Patent Description:
The working units are typically driven processing members such as rakes or tedders. It is desirable to provide machines of greater working width to enable more efficient agricultural operation on a tract of land. This leads to an increased number of processing members being arranged on each side support element. It will be understood that each side support element is mounted at an inboard end to the central support element. Each of the side support elements conveniently take the form of an elongate framework to which the processing elements are mounted. As the side support elements get longer and more processing members are added, it will be understood that under the influence both of the weight of the processing members and the rotating motion of the processing members there is a tendency for the side elements to induce a yaw moment about the central support element and in particular about the connection of the towed agricultural working tool to the agricultural vehicle. Such a motion is also induced as the tools are moved about in the working position. This undesired motion will move the processing members away from an optimum operating position. It can also be a problem that the swaying motion of one side element is passed to the other side element increasing the problem.

However, it also the case that this problem must be set against the need for measures for improving the dynamic behaviour of towed agricultural working tools during driving of the tractor over the field with the side support frame elements in the operating condition, where it is desired for the towed implement to pivot in relation to the tractor when a turn is made.

It is known to provide springs at the articulation point between the central support frame element and a headstock by which the agricultural working tool is secured to the agricultural vehicle to suppress these movements. However, this becomes more and more difficult with increasing working widths and because of the higher forces arising. <CIT> shows a tool having a central frame element and a headstock by which the central frame element may be secured to a towing vehicle in which a leaf spring is provided manage the movement between a central frame and a headstock. The headstock includes upper and lower elements held in fixed relationship with one another. The central frame element includes upper and lower frame elements (also held in fixed relationship to one another) and located between the headstock elements, the upper and frame elements and the upper and lower headstock elements are connected by a leaf spring. The leaf spring is housed in a buffer device mounted between the headstock and the central frame.

<CIT> discloses the use of hydraulic telescopic cylinders mounted between side elements of the main frame and the headstock to suppress these movements. However, such an arrangement is only suitable for side elements of narrow width (that is for tools carrying a single working implement to each side of the central frame) due to the higher forces arising with increasing working widths.

<CIT> discloses a tool in which a mowing unit is carried from a beam of a frame pivotally connected to a second end of a drawbar and not from both left and right side frame elements extending from the central frame. The drawbar is pivotally connected at a first end to a headstock.

The solution to the technical problem is achieved by the subject-matter of independent claim <NUM>, defining per se the invention. Particular embodiments of the invention are defined in the dependent claims.

This has as an advantage that the pivoting movement of the central frame with respect to the headstock, in particular due to induced yaw, is reduced.

Preferably each of the friction discs comprise one of the following: a mix of fiberglass and other materials moulded or woven into the friction disc, woven synthetic fibres, moulded synthetic materials, a mix of silicon dioxide and various metals and additives, sintered or brazed onto the friction disc, or a metal plate coated with a friction material.

Preferably, the at least one processing unit is a rake or a tedder.

But to the contrary, the invention is defined by the subject-matter of claim <NUM>.

Reference to terms such as longitudinal, transverse and vertical are made with respect to a longitudinal axis of the towed agricultural working tool which is parallel to a normal forward direction of travel.

With reference to <FIG>, an agricultural working tool <NUM> in the form of a ten rotor tedder is shown. The agricultural working tool <NUM> is provided with a headstock <NUM> for towing of the agricultural working tool <NUM> by an agricultural vehicle such as tractor, by mounting the headstock <NUM> to a three point hitch provided on the agricultural vehicle. For clarity neither the agricultural vehicle nor the three point hitch are shown in the Figures.

The agricultural working tool <NUM> further comprises a central frame element <NUM> and left and right hand side frame elements <NUM>,<NUM> connected to the central frame element <NUM>, each of the side elements <NUM>,<NUM> supporting at least one processing unit <NUM>, in <FIG> four such processing units <NUM> in the form of tedders are provided on each of the side frame elements <NUM>. It will be understood that the side frame elements <NUM>,<NUM> are, in use, foldable about the central frame element <NUM> between an operating configuration and a transport configuration.

The central frame element <NUM> is generally triangular in plan view, with a base of the triangle to the rear. A further processing member <NUM> is located at each end of the base of the triangle.

The base comprises a rigid framework <NUM> from which an upper triangular frame <NUM> and a lower triangular frame <NUM> extend. An apex <NUM>,<NUM> of each triangular frame <NUM>,<NUM> is pivotally connected to the headstock <NUM>. A front element <NUM> is connected across the lower triangular frame <NUM>. Conveniently a front part of each of the side frame elements <NUM>,<NUM> is connected to this front element <NUM>. A rear of each of the side elements <NUM>,<NUM> is connected to the lateral ends of the rigid framework <NUM>.

The headstock <NUM> compress a horizontal element <NUM>, the ends of which are secured to lower ends of an upwardly extending arch shaped element <NUM>. Each of the lower ends of the arch shaped element <NUM> are provided with connecting elements <NUM> for connecting to the lower links of a three point hitch of an agricultural vehicle. A central upper part of the arch shaped element <NUM> is provided with a further connection element <NUM> for connecting to the upper link of a three point hitch of an agricultural vehicle.

The upper part of the arch shaped element <NUM> is also provided with an upper bracket <NUM> extending across the arch shaped element <NUM>. The apex <NUM> of the upper triangular frame <NUM> is connected to the upper bracket <NUM> so as to provide a first pivoting connection to the headstock <NUM>.

Additionally, upper holding elements <NUM>, conveniently in the form of telescopic rods, are connected between the end of the upper bracket <NUM> and the ends of the rigid framework <NUM> of the central frame element <NUM>.

The horizontal element <NUM> of the headstock <NUM> is also provided with a pivoting connection, whereby the apex <NUM> of the lower triangular frame <NUM> is connected to the headstock <NUM> for pivoting connection in relation to the headstock <NUM>. Lower holding elements <NUM>, conveniently in the form of telescopic rods, are connected between side elements of the lower triangular frame <NUM> and the horizontal element <NUM> of the headstock <NUM>, the lower holding element connections being to either side of the pivoting connection of the apex <NUM>.

The pivoting connection between the apex <NUM> of the lower triangular frame <NUM> and the horizontal element <NUM> of the headstock <NUM> is shown in more detail in <FIG> and <FIG>.

The horizontal element <NUM> of the headstock <NUM> comprises upper and lower elements <NUM>,<NUM> held, in any suitable manner, in fixed relationship to one another. The upper element <NUM> is provided with a number of spaced location openings <NUM>, in the illustrated embodiment two such openings are shown. An end cap <NUM> is provided with a number of corresponding openings <NUM>, in the illustrated embodiment two corresponding openings. Pins <NUM> are provided having a central wider portion <NUM>. A first end <NUM> of each pin <NUM> is located in the spaced location openings <NUM> of the upper element <NUM> and a second end <NUM> extends through a corresponding opening <NUM> in the end cap <NUM>. The central wider portion <NUM> of each pin <NUM> provides a minimum distance between the upper element <NUM> and the end cap <NUM>. The end cap <NUM> is in this way held in a fixed relationship with respect to the upper element <NUM> of the horizontal element <NUM> of the headstock <NUM>.

The apex <NUM> of the lower triangular frame <NUM> comprises a lower element <NUM> extending between the upper and lower elements <NUM>,<NUM> of the horizontal element <NUM> of the headstock <NUM> and an upper element <NUM> extending between the upper element <NUM> of the horizontal element <NUM> of the headstock <NUM> and the end cap <NUM>. The lower element <NUM> and the upper element <NUM> of the apex <NUM> of the lower triangular frame <NUM> are held, in any suitable manner, in fixed relationship to one another. In the illustrated embodiment this is achieved through the use of a spacing plate. The lower element <NUM> of the lower triangular frame <NUM> is conveniently provided with cut away portions <NUM> to prevent possible interference of the lower element <NUM> with the connections made by the ends of the lower holding elements <NUM> secured to the headstock <NUM>.

Friction elements <NUM> are layered between the headstock elements (including the end cap) <NUM>,<NUM>,<NUM> and the lower triangular frame elements <NUM>,<NUM>.

The friction elements <NUM> may be formed in any suitable manner and are conveniently in the form of annular discs. For example, the friction elements <NUM> may be formed as a mix of fiberglass and other materials (including brass in some cases) moulded or woven into a disc, a disc of woven synthetic fibres, a disc of moulded synthetic materials, a disc of a mix of silicon dioxide and various metals and additives, sintered or brazed onto a friction disc, or a metal plate coated with a friction material.

Each of the friction elements <NUM>, the headstock elements <NUM>,<NUM>,<NUM> and the lower triangular frame elements <NUM>,<NUM> are provided with an opening, preferably a circular opening.

A bushing <NUM> having a central through bore <NUM> is provided at a lower end with a radial flange <NUM> and at an upper end with a shoulder <NUM> between a main shank portion <NUM> of a first diameter and an end shank portion <NUM> of reduced diameter. In use, the bushing <NUM> is inserted into and through the lower headstock element <NUM> and the interleaved friction elements <NUM>, lower triangular frame elements <NUM>,<NUM> and the other headstock elements <NUM>,<NUM> such that an upper surface <NUM> of the radial flange <NUM> abuts a lower surface <NUM> of the lower horizontal headstock element <NUM>.

A spring washer <NUM> and a washer nut <NUM> are located about the reduced diameter end shank portion <NUM> of the bushing <NUM>. The washer nut <NUM> has a recessed portion for seating about the end shank portion <NUM> of the bushing <NUM>. A peripheral portion of the washer nut <NUM> abuts the spring washer <NUM>. An upper part of the washer nut <NUM> is also provided with a through opening <NUM> corresponding in diameter to the central through bore <NUM> of the of the bushing <NUM>.

A headed bolt <NUM> is passed though the washer nut <NUM> and the bushing <NUM> such that a head <NUM> of the bolt <NUM> is seated against an upper surface of the washer nut <NUM>. The bolt <NUM> is provided with a thread extending from a free end along at least part of a shank of the bolt <NUM>. A nut <NUM> is then threaded onto the free end of the bolt <NUM> and tightened such that an upper surface of the nut <NUM> is tightened against a lower surface of the bushing <NUM> causing the spring washer <NUM> to clamp the interleaved friction elements <NUM>, lower triangular frame elements <NUM>,<NUM> and the headstock elements <NUM>,<NUM>,<NUM> together.

It may be seen that the bushing <NUM> serves as a pivot pin between the lower triangular frame <NUM> and the headstock <NUM>.

In practice when an induced yaw moment occurs the friction elements <NUM> will act to prevent, or at least further dampen, movement between the central frame element <NUM> and the headstock <NUM>.

It is an advantage that the relatively large friction surface between the friction discs <NUM> and each of the adjacent headstock and central frame elements that it allows for better absorption of the forces and so better absorbs the induced yaw. It may also be seen that the use of the friction discs <NUM> provides a compact solution compared to the use of springs. Further, the use of more or fewer friction discs <NUM>, or friction discs <NUM> having different braking properties, allows modification in view of the desired braking to be applied to overcome the induced yaw.

Claim 1:
A towed agricultural working tool comprising
a central frame element (<NUM>),
a headstock (<NUM>) and
left and right hand side frame elements (<NUM>,<NUM>) connected to the central frame element (<NUM>), each of the side frame elements (<NUM>,<NUM>) supporting at least one processing unit (<NUM>),
in which the central frame element (<NUM>) is connected to the headstock (<NUM>) for pivoting movement at at least one connecting location,
the headstock (<NUM>) comprises a plurality of headstock elements (<NUM>,<NUM>,<NUM>) including an horizontal element (<NUM>) comprising upper and lower headstock elements (<NUM>, <NUM>) held in fixed relationship to one another,
the central frame element (<NUM>) comprises a plurality of central frame elements (<NUM>,<NUM>) held in fixed relationship to one another and located between the headstock elements (<NUM>,<NUM>,<NUM>) and
one or more annular friction discs (<NUM>) are arranged between the central frame element (<NUM>) and the headstock (<NUM>) at one of the at least one connecting locations at least one annular friction disc (<NUM>) is arranged between at least one of the plurality of central frame elements (<NUM>,<NUM>) and one of the plurality of headstock elements (<NUM>,<NUM>,<NUM>), and
the headstock elements (<NUM>,<NUM>,<NUM>), the central frame elements (<NUM>,<NUM>) and the one or more annular friction discs (<NUM>) are clamped together in compression by a fastener,
characterised in that
the headstock elements (<NUM>,<NUM>,<NUM>), the central frame elements (<NUM>,<NUM>) and the at least one annular friction disc (<NUM>) are mounted about a bushing (<NUM>) .