The Mechanical Handling and Storing of Material

7o6 THE MECHANICAL HANDLING OF MATERIAL The third type, termed Intermittent Weighing Machines, are for the purpose of weighing material contained in skips, buckets, or trucks, which, duiing the conveying process, pass a certain point where the weighing apparatus is stationed. They are used in connection with ropeways, mono-railways, and telphers, and may be airanged so that the load is stopped in its progress during the weighing operation, or they may be non-stop weighers, where the weight of the load is recorded during transit. Such appliances can, however, only be used successfully when the tare of the receptacle is known and has been adjusted to exactly the same in all the units which may be used for the conveyance of the load. The weighing machine itself generally weighs each separate lot, and adds the successive weights up to a total. In selecting a weigher it is, of course, necessary to take all the conditions into consideration. Broadly speaking, it may be said that the hopper weighing machine is most suitable for grain, seeds, small coal, etc., the continuous weighing machine for coal and minerals, whilst with the intermittent weighing machine material of any kind may be conveyed in the receptacle passing over the weigher. HOPPER WEIGHING MACHINES The “ Chronos ” Automatic Grain Scale.—This was the first machine for the purpose of automatic weighing, and is the design of Messrs Reuther & Reisert, of Hennef-on-the-Sieg, Germany (see Figs. 1009 and 1010). This weigher consists essentially of a beam scale a, of the usual kind, with arms of equal length, to one of which is suspended the weight c, and to the other a skip b for the reception of the grain, such a skip being capable of rotation on an axis, and being provided with two apertures for the respective operations of receiving and discharging, whilst from the other arm there also hangs a beam board which will take any. ordinary kind of weight. Over the recipient is placed a hopper d, underneath which play two valves, or rather gates, which regulate the flow of feed. The grain pouring through the hopper soon fills up the recipient b, until suddenly the upper gate partially closes, thus shutting off the greater part of the feed, and letting in only two thin streams of grain, which together make up the exact weight set on the beam board. As soon as that point has been reached, a stud attached to the pointer of the beam scale comes in contact with a toggle joint p m l, which serves to support the second flap and bends the former down. I he effect of this is to completely close the inlet, while simultaneously a hook, which has kept the recipient in an upright position for taking in the feed, is released. I he skip then tips forward about 40°, this movement being sufficient to empty it of its contents, but as soon as this has been accomplished it regains its former position, the index x registering the weighing, whereupon the two inlet valves are opened, and it is again held fast by the hook. With the re-entry of the feed the operation already described is repeated. Each revolution of the skip, and. therefore each dischargg of a given weight of grain, is registered on a dial attached to the front of the scale. The two illustrations, Figs. 1009 and 1010, give a clear idea of the movement of the skip B, as well as of the action of the “ Chronos ” machine. To reduce friction to a minimum and to ensure smooth work, it has been the aim of the makers of this machine to shorten as much as possible the arc traversed by the skip in its tipping motion, hence it had to be provided with an outlet distinct from the inlet. Moreover, the recipient has been so shaped and hung, that while the grain, seeds, or other materials are being fed through the inlet, the bottom of the skip