Combination normal-sowing and fine-sowing wheel with integral stop

A combination normal-sowing and fine-sowing wheel for a sowing machine, which has a fine-sowing wheel which can be attached to a sowing shaft by an interlocking and clamping connection and is mounted next to a normal-sowing wheel as a separate component in a sowing housing on the same sowing shaft. The fine-sowing wheel is coupled to the normal sowing-wheel by a coupling bolt that can be secured in two operating positions by stops and both the normal sowing wheel and the fine sowing wheel have a central bore and another bore the accommodates the coupling bolt. The stop in accordance with the present invention is in one piece.

BACKGROUND OF THE INVENTION 
The present invention relates to a combination normal-sowing and 
fine-sowing wheel for sowing machines, wherein a fine-sowing wheel can be 
attached to a sowing shaft by means of an interlocking and clamping 
connection and is mounted next to a normal-sowing wheel as a separate 
component in a sowing housing on the same sowing shaft, wherein the 
fine-sowing wheel can be coupled to the normal-sowing wheel by means of a 
coupling bolt that can be secured in two operating positions by means of 
stops and wherein both the normal-sowing wheel and the fine-sowing wheel 
have, in addition to a central bore, another bore that accommodates the 
coupling bolt. 
A combination normal-sowing and fine-sowing wheel of this type is known 
from German Pat. No. 837,022. The stops for the coupling bolt in this 
known sowing wheel are very expensive to manufacture. Mounting the stops 
in particular demands a lot of expensive and time-consuming manual labor. 
The normal-sowing wheel has a radial bore to accommodate the stops. The 
radial bore intersects with the bore that accommodates the coupling bolt. 
Mounting the stops is a complicated process, involving inserting the 
coupling bolt in its bore in the normal-sowing wheel, positioning a ball 
that operates in relation to the stops and in conjunction with grooves in 
the coupling bolt in the radial bore, inserting in the same bore a spring 
that operates in conjunction with the stops, and screwing into the bore 
the grub screw that secures the stops. The expense of manufacturing and 
assembling the stops is accordingly absolutely unacceptable. 
SUMMARY OF THE INVENTION 
The object of the present invention is to simplify the stops and the 
manufacture and assembly of the sowing wheels. 
This object is attained in accordance with the invention in that the stops 
are in one piece. This results in a very simple stop. The one-piece stops 
in one embodiment can be inserted in the normal-sowing wheel. This is a 
very simple means of ensuring that the one-piece stop is inserted in an 
opening that accommodates it. The stops in one preferred embodiment are in 
one piece with the normal-sowing wheel. This embodiment accordingly 
necessitates absolutely no additional assembly labor to insert the stops 
in the normal-sowing wheel. The stops are integrated into the 
normal-sowing wheel in a very simple way simultaneously with the 
manufacture of the wheel. This is especially simple to attain if the 
normal-sowing wheel is made out of plastic because the stops can be molded 
directly onto it. The stops which are either one-piece or in one piece 
with the normal-sowing wheel, in one preferred embodiment are inherently 
elastic tongues that extend axially and have a cam-like nose on their free 
end, the end that faces the bore. This is an extremely simple way of 
attaining inherently elastic stops. The cam-like noses operate in 
conjunction with associated grooves in the coupling bolt, reliably 
securing the bolt in the particular position in a surprisingly simple way. 
To ensure reliable retention of the coupling bolt at all times, at least 
one elastic stop is provided that rests on a supporting component between 
the normal-sowing wheel and the stop. 
This ensures long life and long-term operation for the stops and 
accordingly a precise stopping of the coupling bolt at any time. 
In one embodiment of the invention there is only one elastic stop. The 
supporting component can be positioned between the hub and the 
circumference of the normal-sowing wheel, and the stop can rest on the 
supporting component. Thus the stop still consists of only one elastic 
component, with the supporting component, which consists of two circular 
segments, designed so that even long-term deformation does not lead to 
plastic deformation and constantly ensures retention of the coupling bolt. 
Since the normal-sowing and fine-sowing wheel are made out of plastic, the 
supporting component and the stop are made extremely simply, in one piece 
with the normal-sowing wheel, since the subassembly is molded on. 
The bore or the coupling bolt in this embodiment has a U-shape 
cross-section. The side that faces the circular section of the bore or of 
the coupling bolt can be a flat surface with the cam-shaped nose, in the 
form of a stop, in its vicinity. This provides an especially effective 
accommodation for the coupling bolt. The contact surface between the stop 
and the coupling bolt is accordingly expanded in an especially practical 
way, ensuring reliable retention of the coupling bolt. The coupling bolt 
in this case can also be made out of plastic for example. 
As elastic component that acts radially is positioned between the 
normal-sowing wheel and the fine-sowing wheel in one especially practical 
embodiment. The elastic component is always a disk spring and is coupled 
to one of the two sowing wheels, preferably to the normal-sowing wheel, 
and is an elastic component that acts on the hub of the fine-sowing wheel. 
This measure forces both the fine-sowing wheel and the normal-sowing wheel 
against the walls of the sowing housing in a practical way, preventing the 
undesired deposits of corrosive materials and dust that occur in the 
cracks between these components of the sowing system with known flow 
regulators and preventing very fine seed from leaving the sowing housing 
uncontrolled. 
Some preferred embodiments of the invention will now be described with 
reference to the attached drawings, wherein:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The combination normal-sowing and fine-sowing wheel 1 illustrated in FIGS. 
1 and 2 is mounted on a sowing shaft 2 inside a sowing housing 3. 
Combination wheel 1 consists of a normal-sowing wheel 4 and of a 
fine-sowing wheel 5 accommodated next to each other in sowing housing 3. 
Fine-sowing wheel 5 has molded-on groove splines 6 positioned in a groove 
7 in sowing shaft 2, providing an interlocking connection between the 
fine-sowing wheel and the sowing shaft. Both normal-sowing wheel 4 and 
fine-sowing wheel 5 have a bore 8 and 9 at the same distance from their 
central bore. Stops 10, which are in one piece with normal-sowing wheel 4, 
are positioned around bore 8. Stops 10 have four tongues 11 uniformly 
distributed around the circumference of bore 8. Two of the tongues are 
larger and two smaller, and the smaller and larger tongues are opposite 
one another. Tongues 11 extend axially and are inherently elastic. Tongues 
11 are secured on one side to normal-sowing wheel 4. At their free end 12 
on the part that faces the axis of bore 8, each tongue 11 has a cam-shaped 
nose 13. The area between cam-shaped nose 13 and the point where the 
tongues are secured to normal-sowing wheel 4 is inherently elastic. 
A coupling bolt 14 slides in the bores 8 and 9 in normal-sowing wheel 4 and 
fine-sowing wheel 5. Coupling bolt 14 is surrounded by two grooves 15 and 
16. The cam-shaped noses 13 on tongues 11 operate in conjunction with 
grooves 15 and 16. The inherent elasticity of tongues 11 forces nose 13 
against coupling bolt 14 and accordingly, depending on the position of the 
coupling bolt, into grooves 15 or 16. 
This design makes it possible to shift coupling bolt 14 into two different 
operating positions. In the position illustrated in FIG. 1, the left-hand 
outer section of coupling bolt 14 engages a bore 18 in the left wall 17 of 
sowing housing 3. When the bolt is in this position, sowing shaft 2 will 
drive only fine-sowing wheel 5, distributing rows of fine seed in 
particular. 
In the other position, represented by means of the broken lines, coupling 
bolt 14' has been forced out of bore 18 and is engaging both normal-sowing 
wheel 4 and fine-sowing wheel 5. In this position, sowing shaft 2 drives 
both normal-sowing wheel 4 and fine-sowing wheel 5, both of which are 
distributing seed. 
In contrast to the wheels illustrated in FIG. 1, the combination 
normal-sowing and fine-sowing wheels 19 illustrated in FIG. 3 are made out 
of metal. Normal-sowing wheel 20 and fine-sowing wheel 21 are mounted 
inside a sowing housing 3 on a sowing shaft 2. Fine-sowing wheel 21 has a 
groove spline 6 that engages a groove 7 in sowing shaft 2. Fine-sowing 
wheel 21 has, at a distance from its central bore, a bore 22, which can be 
engaged by a coupling bolt 14. Normal-sowing wheel 20 also has a larger 
bore 23 at the same distance from the central bore of fine-sowing wheel 21 
as bore 22. Bore 23 accommodates a stop 24. Stop 24 is in one piece and 
made out of plastic. It has inherently elastic tongues 25 that extend 
axially. The free end of each tongue 25, the end facing coupling bolt 14, 
has a cam-shaped nose 13. Noses 13 operate in conjunction with grooves 15 
and 16 in coupling bolt 14. Thus, combination normal-sowing and 
fine-sowing wheel 19 functions like the combination normal-sowing and 
fine-sowing wheel 1 illustrated in FIGS. 1 and 2. 
The combination normal-sowing and fine-sowing wheel 31 shown in FIGS. 4 and 
5 is mounted on a sowing shaft 32 inside a sowing housing 33. Combination 
wheel 31 consists of a normal-sowing wheel 34 and of a fine-sowing wheel 
35 accommodated next to each other in sowing housing 33. Fine-sowing wheel 
35 has a molded-on contact surface 36, in which there is a radial groove 
37. A grub screw that screws into the groove 37 in fine-sowing wheel 35 
secures the wheel to sowing shaft 32. Normal-sowing wheel 34 has an axial 
bore 38 with a U-shaped cross-section and two different diameters, 
creating an edge 39 inside bore 38. The side 41 that faces the circular 
section 40 of bore 38 is a flat surface 42, with an elastic stop 43 in its 
vicinity. Stop 43 has a cam-shaped nose 44 and rests on a supporting 
component 45 between normal-sowing wheel 34 and stop 43. Supporting 
component 45 is elastic and consists of two arcuate segments 46 between 
the hub 47 and the circumference 48 of normal-sowing wheel 34 that support 
stop 43. Between normal-sowing wheel 34 and fine-sowing wheel 35 is an 
elastic component in the form of a disk spring 49 that acts axially. Disk 
spring 49 shown in FIG. 9 is mounted at the four bearing points 50 of 
normal-sowing wheel 34 and acts on the hub 51 of fine-sowing wheel 35, 
forcing the two wheels 34 and 35 in opposite directions against the 
particular walls 52 of the sowing housing. 
A U-shaped coupling bolt 53 shown in FIGS. 7 and 8 and made out of plastic 
slides back and forth in the bore 38 in normal-sowing wheel 34. Coupling 
bolt 53 has two grooves 56 and 57 in the flat surface 54 in the vicinity 
of its smaller cross-section 55. The cam-shaped nose 44 on stop 43 
operates in conjunction with grooves 56 and 57. The inherent elasticity of 
stop 43 forces cam-shaped nose 44 against coupling bolt 53 and 
accordingly, depending on the position of the coupling bolt, into grooves 
56 or 57. 
This design makes it possible to shift coupling bolt 53 into two different 
operating positions. In the position illustrated in FIG. 6, the left-hand 
outer section of coupling bolt 53 engages the bore 59 in the left wall 58 
of sowing housing 33. When the bolt is in this position, sowing shaft 32 
will drive only fine-sowing wheel 5, distributing rows of fine seed in 
particular. 
In the other position, represented by means of the broken lines, coupling 
bolt 53' has been forced out of bore 59 and extends so close to 
fine-sowing wheel 5 that it comes to rest against contact surface 36. In 
this position, sowing shaft 2 drives both normal-sowing wheel 34 and 
fine-sowing wheel 5, both of which are distributing seed. 
The different diameters of bore 38 and the different cross-sections of 
coupling bolt 53 prevent the bolt from being completely forced out of bore 
38 because most of its cross-section comes to rest against edge 39. Thus, 
it is impossible to completely drive coupling bolt 53 out of bore 38. 
It will be appreciated that the instant specification and claims are set 
forth by way of illustration and not limitation, and that various 
modifications and changes may be made without departing from the spirit 
and scope of the present invention.