Contenido
El grano se echa como en las otras cribas en una tontería y sale por una abertura que se agranda o se achica abriendo más o menos una puerta corredera al girar un pequeño cilindro colocado encima, alrededor del cual hay una cuerda pequeña que corresponde a la Casa.
Al salir de la tolva, el trigo se distribuye por una criba que tiene unas mallas de alambre amarillo muy anchas para que el trigo bueno pueda pasar por ellas. Los granos abortados y la mayor parte de los de carbón van con el trigo bueno, y el aire (del que hablaremos luego) los saca.
Esta criba se pone en un cajón ligero de madera con los dos lados y el fondo hechos de unas tablas delgadas. Se dispone de manera que la criba esté un poco inclinada por delante. Como esta circunstancia hace que el trigo corra con más o menos ligereza, se puede arreglar convenientemente la inclinación de la criba por medio de una clavija cilíndrica que da vueltas, la cual tiene en un extremo una ruedecilla dentada sujeta por una lengüeta. Cuando esta clavija da vueltas, se acorta o se alarga una cuerda que levanta o baja el extremo anterior de la criba.
Use of the sieve
Despite this slope, the wheat would not flow if the sieve were not given a movement from one part to another, the effect of which is produced by the following mechanism. At the end of the shaft, opposite the end where the crank is, is a wheel that has notches on the vertical front of the box side. A long rod or lever, slightly curved, corresponds to these notches at the tip. This lever is attached to the drawer at the top of the very obtuse or insensitive angle formed by its two arms. At the end of the lever, opposite the notched wheel, a rope is tied which, passing through the box, leads to the sieve. On the other side of the box there is another rod that acts as a spring and corresponds to the sieve by another rope that also crosses the box. Logically, when the shaft is moved, the notches of the wheel give an oscillating movement to the end of the lever with which it corresponds, and this movement is communicated to the other end and, by means of the rope, to the sieve, which causes the desired movement.
This movement makes the grain pass little by little to the sieve, which is slightly inclined, and what cannot pass through its meshes or holes falls at the end in the form of a water pipe on an inclined plane that throws it out, in front of the front part of the sieve. The one that has passed through the upper sieve falls in the form of rain on an inclined plane of about forty-five degrees, in which it finds a fence or wire grid similar to the previous one, but with slightly narrower meshes or holes so that the small grain falls under the box while the coarse grain goes towards the back of the sieve.
On one side of the box you can see a stork that moves a toothed wheel, which engages in a lantern nailed to the axle, which moves the notched wheel that has been mentioned.
This large shaft (which, by means of the lantern, moves very lightly), has eight wings made of thin slats, which, giving a centrifugal force to the air they beat, produce a considerable wind that throws far away all the dust, chaff and light bodies found in the grain, whether they have passed through the sieve or whether the clods and filth fall through the front part of the sieve.
To form an exact idea of this instrument it is necessary to imagine a man turning the stork, which turns a toothed wheel. This wheel, hooked into the lantern placed above, gives a very lively rotation movement to the large axis that rotates the wings located inside the box and the notched wheel that is found in the other part of the same box. This wheel gives a tremulous movement to the lever that makes the upper sieve move as much as the stork moves.
Another man puts wheat into the hopper. This wheat falls little by little into the upper sieve which, having a slight slope in front and being in a kind of continuous tremor, sifts the wheat, passing it little by little in the form of rain. In this fall it is surprised by a very strong wind caused by the wings nailed to the large axis, and the grain falls on a lower plane where there is another sieve (the lower sieve) that separates the coarse grain from the small ones.
As the pieces that make up this sieve do not require an exact proportion, the scale is enough to indicate with a short difference what their size should be, but it is necessary to note that the large shaft must be made of iron, as should the cylinders or spindles of the copper lantern, without which these pieces would last very little. It is also advisable to make the lower sieve larger so that it can have more divisions with different sized holes to separate the different grains and different seeds.
This wind sieve is excellent for removing dust, chaff, small seeds, and blight grains from good grain; in a word, everything that is lighter or thicker than good wheat. It also separates all clumps formed by moths, mouse or cat droppings, etc.
To produce the best possible effect it is necessary that the barn have windows or louvres "Louvre (architecture)") on two opposite sides. In this way, by placing the end of the sieve in front of the window opposite to the wind, the one who enters the barn joins the one made by the wings of the sieve and throws all the filth to a great distance.
Its usefulness is not limited to this single point. It is also appreciable for separating the good grain from all its filth as it is just taken from the ear, without having to repeatedly bring it and carry it from the threshing floor to the granary and from the granary to the threshing floor.