GB2079126A

GB2079126A - Agricultural machine attachable to the front three-point hitch of a tractor

Info

Publication number: GB2079126A
Application number: GB8118342A
Authority: GB
Original assignee: Claas Saulgau GmbH
Current assignee: Claas Saulgau GmbH
Priority date: 1980-06-19
Filing date: 1981-06-15
Publication date: 1982-01-20
Also published as: DE3022887C2; DE3022887A1; FR2484761B1; NL190260C; FR2484761A1; GB2079126B; NL8102637A; NL190260B

Abstract

A rotary mower 1 or other attachment, having a main frame 8, is provided with a supporting frame 2 which is pivotably connectable to the usual front three-point hitch of a tractor 5 through upper 4 and lower 3 link connections and resilient means (spring 18) for transmitting some of its weight to the tractor. Frame 2 is pivotably connected to the top 7 of frame 8 (at 13) through a tie member 6 which is pivotably attached (at 12) to frame 2 in the region of the upper link connection 4 and which is variable in length to a limited extent between abutments (ends 15, 16 of slot 11). Frame 2 is guided (by pins 14) in the region of the lower link connections 3 to be upwardly movable in slots 10 on frame 8 which extend obliquely upwards sloping from front to rear. A shock absorber 22 may be provided such that the length variation of tie member 6 is braked in one direction, namely that in which the spacing between the pivotal connections 12, 13 increases in size. <IMAGE>

Description

SPECIFICATION Agricultural machine attachable to the front three-point hitch of a tractor The invention relates to an agricultural machine, particularly but not exclusively a rotary mower, attachable to the front three-point hitch of a tractor.

In known constructions of this kind, as may be seen for example from German laid-open specification 27 49 097, the attachment is pivotably connected by means of a supporting frame directly to the lower links of the front threepoint hitch of a tractor and suspended on the tractor by means of a chain at the upper link connection. As a result of this manner of attaching, the attachment projects forwardly from the tractor as little as possible. But on the other hand the disadvantage is accepted that the attachment, in the present case a rotary mower, cannot be attached without conversion of the usual front three-point hitch. In addition, when the lower links are lifted, the rotary mower can tilt forwardly until the chain taking the place of the upper link is in a stretched-out situation and the mowing head can thus dig into the ground when the tractor travels forwards.Thus there is a risk of damaging the machine. With this construction also the attachment can tilt only to a small extent about an axis disposed in the direction of travel, so that in the case of a machine having a considerable working width it cannot adapt itself to ground surface irregularities fully. It is already known (from German published specification 1 5 07 220 for example) to mount the lower links in vertically movable manner, in slots on the supporting frame of the machine, for adaption of a rear-mounted attachment to transverse slopes in the ground surface. But by reason of its other constructional details this proposed constructional form is not generally suitable for mounting an attachment on the usual front three-point hitch of a tractor.

The present invention has as its object to provide an improvement such that the attachment can be connected without special measure to a conventional front three-point hitch of a tractor and can adapt itself more fully to transverse ground inclinations even when the working width is considerable, and cannot tilt forwards when the three-point hitch is raised.

According to the present invention there is provided as agricultural attachment as specified in claim 1 of this specification.

Further features of this invention are shown in the subordinate claims, the following description and drawings wherein the invention is illustrated in a diagrammatic manner and wherein: Fig. 1 shows a rotary mower attachment attached to the front three-point hitch of a tractor and illustrated in a working position wherein it is let down on to the ground, and Fig. 2 shows the same in a transporting position, slightly lifted off the ground.

The rotary mower attachment 1 is connected, through a supporting frame 2 having an upper end portion 25, to the lower links 3 and the upper link 4 of the three-point hitch of a tractor.

The supporting frame 2 is connected to the upper part 7 of the attachment's main frame 8 by means of a pin 13 and a tie member 6 which is pivotably mounted in the region of the upper link connection to the supporting frame at the pin 12.

In the region of the lower link connections the supporting frame 2 is guided to be upwardly movable, in slots 10 provided on the rear part 9 of the attachment's main frame 8, by means of pins 14 for the connections to the lower links 3.

The tie member has a slot 11 at its end directed towards the attachment 1, in which the pin 13 is guided to be longitudinaliy movable (within limits) on the upper part 7 of the main frame 8, such movement being possible up to the end of the slot 11 which serve as abutments 1 5, 1 6. The slots 10 on the rear part 9 of the main frame 8 slope (in the upward direction) from front to rear as viewed in the direction of travel F in the working position of the attachment 1.

For reducing the pressure of the rotary mowing head 1 7 on the ground in the lowered working position of the attachment, a weight relief spring 18 is connected at one end to a lug 1 9 on the main frame 8 and at the other end to the lug 20 on the tractor 5. The weight relief spring 1 8 can be hooked selectively into one of a series of holes 21 situated one above the other on the lug 1 9 of the main frame 8 to vary the pressure on the ground exerted by the rotary mowing head 17.

In the lowered (ground) position of the attachment 1 (Fig. 1) the pin 1 3 is approximately in the middle position between the abutments 1 5 and 1 6 of the slot 11 of the tie member 6, so that the attachment 1 can tilt in the direction of travel and in the opposite direction to adapt itself to ground surface irregularities. Owing to the inclined arrangement of the slots 10 in the rear portion 9 of the attachment's main frame 8, the pins 14 and thus the lower links 3 (the latter are in a floating situation) are held at the lower end of the slots 1 0, whereby the amount of weight relief attachment 1 as set by the spring 18 is maintained.At the same time the attachment can adapt itself to transverse ground slopes within the amount of play allowed by the slots 10. A result of the inclined position of the slots 10, in dependence also on the pushing force with which the attachment 1 is moved over the ground when working, is a downwardly directed component of force of the pins 14 and thus the lower links 3, so that the adaption of the attachment 1 to transverse ground slopes takes place in a damped manner. This also avoids impact on the attachment in the event of abrupt ground surface unevenness being encountered.

When the three-point hitch 3, 4 is raised by means of the hydraulic system of the tractor, the pins 14 slide obliquely upwards and rearwards in the inclined slots 10 at the rear end 9 of the main frame 8 until they reach the upper end of the slots 10. The upper end of the supporting frame 2, being carried upwards by the pins 14, also moves relatively towards the tractor 5 until the pin 13 at the upper end 7 of the main frame 8 abuts on the end 16 of the slot 11 in the tie member 6. The construction is such that the ends of the slots 10 and 11 are reached substantially at the same time.

Then, on further raising of the three-point hitch 3, 4 (Fig. 2) the attachment 1 is lifted off the ground. When this happens, the tie member 6 prevents the attachment from tilting forwards and thus possibly digging into the ground when the tractor traveis forwards.

A notable feature of the arrangement is that there is associated with the tie member 6 a hydraulic shock absorber 22 which can be pivotally connected either to the pins 12, 13 or, as illustrated in the drawings, to pins 23, 24 at the upper end 25 of the supporting frame 2 and at the upper end 7 of the main frame 8 of the attachment. The hydraulic shock absorber 22 is so arranged that only the movement of the pivot pin 13 in the slot 11 in the direction of abutment 1 6 is braked. In this way it is possible to achieve the result that the attachment 1 can tilt upwards rapidly with its front portion when ground elevations are encountered but can tilt downwards only in a damped manner when depressions or hollows in the ground occur. Thus the attachment 1 is saved unnecessary stressing during the operation.

Claims

1. An agricultural machine for attachment to a front three point-hitch of a tractor, the attachment (i.e. said machine) including a main frame, a supporting frame pivotably connectable to the front three-point hitch through upper and lower link connections, and resilient means for transmitting some of the weight of the attachment to the tractor, the supporting frame being pivotably connected to the top of the attachment's main frame through the agency of a tie member which is pivotably attached to the supporting frame in the region of the upper link connection and which, during operation, is variable in length to a limited extent between abutments, and the supporting frame being guided in the region of the lower link connections to be upwardly movable in slots provided on the main frame, which slots extend obliquely upwards sloping from front to rear as considered in the direction of forward travel when the attachment is in the working position.

2. An agricultural attachment according to claim 1, wherein the spring is constructed as a draw or tension spring to be attached to lugs on the tractor and on the main frame such that the operating direction of the spring extends within the vertical zone between the upper and the lower link connections of the supporting frame.

3. An agricultural attachment according to claim 2, wherein at least one of the lugs comprises a plurality of holes situated one above the other for selective setting of the spring therein at different heights.

4. An agricultural attachment according to any one of claims 1-3, wherein the tie member comprises at one end a slot through which a pivot pin mounted in the main frame or on the supporting frame extends and whose ends serve as the abutments for limiting the variation in length of the tie member.

5. An agricultural attachment according to any one of claims 1-4, wherein the tie member is variable in length in such a manner that the variation is braked in one direction, by association of a shock absorber with the said member, said direction being that in which the spacing between the pivotal connections of the tie member increases in size.

6. An agricultural attachment according to any one of claims 1-5, the attachment being a rotary mower.

7. An agricultural attachment or the combination of such an attachment with a tractor, substantially as herein described with reference to the accompanying drawings.