GB2151891A - Mobile boom type apparatus - Google Patents

Abstract

A mobile boom type apparatus such as agricultural spraying apparatus 10 comprises a boom 20 having boom portions 22, 24 mounted on a central frame 26. The boom portions are connected by pivot means 34, 36 to central frame 26. Lever arms 42, 44 are connected to the boom portions and pivotally interconnected by linkage means 70 comprising transport position rams 38, 40 and a compensating member 76 pivotally connected to central frame 26. Rubber buffers serve to resiliently resist yawing movement of the boom portions. The arrangement is such that turning movement of one boom portion about its pivot means causes a force on the other boom portion tending to turn it in the opposite direction. <IMAGE>

Description

SPECIFICATION Mobile boom type apparatus This invention relates to mobile boom type apparatus such as agricultural or horticultural spraying apparatus of the kind which is tractor-mounted or incorporated in a self-propelled spraying vehicle.

In the case of agricultural spraying apparatus of the tractor-mounted or self-propelled form, increases in the popularity of spraying techniques in relation to cereal and other crops, including the adoption of tram-lining techniques very widely in agricultural practice, have led to the use of larger and larger spray booms in the spraying apparatus.

Booms of 24 metres total length and beyond are currently available and it is to be expected that this trend in increasing boom length will continue for some time.

However, problems arise in relation to the mounting of such long structures on the generally un-sprung chassis of a tractor or self-propelled sprayer. The rough terrain over which sprayers are sometimes required to operate cause the boomsupporting vehicle to execute relatively short but rapid up and down and turning movements as it advances, and these movements are translated into large accelerations at the opposite ends of the long boom arms.

In practice it is found that the stressing of the booms in this way can lead to metal fatigue and premature boom failure. Moreover, the oscillation of the boom end portions leads to irregularity in the effective spray pattern. In this latter regard it will be appreciated that as the boom moves upwards and downwards relative to the ground the effect on the generally conical form of the spray pattern obtained from each nozzle is to increase the area covered as the boom moves upward and to decrease it as it moves downwards, thus decreasing and increasing the rate of dosage respectively. Likewise, as the boom end portions flex in the back and forth direction as a result of sideways accelerations of the tractor the result is that parts of the area sprayed are covered twice so that the rate of dosage is increased, while other areas receive a corresponding decrease.This results in a generally saw-tooth spraying pattern which is quite characteristic of large spray booms.

Proposals have been made for providing agricultural spraying apparatus with various types of resilient suspension whereby shock loading of the booms by virtue of vertical movement of a tractor is intended to be reduced. However, these proposals have in practice by no means solved the problem and moreover do not attempt to meet the problem of spray pattern irregularity arising from spray boom movement in the fore/aft direction as opposed to the vertical direction. The present Applicants believe they may be the first to have identified this particular aspect of spray boom movement as representing a technical problem requiring its own solution.

An object of the present invention is to provide mobile boom type apparatus, such as agricultural or horticultural spraying apparatus offering im provements in relation to one or more of the short comings of the prior art as discussed above or generally.

According to the invention there is provided mo bile boom type apparatus such as agricultural or horticultural spraying apparatus comprising a boom adapted to be mounted on a support vehicle and positionable to extend generally laterally outwardly with respect to the direction of operative forward motion of the vehicle characterised in that said boom is pivotally mounted so as to permit fore/aft movement of the outer end of the boom, control means being provided to control the pivotal movement of the boom and thereby control said fore/aft movement of the boom end.

Preferably, said control means comprises pivot means for the boom arranged so that pivotal movement of the boom from its operative position causes at least the outer end of the boom to be raised. The pivot means may comprise a pair of pivot assemblies with one of said assemblies suita bly offset from a vertical axis through the other.

The pivot assemblies may comprise ball joints or the like permitting pivotal movement about more than one axis. Alternatively, the pivot means may comprise a pivot joint having a pivot axis inclined with respect to the vertical.

According to a further aspect of the invention there is provided mobile boom type apparatus or agricultural or horticultural spraying apparatus comprising two booms or boom portions adapted to be mounted on a supporting vehicle and positionable so as to extend generally laterally outwardly from opposite sides of the vehicle with respect to the direction of operative forward motion of the vehicle, characterised in that said booms or boom portions are pivotally mounted in the region of their inner ends so as to permit fore/aft movement of their outer ends, control means being provided to control said pivotal movement of the booms and thereby control said fore/aft movement of the boom ends, the control means comprising link means between the booms or the boom portions whereby pivotal movement of one boom causes a turning force to be applied to the other boom or boom portion.

Preferably said boom pivots are spaced apart and mechanical link means is provided therebetween. Said mechanical link means may comprise a lever arm on each boom and a laterally extending link structure pivotally connecting said lever arms. The link structure may include a compensating mechanism to modify the movement . transmitted between the booms or boom portions according to the operating situation. The compensating mechanism may comprise a pivotally mounted compensating member and link members pivotally connecting the compensating member to the boom lever arms.

The resilient means may be provided connected to said boom or boom portions to resist pivotal movement thereof. The boom pivot means may be disposed so as to cause the boom, or a portion thereof, to be raised upon the boom executing such pivotal movement.

The mechanical linkage between the booms or boom portions may comprise one or more hydraulic rams or like thrust devices for pivoting the boom or boom portions to a transport position.

Resilient means may be connected to the mechanical link between the booms or boom portions. The resilient means may comprise rubber buffer means. The rubber buffer means may be associated with a fixed member connected to a frame of the apparatus. The rubber buffers may be associated with said compensating member.

The invention also provides any novel feature or concept or novel combination of features or concepts disclosed herein.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a perspective view from the rear and to one side of agricultural spraying apparatus of the tractor-drawn kind; Figure 2 shows, partly cut away, a portion of the apparatus of Fig 1 as viewed in rear elevation and on a larger scale, the direction of viewing being indicated in Fig 1 by arrow II; and Figure 3 shows a plan view of the apparatus of Fig 2, the direction of viewing being indicated by arrows lil in Figs 1 and 2.

As shown in Fig 1 agricultural spraying apparatus 10 comprises a chassis 12 mounted on ground wheels 14 and having a draw bar 16 connected to an agricultural tractor 18 to be towed thereby.

Spraying apparatus 10 further comprises a boom 20 comprising left and right hand boom portions 22, 24 respectively mounted on a central frame 26 which is carried by parallel links 28 actuated by lift rams 30 whereby boom 20 can be raised and lowered.

Boom 20 carries spray nozzles (not shown) connected by spray pipes (not shown) from a tank 32 whereby apparatus 10 can spray the ground across the full transverse operating width of boom 20.

Liquid from tank 32 is delivered to the spray nozzles under pressure by virtue of a pump (not shown) driven by the p.t.o. of tractor 18.

As shown in Figs 2 and 3, boom 20 comprises left hand boom portion 22 connected by pivot means 34 to central frame 26, and right hand boom portion 24 connected by pivot means 36 also to frame 26. Hydraulic rams 38, 40 are connected to lever arms 42, 44 fixed to boom portions 22, 24 whereby the boom portions can be pivoted about pivot means 34, 36 from their working position shown in Fig 1 to a transport position in which they extend in the fore/aft direction alongside tank 32 on opposite sides thereof. The outer end portions 46, 48 of the boom portions 22, 24 can be further folded to render the transport position of the apparatus more compact.

Central frame 26 is connected by pivot means 50 having a pivot axis 52 extending in the fore/aft direction to a primary frame which is not seen in Figs 2 and 3 and which is carried on parallel links 28. Pivot means 50 enables the entire boom assembly 20 to pivot about axis 52 whereby turning movement of chassis 12 about a fore/aft axis is not transmitted to the boom and the latter floats freely and smoothly over the ground, unaffected by ground irregularities.

Pivot means 34 and 36 each comprise upper and lower pivot joints 54, 56 and 58, 60. Each pivot joint comprises a ball joint 62 interconnecting a central hinge plate 64 rigidly fixed to central frame 26 and a pair of spaced hinge plates 66, 68 rigidly fixed to the respective boom portions 22, 24.

As shown in Figs 2 and 3, the axes of the pairs of pivot joints 54, 56 and 58, 60 are laterally offset.

from vertical alignment whereby folding of the boom portions 22, 24 to their forward transport positions causes the boom portions to be raised, and this damps the movement of the booms away from their working attitudes.

Lever arms 42, 44 are rigidly connected to the boom portions 22, 24 and pivotally interconnected by linkage means 70 comprising transport position rams 38, 40 and a compensating member 76. The compensating member is pivotally connected at 78 to central frame 26 and at 80 and 82 to rams 38, 40. The rods of rams 72, 74 are connected at pivots 84, 86 to lever arms 42, 44.

Compensating member 76 comprises upper and lower plates 88, 90 interconnected as a rigid assembly by radial plates 92, 94. Generally wedge shaped rubber buffers 96, 98 are located between radial plates 92, 94 and a central fixed plate 100 secured to frame 26 and extending between upper and lower plates 88, 90 of the compensating member 76.

Rams 72,74, are double acting and powered by tractor 18. When the rams are retracted, boom portions 22, 24 are pulled rearwards to their operating positions as shown in Fig 1. In their transport positions, the boom portions are raised so that lift rams are not required for this purpose. Such raising of the boom portions arises from the geometry of the pivot means 34, 36, and more specifically from the non-alignment of the axes of pivot joints 54, 56 and 58, 60.

In use, linkage means 70 interconnecting lever arms 42, 44 of the boom portions 22, 24 serves to ensure that turning movement of one boom portion about its pivot means 34 or 36 causes a corresponding turning force to be applied to the other boom portion, tending to turn it in the opposite direction. Thus, the boom portions cannot both swing forwards or both swing backwards, they can only swing either generally clockwise or generally anticlockwise about their respective pivots. This avoids the problem of the boom portions tending to both hang back rearwards on upward slopes or forwards on downward slopes.

Moreover, in the same way that rapid turning movements of the tractor or the spraying apparatus chassis about a fore/aft axis is effectively isolated from the boom by virtue of pivot means 50, so likewise the boom 20 is isolated by pivot means 34, 36 and linkage 70 from rapid back and forth motion of the boom ends in the fore/aft direction.

Transmittal of motion from one boom portion to the other is limited to some extent by the rubber buffers 96, 98 on opposite sides of the fixed plate 100 and sandwiched between the radial plates 92, 94 and plate 100. The rubber buffers resiliently resist pivotal motion of the boom portions about their respective pivots, as indeed do the relative dispositions of the pivot axes.

Moreover, compensating member 76, being pivotally mounted on frame 26 about pivot 78 has the effect of changing the degree of pivotal movement transmitted between the boom portions. When compensating member 76 turns clockwise about pivot 78, as seen in Fig 3, then pivot 80 tends to move more in the fore/aft direction F than in the lateral direction L with respect to the direction of motion of the apparatus. Correspondingly, pivot 82 moves more in the lateral direction L and less in the fore/aft direction F. These two facts emerge purely from the geometry of the system.

The result of this however is that when the right hand boom portion tends to swing forwards (such as when the tractor turns in the right hand direction) the left hand boom swings in the rearward direction by a shorter distance than the right hand boom swings forwards. Likewise, when the right hand boom swings in the rearwards direction (such as when the tractor turns to the left), the left hand boom swings in the forward direction by a lesser distance than the right hand boom swings rearwards.In short, the boom portion which swings rearwards swings more than the one which swings forwards with the result that the boom portion on the outside of a turn of the apparatus is swung back an extra distance whereby acceleration of the boom end is minimized and the difference in mechanical advantage between the two boom potions in relation to their mechanical linkage gives rise to a damping effect on such swinging movement of the booms.

The principal advantages of the embodiment described above lie in its steady and smooth spraying characteristics despite rapid limited movements of the tractor and trailed sprayer.

Moreover, the boom is relatively unstressed and is far less subject to breakdown due to stress. The damping of the boom swinging movement minimizes such movement and moreover the boom pivot disposition enables the boom portions to be lifted without the provision of hydraulic lift rams, for transport purposes.

Many modifications can be made to the above described embodiment without departing from the scope of the invention including modifications of the structure of the boom itself, the exact disposition of the boom hinge elements, the detailed structure of the compensating member and its associated mechanical linkage and the associated damping means. For example, coiled springs could replace the rubber buffers, or indeed pneumatic accumulators or some other resilient equivalent.

Claims (18)

1. Mobile boom-type apparatus such as agricultural or horticultural spraying apparatus comprising two booms or boom portions adapted to be mounted on a supporting vehicle and positionable so as to extend generally laterally outwardly from opposite sides of the vehicle with respect to the direction of operative forward motion of the vehicle characterised in that said booms or boom portions are pivotally mounted in the region of their inner ends so as to permit fore / aft movement of their outer ends, control means being provided to control said pivotal movement the the booms and thereby control said fore / aft movement of the boom ends , the control means comprising link means between the booms or the boom portions whereby pivotal movement of one boom causes a turning force to be applied to the other boom or boom portion.

2. Apparatus according to claim 1 wherein said boom pivots are spaced apart and mechanical link means is provided there between.

3. Apparatus according to claim 2 wherein said mechanical link means comprises a lever arm on each boom or boom portion and a laterally extending link structure pivotally connecting said lever arms.

4. Apparatus according to claim 3 wherein said link structure includes a compensating mechanism to modify the movement transmitted between the booms or boom portions according to the operating situation.

5. Apparatus according to claim 4 wherein the compensating mechanism comprises a pivotally mounted compensating member and link members pivotally connecting the compensating member to the boom lever arms.

6. Apparatus according to any one of the preceding claims wherein resilient means is provided connected to said boom or boom portions to resist pivotal movement thereof.

7. Apparatus according to claim 6 wherein the boom pivot means is disposed so as to cause the boom, or a portion thereof, to be raised upon the boom or boom portion executing such pivotal movement.

8. Apparatus according to claim 2 or any of claims 3 to 7 when dependent on claim 2 , wherein said mechanical linkage between the booms or boom portions comprises one or more hydraulic rams or like thrust devices for pivoting the boom or boom portions to a transport position.

9. Apparatus according to claim 2 or any one of claims 3 to 8 when dependent on claim 2 wherein resilient means is connected to the mechanical link between the booms or boom portions.

10. Apparatus according to claim 9 wherein the resilient means comprises rubber buffer means.

11. Apparatus according to claim 10 wherein said rubber buffer means is associated with a fixed member connected to a frame of the apparatus.

12. Apparatus according to claim 11 when dependent on claim 4 wherein the rubber buffer means is associated with said compensating mechanism.

13. Mobile boom type apparatus such as agricultural or horticultural spraying apparatus comprising a boom adapted to be mounted on a support vehicle and positionable to extend gener ally laterally outwardly with respect to the direction of operative forward motion of the vehicle characterised in that said boom is pivotally mounted so as to permit fore / aft movement of the outer end of the boom , control means being provided to control the pivotal movement of the boom and thereby control said fore / aft movement of the boom end.

14. Apparatus according to claim 13 wherein said control means comprises pivot means for the boom arranged so that pivotal movement of the boom from its operative position causes at least the outer end of the boom to be raised

15. Apparatus according to claim 14 wherein the pivot means comprises a pair of pivot assemblies with one of said assemblies suitably off set from a vertical axis through the other

16. Apparatus according to any one of claims 14 and 15 wherein said pivot means comprises ball joints or the like permitting pivotal movement about more than one axis.

17. Apparatus according to any one of claims 14 to 16 wherein said pivot means comprises a pivot joint having a pivot axis inclined with respect to the vertical.

18. Mobile boom type apparatus substantially as described herein with reference to the accompanying drawings.