GB2100564A - Rotary cultivators - Google Patents

Abstract

A rotary cultivator 10 comprises a pick tine rotor 16 which co-operates with a spring tine stator 20 positioned so as to hold the soil against the action of the rotor 16. This results in an element of shear being introduced into the soil cultivation process taking place during operation of the cultivator. Alternative designs for the rotor 16 are disclosed. <IMAGE>

Description

SPECIFICATION Rotary cultivators The present invention relates to rotary cultivators and in particular, but not exclusively, to power driven rotary cultivators.

Currently available power driven rotary cultivators are subject to certain disadvantages, e.g. a tendency to smear the surface of the soil, to produce too fine a tilth, and to have an unnecessarily high power requirement. They are also difficult to set correctly for wet conditions in so far as too great a ground reaction from the cultivator rotor can result in wheel skid at the towing tractor.

According to the broadest aspect of the present invention there is provided a rotary cultivator comprising rotatable soil-engaging rotor members which operate in a region of soil at least to some extent responsive to the presence of non-rotatable soil-engaging stator members so as in operation of the cultivator to produce a shearing effect on soil in said region. This shearing effect will take place in addition to the cultivation effects normally individually associated with the two sets of members and other cultivation mechanisms such as impact and compression may also be present.

Although cultivators are already known which have, in common with the present invention, the feature of incorporting both soil-engaging rotor members and soil-engaging stator members in the one machine, these prior arrangements either involve remotely positioned statortines presenting the rotor with loosened clods etc to be further broken up by the rotor or they use a rotor in which radial knives break up the soil by a slicing or cleaving action as opposed to a shearing action. In both instances, the soil-breaking mechanism involves a relatively high power requirement as compared with the cultivators of the present invention and difficulties arise in accurately controlling the fineness of the tilth produced by the machine.

In preferred embodiments of the present invention, the second members will rotate in the same sense as any landwheels present in the cultivator.

Alternatively however they could rotate in the opposite sense.

Conveniently, the rotor members will be power driven but it is envisaged that in some embodiments useful results may also be obtained by having these members land driven, e.g. driven by direct contact with the soil or by a conventional or other drive from a landwheel of the cultivator.

In preferred embodiments, the operative portions of the rotor members will enter the soil slightly behind the operative portions of the stator members.

Conveniently, the rotor members comprise L blades or spikes etc., e.g. of the sort conventional to existing rotary cultivators. Alternatively the rotor members may comprise pick tines or serrated discs etc., e.g. of the sort conventional to existing disc harrows.

Conveniently, the stator members comprise tines of the sort conventional to existing rigid tine or spring tine cultivators for example. Conveniently, the operative portions of the stators are inclined at between, say, 15 and 400 to the horizontal so that they lift the soil as they pass through it, an angle of around 20 being preferred.

It has been found that in the power driven versions of the cultivator of the present invention, the absorption of rotor thrust by the stationary tines has resulted in a more balanced arrangement than is available with conventional designs of rotary cultivator, e.g. the p.t.o. power of the tractor used to drive the rotor has been more suitable related to the draft power of the tractor used to pull the cultivator over the ground and this has resulted in less likelihood of wheel skid in wet conditions and smearing. Moreovear the greater efficiency of the machine allows lower rotor speeds to be used than in conventional rotary cultivators thereby reducing the power requirement and more especially the excessively high power requirement previously associated with low forward speeds.Typically, for normal forward speeds, for example, the rotor speed would be reduced from the 200 r.p.m. (good soil) to 260 r.p.m. (bad soil) associated with current designs of rotary cultivator to 150 r.p.m. and 180 r.p.m. respectively, with a roughly proportionate saving in p.t.o. power.

These reduced rotor speeds also means that the performance of the rotor will be less affected by its relationship to the forward speed of the machine making the rotor speed setting less critical than heretofore.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view, partly broken away, of a first embodiment of the invention in which rotor members of pick tine form co-operate with spring tine stator members; Figure 2 is a plan view of the embodiment of Figure 1; Figure 3 is a side view, partly broken away, of a second embodiment of the invention in which the spring tine stator members of the first embodiment have been replaced by rigid tines; and Figures 4 to 4h show side and perspective views of alternative designs of rotor and rotor members for use in the embodiments of Figures 1 and 2 or Figure 3.

Then referring first to Figures 1 and 2 of the drawings, a rotary cultivator 10 according to the present invention comprises a frame 12 supported by trailing landwheels 14 and carrying a rotor 16 adapted to be power driven in the same rotational sense as the landwheel 14.

The soil working members on the rotor 16 are provided by pick tines 18 which are arranged to enter the ground slightly behind a line of stator spring tines 20 also mounted on the frame 12. It will be observed that the operative portions of the stator tines are inclined at about 200 to the horizontal so as to provide a lifting effect on the soil as already described in general terms.

The arrangement is completed by a three point linkage (not shown) for connecting the cultivator with the tractor (not shown) which is to pull the machine over the ground and which is to provide the p.t.o. for driving the rotor 16 as above described.

The relative widths and spacings of the cooperating rotor and stator tines (as viewed in Figure 2) is an important practical detail of any cultivator constructed in accordance with the present invention. With the arrangement of Figure 2, for example, there would be 15 to 20 stator tines each of some 11/2 inches to 31/2 inches width (i.e. measured in a direction across the width of the machine) with adjacent stator tines separated by 1 inch to 4 inches respectively. In this case there would be a similar number of rotor tines of 11/2 inches to 2 inches width and the same inter-tine spacing with each rotor tine positioned so as to lie in a plane mid-way between the two co-operating stator tines. The total width of such a machine might be about 10 feet, say.

As already indicated, the embodiment of Figure 3 differs from that of Figures 1 and 2 only in that rigid statortines 24 have been used instead of spring tines 20 and with this exception the same numerals have been used to indicate corresponding parts in the two embodiments.

Figures 4 to 4h indicate some of the alternative designs of rotor element which can be used in place of pick tines 18 in the embodiments of Figures 1 and 2 and Figure 3, namely a straight spike 26, basic L-blade 28, curved spike 30, twisted blade 32 which may either be mounted radially (Figure 4e) or tangentially (Figure 4f), and extended L-blade 34.

Also illustrated is a serrated disc 36 which can be used to replace the entire rotor 16 rather than just its tines. A pick tine 18 is included for completeness. It will be appreciated of course that these various items are not to scale.

The shear action on which the cultivator of the present invention relies is thought to provide a better soil breakdown than can normally be achieved with conventional designs of rotary cultivators and it also results in better trash incorporation and in a more suitable tilth, i.e. neither too fine nor too coarse across the width of the machine.

Claims (11)

1. A rotary cultivator comprising soil-engaging rotor members which operate in a region of soil at least to some extent responsive to the presence of non-rotatable soil-engaging stator members so as in operation of the cultivator to produce a shearing effect on soil in said region.

2. A cultivator as claimed in Claim 1 in which the rotor members will rotate in the same sense as any landwheels present in the cultivator.

3. A cultivator as claimed in Claim 1 or Claim 2 in which the rotor members are power driven.

4. A cultivator as claimed in any preceding claim in which the operative portions of the rotor members will enter the soil slightly behind the operative portions of the stator members.

5. A cultivator as claimed in any preceding claim in which the rotor members comprise simple or extended L-blades, curved or straight spikes, pick tines, twisted blades for radial or tangential mount ing or a serrated disc.

6. A cultivator as claimed in any preceding claim in which the stator members comprise rigid tines or spring tines.

7. A cultivator as claimed in any preceding claim in which the operative portions of the stator mem bers are inclined at an angle of between 1 and 40 to the horizontal.

8. A cultivator as claimed in Claim 7 in which the angle is around 20 .

9. A cultivator substantially as hereinbefore described with reference to, and as illustrated in, Figure 1 and 2 ofthe accompanying drawings.

10. A cultivator substantially as hereinbefore described with reference to, and illustrated in Figure 3 of the accompanying drawings.

11. A cultivator as claimed in any of Claims 1 to 10 in which the first members are substantially as described with reference to, and as illustrated in, any of Figures 4 to 4h of the accompanying drawings.