The pair of projections maybe provided on the first tine part, and the two, .»- pairs of recesses may be provided in the second tine part. However, it should be understood that it is within the scope of the compact tractor attachments for the position of the projections and the recesses to be reversed.
The projections preferably comprise cylindrical pegs, and which may be formed during the formation of the first tine part e.g. by forging.
According to a second aspect of the compact tractor attachment there is provided a power harrows having a frame, a set of rotary harrow tines each mounted on the frame via respective rotatable mountings, and a drive train arranged to provide rotary power to rotate the harrow tines, in which each harrow tine is as defined in the first aspect of the compact tractor attachment.
According to a third aspect of the compact tractor attachment there is provided a method of adjusting a worn tip of a two part tine having a working part and a mounting part, in a power harrow as defined by the second aspect of the compact tractor attachment, in which: the working tine part is loosened and / or released from the mounting tine part by which the tine is mounted on the frame of the harrow; and, the working tine part is adjusted so that the opposite tine tip takes-up the working position and / or the worn tip is adjusted lengthwise relative to the mounting part so as to project by a greater distance from the mounting tine part and allow further wear to take place.
A preferred embodiment of the compact tractor attachment will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a perspective illustration of a typical design of existing rotary power harrow, in which an embodiment of the compact tractor attachment may be provided;
Figure 2 is a detail view showing how a one-piece rotary harrow tine of known design is mounted on a rotatable mounting on a frame of the power harrow shown in Figure 1;
Figure 3 is a perspective illustration, in assembled form, of a preferred embodiment of two part rotary harrow tine according to the compact tractor attachment and comprises a mounting part and a harrow tine part;
Figure 4 is a view, similar to Figure 3, but showing the two parts in exploded form and also showing the non-engaging face of the harrow tine part uppermost; and,
Figure 5 also shows the two parts of the harrow tine separated from each other prior to assembly, and illustrating in more detail a co-operative arrangement of projections and pairs of recesses, and a number of different fastening holes, together providing initial wear adjustment, and final wear adjustment of each of two opposed pairs of working tips of a working part of the harrow tine i.e. to provide possibility of four different wear compensating adjustments of the harrow tine.
Referring first to Figures 1 and 2, there will be described, by way of background to the compact tractor attachment, a typical existing design of rotary harrow power tine, and which is normally intended to be mounted at the rear of a tractor, and from which drive power is transmitted to a number of rotary harrow tines mounted on a frame of the harrow. The harrow is designated generally by reference 10, and has a frame 11, and a series of one-piece rotary harrow tines 12 mounted on the underside of the frame 11 via respective rotatable mountings.
Figure 2 is a detail showing how a known one piece harrow tine 12 is mounted on a circular rotatable mounting 13 on the underside of frame 11. Figure 2 shows the mounting 13 partly in section. As discussed in the introduction to the specification, the use of one-piece harrow tines, for use in power harrows, provides robust and durable tines. However, given that the parts of the tines which are most exposed to wear i.e. the working tips, only constitute about 30% of the overall tine construction, when unacceptable tip wear occurs, it is then necessary to scrap the remaining 70% of the tine, and replace with a completely new replacement one-piece tine.
Also, as referred to in the introduction, the replacement of worn one-piece rotary harrow tines cannot easily be carried out in the field, and therefore usually must be carried out as part of regular maintenance in the workshop. In the event of damage to a harrow tine in the field, it is not easy to carry out individual replacement straight away.
A preferred embodiment of two part rotary harrow tine will now be described with reference to Figures 3 to 5. The rotary harrow tine is designated generally by reference 14, and has a first mounting part 15 which is adapted to be mounted on a respective rotatable mounting (e.g. 13 in Figure 2) on a frame 11 of a power harrow 10, and a second working part 16 having a ground / soil working tip 17.
The first part 15 has a frame mounting portion 18 which can be mounted e.g. by bolts onto the rotatable mounting, and also has a tip mounting portion 19 at its op osit . „ end. The second part 16 is detachably engageable with the tip mounting portion 19, and is releasably secured thereto via a single releasable fastener 20.
A first one of the tine parts (15, 16) has a pair of projections, and a second one of the tine parts has two pairs of recesses, each recess being of a size to be capable of receiving one of the projections. In the illustrated embodiment, by way of example only, projections 21 are provided on the underside of the tip mounting portion 19 of first mounting part 15, and two pairs of recesses 22, 23 are provided in the working part 16 (see the facing surface of part 16 in Figure 5). It will be noted that the pairs of recesses 22 and 23 are arranged one on either side of the fastener 20, when the latter is taken through a central one of a set of three fastening holes 24, 25 and 26, provided also in the working part 16. A single fastening hole 27 is provided in the tip mounting portion 19 of mounting part 15. Evidently, the positions of the projections 21 and the pairs of recesses 22 and 23 may be reversed, and similarly also the single fastening hole 27, and the set of three fastening holes 24, 25, 26 also may be reversed. Figure 3 shows the tine parts 15 and 16 assembled together, and Figures 4 and 5 show them separated. Also, Figure 4 shows the non-engaging face of the working part 16 uppermost and usually the threaded fastener 20 will have an integral driving head (not shown) which is engaged by a spanner or other tool to drive the thread of the fastener into driving engagement with a nut 21a, in order to clamp the parts 16, 18 together. It will be noted from Figures 4 and 5 that the working part 16 has opposed working tips, of which the one presently in the working position is designated by reference 17, and the opposite tip, presently in the inoperative position, is designated by reference 17a. There are also adjacent co-operative working edges 18 and 18a respectively.
The provision of single fastening hole 27, and the set of three fastening holes 24, 25 and 26 permits lengthwise adjustment of the working part 16 relative to the mounting part 15, when tip wear occurs, whereby the distance from any particular working tip and the fastening hole 27 can be extended, to compensate for tip wear.
The provision of the projections 21, and the pairs of recesses 22 and 23, allows the parts 15 and 16 to be securely fastened together, and held securely against rotation about the axis of the fastener 20, by reason of engagement of the projections 21 in any pair of the recesses 22; 23, for all adjusted positions.
Evidently, the working part 16 is reversible, whereby, when tip 17 becomes initially worn, loosening and / or release of the fastener 20 allows the working part 16 to rotate through 180°, and to bring the previously inoperative working tip 17a to the working position. There will continue to be engagement of the projections 21 in recesses, but in this case instead of being received by the pair of recesses 23, the projections will be received by the pair of recesses 22.
Generally, after initial wear of the tips 17 and 17a has arisen, it will then be possible to maintain use of the working part, subject to lengthwise adjustment, by bringing either fastening hole 24 or 26, into alignment with single fastening hole 27, and securement together by the fastener 20, whereby the particular partly worn working tip (17, 17a) projects by a greater distance lengthwise of the single fastening hole 27, and allows further wear to take place.
When a particular working tip has undergone two separate wearing actions, as described above, the working part may then be reversed, so that a partly worn tip can then undergo final wear. It will only be when both working tips have been subjected to these two separate wearing actions, and necessary adjustment, that the harrow tine will require to be repaired. However, it will only be necessary then to remove the working part 16, and replace it with a further working part, as the wear to which the mounting part 15 is exposed is generally less arduous in service, and repair and replacement of the working of the mounting part 15 will generally be required much less frequently.
The preferred embodiment therefore provides a reversibly mounted harrow tine part (the second part 16) which has opposed working tips, either one of which can be brought to the working position when required e.g. when unacceptable wear has occurred to the tip presently in the working position. In addition, when unacceptable initial wear has taken place for both working tips, either one of the worn tips can be adjusted to project a greater distance lengthwise of the mounting part 15 by lengthwise adjustment of the working part 16. Further reversal of the working part then allows the further worn tip to be replaced by an only partly worn tip.
Accordingly, the compact tractor attachment provides a harrow tine part (the working part 16) in which four separate wearing actions may take place i.e. initial and then final wear on each working tip 17, 17a, before the tine part needs to be replaced.
Fυrth π πre. by use of a single fastener 20 (located below the level of the frame -. 11 of the harrow 10), easy access can be had to the fastener 20, which allows wear-related adjustment to be carried out in the filed.
The projections 21 are preferably formed integrally with the formation of the tine part (15, 16) on which it is provided, and conveniently such part is formed by forging.
Evidently, the preferred embodiment of rotary harrow tine described above may be incorporated in a power harrow having a frame, a set of rotary harrow tines each mounted on the frame via respective rotatable mountings, and a drive train arranged to provide rotary power to rotate the harrow tines.
The compact tractor attachment may also allow for an easy method of adjusting a worn tip of a two part tine (having a working part and a mounting part), which is provided in a power harrow, and in which the potential adjustment steps comprise one or more of the following:
(1) the working tine part is loosened and / or released from the mounting tine part by which it is mounted on the frame of the harrow;
(2) the working tine part is rotatably adjusted so that the opposite tine tip takes-up the working position; and, (3) the worn tip is adjusted lengthwise relative to the mounting part so as to project by a greater distance from the mounting tine part and allow further wear to take place.