1 INTRODUCTION
The POLYMAT W is a pneumatic drill capable of applying
most seeds with diameters ranging from 1 to 10 mm.
The PTO-driven fan A (fig. 1) causes a flow of air which
transports the seeds towards the coulters E.
The metering device B at the bottom of the elevation column
C ensures that the seeds are taken up by the air flow.
Because of the whirls in the air flow, generated in the
corrugated part of the elevation column, the seeds are
distributed evenly among the hose connections of the
distributor D. Thus an effective seed distribution across the
entire working width is ensured, even when drilling on a
sloping plot.
The cell wheel F of the metering device is actuated by a
ground-driven metering wheel G which implies that seed
metering is not dependent on forward speed. This is an
advantage, particularly on sloping fields where it is not
always possible to operate at a constant speed.
The POLYMAT W can be operated either with a
LELYTERRA Power Harrow or as an individual machine.
The POLYMAT W is equipped with two land wheels (fig. 2)
enabling the machine to follow ground contours
independently of the LELYTERRA or tractor.
The POLYMAT W rests on its land wheels rather than on the
LELYTERRA which ensures a consistent working depth
whilst avoiding overload of the machine. It is therefore
possible to operate with a lighter and/or smaller roller than
would be the case for combinations whereby the seed drill is
supported by the power harrow. Moreover, the risk of
clogging of the roller is reduced considerably, particularly in
moist conditions.
Thanks to a combined hydraulic control, only one valve has
to be used for lifting and lowering the markers and coulters.
The operation of the hydraulic system is such that, after every
valve control, the LH and RH markers are lowered
alternately. In addition to this, the markers can be controlled
individually by means of a second hydraulic connection. This
makes it possible to lift a marker in order to avoid an obstacle
without interfering with the operation of the POLYMAT.
If a tramline system is used, its rhythm is not interrrupted.
39
1
2
A
B
C
D
E
F
G
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