SELF-CLEANING ROTARY TRASH HARROW

Abstract: A self-cleaning rotary trash harrow comprising a main beam with for attachment to a prime mover to be drawn at right angles to the direction of travel at least one sub-frame fixed to the main beam and extending rearwardly therefrom the or each sub-frame supporting a spiked roller at an angle of between 50 DEG and 55 DEG to the direction of travel. The spikes are affixed at locations lying on a helix around the roller, and the angle of the helix to the axis of the roller is between 50 DEG and 55 DEG . Additionally the angle between the axis of each spike and axis of the roller is between 50 DEG and 5 DEG , to enable the axis of each spike to be parallel to the direction of travel when the spike passes through the horizontal plane at the trailing edge of the roller.

Description: CT/AU97 0315 SELF-CLEANING ROTARY TRASH HARROW Known harrows have cultivating members, for example spikes, spring teeth or discs arranged to be drawn over the ground to pulverise and smooth the soil. When the ground has stubble, weeds or other trash on its surface, the cultivating members become clogged so that it is necessary to cease cultivation and clear away the trash. It is an object of the present invention to provide harrows which are less liable to clogging than those presently available. The present invention accordingly provides harrows comprising a main beam, means for attaching the main beam to a prime mover to be drawn at right angles to the direction of travel at least one sub-frame fixed to the main beam and extending rearwardly of the main beam, each sub-frame supporting a spiked roller at an angle of between 50° and 55° to the direction of travel. The preferred angle between each roller and the direction of travel is 53°. The spikes on each roller are preferably located on a helical line around the surface of the roller, with the helices on all rollers running in the same direction. The angle of such a helix to the axis of the roller is between 50° and 55°, preferably 53°. Preferably, each spike extends from the surface of the roller so that the angle between the axis of the spike and the axis of the roller is between 50° and 55°. The most preferred angle between the axis of the spike and the axis of the roller is 53° It is also preferred that the angles: between the roller and the direction of travel; and between the axis of the spike and the axis of the roller, are chosen such that the axes of the spikes are substantially parallel to the direction of travel when the spikes at the trailing edge of the roller pass through a horizontal plane. Practical embodiments of harrows according to the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a schematic plan view of one embodiment of the harrows; Fig. 2 is an elevation on a larger scale of a roller in the direction 2-2 of Fig. 1; Fig. 3 is an elevation on the direction 3-3 of Fig. 1 showing the matter of mounting a roller on a sub-frame. Referring now to figures 1 to 3 of the drawings, the harrows comprise a main beam 10 having a tow-bar 11 fixed thereto centrally at right angles. Struts 12 maintain the members 10 and 11 at right angles when subjected to the stresses encountered in use. The height of the beam 10 above the ground can be adjusted in known manner by raising or lowering the ground wheels 13. Four sub-frames each comprising two rigid beams, of which the beams 14 are shorter than the beams 15 are fixed at right angles to the beam 10, ie. parallel to the direction of travel. Each sub- frame further comprises a carrier beam 16 fixed to the rearward ends of the beams 14 and 15. The sub-frames are mounted in known spring-loaded manner (not shown in the drawings) to provide "stump jump" ability. The relative lengths of the beams 14 and 15 are such that the angle 17 between the beam 16 and the direction of travel is 53°. Check plates 18 extend below the beams 16 at each end thereof. A roller 19 is journalled in the check plates 18 to extend between them. Spikes 20 are fixed to the outer surface of the roller 19 at locations lying on a helix. The helices on all the rollers run in the same direction. The angle of the helix to the axis of the roller is 53°. Each spike protrudes from the roller such that its axis is at an angle of 53° to the axis of the roller. The spacing of the sub-frames is such that the areas of ground traversed by the rollers 19 overlap to a small extent. In use, as the harrows are drawn across the ground the rollers 19 rotate as a result of engaging with the ground. Trash caught up in the spikes is pushed laterally towards the outer edges of the area traversed. If it is desired to concentrate the trash in a central pile, the disposition of the rollers with respect to the direction of travel is reversed, by arranging the shorter beams 14 nearer to the central axis of the harrows than the beams 15. The angles 17, of 53°, would then be located on the opposite sides of the beams 14 and 15. A further embodiment of the invention having only one roller is useful in confined areas such as between the rows of trees in an orchard. (This embodiment is not illustrated in the drawings.) This embodiment is based on a single sub-frame similar to each of the four sub-frames illustrated in Figure 1. This embodiment of the harrows includes a short main beam having only two rigid beams (similar to beams 14 and 15 of Figure 1) fixed at right angles to the main beam. As with the embodiment of Figure 1, a carrier beam similar to 16 is fixed to the rearward ends of these rigid beams. Check plates similar to check plates 18 extend below this carrier beam. A spiked roller similar to spiked roller 19 is journalled in these check plates to extend between them. Yet further embodiments of the invention incorporate a relatively smaller roller disposed centrally of the other rollers of the harrow. Such an embodiment of the invention could be similar to the embodiment of Figure 1, but differing from that figure in that there is a fifth roller disposed between the innermost two rollers, and straddling the central axis of the machine. The longitudinal axis of such a roller may be at an angle either clockwise or anti-clockwise from the direction of travel. Such a roller covers the gap in ground coverage between the inner edges of the two inner rollers, and can also be used for spreading chemicals.

Claims: We claim: 1. Harrows comprising a main beam, means for attaching the main beam to a prime mover to be drawn at right angles to the direction of travel, at feast one sub-frame fixed to the main beam and extending rearwardly of the main beam, each sub-frame supporting a spiked roller at an angle of between 50° and 55° to the direction of travel. 2. Harrows according to claim 1 wherein there are two or more sub-frames, at least one sub- frame supporting a spiked roller at an angle of between 50° and 55° clockwise from the direction of travel, and at least one sub-frame supporting a spiked roller at an angle of between 50° and 55° anti-clockwise from the direction of travel. 3. Harrows according to claim 2, wherein rollers on one side of a central, axis of the harrow are disposed clockwise from the direction of travel and rollers on the other side of said axis are disposed anti clockwise from the direction of travel. 4. Harrows according to any one of the preceding claims wherein the angle between the rollers and the direction of travel is 53°. 5. Harrows according to any one of the preceding claims, wherein the spikes on each roller are fixed to the roller at locations lying on a helix around the surface of the roller and wherein the helices on all rollers run in the same direction. 6. Harrows according to claim S. wherein the angle of the helix to the axis of the roller is between 50° and 55°. 7. Harrows according to claim 6, wherein the angle of the helix to the axis of the roller is 8. Harrows according to any one of the preceding claims, wherein each spike extends from the surface of the roller so that the angle between the axis of the spike and the axis of the roller is between 50° and 55°. 9. Harrows according to claim 8, wherein the angle between the axis of the spike and the axis of the roller is 53°. 10. Harrows according to any one of the preceding claims, wherein the axis of each spike is substantially parallel to the direction of travel when the spike passes through the horizontal plane at the trailing edge of the roller. 11. Harrows substantially as herein described with reference to and as illustrated by the accompanying drawings.

Inventors: BROWN GARY JOHN, BROWN, GARY, JOHN
Applicants: BROWN GARY JOHN, BROWN ROBYN, BROWN, GARY, JOHN, BROWN, ROBYN
Application year: 1997
Main classification: A01B21
IPC codes: A01B21