Grain Drill Feed Mechanisms

External force feed. A shaft under the seed hopper carries a number of revolving fluted rollers, one for each coulter. The flutes carry grain from the hopper to the flexible plastic seed tubes at the required rate. Many external force feed drills are only suitable for cereal crops but some models have an adjustable shutter close to the fluted rollers. The clearance between shut­ters and feed rollers can be varied to suit differ­ent sizes of seed.

Seed rate is altered by:

1. Changing the length of fluted roller in con­tact with the seed. A lever is used to adjust the amount of fluting carrying seed from the hopper. A graduated scale provides a guide for setting the seed rate.

2. The speed of the fluted rollers is changed with a gearbox. Maximum seed rate is achieved with the highest roller speed and the full length of the fluted rollers in contact with the grain.

Figure 16. The grain metering unit on this drill is driven by the land wheel and the seed tubes deliver grain to three staggered rows of coulters. Compression springs on the coulter arms maintain the required sowing depth.

Studded roller feed. This is another form of external force feed. The fluted rollers are replaced with studded or pegged rolls. Seed is carried from the hopper to the seed tubes by the studs as the mechanism turns on its shaft. Seed rate is controlled by:

1. The speed of the studded rolls.

2. The position of an adjustable flap which con­trols seed flow from the hopper to the feed mechanism.

3. The type of studded roll. With some drills, rolls with different sizes and numbers of studs can be used.

The studded roller feed is suitable for drilling most types of seed.

Figure 17. This modular precision grain drill is made in working widths of 2.5 to 8 m

and has a 166 mm (6.6 in) row spacing.

Figure 18. Studded roller force-feed mechanism

Figure 19. Fluted roller force-feed mechanism.

Поиск по сайту: