The Mechanical Handling and Storing of Material

WORM OR ARCHIMEDEAN SCREW CONVEYORS 53 splitting. These rings or collars are not necessary when stout steam piping or hydraulic piping is used. Fig. 55 shows another coupling with a short gudgeon, and two cotter bolts for each fastening. In this case the collar over the end of the pipe is indispensable. Fig. 56 shows yet another mode of coupling worms together. The coupling consists of two short gudgeons, each with a square hole into which a short coupling piece fits. The advantage of this coupling is that it can be very quickly disconnected, as it is only necessary to slacken the set-screws and push one half of the worm 3 or 4 in. to one side, when the coupling piece can be taken out. Fig. 57 shows a coupling sometimes used in connection with continuous worm conveyors. The coupling consists of a worm section with a stout sleeve which is split longitudinally, and is secured tightly over the junction of the two halves of the worm. Drummond End Flights.—When handling abrasive or gritty materials with continuous worm conveyors, considerable wear is found on the flights on either side of the intermediate bearing where the worm is of necessity interrupted. This tends to accumulate material, and imposes extra work on the end flights in pushing it past the bearing into the path of the next section. The interruptions pertaining to the repairs of Fig. 57. Coupling for Continuous Worm Conveyor. such parts are very considerable, and to minimise them these end flights have been introduced by the Link Belt Company. It is the invention of the late D. D. Drummond, vice-president and genera] manager of the Chicago Portland Cement Co. These flights are made of manganese steel, and are easily renewed, being in halves so as to fit the gudgeon. Ordinary end flights, f in. thick, have been known to be destroyed in a few weeks by cement clinker, whilst the improved ones show hardly any signs of wear after six months’ work on the same material. General Remarks.—Delivery of the material from a worm conveyor can be effected at any number of points, it only being necessary to provide a suitable outlet having a slide to close the aperture when necessary. Such an outlet should be as long and as wide as the diameter of the worm, if it is desired to get the whole of the feed through it. This must be so, as the worm delivers only on its leading side, and is practically empty on the other side. The lid which covers the worm box or trough should not be fixed, but should lie loose on top, because in the event of an accumulation of material occurring through the choking of a spout, unless the material in the worm can force the lid and throw the stuff out, the worm, if continuous, will be stripped, or the blades broken, if it be a paddle worm. Tubular Worm Conveyors.—These consist of cylindrical iron tubes with a continuous spiral fitted to the inner periphery as shown in Fig. 58. When at work the •cylinder revolves bodily round an imaginary axis, supported outside by suitable rollers. 1 his type of conveyor does not strictly conform with the attributes given at the heading