two for the sack bands 15 H.P. each. The actual power consumed is, however, less than this. Fig. 1001 gives a photographic view. A Typical Modern Granary.—Fig. 1002 shows a very compact granary equipped with interlaced timber silos. It consists of a balanced barge elevator with a range of 20 ft. up and down motion, and with a capacity of 60 tons per hour. From this barge elevator the grain is spouted through the outer annexe into the silo warehouse, where it is lifted by the shorter elevator to a hopper, from which it passes through a weighing machine which weighs 1 ton at each charge; from there it is conveyed into a second hopper, and into a preliminary grain-cleaning machine; from thence again to a third elevator, which takes it to the top of the building, and delivers it into a series of silos by means of a band conveyor with a throw-off carriage. All the elevators and conveyors have a capacity of 60 tons per hour. The silos are forty-six in number, and are 8 ft. 6 in. square by 80 ft. deep, having a total capacity of 24,000 qrs. The whole installation is driven by electricity, and the plant has special facilities for mixing the grain as it is leaving the warehouse. It is also provided with a separate intake elevator of a capacity of 30 tons for the reception of English wheats. The whole warehouse plant is driven by three electro-motors : one for the^top floor with its machinery of 38 a second driving the plant in the receiving annexe of 24 and a third which drives the conveyors on the ground floor of 10 B.H.P. Granary at the Avonmouth Dock.'2—A large installation of grain-handling plant has recently been completed at the Royal Edward Dock, Avonmouth, Bristol. 1 See page 482. 2 Extract from The Engineer, 10th July 1908 and 25th September 1909.