THE YOUNG MILL-WRIGHT and MILLER'S GUIDE, by Oliver Evans
Fig. 12, Plate VII., is a hopper-boy; which consists of a perpendicular shaft, A B having a slow motion, (not above 4 revolutions in a minute,) carrying round with it the horizontal piece C D, which is called the arm; this, on the under side, is set full of small inclining boards, called flights, so as to gather the meal towards the centre, or to spread it from the center to that part of the arm which passes over the bolting hopper; at this part, one board is set broadside foremost, as E, (called the sweeper,) which drives the meal before it, and drops it into the hoppers H H, as the arms pass over them. The meal is generally let fall from the elevator, at the extremity of the arm, at D, where there is a sweeper, which drives the meal before it, trailing it in a circle the whole way round, so as to discharge nearly the whold of itsload, by the time it returns to be loaded again: the flights then gather it towards the centre, from every part of the circle; which would not be the case, if the sweepers did not lay it round; but the meal would, in this case, be gathered from one side only of the circle. These sweepers are screwed on the back of the arm, so that they may be raised or lowered, in order to make them discharge sooner or later, as may be found necessary. The extreme flight at each end of the arms is put on with a screw, passing through its centre, so that they may be turned to drive the meal outwards; the use of which is, to spread the war, meal as it falls from the elevator, in a ring, round the hopper-boy, while it, at the same time gathers, the cooled meal into the bolting hopper; so that the cold meal may be bolted, and the warm meal spread to cool, by the same machine, at the same time, if the miller chooses so to do. The foremost edge of the arm is sloped up in order to make it rise over the meal, and its weight is nearly balanced by the weight w, hung to one end of a cord, passing over the pulley P, and to the stay iron F. About 4 1/2 feet of the lower end of the upright shaft is made round, passing loosely through a round hole in the floght arm, giving it liberty to rise and fall freely, to suit any quantity of meal under it. The flight arm is led round by the leading arm L M, there being a cord passed through the holes L M, at each end, and made fast to the flight D C. This cord is lengthened or shortened by a hitch stick N, with two holes for the cord to pass through its end being passed through a hole at D, and fastened to the end of a stick; this cordmust reeve freely through the holes at the end of the arms, in order that the ends may both be led equally. The flight arm falls behind the leader about 1-6th part of the circle. The stay-iron C F E, is formed into a ringat F, which fits the shaft loosely, keeps the arm steady, and serves for hanging the hands of an equal height, by mean of the screws C E. Fig. 13, Plate VII., is a perspective view of the under side of the flight arms. The arm a c, with flights and sweepers complete; s s s show the screws which fasten the sweeper to the arms. The arm c b, is to show the rule for laying out for the flights. When the sweeper at b is turned in the osition of the dotted line; it drives the meal outwards. Fig. 14, Plate VII., represents a plate of metal on the bottom of the shaft, to keep the arm from the floor, and 15 is the step gudgeon.
This machine, also has appeared under various constructions, the best of which is represented by fig. 12, Plate VII.-(See the description Art. 88.) To make the flight-arm C D, take a piece of dry popular of other soft scantling 14 feet long, 8 by 2 1/2 inches in the middle, 5 by 1 1/2 inches at the end, and straight at the bottom: on this sltlrike the middle line a b, fig 13. Consider whihc way it is to revolve, and cipher off the under side of the foremost edge from the middle line, leaving the edge 3/4 of an inch thick, as appears by the shaded part. Then, to lay out the flights, take the following
Set your compasses at 4 1/2 distance, and begining with one foot in the centre c, step towards the end b, observing to lessen the distance one-sixteenth part of an inch ever step; this will set the flights closer together at the end than at the centre. Then, to set the flights of one arm to track truly between those of the other, and to find their inclination, with one point in the centre c, sweep the dotted circle across every point in one arm; then, without altering the centre or distance, make the little dotted marks on the other arm, and between them the circles are to be swept for the flights in it. To vary their inc;omatopm regularly, from the end of the centre c, and 2 1/2 inches from the middle line at d, and then with the compasses set to half an inch, set off the inclination from the dotted circles, on the line c d; the line c d then approaches the middle line, the inclination is greater near the centre than at the end, and varies regularly. Dove-tail the flights into the arm, observing to put the side that is to drive the meal to the line of inclination. The Bottom of them should not extend past the middle line, the ends being all rounded and dressed off at the back side, to make the [oint sharp, leaving the driving side quite straight, like the floug r. (See them complete in the end c a.) The sweepers should be 5 or 6 inches long, screwed on behing the flights, at the back side of the arms, one at each end of the arm, and one at the next part that passes over the hopper: their use is described in Art. 88. The upright shaft, should be 4 by 4 inches, and made round for about 4 1/2 feet at the lower end, to pass lightly through the center of the arm. To keep the arm steady, there is a stay-iron 15 inches high, is legs 1/2 inch by 3/4, to stride 2 feet. The ring at the top should fit the shaft neatly, and be smooth and rounded inside, that it may slide easily up and down; by this the arm hangs to the rope that passes over a pulley at the top of the shaft, 8 inches diameter, with a deep groove for the rope or cord to run in. Make the leading arm 6 by 13/4 inches in the middle, 2 by 1 inch at the end, and 8 feet long. This arm must be braced to the cog-wheel above, to keep it from splitting the shaft by an extra stress. The weight of the balance w, must be so nearly equal to the weight of the arm, that when it is raised to the top it will decend quickly. In the bottom of the upright shaft is the step gudgeon (fig. 15.) which passes through the square plate 4 by 4 onches (fig. 14;) on this plate the arm rests, before the flights touch the floor. The ring on the lower end of the shaft is less than the shaft, that it may pass through the arm: this gudgeon comes out, every time the shaft is taken out of the arm. If the machine is to attend but one bolting-hopper, it need not be above 12 or 13 feet long. Set the upright shaft close to the hopper, and the flights all gather as the end c b, fig. 13. But, if it to attend, for the grinding of two pair of stones, and two hoppers, make it 15 feet long, and set it between them a little to one side of both, so that the two ends may not both be over the hoppers at the same time, which would make it run unsteadily: then the flights between the hoppers and the centre must drive the meal outwards to the sweepers, at the end c a, fig. 13. If it be to attend two hoppers, and cannot be set between them for want of room, then set the shaft near to one of them; make the flights so that they will all gather to the centre, and put sweepers over the outer hopper, which will be first supplied, and the surplus carried to the other. The machine will regulate itself to attend both, although one should feed three times as fast as the other. If it be to atend three hoppers, set the shaft near the middle one, and put sweepers to fill the shaft near the middle one, and put sweepers to fill the other two, the surplus will come to the centre one, and it will regulate to feed all three; but should the centre hopper over stand while the other are going, (of either of these last applications,) the flights next to the centre must be movable, that they may be turned, and set to drive the meal out from the centre. Hopper-boys should be driven by a strap in some part of their movement, that they may easily stop if any thing catch in them; but many millwrights prefer cogs; they should not revolve more than 4 times in a minute.
1. When the meal elevator is set in motion to elevate the meal, the hopper-boy must be set in motionalso, to spread and cool it; and as soon as the circle is full, the bolts may be started; the grinding and bolting may like wise be carried on regularly together; which is the best way of working. 2. But if you do not choose to bolt as you grind, turn up the feeding sweepers and let the hopper-boy spread and cool the meal, and rise over it; and when you begin to bolt, turn them down again. 3. If you chose to keep the warm meal seperate from the cool, shovel about 18 inches of the outside of the circle, in towards the centre, and turn the end flights, to drive the meal outwards; it will then spread the warm meal outwards, and gathter the cool meal into the bolting hopper. As soon as the ring is full with warm meal, take it out of the reach of the hopper-boy, and let it fall again. 4. To mix tail flour or bran, &c., with a quanity of meal that is under the hopper-boy, make a hold for it in the meal quite to the floor, and put it in; and the hopper-boy will mix it regularly with the whole. 5. If it do not keep the hopper full, turn the feeding sweepers a little lower, and throw a little meal on the top of the arm, to make it sink deeper into the meal. If the spreading sweepers discharge their loads too soon, and do not tail the meal all around the circle, turn them a little lower; if they do not discharge, but keep too full, raise then a little.
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