GB2184633A - Boom mounting arrangement - Google Patents

Abstract

A boom, primarily for an agricultural crop sprayer, has elongate wing portions 10, 11 which are cantilevered out from a cradle mounting (17). The cradle mounting is pivotally connected to a mounting sub-assembly (18) (Fig 2) for rotational movement about a horizontal axis (19). The sub-assembly is pivotally connected to a vehicle for rotational movement about another horizontal axis. Both axes lie longitudinally of the vehicle. A pneumatically operated ram (34) is connected between the cradle mounting and the sub-assembly for adjusting the relative rotational position therebetween and thereby enable the boom to be maintained parallel to the ground. The ram has an inherent spring stiffness which means that dynamic forces are not transmitted in full between the vehicle and boom as such forces are at least in part absorbed by the ram. <IMAGE>

Description

SPECIFICATION Boom mounting arrangement This invention relates to a mounting arrangementfor a boom such as is used in agricultureforcropspraying.

In agricultural crop sprayers, an elongate boom is used to carry a plurality of spray heads. The boom is mounted transversely, often on a trailer which is towed behind a tractor, but sometimes on the tractor itself or on some other suitable vehicle. In orderto achieve an even spray distribution over the crop and minimise overlap, it is desirablethatthe boom should remain as nearly parallel to the ground as possible when spraying. As the vehicle mounting the boom may have to travel over uneven ground, it is preferred to have some means for adjusting the in clination ofthe boom relative to the vehicle so asto be abieto keep the boom parallel to the ground. In a conventional boom mounting arrangement, as exemplified by 2014834, adjustment means is proposed in the form of a hydraulic ram.The problem wit this mounting arrangement is that, as the hydraulic ram effectively provides direct mechanical connection between the vehicle and boom, dynamic lateral forces from the vehicle as it is rocked from sideto side when travelling over uneven ground are transmitted directly to the boom,tending to induce a lateral motion of the boom. Lateral motion of the boom is undesirable because it leads to uneven spraying.

Furthermore, as booms can have considerable inertia, weighing sometimes 3/4 ton and having a span of some 80 ft, the induced rolling motion of the boom puts severe stress on the boom mounting.

The present invention is based upon an appreciation of the existance of this problem and a recognition ofthe significant advantages that are to be gained by its alleviation.

Accordingly, in a first aspect the invention provides an arrangement for mounting a boom on a vehicle, the arrangement comprising a mounting subassembly, means pivotally connecting the sub-assembly to the vehicle for rotational movement about a first horizontal axis extending longitudinally ofthe vehicle, means pivotally connecting the boom to the sub-assemblyfor rotational movement about a second horizontal axis extending longitudinally of the vehicle, and means connected between the boom and the sub-assembly for adjusting the relative rotational position therebetween, said adjusting means including spring means capable of absorbing at least in part dynamic forces arising out of relative movement between the boom and sub-assembly.

In a second aspect the invention provides an auto maticcontrol system for a boom mounting arrangement on a vehicle, the system comprising means to monitor the inclination of the boom relative to the ground, and means to adjustthe inclination ofthe boom automatically in response to the monitoring meansformaintaining the boom parallel to the ground, the adjusting means including spring means capable of absorbing at least in part dynamicforces arising out of relative movement between the boom and vehicle.

Bywayof example, an embodiment ofthe inven- tion will now be described with reference to the accompanying drawings, in which Figure lisa perspective view showing a boom and its cradle mounting, Figure 2 is a perspective view showing the boom mounting sub-assembly and its support, and Figure3is an elevational view showing a detail of the boom cradle mounting and the sub-assembly.

A boom, as seen in Figure 1, comprises a pairof elongate wing portions 10 and 11. Each wing portion 10, 11 is pivotally connected to a mounting bracket 12, 13 from which the wing portions cantilever out.

Rams 14, 15 are provided for pivoting the wing portions 10, 11 between a working position, as shown in Figure 1,where the wing portions extend out sideways, and a stowed position where the wing portions are folded together forwardly. The wing portions 10,11 themselves comprise a numberof articulated sections which are movable by further ramstoenablethewing portions to be collapsed down into the forward stowed position. Each wing portion 10,11 carries the usual spray heads 16 along its length.

Each mounting bracket 12, 13 for the wing portions 10, 11 of the boom is pivotally connected to a cradle mounting 17. The pivotal connection of each mounting bracket 12, 13 has a forwardly sloping axis, as seen in Figure 1, seas effectively to form a rising hinge. Accordingly to this rising hinge arrangement, each mounting bracket 12, 13 will tend to fail back into the position shown in Figure 1 undertheinflu- ence of gravity. However, the arrangement allows there to be pivotal movement of either mounting bracket 12, 13 rearwardly. This means that when the boom is in its extended position, if either of the wing portions10,11 isfouled,forexample by a hedge, whilethevehicletravelsforwardthewing portion can simply fold back and therefore damage to the boom is prevented.When the obstruction is cleared, the wing portion swings backto its normal position on the rising hinge.

The cradle mounting 17 is pivotally connected to a mounting sub-assembly 18, which is seen in Figure 2, about a horizontal axis 19. By virtue ofthis pivotal connection, the boom, comprising the two wing portions 10,11 their mounting brackets 12, 13 and the cradle mounting 17, is able to rotate about the hori- zontal axis 19, (so-called roll motion). A pairofdam- pers 36, 37 (described more fully below) act to damp down roll motion ofthe boom.

Referring to Figure 2, the mounting sub-assembly 18 can be seen with its pivotal connection forthe cradle mounting 17 forming the horizontal axis 19.

The mounting sub-assembly 18 is itself pivotally connected to a carrier bracket 20 by means of a balljoint 21. The carrier bracket 20 is in turn pivotally mounted on an adjustablesupportassembly22 which is carried by or may be part of a vehicle. The vehicle may be a trailerfortowing behind a tractor, for example, or may itself be a tractor. The adjustable support assembly 22 comprises a pair of columns 23, 24 on which is pivotally mounted an H-shaped yoke 25. The yoke 25 can be rotated about its pivotal mount on the columns 23,24 by means of rams 26, 27 connected between the yoke 25 and the columns.

Atie 28 is pivotally connected between cradle mounting 17 and a brace 29 between the columns 23, 24 so that, by parallel motion, the inclination ofthe mounting sub-assembly 18 and cradle mounting 17 remains unchanged by rotation of the yoke 25.

Thus, by operation ofthe rams 26,27, the boom can be raised into an upper position for storage or lowered and adjusted into a suitable working position.

By reference to Figures 1 and 2, itwill be seen that the dampers 36,37 are pivotally connected between the mounting cradle 17 and the carrier bracket 20. As mentioned above,the dampers 36,37 serve to damp down the roll motion ofthe boom.

The pivotal connection ofthe mounting subassembly 18to the carrier bracket 20 by means ofthe ball joint 21 gives the mounting sub-assemblyfree- dom of rotation. To limit this freedom, a control buf fer30 is provided. The control buffer30 comprises a flexible, resilient (e.g. elastomeric) block31 which is sandwiched between two plates 32 and 33. One plate 32 is attached to the mounting sub-assembly 18 and the other plate 33 is attached to the carrier bracket 20.

Rotational movement ofthe mounting sub-assembly 18 about a vertical axis through the ball joint 21 (socalled yaw motion) will cause deformation of the block 31, which thereby provides a cushion. The limits ofthe yaw movement ofthe mounting subassembly 18 are reached if the mounting subassembly comes into abutting engagement with the carrier bracket 20. in practice, the allowable yaw movement is preferably restricted to fractions of an inch.

Rotational movementofthe mounting subassembly 18 about a horizontal axis extending transverselyofthevehicle (i.e. at rightanglesto axis 19) is prevented by virtue ofthe parallel motion arrangement involving the tie 28 as described above. (This is so-called pitch motion).

Between the mounting sub-assembly 18 and the cradle mounting 17 of the boom there is pivotally connected a ram 34. By extension and retraction of ram 34the rotational position ofthe boom relative to the mounting sub-assembly about horizontal axis 19 is adjustable. This can be seen clearly in Figure 3, where arrow 35 indicatesthe rotational adjusting movement. If the vehicle carrying the boom tilts side- ways while spraying, as ittravelsoveruneven ground for example, the operator is able to adjustthe inclination ofthe boom by actuating the ram 34so that the boom remains parallel to the ground. The ram 34 here is pneumatically operated and is double- acting. Pressure is maintained in the ram 34atall times while spraying.The purpose of this is ef fectively to provide a gas spring acting between the boom and the mounting sub-assembly. According to this arrangement, if the vehicle rocks sideways dur- ing spraying,the resulting dynamic sideways force acting through the adjustable support assembly 22, thecarrierbracket20 and the mounting subassembly 18will not be transmitted directlyto the boom but will in part be absorbed by the effective gas spring. This has the advantage that there is less tendencyfor roll motion to be induced in the boom, leading to less waywardness in the spray distribution. Afurther advantage is that the cushioning effect of the gas spring helps to reduce the sideways load on the boom mounting arrangement.As booms can have considerable inertia, weighing sometimes 3/4 ton and having a span of some 80 ft, this is a significant advantage.

In the above described embodiment of the invention, the operator has to keep a watch on the inclination of the boom while spraying and make any necessary adjustments to keep it parallel to the ground by manually actuating the pneumatically operated ram.

In a further aspect of the invention, means is provided for the adjustment control ofthe boom to be carried outautomatically.

The automatic control includes a device for monitoring the inclination of the boom relative to the ground. This device may take the form of a mechanical link between the boom and the ground, for example, or may operate using a system oftransmitted and reflected signals, such as sonic waves or optical or electromagnetic beams. in a convenient form, the monitoring device may comprise a pair of signal transmitters mounted on the boom tips. Further included in the automatic control is a device for making appropriate adjustements to the inclination of the boom in response to signals from the monitoring device. In the case where the pneumatically operated ram adjusts the inclination of the boom, the control device is linked to the air supply to the ram. The use of a pneumatically operated ram in such an automaticcontrol system is particularly suitable because of the progressive nature of its operation and an inherent spring stiffness. Adjustment of the boom is thus able to be achieved withoutjerky movements which would tend to put great stress on the boom and its mounting arrangement.

Claims (10)

1. An arrangement for mounting a boom on a vehicle, the arrangement comprising a mounting sub-assembly, means pivotally connecting the subassembly to the vehicle for rotational movement about a first horizontal axis extending longitudinally of the vehicle, means pivotally connecting the boom to the sub-assembly for rotational movement about a second horizontal axis extending longitudinally of the vehicle, and means connected between the boom and the sub-assembly for adjusting the relative rotational position therebetween, said adjusting means including spring means capable of absorbing at least in part dynamic forces arising out of relative movement between the boom and sub-assembly.

2. A mounting arrangement as claimed in claim 1 wherein the adjusting means comprises pneumatically-operated linear actuator means pivotally connected between the boom and the sub-assembly, the gas stiffness of the actuator means providing the spring means.

3. A mounting arrangement as claimed in claim 2, wherein the actuator means comprises a single actuatorwhich is double-acting.

4. A mounting arrangement as claimed in claim 1, claim 2 or claim 3 wherein the means pivotally connecting the sub-assembly to the vehicle also allows relative rotational movementtherebetween about a vertical axis, and there is means to iimitthe relative rotational movement therebetween.

5. A mounting arrangement as claimed in claim 4 wherein the limiting means inciudes resiliently deformable means capable of cushioning said relative rotational movement.

6. A mounting arrangement as claimed in any preceding claim wherein the means pivotally con necting the sub-assemblyto the vehicle is mounted via adjustable support means on the vehicle wherebyto allow the vertical position of the subassembly relative to the vehicle to be adjusted.

7. Amounting arrangementas claimed in claim 6, wherein the means pivotally connecting the subassembly to the vehicle also allows relative rotation therebetween about a third horizontal axis extending transversely of the vehicle, and there is means ensure parallel motion of the sub-assembly when its vertical position relative to the vehicle is adjusted.

8. An arrangement for mounting a boom on a vehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. An automatic control system for a boom mounting arrangement on a vehicle, the system comprising meanstomonitortheinclinationofthe boom relative to the ground, and means to adjust the inclination of the boom automatically in response to the monitoring meansformaintaining the boom par- allel to the ground, the adjusting means including spring means capable of absorbing at least in part dynamic forces arising out of relative movement between the boom and vehicle.

10. An arrangement for mounting a boom on a vehicle as claimed in any one of claims 1 to 8 having an automatic control system as claimed in claim 9.