A rotary harrow has a frame for attachment to a prime mover, a portion of the frame having generally vertical shafts with soil-working members journalled therein and arranged side-by-side in a row that extends transverse to the direction of travel. Each soil-working member includes a generally horizontal support, the inner end of which is connected to its respective shaft and the outer end extends radially from the shaft with a tine holder for retaining a single upright tine. Adjacent soil-working members are driven in opposite directions and the working members can be arranged in groups which are positioned out of phase with respect to one another. A screening member is connected to the support to extend in the direction of rotation and protect the upper part of the soil-working members, including its

According to the invention, there is provided a rotary harrow of the kind 
set forth, wherein each soil working member or rotor is provided with at 
least one tine at only one side of the corresponding axis of rotation, and 
wherein the tines of each group of soil working members or rotors which 
are arranged to rotate in during the use of the harrow are angularly out 
of phase relative to one another about the corresponding axes of rotation.

Referring to the drawings, the rotary harrow that is illustrated has a 
frame portion 1 that is afforded principally by a hollow beam of sheet 
iron or other sheet metal construction that extends substantially 
horizontally perpendicular to the intended direction of operative travel 
of the harrow which is indicated by an arrow A in FIGS. 1 and 6 of the 
drawings. The hollow beam of the frame portion 1 accommodates a row of 
twelve vertical or substantially vertical shafts 2 that are arranged in 
side-by-side relationship with each shaft 2 carrying a corresponding soil 
working member or rotor that is generally indicated by the reference 3 at 
its lower end. It is emphasised that a rotary harrow having 12 shafts 2 
and corresponding soil working members or rotors 3 is described only by 
way of example and that a harrow in accordance with the invention could 
equally well comprise a greateror lesser number of such shafts and soil 
working members. The shafts 2 are rotatably mounted in substantially 
vertical bearings 6 lodged in recesses in the lower surface of the hollow 
beam affording the frame portion 1 and the axes of rotation of 
neighbouring shafts 2 are preferably spaced apart from one another by 
perpendicular distances of substantially 25 centimeters. The top of the 
hollow beam which affords the frame portion 1 is in the form of a 
substantially flat plate bolted to substantially horizontally disposed 
rims of the remainder of the beam which latter is of generally 
channel-shaped configuration. Each shaft 2 is provided inside the hollow 
beam with a corresponding pinion 4A having straight or spur teeth and it 
will be seen from FIGS. 1 and 6 of the drawings that the teeth of the 
twelve (in the example which is being described) pinions 4A are all in 
mesh with those of their neighbour or neighbours in the row. 
The lower ends of the twelve shafts 2 project from beneath the 
corresponding bearings 6 at the bottom of the frame portion 1 and are 
there provided with corresponding horizontally or substantially 
horizontally disposed tine supports 4 each of which projects from the 
corresponding shaft 2 in only one substantially radial direction. The end 
of each support 4 that is remote from the corresponding shaft 2 carries a 
substantially vertically disposed sleeve-like tine holder 5 that receives 
an upper fastening portion of a corresponding single tine 7 that projects 
substantially perpendicularly downwards from beneath the holder 5. The 
fastening portions of the tines 7 have screw-threaded upper extremities 
which receive nuts 8 that are tightened to center the tines 7 in their 
holders 5 and prevent undesired detachment of the tines from the holders. 
In FIG. 1 of the drawings, neighboring soil-working members or rotors 3 
rotate in relative opposite directions and are arranged in two groups with 
each member of one group being flanked by members of a second group. The 
tine supports 4 of consecutive soil-working members of each group are out 
of phase by multiplies of about 90.degree. i.e., 90.degree., 180.degree. 
or 270.degree.,from one another measured clockwise when the leftmost 
support of the first group extends about 180.degree. with respect to the 
first leftmost support of the second group. With such a phase difference, 
a smooth and steady operation of the harrow is attained. 
It can be seen from FIGS. 3, 4 and 5 of the drawings that each tine support 
4 is provided with a deflector for stones and other potentially damaging 
objects, said deflector taking the form of a screen 9 one edge of which is 
welded or otherwise rigidly secured to the corresponding shaft 2, support 
4 and holder 5 and which is inclined forwardly and upwardly from that edge 
with respect to the intended direction of rotation B of the corresponding 
soil working member or rotor 3. Each screen 9 is afforded principally by a 
plate that extends throughout substantially the whole of length of the 
corresponding tine support 4, said plate including an inclined portion 10 
whose lowermost and rearmost (with respect to the direction B) edge is 
rigidly secured to the corresponding shaft 2, support 4 and holder 5 as 
described above. The plate also includes a substantially horizontal free 
edge portion 11 at the uppermost and leading (with respect to the 
direction B) extremity of the portion 10. A brace 12 of less width than 
the remainder of the screen 9 rigidly interconnects a top region of the 
corresponding tine support 4 and the junction between the two portions 10 
and 11 of the plate principally affording the screen 9. 
Two arms 13 are turnable upwardly and downwardly about substantially 
horizontally aligned pivots located at the opposite ends of the frame 
portion 1 and at the front thereof with respect to the direction A, said 
arms 13 extending rearwardly from the pivots with respect to the direction 
A. The arms 13 move alongside substantially sector-shaped plates 14 that 
are fastened to the opposite ends of the frame portion 1 so as to lie in 
substantially vertical planes extending substantially parallel to the 
direction A. Each plate 14 is formed adjacent a rearward curved edge 
thereof with an arcuately curved row of holes 15 each of which is at the 
same distance from the axis afforded by the pivots that connect the arms 
13 directly or indirectly to the frame portion 1. Each arm 13 is provided 
with a substantially horizontal locking pin 16 whose tip can be entered in 
any chosen one of the corresponding curved row of holes 15 to maintain 
that arm in a corresponding angular setting about the axis afforded by the 
pivots that have just been mentioned. A soil compression member in the 
form of a roller 17 is rotatably mounted between the rearmost ends of the 
two arms 13 so that said roller 17 lies just behind the frame portion 1 
and soil working members or rotors 3 with respect to the direction A. The 
roller 17 comprises a plurality, such as five, of regularly spaced apart 
substantially vertical support plates 19 and a plurality, such as eight, 
of elongated tubular elements 18 that are entered loosely through holes in 
the peripheries of the support plates 19 in such a way as to be wound 
helically to some extent around the axis of rotation of the roller. 
Plates 21 are disposed immediately beyond the opposite ends of the row of 
soil working members or rotors 3 and bear slidably against the ground 
surface by their lowermost edges during the use of the harrow. The plates 
21 are connected by pairs of arms 20 to substantially horizontal pivots 
affording axes that extend substantially parallel to the direction A and 
said plates 21 can thus turn upwardly and downwardly to match undulations 
in the surface of the ground over which the harrow is travelling during 
the use thereof. Moreover, the plates 21 and their supporting arms 20 can 
be turned upwardly through substantially 180.degree. about their pivotal 
connections with the top of the frame portion 1 to bring them to inverted 
positions that are suitable for the inoperative transport of the harrow in 
which positions they bear downwardly against the top plate of the frame 
portion 1. The shaft 2 of one of the center pair of the twelve soil 
working members or rotors 3 has an upward extension through the top of the 
frame portion 1 into a gear box 22 which is accordingly located slightly 
to the left of the center of the harrow as viewed from the rear in the 
direction A. The extension shaft which has just been mentioned is 
provided, inside the gear box 22, with a bevel pinion 22A whose teeth are 
in driven mesh with those of a smaller bevel pinion 22B mounted on a 
rotary input shaft 23. The rotary input shaft 23 extends substantially 
parallel to the direction A, its rear end that carries the pinion 22B 
being located inside the gear box 22 while its leading forwardly 
projecting end is splined or otherwise keyed for connection to the power 
take-off shaft of an operating agricultural tractor or other vehicle by 
way of an intermediate telescopic transmission shaft 26 of known 
construction having universal joints at its opposite ends. The front of 
the frame portion 1 with respect to the direction A is provided with a 
generally triangular coupling member 24 arranged for connection to the 
lifting links of the three-point lifting device or hitch of an operating 
agricultural tractor or other vehicle in the manner which is shown in 
outline in the drawings. Two tie rods 25 rigidly interconnect the apex of 
the coupling member 24 and horizontally spaced apart anchorages at the top 
and rear, with respect to the direction A, of the frame portion 1, said 
tie rods 25 converging towards the coupling member 24 when the harrow is 
viewed in plan (FIGS. 1 and 6). 
In the use of the rotary harrow that has been described, its coupling 
member 24 is connected to the three-point lifting device or hitch of an 
agricultural tractor or other operating vehicle in the manner shown in the 
drawings and the rotary input shaft 23 of the gear box 22 is placed in 
driven connection with the power take-off shaft of the same tractor or 
other vehicle by way of the intermediate telescopic transmission shaft 26. 
As the harrow is moved over the ground, the soil working members or rotors 
3 rotate in the opposite directions that are indicated by arrows B in FIG. 
1 of the drawings, it being preferred that said members or rotors 3 should 
rotate at speeds of substantially 500 revolutions per minute and certainly 
not less than substantially 400 revolutions per minute. Since the paths 
traced by the tips of the tines 7 during rotation of the shafts 2 overlap 
one another, the harrow will effectively work a single broad strip of land 
provided that the soil working members or rotors 3 thereof rotate at the 
speed just noted. As previously mentioned, the arrangement of the tine 
supports 4 and tines 7 of neighbouring soil working members or rotors 3 in 
staggered relationship about the axes of rotation of the shafts 2 so as to 
be not more than 180.degree. cut of phase with one another ensures a 
smooth and steady operation of the harrow and avoids any appreciable 
tendency to lateral reciprocatory of the frame portion 1. Since each soil 
working member or rotor 3 has at least one tine 7 at only one side of the 
corresponding rotary shaft 2, large gaps are left between the tines 7 
during operation thus greatly reducing the tendency for stones, pieces of 
wood, roots and other hard objects on or in the soil to become jammed 
between the tines. The deflectors that are afforded by the screens 9 
fastened to the tine supports 4 tend to direct any stones or other objects 
of the kind which have just been mentioned downwardly to a level beneath 
that of the tine supports 4 and the retaining nuts 8 that are disposed 
above the upper ends of the tine holders 5. The tines 7 which have been 
described and illustrated project substantially perpendicularly downwards 
towards the ground surface but these tines may be replaced by tines whose 
lower soil working portions are inclined at a few degrees to the vertical 
and downwardly and rearwardly with respect to the intended directions of 
rotation B. Such tines may be said to "trail" with respect to the 
directions of rotation B and the use of such trailing tines has been found 
to be particularly advantageous in the working of heavy soil. 
The rotary harrow illustrated in FIG. 6 of the drawings is identical to 
that already described with reference to FIGS. 1 to 5 thereof with the 
exception of the relative disposition of the tine supports 4 and tines 7 
of the various soil working members or rotors 3. In the arrangement 
illustrated in FIG. 6 of the drawings, there are two groups of soil 
working members or rotors 3 each of which groups totals six in number. The 
six soil working members or rotors 3 of one group rotate in one direction 
and the six which comprise the other group rotate in the opposite 
direction and it will accordingly be realised that each soil working 
member or rotor 3 of any one group is flanked at both its opposite sides 
by two soil working members or rotors 3 of the other group with the 
exceptions of the two soil working members or rotors 3 that are located at 
the opposite ends of the single row thereof. Each group of soil working 
members or rotors 3 comprises six thereof and the tine support 4 and tines 
7 of each member or rotor 3 are angularly displaced around the axes of the 
corresponding shafts 2 by 360.degree. divided by the number of members of 
the group (i.e. six) relative to the next member of the group. Thus, each 
member of the group has its tine support 4 and single tine 7 substantially 
60.degree. out of phase around the axis of rotation of the corresponding 
shaft 2 as compared with the next, or the next and preceding, member of 
the same group. In order to avoid any fouling of the tines 7, the tine 
supports 4 and tines 7 of two neighbouring soil working members or rotors 
3 of the two different groups are substantially 150.degree. out of phase 
with one another around the axes of rotation of the shafts 2 as 
illustrated in FIG. 6 of the drawings. The described arrangement of the 
tine supports 4 and tines 7 in two groups and of the different supports 
and tines in one group relative to one another and of the two groups 
relative to one another produced a particularly smooth and steady 
operation of the harrow despite the fact that each soil working member or 
rotor 3 has only one tine at one side of the corresponding axis of 
rotation. 
Although not illustrated in the accompanying drawings, it is to be noted 
that it is within the scope of the invention to provide each tine support 
4 with a group of two or more tines 7 each of which is disposed at 
substantially the same side of the corresponding shaft 2. 
Although certain features of the rotary harrow that has been described and 
illustrated in the accompanying drawings will be set forth in the 
following claims as inventive features, it is emphasised that the 
invention is not necessarily limited to those features and that it 
includes within its scope all of the parts of the harrow that has been 
described and/or illustrated both individually and in various combinations 
.