horsch Focus 4 TD, Operating Instructions Manual, Page: 83 / 108

Metering unit | 10
60059040 • 02 • 07/2021 • en 83
Adapter frame
Ø
If necessary, mix talc or graphite powder with the seed.
Large seed grains partly have poor trickling characteristics and thus do not fill
the roller flutes completely.
Ø
When using the adapter frame you must install and adjust the wider sealing lip
- see adjusting the sealing lip.
Ø
Use the special rotors for coarse seeds.
These are available in different sizes to match the different working widths
and seed quantities.
10.2 Metering unit with Venturi-type injector
The metering units in machines with normal hopper and injector fall sluice are
equipped with a lid (V2A) with machined recesses.
During operation the injector nozzle is exposed to vacuum. This lid adds additional
air to the air flow.
Metering unit with lid for injector nozzle
The adjustment between injector nozzle and lid works up to a max. possible seed
quantity.
Exceeding this quantity results in a dynamic pressure at the injector nozzle. This may
blow seed out through the perforated plate, which leads to a strip-like emerging of
the seeds.
These grains are visible on the surface of the field before they are covered by the
packer or the harrow.
Under extreme conditions overpressure can block the seed flow in the hopper. This
causes seed failure.