GB2043416A - Harrow - Google Patents

Abstract

A harrow comprises a rigid horizontal frame (1) and a plurality of tine support bars (24, 25) suspended below the frame and extending transversely thereof, each bar carrying a plurality of tines (27a). A linkage (7 to 11) is provided for raising and lowering the support bars relative to the frame to adjust the height of the tines. A separate linkage (16 to 19) is provided for independently twisting the bars to adjust the pitch of the tines. Two rows of fixed tines (6) are mounted forwardly of, and a crumbling roller (28) is mounted rearwardly of the adjustable tines (27a). <IMAGE>

Description

SPECIFICATION A harrow This invention relates to a harrow for cultivating soil to a shallow depth.

It is an object of the invention to provide a readily adaptable implement for use in different soil conditions, which will effectively break up and pulverize the soil in one pass only to leave a fine tilth suitable for sowing. It is a further aim of the invention to provide an improved linkage means which will tend to dissipate any sudden stress imposed on the implement during operation by passing over projecting obstacles.

According to the present invention a harrow comprises a rigid substantially horizontal frame, a first cultivating means including at least one tine support bar mounted below and extending transversely of the frame, a plurality of downwardly projecting tines mounted on said bar, means for raising and lowering the bar relative to the frame whereby in use of the harrow the height of the tines relative to ground surface may be adjusted, and means for rotating the bar so as to alter the pitch of the tines.

Further according to the invention a harrow includes a second cultivating means comprising at least one row of a plurality of downwardly projecting tines fixedly attached to and extending transversely of, said frame at a position forwardly of said first cultivating means.

Yet further according to the invention a harrow includes a third cultivating means comprising a freely rotatable crumbling roller supported from said frame and positioned rearwardly of said first and second cultivating means.

Preferably the harrow is connectable to a mechanically propelled vehicle such as a tractor by means of an upstanding centrally positioned three-point linkage means, wherein the uppermost linkage point is connected to the frame by a link which includes a spring which is adapted to absorb shocks imposed on the tines.

In a preferred embodiment the second cultivating means comprises two parallel rows of fixed tines disposed forwardly of the first cultivating means which comprises two parallel rows of tines, smaller in size than the fixed tines, and preferably of the type comprising a curved-spring member with a detachable blade member. The means for raising and lowering the tines comprises a linkage which is foldable about pivot pins so as to raise and lower tine support bars. The means for rotating the bars comprises a linkage which serves to alter the pitch of the tines relative to the support frame to vary the angle of flexure of the tines relative to the ground surface.

Two embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a side elevation of a first embodiment of the invention.

Figure la is a side elevation of a first embodiment of the invention as viewed along section line A-A' of Fig. 3.

Figure 2 is a front end elevation of a first embodiment of the invention, omitting the tines for clarity.

Figure 3 is a plan view of a first embodiment of the invention.

Figure 4 is a side elevation of a second embodiment of the invention.

With reference to Figs. 1 to 3 of the drawings, a harrow comprises a rectangular steel frame 1 which is strengthened by longitudinal members 2 and 3 disposed along the length of the frame. Two front tine support bars 4 and 5 are welded to the underside of the front half of the frame, and are disposed across the width of the frame. A second cultivating means comprising two rows of front tines 6 are bolted onto the tine support bars and are curved in the manner shown in Fig. 1 so as to project downwardly and always be inclined in the direction of forward travel of the implement when in operation, by virtue of the spring action imparted by the curvature.

Suitably, there are 9 tines fixed to the support bar 4, and 1 2 tines fixed to the support bar 5, all the tines normally being equally spaced along each support bar, but those of support bar 4 being alternately opposed to those of support bar 5. The tines are made from spring steel in well known manner.

A first cultivating means comprising two rows of rear tines 27a, and having a curved spring member 26 and a detachable blade member 27, are disposed behind and parallel to the two rows of front tines 6. The front tines 6 are fixed relative to the frame 1, but the rows of rear tines 27a are provided with raising and lowering means comprising four linkages 7 to 15, located at rearward portions of the two side members 1 a of the frame and the two cross members 2 and 3. Downwardly projecting links 7 and 8 are pivotally connected to side frame members 1 a and cross members 2 and 3 by pivot pins 9 and are connected to one another by a pair of horizontal cross-links 10, one to each side of each of the downwardly projecting links 7 and 8 through pivot pins 11.Two downwardly projecting links 8 also project above the level of the frame 1 and are adapted to provide raising and lowering means for the height adjusting linkage 7 to 1 5. The means comprises a movable handle 1 2 held in position by brackets 13, and co-operable with a notched plate 14. The uppermost end 1 5 of the bar 8 is bent over at a right angle so as to form a covering for the handle 1 2.

The means for rotating the rear tines com prises seven linkages 1 6 to 23. Upstanding links 1 6 are pivotally connected at their lower ends to the cross-links 10 by pivot pins 17, and are pivotally interconnected at their upper ends by a pair of horizontal cross-links 18, by means of pivot pins 1 9. One of the centrally located upstanding links 1 6a projects above the level of the frame 1 and is adapted to provide a means for rotating the rear tines, by pivoting the tine support bars 24 and 25, which are fixed to the ends of the links 1 6 and 1 6a about the cross-links 10.The link 16a comprises a handle 20, brackets 21, notched plate 22, and handle covering 23, similar to the raising and lowering means of the height adjusting linkage 7 to 1 5. The handles may be fitted with springs 20a (as shown in Fig. 2) to restrain the handles in a locked position, as hereinafter described.

The rear tine support bars 24 and 25 are welded to the lower end surfaces of the upstanding bars 16, and are disposed across the width of the frame 1, and at a level approximately half way between the level of the frame 1 and ground level. Suitably, there are twelve tines fixed to the tine support bar 24 and eighteen tines fixed to the tine support bar 25, those fixed to bar 24 normally being alternately opposed to those fixed to bar 25.

A crumbling roller 28 is formed by welding flat lengths of steel 29, suitably twelve in number, by their edges to the outer surfaces of a series of equally spaced annular rims 30, all of the same diameter. The rims 30, each have two spokes 31 welded to their inner surface and to an axle 32, and are aligned diametrically across the rim. The axle is freely rotatable about bearings 32, which are bolted onto the ends of supporting bars 33 which project rearwardly and downwardly from the frame. The bars 33 are pivotally connected to the side members 1 a of the frame 1 by means of a pivot pin inserted through two upstanding plates 34 fixed one to each side of the side members 1 a.

A means to restrict the vertical movement of the crumbling roller consists of two upstanding plates 35, between which the supporting bar 33 passes, located at both rear corners of the frame 1. A bridging plate holds the two plates 35 rigidly apart, through which passes a handle 36, having a screw-threaded shaft co-operable with the supporting bar 33.

A three-point linkage means comprises two upstanding bars 37 which are bent at an angle so as to be inclined towards each other, and connected pivotally to two projecting plates 38 which are fixed to the front end of the frame 1. Pivot pins 39 provide the two lower linkages. A securing bolt 40 connects the uppermost ends of the bars 37 and also passes through a U-shaped bridging plate 41.

There are two holes 42 at the top of the bridging plate 41 through which a pin may be passed thus providing the top linkage point.

The upstanding bars 37 are supported by an A-frame 43 inclined at an angle of approximately 30 to the frame 1, and pivotally connected to it by upstanding plates 44 fixed to the inner sides of cross-members 2 and 3.

The A-frame 43 is pivotally connected to the bars 37 by bolt 45. A compression spring 46 is connected at one end to the securing bolt 40 and at the other end by a screw 47 which passes through the cross bar of the A-frame 43. By turning the screw 47, the tension of the spring may be adjusted.

In operation, the harrow is first linked up to a mechanically propelled vehicle such as a tractor by the standard three-point linkage method. The front two rows of tines 4 and 5 are adapted to dig deeply into the ground and cut up the soil into large lumps. The rear two rows of tines 24 and 25 serve to break up the soil still further, and depending on the soil condition i.e. tilth, moisture content etc., the height and pitch of the rear tines may be altered as required.The height of the tines may be adjusted by raising the handles 1 2 upwardly to disengage them from the notched plates 1 4. The handles 1 2 are then pushed forward which causes the two links 8 to pivot about pivot pins 9 thus causing the linkage 7, 8, 10 to fold upwardly and rearwardly to raise the tines to the desired height relative to the frame 1. The tines can be locked in this position by releasing the handles 1 2 such that they each engage in a notch in the plates 14.

The pitch may be altered independently by raising the handle 20 upwards, and then moving the link 1 6a forwardly through an arc about pivot pins 1 9. This causes the tine support bar 25 to rotate through about 90 (the ends of the tine support bars 24, 25 are journalled in the opposed cross-links 10). The forward movement of the link 1 6a is transmitted to the links 1 6 by cross-links 1 8 thus causing the simultaneous rotation of tine support bar 24. The rotational movement of the bars 24, 25 is translated through the spring steel members 26 to the tine blades 27 so as to alter the pitch of the blades. When the tines are at the required pitch with respect to ground level, the handle 20 is then released so as to engage with a different notch on the notched plate 22. It is possible to raise the rear tines completely clear of the ground, without raising the harrow by hydraulic or other means, if desired. The crumbling roller 28 serves to pulverise the surface soil, and by turning the handle 36 so as to move its screw-threaded shaft up and down, it is possible to give the supporting bars 33 a greater or lesser freedom of vertical movement within the space defined between the upstanding plates 35.

Fig. 4 shows a second embodiment of the invention wherein the basic arrangement of the harrow is the same as shown in Figs. 1 to 3 except that the first cultivating means comprises 3 rows of tines 48 instead of 2 rows.

Each of the 3 rows of tines are connected by very similar linkages to those of the first embodiment such that the 3 rows together are adjustable in height and pitch as described above.

Fig. 4 also shows an alternative means for restricting the vertical movement of the crumbling roller which can be a biassing means such as a compression spring 49 which acts on the supporting bars 33 to bias the roller 28 downwardly but capable of yielding upwardly to absorb any shocks which might be caused by passing over an obstruction when the harrow is in operation.

Hydraulic means could also be employed to raise and lower the linkages of the first cultivating means on larger harrows. It may also be desirable to adapt the three point linkage so that the whole frame of the harrow may be raised or lowered relative to the three point linkage by hydraulic or other means to allow convenient transport of the harrow when mounted on a vehicle.

It is emphasised that the invention is not necessarily restricted by the number of tines, nor by the particular array of tines as described in the two embodiments of the invention with reference to Figs. 1 to 3 or Fig. 4 of the accompanying drawings.

Claims (16)

1. A harrow comprising a rigid substantially horizontal frame, a first cultivating means including at least one tine support bar mounted below and extending transversely of the frame, a plurality of downwardly projecting tines mounted on said bar, means for raising and lowering the bar relative to the frame whereby in use of the harrow the height of the tines relative to ground surface may be adjusted, and means for rotating the bar so as to alter the pitch of the tines.

2. A harrow as claimed in claim 1, including a second cultivating means comprising at least one row of a plurality of downwardly projecting tines fixedly attached to, and extending transversely of, said frame at a position forwardly of said first cultivating means.

3. A harrow as claimed in claim 2, including a third cultivating means comprising a freely rotatable crumbling roller supported from said frame and positioned rearwardly of said first and second cultivating means.

4. A harrow as claimed in any of the preceding claims wherein the tine support bar is suspended below the frame by means of at least one first linkage comprising a plurality of links which are pivotable relative to each other to raise or lower the tine support bar relative to the frame.

5. A harrow as claimed in claim 4 wherein the or each first linkage comprises three links, two of which are pivotally connected to the frame, and extend downwardly below the frame, and a remaining substantially horizontal link forming a connection between the free ends of the said two links and pivotally connected thereto, so that the linkage may be foldably raised and lowered relative to the frame by means of a handle portion on one of the said two links.

6. A harrow as claimed in claim 5 wherein the linkage may be raised and lowered by hydraulically operable means.

7. A harrow as claimed in claim 5 wherein the means for rotating the bar so as to alter the pitch of the tines comprises at least one second linkage, operable independently of said first linkage, the or each second linkage comprising at least one link member connected at one end to the bar and at the other end to handle means and pivoted intermediate its length about said remaining substantially horizontal link, such that pivoting of the said link member serves to rotate the bar.

8. A harrow as claimed in any preceding claim wherein the first cultivating means includes two tine support bars.

9. A harrow as claimed in any of claims 5 to 8 whereby means are provided to lock the said first linkage in a predetermined position relative to the frame.

10. A harrow as claimed in any of claims 5 to 8 whereby means are provided to lock the said second linkage in a predetermined position.

11. A harrow as claimed in any of claims 8 to 10 wherein each tine support bar is connected to one end of a respective link member of the second linkage, each other end of each respective link member being pivotally interconnected by a cross link, so that all of the tine support bars are together rotatable by pivoting the link member which serves to rotate the bars.

1 2. A harrow as claimed in any preceding claim including a three point linkage at the front of the frame for connection to a vehicle which includes means for absorbing shocks imposed on the harrow when in use.

1 3. A harrow as claimed in claim 1 2 wherein said means is a compression spring.

14. A harrow as claimed in claim 3 wherein crumbling roller supports are pivotally mounted on the frame enabling substantially vertical movement of the crumbling roller relative to the frame, including means to restrict said vertical movement.

1 5. A harrow as claimed in claim 1 4 wherein the means, for restricting vertical movement comprises a vertical shaft cooperable with each crumbling roller support, which shaft is adjustable so as to allow a greater or lesser freedom of movement of the supports in the space between the frame and the said shaft.

16. A harrow as claimed in claim 14 wherein the means for restricting vertical movement comprises a spring acting on the crumbling roller supports so as to bias the crumbling roller towards ground surface.