^* This invention relates to a trailer vehicle having a

_Λ supporting frame carried by at least one pair of wheels and with a tipping body mounted thereon, the body being tipped by at least one tipping jack about a pivot mounted

5 above the frame.

Trailer vehicles with tipping bodies are commonly used in agriculture for transporting products such as sugar beet, and will typically be towed by an agricultural tractor. In order to be able to tip beet, in particular, 10 into a high enough mound to resist attack by frost, the vehicle is arranged so that the tipping body is pivoted adjacent its upper edge rather than at the level of the main frame of the vehicle. A problem which can arise with this arrangement is that it is necessary to elevate the 15 body until the base is nearly vertical before the contents of the body will discharge satisfactorily, and as the body is elevated, the centre of gravity of the load moves rearwardly. In order to limit the load on the tractor's tow bar, the wheels of the trailer vehicle are positioned 20 so that the load is substantially balanced over the wheels, but the shift of centre of gravity upsets this balance and this can lead to the trailer vehicle lifting the tractor by its tow bar. For these reasons, the maximum design load has to be limited to 6 to 8 tonnes 25 where a load of 10 tonnes or even higher may be economically preferable to the farmer. It is not possible to compensate substantially for this shift in centre of gravity by arranging for more weight to be placed on the tractor's tow bar initially, since an excessive load on ^ 30 the tow bar might tend to lift the front wheels of the tractor during towing.

Accordingly, the trailer vehicle of .the present invention is characterised in that the tipping body and pivot are movably mounted on the frame and actuating means

35 are provided for moving the tipping body and pivot

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relative to the frame, and in that the actuating means are arranged to cause the tipping body and pivot to move forward relative to the frame as the body is elevated about the pivot. The actuating means may comprise a hydraulic ram between the body, or preferably the mount for the pivot, and the frame, but chain or gear drives, or even manually operable levers, may also be suitable.

In an alternative embodiment, the actuating means comprise a rigid link or arm pivotally mounted ^* on the frame and extending to the body, the link being positioned such that, as the body is elevated, the link draws the body forwardly along the frame.

The amount of sliding of the body will be chosen to ensure that the centre of gravity does not move substantially forward of the wheels, relative to the direction in which the trailer vehicle is towed.

The trailer vehicle of the invention can be made of greater carrying capacity than existing trailers of the same general type, without the risk of lifting the tractor or other towing vehicle off the ground during tipping, or of overloading the tractor's tow-bar during towing. Reference is made to the drawings, in which : Figure 1 is a diagrammatic side elevation of the trailer vehicle in accordance with the invention, with the tipping body in its towing position;

Figure 2 shows the trailer vehicle of Figure 1 with the tipping body partially raised in the tipping position; Figure 3 is a partial rear elevation on an enlarged scale of the vehicle illustrated in Figures 1 and 2; and

Figures 4 and 5 are views corresponding to Figures 1 and 2, showing an alternative embodiment of the invention. The vehicle has a main frame 1 carried by two pairs of road wheels 2, the suspension for which is not shown for the sake of clarity. The main frame 1 has a draw-bar 3 extending from the front end thereof for connection to the tow bar of a tractor, for example. A tipping body 4

is open-topped and has a sloping rear surface 5 to assist in discharge of material therefrom. The body 4 is pivotally connected adjacent to the upper edge of the surface 5 to a pivot support 6 whereby the height at which the material is discharged is elevated.

The pivot support 6 has a portion 7 extending beneath the lower surface 8 of the body and carrying rollers 9 which run in channel members 10 (Figure 3) forming the sides of the main frame. A substantially horizontal double-acting hydraulic ram (not shown) is arranged between the main frame 1 and the pivot support 6 to move the support 6, and with it the body 4, between the position for towing as illustrated in Figure 1 and the tipping position illustrated in Figure 2. The body 4 may simply be in contact with the main frame -1 during the sliding movement, or rollers or some other bearing means may be interposed between the frame and the body.

Where a hydraulic ram is used to move the body and support, this may be hydraulically connected with the side thereof causing movement towards the tipping position in parallel with the twin single-acting three-or four-stage lifting rams 11 which serve to tip the body, but with a valve dividing the flow of hydraulic fluid between the lifting rams 11 and the horizontal ram in proportions such that the body tips and slides simultaneously so that the horizontal movement of the centre of gravity of the body is kept to a minimum. The rams 11 are mounted between the body 4 and the forwardly extending portion 7 of the pivot support 6 so as to slide with the support and body. The length of the draw bar 3 is arranged to be sufficient to ensure that the body is clear of any towing vehicle during tipping. Where a greater tipping height is required, the support 6 may be extended upwardly, and the rear surface 5 of the body 4 is then also extended by a corresponding amount beyond the upper extent of the sides of the body.

Referring to Figures 4 and 5, the trailer vehicle

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illustrated is identical with that shown in Figures 1 and 2, except that no horizontal ram is provided to move the body 4 relative to the frame 1. Instead, one or more rigid arms or links 40 are provided between the body 4 and the frame 1. For clarity, one link 40 is illustrated attached to the sides of the body and frame, but the link may, with some arrangements, be positioned beneath the body 4. As the body 4 is elevated by the lifting rams 11, the distance between the pivot points 41 and 42 of the links 40 ^' would, if the link were not present increase. The presence of the links 40 causes the support 6 and the body 4 to be drawn forward along the frame 1 as the angle of inclination of the body relative to the frame increases, until the position of maximum elevation is reached as illustrated in Figure 5. The links are di¬ mensioned and arranged such that this position corresponds to the maximum forward movement of the body 4 relative to the frame 1. It will be seen that lowering of the body will cause the body to be urged rearwardly again, relative to the frame, returning towards the position illustrated in Figure 4.

Further, the links are also dimensioned and arranged such that the horizontal movement of the centre of gravity during tipping is kept as small as possible. The position of the rearward pivotal attachment for each link is on or above a line joining forward pivotal attachment of each link to the pivot axis of the tipping body.

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