The present invention relates to an agricultural separating device
and an agricultural separator including such a device.
It is well-known in the agricultural field to use starwheels when
separating materials, eg clod and/or stones from root vegetables or bulbs, eg during
harvesting, in de-stoning machines and also in static cleaning or grading equipment.
Starwheels have a plurality of resiliently deformable "fingers" arranged around
a central hub or boss and are at present formed from polyurethane or rubber, but
could be formed from any other suitable material. In use, a plurality of starwheels
are mounted on a rotatable shaft, commonly known as a "starshaft".
During use, damp soil may stick to the starwheels, or hard material,
eg stones, may become jammed between the starwheels. This will reduce separation
and produce wear of the starwheels.
GB 2 145 612 discloses two parallel starshafts arranged upstream of
a counter rotating clod roller for use in separating clod and/or stones from root
vegetables or bulbs. In practice, the fingers of the starwheels of adjacent starshafts
are staggered and fit into the gaps between the starwheels of the adjacent starshaft.
In such a position, the starshafts are said to be "interleaved". When separating
potatoes, potato haulm can become wrapped around the starshafts, and interleaving
the starshafts provides a degree of self-cleaning.
It is also known from EP 0 410 808 to arrange starshafts in a lifting
conveyor. Although the starwheels may be interleaved, it is particularly advantageous
in a de-stoning machine for there to be a radial gap between the ends of the fingers
of the starwheels of adjacent starshafts, ie the starwheels of adjacent starshafts
are not interleaved. There is- therefore, no self-cleaning of the starshafts.
A device according to the preamble of claim 1 is known from US-A-1
An object of the present invention is to provide starshafts in which
build up of material is reduced and, in certain applications, self-cleaning is
The invention provides an agricultural separating device having a
starshaft comprising a row of resilient starwheels mounted on a rotatable shaft,
wherein rings formed of a rigid material, and having an outer diameter such that
they extend radially along 40-80% of the radial length of the fingers of the starwheels,
are mounted between adjacent starwheels so as to close off the radially inner space
between the fingers without reducing the length and therefore flexibility of the
By in effect enlarging the boss diameter, the area between starwheels
into which separated material (soil, small stones and plant material) can be lodged
is reduced, thereby reducing the build up of material, and also allowing self-cleaning
with a lesser degree of interleaving of the starwheels.
The agricultural separating device may be used in any agricultural
separator, eg in a stone and/or clod separator, in a machine for separating soil
and clod from root vegetables or bulbs, in a harvester and also in static cleaning
The invention also provides an agricultural separator including an
agricultural. separating device according to the invention. Preferably, the agricultural
separator includes at least two agricultural separating devices according to the
invention, wherein the starshafts are arranged adjacent and parallel to each other.
Preferably, a clod roller is arranged adjacent and parallel to the downstream starshaft
in the direction of movement, in use, of material being separated.
In a preferred embodiment, the clod roller and the downstream starshaft
are movable as a unit relative to the adjacent upstream starshaft so as to vary
the degree of interleaving between the starwheels of the said upstream and the
downstream starshafts or to create or vary a radial spacing between the tips of
the fingers of the starwheels of the said upstream and downstream starshafts.
Such a separator allows adjustment between a first position in which
the starwheels are interleaved for self-cleaning, eg during separation of soil
and clod from potatoes, and a second position in which the starwheels of adjacent
starshafts are not interleaved, eg during harvesting carrots, or in a destoner,
or when used merely as a separating conveyor.
The invention will be further described with reference to embodiments
shown in the accompanying drawings, wherein:
- Figure 1 shows in plan view parts of two interleaving starshafts of an agricultural
- Figure 2 shows in side view a ring of the separator of Figure 1,
- Figure 3 shows in side view a starwheel of the separator of Figure 1,
- Figure 4 shows diagrammatically in side view an agricultural separator in which
one of the starshafts and the clod roller are movable together as a unit relative
to an interleaved starshaft, and
- Figure 5 shows diagrammatically in side view the separator of Figure 4 in which
the starwheels of the starshafts have been separated.
In Figure 1, a first starshaft 1 comprises a plurality of starwheels
2 mounted on a shaft (not shown). Each starwheels 2 has a boss 3 and a plurality
of curved, radially-extending resilient fingers 4, as can be seen also from Figure
3. The starwheels are preferably formed from polyurethane or rubber with a resilience,
depending on the particular use, but could be formed from any other suitable material.
As can be seen from Figure 1, the sides of the bosses 3 of adjacent
starwheels 2 abut each other and form a spacer between the fingers of adjacent
Rings 5 of rigid material are mounted on the bosses 3 between adjacent
starwheels 2 so as to extend radially along 40-80% of the radial length of the
fingers. Preferably, the rigid rings 5 extend approximately 50% along the fingers
as shown in Fig. 1. The rigid rings 5 are preferably made of plastics material,
eg nylon or polypropylene, but any other suitable rigid material could be used.
There is a clearance play between the inner diameter of the rings
5 and the bosses 3 to facilitate fitting of the ring, although this is not essential.
As can be seen from Figure 1 the sides of the fingers 4 of the starwheel
2 taper inwardly away from the rings 5 in a radially outward direction, so as to
provide a gap 13 between each ring 5 and the adjacent fingers 4; the gap 13 increases
in a radially outward direction. This allows lateral flexing of the fingers 4 when
a stone is drawn down between the starwheels. However, the rings 5 would still
function reasonably well if the gaps 13 were absent, ie if the sides of the fingers
4 were parallel.
As can be also seen from Figure 1, a second starshaft 6 is arranged
parallel to and adjacent the starshaft 1. The starwheels of the starshafts 1 and
6 are staggered so that the fingers 4 of the starwheels 2 of one starshaft enter
the gaps between the starwheels 2 of the adjacent starshaft. The starwheels of
adjacent shafts 1 and 6 are said to be "interleaved".
As already explained, the rigid rings 5 shown in Figures 1 and 2 may
be mounted on starshafts incorporated in an agricultural separator, eg in a root-crop
harvester (eg a potato harvester), a de-stoning machine, or in static cleaning
or grading apparatus.
In Figures 4 and 5 an agricultural separator is shown having a pair
of adjacent, parallel starshafts 7, 8 arranged upstream of a parallel clod roller
9, which may be arranged to rotate in the same direction as the starshafts 7, 8
(eg when harvesting carrots) or in the opposite direction (eg when harvesting potatoes).
The starshafts 7, 8 shown in Figures 4 and 5 are similar to the starshafts
1, 6 shown in Figure 1, ie they each have a plurality of starwheels 2 having bosses
3 and resilient fingers 4. They also have rigid rings 5 arranged on the bosses
3 between adjacent starwheels.
The downstream starshafts 8 and the clod roller 9 are mounted in the
separator as a unit, which is pivotable as a unit about an axis 10 to enable the
starshaft 8 to be moved away from the starshaft 7 to alter the degree of interleaving
therewith. As can be seen from Figure 5, the pivoting movement may be such as to
remove the interleaving altogether, so that there is a radial gap 11 between the
tips of the fingers 4 of the starwheels 2 of the starshafts 7 and 8, eg when separating
carrots; the pivoting movement may be used to adjust this gap depending on the
material being separated.
Thus, the separator shown in Figures 4 and 5 may be used for separating
both carrots and potatoes. When separating potatoes the starwheels are interleaved
as shown in Figure 4, whereas when separating carrots the starwheels are separated
as shown in Figure 5.
Alternatively, the separator shown in Figures 4 and 5 could be operated
as shown in Figure 5, and moved into the interleaving position of Figure 4 merely
for self-cleaning between periods of operation.
An advantage of the separator as shown in Figures 4 and 5 is that
the starshafts 7, 8 can be moved apart without altering the overall length of a
When the separator as shown in Figure 4 is used for harvesting potatoes,
the counter-rotating clod roller 9 tends to force potato haulm into the gaps between
the starwheels 2 of the starshaft 8. Interleaving of the starwheels 4 of the starshafts
7 and 8 is necessary to remove this haulm. Furthermore, with the rigid rings 5
arranged on the starshafts 7, 8 between the starwheels 4, the degree of interleaving
required to produce self-cleaning is substantially less than without the rings
The group of the starshafts 7, 8 and clod roller 9 as shown in Figures
4 and 5 may be arranged in series with one or more similar groups to form a separating
surface in which the downstream starshaft and clod roller of each group are pivotable
as a unit relative to the respective upstream starshaft. Thus, in Figures 4 and
5 the starshaft 12 shown on the left of each Figure could be the upstream starshaft
of a further group comprising two starshafts and a clod roller.