Seed Cleaners

From Farm Machinery and Equipment
by Harris Pearson Smith
copyright 1937

This book has been loaned to SFJ by Noel Ditmars of NE. Watch next issue for a reprint from the same volume on setting the suction for a plow share.

The importance of cleaning grain before marketing and the cleaning and grading of seed before planting is being recognized by grain growers more and more every year. The selection of good seed is a very essential step in the production of any crop. Certified seed breeders practice cleaning and grading of the seed they plant and sell.

Types of Cleaners. – There are several types of grain-cleaning machines. Some types are suited for use in elevators or large granaries; other types are adaptable for farm use.

In general, grain cleaners and grain graders clean and grade the seeds according to:

1. The size of the seeds
2. The shape of the seeds
3. The specific gravity of the seeds
4. The combinations of either size, shape, or weight of the seeds.

The actual separation is accomplished by means of sieves and air, by cylinders, and by pockets in the sides of disks or belts. The cleaners using sieves and air methods of separation are termed fanning mills.

Fanning Mills. – Fanning mills are made in sizes suitable for use in elevators and on farms. Figure 667 shows a cross-sectional view of a mill used in elevators, while Fig. 668 shows a cross-section of a small farm fanning mill. The grain to be cleaned is poured into a hopper on top of the mill from which it is fed on to the sieves or screens. These sieves are shaken either sidewise or endwise. In the side-shake mill, the movement of the sieves is at right angles to the flow of grain, while in the end-shake type, the movement is parallel to the flow of the grain.

The number of sieves used and the angle at which they are set vary in the different makes of fanning mills. It is always best to follow the operating directions furnished by the manufacturer. Different types of perforated sieves and screens can be placed in the machine to clean and grade different kinds of seeds.

The fan should furnish a blast of air of sufficient volume and velocity to remove dust, pieces of straw, and light, immature, and diseased seeds. The blast can be regulated by the wind boards on each end of the fan-case housing.

In fanning mills the blast may operate through, above, under, parallel to, or at right angles to the sieve and grain.

Oat Kickers. – The machine shown in Fig. 669 is commonly called an oat kicker. It differs from the fanning mill in that the sieves are placed at a great angle and are similar in construction to the chaffer of a thresher. The wheat kernels pass through the angle in the throat of the sieve, while the oats, being too long to pass through this angle, are kicked backward and are finally discharged from the machine. The wheat kernels and fine seeds fall through the sieves on a screen below, where the fine seeds are screened from the wheat.

Disk Cleaner and Grader. – The disk type of cleaner, as shown in Fig. 671, is also called a pocket cleaner, because there are sieves of pocketed vertical disks used as the separating mechanism. In cleaning wheat, the weeds that are shorter than the wheat kernels fall into and remain in the pockets. Then, as the disk passes upward through the grain and weed seeds the latter are carried out of the grain and discharged into a trough or hopper. Since the wheat kernels and wild oats are too long to remain in the pockets, they are moved to another part of the machine in which the pockets are large enough to remove the wheat kernels from the wild oats. (Fig. 671).

Disk cleaners are built in sizes suitable for use with threshing machines, on combines in farm granaries (Fig. 672), and small elevators.

Gravity Separator. – The spiral gravity separator (Fig. 673) utilizes both the difference in shape of the seeds and the difference in weight. As a stream of seed flows down on the flat spiral incline, the heavier seed move faster and swing to the outside of the chute and are separated from the lighter seed.

CYLINDER CLEANERS AND GRADERS

For Wheat. – The cylinder cleaner and grader, as shown in Fig. 674, operates on the same general principal as that of the disk cleaner. Instead of pockets on the sides of the disks, however, there are indented pockets on the inside circumference of the cylinder (Fig. 675).

The wheat and small seeds are caught in the pockets and carried upward out of the oats and dropped into a conveyor trough and conveyed separately out of the cylinder. Further separation of weed seeds and wheat is accomplished in another cylinder having pockets of suitable size (Fig. 675). The size and capacity of the machine are determined by the number of cylinders used.

For Corn. – A small inexpensive cylinder corn grader is shown in Fig. 676. It consists of a single or double cylinder with sections having different size holes to allow different size kernels to pass through. One end of the cylinder is lower than the other which causes the kernels to move along inside the cylinder until they come to the section having the proper size outlet.

For Cotton. – Cylinder graders are also used to grade cottonseed (Fig. 677). The cylinder is constructed, as in the cast of the corn grader, with sections having different sized holes. In general, the action is similar to that of a sieve, but instead of a vibrating action there is a revolving movement to agitate the seed.

For Peanuts. – Figure 678 shows a cylinder constructed to grade peanuts.

Belt Separator. – The belt separator shown in Fig. 679 separates round from unround seeds by means of an endless up-travel belt, the pitch of which can be changed. As the belt travels upward, the round seed roll down and off the lower side, and the unround seed are carried up and over the upper side and discharged into a hopper.