GB2257343A

GB2257343A - Agricultural implement for soil treatment.

Info

Publication number: GB2257343A
Application number: GB9111575A
Authority: GB
Inventors: Leslie Frederick Field
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-05-30
Filing date: 1991-05-30
Publication date: 1993-01-13
Anticipated expiration: 2011-05-30
Also published as: GB2257343B; GB9111575D0

Abstract

An implement for soil treatment, such as a harrow, comprises a frame (2, 10) attachable to a tractor and having a ground wheel (8) at each end. Mounted on the frame are a plurality of tine arms pivotal about a spindle whose axis is parallel to the wheels, each arm carrying a tine. A torsion spring acts on each tine, such that the downward force on the tine is determined partly by adjustment of the top link of the three-paint tractor linkage and partly by the spring. The tine arms may be of alternating length; and the implement may be constructed in three sections, with two outer sections hinged to a central section which includes the ground wheels (8). <IMAGE>

Description

Title: AGRICULTURAL IMPLEMENT FOR SOIL TREATMENT Field of the invention This invention relates to an agricultural implement for soil treatment, more especially an implement in the form of a harrow or scarifier.

Background to the invention British Patent Specification GB 2197771 discloses an agricultural implement comprising a-main frame, a plurality of tine arms each pivotally mounted to the main frame and extending in use rearwardly from the pivotal mounting, a tine for soil penetration secured to the rearward end of each tine arm, and means for biassing each tine arm to cause the tines in use to penetrate the soil during forward movement of the implement, said means for biassing comprising an adjustable cross member extending over the. tine arms and spring means connecting the tine arms to the cross member, whereby in use adjustment of the cross member varies the pressure with which each of the tines is urged to penetrate the soil.

While an agricultural implement as described represents a substantial improvement over conventional equipment, it is nevertheless somewhat complicated and expensive to manufacture, and also tends to have a high centre of gravity.

It is an object of the present invention to provide an alternative form of construction for such an implement. Summary of the invention According to the present invention there is provided an improved agricultural implement comprising: a main frame; a ground wheel mounted at each side of the frame for rotation about a wheel axis; means for connecting the main frame to a three-point linkage of a tractor; a plurality of tine arms each mounted about a pivotal axis on the frame which is substantially parallel to the wheel axis; a tine secured to the end of each tine arm; and spring means mounted around said pivotal axis and acting on each tine arm, whereby the downward force on each tine is determined in part by the force of the spring means and in part by adjustment of the top link of the three-point linkage which pivots the main frame about the ground wheels axis.

In one embodiment the spring means is a helical torsion spring, one for each tine arm, the spring being loosely wound around a spindle defining the pivotal axis of the tine arm.

Preferably there are a plurality of aligned spindles, each serving an assembly of four tine arms.

The torsion springs may be formed in pairs to act on adjacent tine arms.

The two springs of a pair may be formed as an integral spring.

Alternate tine arms may be of differing lengths so that a shorter tine arm is sandwiched between two longer tine arms.

Advantageously a scraper plate is secured at each side of the frame to engage with the periphery of the respective ground wheel, to prevent a build-up of soil on the wheels, and thereby maintain sensibly constant the height of the frame above the mean ground level. This helps to prevent variations in the downward force on the tines.

In a modified embodiment of the invention the implement is formed in three sections, comprising a central section including the ground wheels, and two outer sections each hinged relative to the central section about a horizontal axis. The implement can then be transported with the outer sections hinged in an upward position, so reducing the overall width requirement and enabling the implement to be transported on roads and through gateways.

Brief description of the drawings An agricultural implement constructed in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of the complete implement; Figure 2 is an end view with an end plate removed to show a tine spring; Figure 3 is a perspective view of an assemply of a set of tine arms; and Figure 4 is a perspective view of one end of implement with a ground wheel removed.

Detailed Description Referring first to Figures 1 to 3 of the drawings, the harrow implement shown comprises a main frame 2 made up of a transverse beam 4 of square cross-section and box section arms 6 welded to each end. A ground wheel 8 is rotatably mounted at the outboard end of each arm 6.

Mounted at the centre of the beam 4 is a linkage frame 10 for attachment to a three-point linkage of a tractor. At regular spacings along the beam 4 are plates 12 welded to the beam, and removably secured to these plates are apertured plates 14 for supporting a spindle 16.

Fitted over the spindle 16 are sleeves 17 which pivotally carry four tine arms which are alternately short and long.

In Figure 3 two of the four arms have been omitted to reveal the detail of the mounting. As shown, the longer tine arm is designated 18 and the shorter arm 19. Secured to the ends of the arms are tines 20, whose lower pointed ends are engageable with the soil to be harrowed.

Between adjacent tine arms 18, 19 are pairs or torsion springs 22, 23 coiled -about the sleeve 17, each spring having one end secured to a respective tine arm and an opposite end engaging against the face of the beam 4. The springs thus individually force the tine arms (and in turn the respective tines), in a downward direction. Downward movement of the tine arms by the springs is limited by the engagement of the forward ends of the tine arms with the underside of the beam 4.

When attached to the three point linkage of a tractor, the implement can be tilted about the axis of the wheels 8 by adjusting the length of the top link joining the upper point of the three point linkage to the top of the linkage frame 10,thereby varying the nominal position of the tines relative to the ground. The degree of penetration of the tines into the soil is thus determined not only by the force of the springs 22, 23 acting on the tine arms 18 but also by adjustment of the lenth of the top link of the three-point linkage.

As shown in Figure 4, the wheels 8 are carried on stub axles one of which is shown as 24 welded to the box section arm 6. Welded to the arm 6 behind the axle 24 is a scraper plate 26 which in use engages with the periphery of the wheel 8- to prevent the build up of soil on the wheel.

Although not shown, the implement may be formed in three sections comprising a main central section similar to that described above, and two end sections hinged to the outboard ends of the central section, each end section being similar to the central section and having tine arms and tines mounted there along in a similar manner to the central section. The end sections can thus be raised to reduce the width of the implement, eg.-for transportation and when not in use.

It will be apparent that the implement described can be manufactured more simply and cheaply than the implement described in the above mentioned Patent Specification and has the additional merit of being iighter in weight and having a lower centre of gravity.

Claims

1. An agricultural implement comprising: a main frame; a ground wheel mounted at each side of the frame for rotation about a wheel axis; means for connecting the main frame to a three-point linkage of a tractor; a plurality of tine arms each mounted about a pivotal axis on the frame which is substantially parallel to the wheel axis; a tine secured to the end of each tine arm; and spring means mounted around said pivotal axis and acting on each tine arm, whereby the downward force on each tine is determined in part by the force of the spring means and in part by adjustment of the top link of the three-point linkage which pivots the main frame about the ground wheels axis.

2. An implement according to claim 1 in which the spring means is a helical torsion spring, one for each tine arm, the spring being loosely wound around a spindle defining the pivotal axis of the tine arm.

3. An implement according to claim 2 in which there are a plurality of aligned spindles, each serving an assembly of four tine arms.

4. An implement according to claims 2 or claim 3 in which the torsion springs are formed in pairs to act on adjacent tine arms.

5. An implement according to claim 4 in which the two springs of a pair are formed as an integral spring.

5. An implement according to any one of claims 1 to 5 in which alternate tine arms are of differing lengths so that a shorter tine arm is sandwiched between two longer tine arms.

7. An implement according to any one of claims 1 to 6 in which a scraper plate is secured at each side of the frame to engage with the periphery of the respective ground wheel, to prevent a build-up of soil on the wheels, and thereby maintain sensibly constant the height of the frame above the mean ground level.

8. An implement according to any one of claims 1 to 7 in which the implement is formed in three sections, comprising a central section including the ground wheels, and two outer sections each hinged relative to the central section about a horizontal axis.

9. An agricultural implement substantially as herein described with reference to, and as illustrated in, the accompanying drawings.