EP0126757A1

EP0126757A1 - Hitch mechanism

Info

Publication number: EP0126757A1
Application number: EP19840900079
Authority: EP
Inventors: Malcolm Dean; Garath Bryn Jones
Original assignee: Massey Ferguson Services NV
Current assignee: Massey Ferguson Services NV
Priority date: 1982-12-03
Filing date: 1983-11-30
Publication date: 1984-12-05
Also published as: GB2131269A; WO1984002053A1; GB2131269B

Abstract

Un mécanisme d'attelage est approprié pour relier un outil aux deux bras de levage arrière (12) d'un tracteur de manière à décaler l'outil d'un côté du tracteur. Le mécanisme comprend des moyens (35) qui augmentent la longueur effective de levage d'un bras (12) du côté décalé par rapport à celle de l'autre bras (12) de manière à ce que le même mouvement angulaire de levage pour les deux bras produise un mouvement de levage vertical supérieur à une extrémité du bras mentionné en premier et par conséquent incline l'outil vers le haut vers son extrémité extérieure. Les moyens (35) peuvent comprendre un organe d'extension qui s'étend dans le sens longitudinal et possède un point de connexion (36) relié de manière pivotante à un cadre (5) du mécanisme d'attelage et un autre point de connexion (10) relié à l'un de ces bras (12) et est espacé par rapport au point de connexion (36) dans le sens longitudinal. Ces moyens (35) peuvent être reliés à ce premier bras du côté décalé au niveau de l'autre point de connexion (10) espacé vers l'avant par rapport au point de connexion (36).A coupling mechanism is suitable for connecting a implement to the two rear lifting arms (12) of a tractor so as to offset the implement to one side of the tractor. The mechanism comprises means (35) which increase the effective lifting length of one arm (12) on the side offset from that of the other arm (12) so that the same angular lifting movement for the two arms produce a vertical lifting motion greater than one end of the first mentioned arm and therefore tilt the tool up towards its outer end. The means (35) may include an extension member which extends longitudinally and has a connection point (36) pivotally connected to a frame (5) of the coupling mechanism and another connection point (10) connected to one of these arms (12) and is spaced relative to the connection point (36) in the longitudinal direction. These means (35) can be connected to this first arm on the side offset at the other connection point (10) spaced forward relative to the connection point (36).

Description

HITCH MECHANISM

Technical Field

This invention relates to a hitch mechanism suitable for connecting an offset implement to the two lifting links of a tractor with the implement extending laterally from one side of the tractor.

The tolerances and clearances of the hitch mechanisms of known offset agricultural implements, such as mowers, are such that the implements assume a downwardly sloping attitude towards their outer end when lifted off the ground. This characteristic may be acceptable in shorter implements, but it causes increased difficulty with longer implements because of the reduced ground clearance at the outer end of the implement.

Disclosure of the Invention

An object of the present invention is to alleviate this problem. This is achieved according to the present invention by providing means that changes the effective length of one of two links on which the implement is lifted so that the same angular lifting movement of both links will produce a greater vertical movement at the end of the longer link as compared with the other. Thus the implement is tilted as it is lifted, thereby raising the outer end of the implement an extra amount relative to its inner end.

Said means to change the effective length of a link could either be associated with that link furthest from the offset implement and would serve to shorten the link, or could be associated with that link nearest the offset implement and would serve to lengthen the link. Generally, extension of a link would be preferred because it is simpler to achieve than shortening of a link.

Means that extends or shortens the effective length of a link could simply be a longer or shorter link, but this would involve the inconvenience of replacing the conventional link with the longer or shorter link every time the particular offset implement is used. Preferably, therefore, said means comprises an extension member that extends in the fore-and-aft direction and is pivotably connected to the frame of the hitch mechanism at one connection point and carries releasable coupling means for connection to a tractor lifting link at another connection point spaced from said one connection point in the fore-and-aft direction.

The invention will be described by way of example with reference to the accompanying drawings in which

Description of the Drawings

Figure 1 is a plan view of a mower hitch mechanism according to the invention.

Figure 2 is a rear view of the hitch mechanism of Figure 1,

Figure 3 is a rear view of a mower on the three point linkage of a tractor.

Figure 4 is a side view of the extension member of the hitch mechanism of Figures 1 and 2, and

Figure 5 is a plan view of the extension member of Figure 4.

Best Mode of Carrying Out the Invention

The mower illustrated in Figures 1 and 2 is a drum mower comprising two cutting drums 1 rotatably mounted on a beam 2 carried at the outer end of a drag bar 3 that is pivotally connected to a hitch mechanism 4. The cutting drums are driven by the tractor P.T.O. through a drive line 44 connected to the top of the drums. The hitch mechanism comprises an inverted V-shaped frame 5 carrying a central upright sleeve 6 in which a bar 7 is rotatably supported, the lower end of the bar 7 being connected to the inner end of the drag bar 3 at a point offset from the upright pivotal axis X-X of the bar and sleeve 6. A mounting plate 8 is connected to the outer end of each leg 9 of the frame 5 and carries an outwardly projecting pivot pin 10 that is adapted for connection to one of the ball-joint sockets 11 at the end of the lower draft links 12 of the tractor 13. A connection 14 at the top of the sleeve 6 is adapted for connection to the top link 15 of the tractor so that the mower is fully mounted on the three links and can be raised and lowered thereby through the action of the tractor hydraulic lift mechanism.

When the mower is in work, the drag bar 3 and beam 2 extend laterally to one side of the tractor so as to cut a swath alongside the tractor. A latch mechanism 16 serves to hold the mower in this work position. A latch bar 17 is pivotally connected at one end 18 to a bracket 19 on the drag bar 3 and is connected at its other end 20 to a drag link 21 that extends rearwards from the offside mounting plate 8. A striker 22 extends laterally from the end of the ]atch bar 17 adjacent the drag link 21, and a latch member 23 is pivotally connected to the drag bar 3 so as to cooperate with the striker 22.

Disengagement of the latch mechanism 16 allows the drag bar to swing rearwards away from the latch bar 17 to a transport position trailing behind the tractor. The drag bar pivots about the pivot axis X-X of sleeve 6 and bar 7. The pivot connection 18 between the latch bar 17 and drag bar 3 also lies on this axis X-X below the sleeve 6 so that the latch bar 17 remains substantially unaffected by the relative pivotal movement of the drag bar.

A se cond latch mechanism 24 serves to hold the mower in the transport position, the latch m echanism comprising a outwardly projecting latch member 25 pivotally mounted on the nearside mounting plate 8 and a striker 26 formed by the extreme end of the bar 7.

When the mower is in work, it rides over the ground on skids 27 mounted on the underside of the drum support beam 2. The beam pivots relative to the drag bar 3 about a fore-and-aft pivotal connection 28 so as to follow lateral ground contours. However, this pivotal movement is restricted by a linkage 29 that serves to support the beam in a substantially horizontal position when the mower is lifted on the tractor links (Figure 2). The linkage 29 comprises a first link 30 connected at its lower end to the pivotal connection 28 and pivotally connected at its upper end via a second link 31 to a frame 32 that interconnects the top of both cutting drums 1. A third link 33 is connected between the mid-region of the first link 30 and the top of the bar 7 so as to act as a tie when the mower is lifted off the ground. A pin-and-slot connection 34 between the third link 33 and the bar 7 allows the limited pivotal movement of the beam 2 when the mower is in work.

It will be appreciated that the tolerances and clearances in the linkage 29 and the hitch mechanism can be such as to allow the beam 2 to assume an outwardly and downwardly inclined attitude when lifted. This causes particular difficulties with wide-cut mowers because the corresponding increased length of the beam 2 reduces the ground clearance at the outer end. Thus irregular ground contours can cause the mover to hit the ground, and the passage of the mower over swaths may result in further cutting and spreading of the crop.

In order to overcome the above difficulties, the offside mounting plate 8 and associated pivot pin 10 are specially adapted as shown in Figures 3 and 4 so as effectively to extend the lifting length of the offside lower draft link 12. Instead of connecting the pivot pin 10 directly to the plate 8 as with the nearside mounting plate, the pin 10 is connected to an extension plate 35 that is pivotally connected to the mounting plate 8 rearwards of pin 10.

A pin 36 is connected to plate 8 and projects outwards through a bush 37 in plate 35 so as to pivotally support the latter. A clevis pin 38 engages the end of pin 36 to retain the extension plate in place. Bush 37 engages the head of pin 36, and a spacer block 39 on the inner face of the extension plate above pin 36 engages the mounting plate 8 to hold the two plates apart. The pin 10 connected to the extension plate 35 also extends inwards through an arcuate slot 40 formed in plate 8 and has a threaded end that receives a lock-nut 41 to hold the two plates together. Thus the two plates are mutually supported against relative lateral movements and the extension plate 35 can only move vertically.

The extension plate 35 is effectively made rigid with the lower shaft link 12 during lifting of the mower by providing an abutment block 42 on a forwardly projecting end 43 of the extension plate beyond the pin 10 so as to abut the underside of link 12.

The affect of the extended lover link lifting length is indicated in Figure 2 by the full-line and broken-line representations of the mower. The broken-line mower is that illustrated with the extended lower link, whereas the fullline mower is one with the offside mounting plate end connecting pin the same as that on the nearside, i.e. the conventional arrangement. The increased vertical movement of the offside lifting point and the rerrultant increased lift at the outer end of the mower can be clearly seen. In alternative embodiments of the invention, the extension plate 35 could be rigidly connected to the lower draft link, for example, by providing on the projecting end 43 means to embrace both sides of the lower link or pin-and-hole connection means.

In another embodiment of the invention the whole of the offside lower draft link could be replaced by a longer link or by an extendible link suitably adjusted so that it can directly engage on the pin 36 without the intermediary of an extension member.

In yet other embodiments of the invention, the offside link and its connection to the implement are standard, and instead, the nearside lower draft link is replaced by a shorter link or is connectable to the implement via an intermediate member that is connected to the implement at a point forward of the end of the link, thereby effectively shortening the length of the nearside link.

Claims

1. A hitch mechanism for an offset implement to allow it to be releasably connected to the two lifting links of a tractor with the implement extending laterally from one side of the tractor, comprising a frame and individual releasable coupling means each connectable to one of the two lifting links, characterised in that one, and only one, of said coupling means is carried on an extension member that extends in the fore-andaft direction and is pivotally connected to the frame at one connection point and carries said releasable coupling means at another connection point spaced from said one connection point in the fore-and-aft direction so that in use the extension member changes the effective lifting length of the associated link relative to that of the other link.

2. A mechanism as claimed in claim 1 in which said associated link is the one on that side of the tractor from which the offset implement is to extend in use, said extension member being such that said one connection point is spaced rearwards from said other connection point and thereby increases the effective lifting length of said one link.

3. A mechanism as claimed in claim 1 or 2 in which the extension member carries an abutment member that is spaced forwards of said other connection in the plane of vertical movement of the associated link so as to engage the latter during lifting and lock the extension member and said associated link rigidly together.

4. A mechanism as claimed in claim 3 in which the extension member comprises an upright plate that is pivotally connected to an upright plate of.the frame so that the two plates lie alongside one another and abut one another at spaced points.

5. A mechanism as claimed in claim 4 in which said other connection is formed by a pin that extends through both plates and moves in a slot in the plate of the frame to accommodate relative pivoting movement between said plates during lifting, the pin carrying fastening means that serves to hold the two plates in sliding face to face abutment.

6. An offset implement having a hitch mechanism to allow it to be releasably connected to the two lifting links of a tractor with the implement extending laterally from one side of the tractor comprising a frame and individual releasable coupling means each connectable to one of the two lifting links characterised in that an extension member extending in the fore-and-aft direction is pivotally connected to the frame at one connection point and carries one of said releasable coupling means at another connection point spaced from said one connection point in the foreand-aft direction so that in use the extension member changes the effective lifting length of the associated link relative to that of the other link, that link nearer said one side from which the implement extends laterally having a longer effective lifting length than the other link.

7. An implement as claimed in claim 6 in which the hitch mechanism is as claimed in any one of claims 1 to 5.

8. A tractor having two lifting links that extend alongside one another, and an implement that is connectable to said links so as to project laterally from one side of the tractor when in work, the effective lifting length of the two links being such that the length of that on said one side of the tractor is greater than that on the other side of the tractor.

9. A tractor and implement as claimed in claim 8 and which includes a hitch mechanism as claimed in any one of claims 1 to 5 to connect the tractor and implement together.

10. A hitch mechanism substantially as herein described with reference to the accompanying drawings.