GB2115669A - Mowers - Google Patents

Abstract

A tractor comprising a laterally extending arm is provided with a breakout device to move the cutter head mounted on the outer end of the arm upwardly and rearwardly if it encounters an obstacle which might damage it. Figure 3 shows the breakout device in the operative position in which the inboard end of the arm has been lifted and moved rearwardly by movement of a swinging link (22) mounting the said inboard end and about a pivot between the link and the tractor. <IMAGE>

Description

SPECIFICATION Mowers This invention relates to mowers of the kind comprising a cutting head mounted on the outer end of a system of arms of which the inner end is mounted on a tractor so that the arms can extend laterally of the tractor, for example to cut a roadside verge when the tractor drives along the road. The cutter head can be positioned, by use of hydraulic rams and the like, and the driver if skilled can perform the difficult feat of steerlng and controlling the tractor and maintaining a close cut over a surface which may undulate or change in angle along the length of the road. However, even the most skilfull driver cannot cope with hidden obstacles such as dumped rubbish, and even visible obstacles (such as saplings) may cause difficulty if the driver is distracted at a critical moment.

It is therefore conventional to provide a socalled "breakout" device. In one example of this the arm system is pivoted at a joint, and the pivoting is prevented by a spring loaded detent. If forward movement of the head is arrested whilst the tractor continues on its way, the detent allows the arm to pivot rearwardly. However, the leverage applied by the system of arms results in the breakout force being variable. A minor obstacle, which can safely be mown through, can cause breakout at full stretch, or breakout is too difficult at minimum stretch. Existing designs have to compromise. If breakout occurs, the tractor must be stopped and reversed, and the driver needs to do something to re-establish the joint before proceeding. Such a system is also consequently slow and expensive in use, and it is the object of the invention ro provide improvements.

In accordance with the invention a mower comprises an arm extending laterally from an inboard mounting on a tractor, and a breakout device whereby the cutter on the free end of the arm is moved upwardly and rearwardly if it encounters an obstacle, the breakout device comprising a link extending forwardly and upwardly from a pivot on the tractor, the arm being pivoted to the forward and upper end of the link, and the arm normally resting on an abutment on said link.

Preferably the arm is connected to the tractor via the breakout device and also, at a position further along the length of the arm, by a more simple pivot, whereby both upward and rearward movement is magnified.

Preferably also the link has a limited angular movement such that the weight of the arm and cutter may return the parts to the normal position after breakout, so that the driver of the tractor may not need to leave the driving position in order to reset the system after breakout.

The invention is more particularly described with reference to the accompanying drawings wherein: Figure 1 is a plan view of an arrangement and Figures 2 and 3 are fragmentary elevations showing the same parts in different positions.

Referring to the drawings, a mower comprises a cutter head 10 mounted at the outer end of an arm system 1 2 pivoted on a bracket 1 4 fixed to a substantial box beam 1 6 which extends across the rear of the tractor. The box beam 1 6 may comprise the hydraulic reservoir and power pack for the mower. Beam 1 6 is supported by the usual linkage system 18, 20 at the rear of the tractor.

As best seen in the plan view of Figure 1 ,the link 18 is duplicated and that most remote from the cutter head is connected to the box beam 1 6 through a simple pivot. The one nearest the cutter head is connected to a breakout device more particularly described hereinafter.

A third link 20 is also pivoted to the box beam, links 1 8, 20 collectively being used for lifting and lowering the box beam with the complete arm set.

The breakout device comprises a link 22 pivoted on axis 24 to the said link 1 8.

The link 22 carries an abutment 28 and in the normal position for use of Figure 2, the arm assembly is effectively carried by that abutment.

Lugs 30 fixed to the box beam 1 6 are pivoted at 32 on the link, and an abutment in the form of a bolt 34 actually transfers weight to the abutment 28. Hence Figure 2 represents the resting position of the system, and the normal position for mowing.

In the event of the cutter head encountering an obstacle of sufficient magnitude, the link can swing to the Figure 3 position thus lifting the inner end of the arm system, that is to say the lugs 30 a short distance and displacing them rearwardly for a short distance. This movement is magnified due to the length of the arm system and the fact that movement at the other links 1 8, 20 is only a simple pivoting movement about (for example) semi-universal joint connections (ball joints).

Hence the cutter head may well be not only displaced rearwardly from the obstacle through a sufficient distance to avoid damage to the mower, whilst the tractor is continuously driven and before the driver can take any avoiding action, but in addition the lifting movement may well be sufficient to lift the cutter head over the obstacle when effectively the parts will return to the Figure 2 position under their own weight and the mowing operation can continue without the driver taking any action.

A chain 36 limits the extent of movement which is possible.

Conveniently the whole breakout arrangement is duplicated, i.e. a link 22 is used at both links 18, but in one case the bolt 34 is used to clamp the abutment 28 to the lug 30. This simplifies design in enabling left or right hand mowing to be provided for. Figure 1 illustrates left hand mowing.

1. A mower comprising an arm extending laterally from an inboard mounting on a tractor, and a breakout device whereby the cutter on the free end of the arm is moved upwardly and rearwardly if it encounters an obstacle, the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Mowers This invention relates to mowers of the kind comprising a cutting head mounted on the outer end of a system of arms of which the inner end is mounted on a tractor so that the arms can extend laterally of the tractor, for example to cut a roadside verge when the tractor drives along the road. The cutter head can be positioned, by use of hydraulic rams and the like, and the driver if skilled can perform the difficult feat of steerlng and controlling the tractor and maintaining a close cut over a surface which may undulate or change in angle along the length of the road. However, even the most skilfull driver cannot cope with hidden obstacles such as dumped rubbish, and even visible obstacles (such as saplings) may cause difficulty if the driver is distracted at a critical moment. It is therefore conventional to provide a socalled "breakout" device. In one example of this the arm system is pivoted at a joint, and the pivoting is prevented by a spring loaded detent. If forward movement of the head is arrested whilst the tractor continues on its way, the detent allows the arm to pivot rearwardly. However, the leverage applied by the system of arms results in the breakout force being variable. A minor obstacle, which can safely be mown through, can cause breakout at full stretch, or breakout is too difficult at minimum stretch. Existing designs have to compromise. If breakout occurs, the tractor must be stopped and reversed, and the driver needs to do something to re-establish the joint before proceeding. Such a system is also consequently slow and expensive in use, and it is the object of the invention ro provide improvements. In accordance with the invention a mower comprises an arm extending laterally from an inboard mounting on a tractor, and a breakout device whereby the cutter on the free end of the arm is moved upwardly and rearwardly if it encounters an obstacle, the breakout device comprising a link extending forwardly and upwardly from a pivot on the tractor, the arm being pivoted to the forward and upper end of the link, and the arm normally resting on an abutment on said link. Preferably the arm is connected to the tractor via the breakout device and also, at a position further along the length of the arm, by a more simple pivot, whereby both upward and rearward movement is magnified. Preferably also the link has a limited angular movement such that the weight of the arm and cutter may return the parts to the normal position after breakout, so that the driver of the tractor may not need to leave the driving position in order to reset the system after breakout. The invention is more particularly described with reference to the accompanying drawings wherein: Figure 1 is a plan view of an arrangement and Figures 2 and 3 are fragmentary elevations showing the same parts in different positions. Referring to the drawings, a mower comprises a cutter head 10 mounted at the outer end of an arm system 1 2 pivoted on a bracket 1 4 fixed to a substantial box beam 1 6 which extends across the rear of the tractor. The box beam 1 6 may comprise the hydraulic reservoir and power pack for the mower. Beam 1 6 is supported by the usual linkage system 18, 20 at the rear of the tractor. As best seen in the plan view of Figure 1 ,the link 18 is duplicated and that most remote from the cutter head is connected to the box beam 1 6 through a simple pivot. The one nearest the cutter head is connected to a breakout device more particularly described hereinafter. A third link 20 is also pivoted to the box beam, links 1 8, 20 collectively being used for lifting and lowering the box beam with the complete arm set. The breakout device comprises a link 22 pivoted on axis 24 to the said link 1 8. The link 22 carries an abutment 28 and in the normal position for use of Figure 2, the arm assembly is effectively carried by that abutment. Lugs 30 fixed to the box beam 1 6 are pivoted at 32 on the link, and an abutment in the form of a bolt 34 actually transfers weight to the abutment 28. Hence Figure 2 represents the resting position of the system, and the normal position for mowing. In the event of the cutter head encountering an obstacle of sufficient magnitude, the link can swing to the Figure 3 position thus lifting the inner end of the arm system, that is to say the lugs 30 a short distance and displacing them rearwardly for a short distance. This movement is magnified due to the length of the arm system and the fact that movement at the other links 1 8, 20 is only a simple pivoting movement about (for example) semi-universal joint connections (ball joints). Hence the cutter head may well be not only displaced rearwardly from the obstacle through a sufficient distance to avoid damage to the mower, whilst the tractor is continuously driven and before the driver can take any avoiding action, but in addition the lifting movement may well be sufficient to lift the cutter head over the obstacle when effectively the parts will return to the Figure 2 position under their own weight and the mowing operation can continue without the driver taking any action. A chain 36 limits the extent of movement which is possible. Conveniently the whole breakout arrangement is duplicated, i.e. a link 22 is used at both links 18, but in one case the bolt 34 is used to clamp the abutment 28 to the lug 30. This simplifies design in enabling left or right hand mowing to be provided for. Figure 1 illustrates left hand mowing. CLAIMS

1. A mower comprising an arm extending laterally from an inboard mounting on a tractor, and a breakout device whereby the cutter on the free end of the arm is moved upwardly and rearwardly if it encounters an obstacle, the breakout device comprising a link extending forwardly and upwardly from a pivot on the tractor, the arm being pivoted to the forward and upper end of the link, and the arm normally resting on an abutment on said link.

2. A mower as claimed in Claim 1 wherein the inboard end of the arm system is mounted on a box beam extending transversely of the tractor, and the box beam is connected to parallel links of the tractor by a simple pivot in one case and by the breakout device in the other case.

3. The mower as claimed in Claim 1 wherein the part of the system which rests on the said link abutment is adjustable in position.

4. A mower having a breakout device substantially as described and with reference to the accompanying drawings.