GB2158024A - Folding gooseneck of trailer - Google Patents

Abstract

A heavy duty trailer comprises a folding gooseneck which can be detached from a tractor vehicle and folded to form a ramp over which machinery can be loaded and unloaded. A quadrilateral linkage connects the gooseneck (12) to the trailer platform (11) and includes front link (16) and rearlink (17), separately pivotally connected to the gooseneck and the platform, and a diagonally extending ram (22). The front link can be releasably locked at a pre-determined position and there is a lost motion coupling (19) (28) between the gooseneck (12) and the rear link (17). The invention enables the same ram (22) to be used firstly to raise and lower the front end of the trailer platform (11), and secondly to tilt the gooseneck (12) to uncouple kingpin (23). <IMAGE>

Description

SPECIFICATION Trailer This invention relates to a trailer for towing behind a tractor vehicle and specifically relates to the type of trailer having a folding gooseneck. The invention has particularly been devised in relation to trailers for transporting heavy machinery such as earth moving machines and the like which can be loaded onto, and unloaded from the trailer under their own motive power.

It is known to provide a trailer with a folding gooseneck by means of which it is attached to the tractor vehicle. In order to detach the trailer from the tractor, it is necessary to provide power means which are operated in a number of stages, firstly to lower the platform of the trailer to a position where it is supported by the ground, secondly to raise at least the forward end of the gooseneck to detach it from the "fifth wheel" of the tractor and finally, after the tractor has been driven away, to lower the gooseneck to the ground to form a ramp, over which the machinery on the platform can be unloaded.

Previously known folding gooseneck trailers of this general type have either utilised separate power means for different stages of uncoupling and unloading or have had to incorporate complex linkages in order to perform the whole sequence of operations using a single power means.

While this might be acceptable if the trailers were of relatively light weight, it adds to manufacturing costs and difficulties and makes the mechanism susceptible to damage where very heavy trailers are concerned, for example trailers capable of taking a pay-load of the order of 45 tonnes. The trailer platform can be weakened by peforations used attach such linkages.

It is an object of the present invention to provide a simple and economically constructed folding gooseneck which avoids complicated linkages having a plurality of moving parts and which may avoid major attachments involving perforations in the structural sides of the trailer platform.

According to the invention there is provided a trailer comprising a load carrying platform; a gooseneck for connection to a tractor vehicle; and a linkage linking the gooseneck and the platform; the linkage comprising at least one front link and at least one rear link, each link being pivotally connected to both the gooseneck and the platform to define a quadrilateral linkage, and power means disposed generally diagonally of the quadrilateral linkage, wherein a lost motion coupling is provided between the upper end of the rear link and the gooseneck.

The lost motion coupling may comprise a slot in the upper end of the rear link cooperable with a pivot on the gooseneck.

Locking means may be provided for locking the front link in a pre-determined angular relationship with the platform.

Preferably, the power means comprise a hydraulic piston and cylinder assembly.

The power means may be connected to the gooseneck and the platform.

A trailer embodying the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which Figure 1 is a side elevational view, partly broken away of a trailer, Figure 2 is a detail view of a rear link of the folding gooseneck of the trailer shown in Figure 1, Figures 3-10 show stages in the operation of detaching the trailer from a tractor unit, unloading the trailer and re-attaching the tractor.

Referring firstly to Figure 1 of the drawings there is shown a trailer generally indicated at 10 and comprising a platform 11, a gooseneck 12, twin axles 13 on which are mounted road wheels 14, and a folding gooseneck linkage generally indicated at 15. The linkage 15 comprises a pair of front links 16 and a pair of rear links 17. The front links 16 and rear links 17 are separately pivoted at 18 and 19 respectively to the gooseneck 12. There are also separately pivoted at 20 and 21 respectively to the forward end of the platform 11. The resulting linkage 15 is of quadrilateral form.

A hydraulic piston and cylinder assembly 22 is connected across the quadrilateral linkage between fixed points on the gooseneck 12 and platform 11 respectively (not shown). The ram 22 acts between a position near the base of the front link and a position near the upper end of the rear link.

At the forward end of the gooseneck 12, a king pin 23 of generally known type is provided to connect with a tractor unit (not shown) via a conventional fifth wheel arrangement. The extreme forward end 24 of the gooseneck 12 is tapered to provide a ramp for loading and unloading the platform 11.

In addition to the pivotal connection 20 between the lower end of the front link 16 and the platform 11, there is another connection. A locking pin 25 is inserted in aligned openings in the platform 11 and front link 16 in normal running condition of the trailer and during certain stages of loading and unloading which will be described in relation to Figures 3 to 7.

Figure 2 of the drawings shows in more detail the shape of the rear link 17 of the trailer. It will be appreciated that, for reasons of symmetry, identical linkages 15 are provided at each lateral side of the trailer. For simplicity of description, however, only one linkage 15 will be described.

The rear link 17 has an opening 26 at its lower end to receive the pivot 21. At its upper end, it is provided with an integrally secured slotted plate 27 having an arcuate slot 28 to receive the pivot 19 associated with the gooseneck 12. The pivot 19 and slot 28 together form a lost motion coupling, the operation of which will become clear in the following description. Although this construction is believed to have the merit of simplicity and ease of construction, it may be possible to reverse the lost motion coupling by providing a fixed pivot on the link 17 and a suitable guideway or slot on the gooseneck 12.

Turning now to the operation of the trailer, in relation to Figures 3 to 10 of the drawings, Figure 3 shows the running condition of the trailer diagrammatically, only the region of the linkage 15 being shown.

In the running condition of the trailer, the gooseneck 12 is connected by the king pin 23 to the tractor (not shown). The forward end of the platform 11 is therefore raised off the ground, the level of which is indicated at 26. The locking pin 25 is in position, holding the front link 16 at a pre-determined angle in relation to the platform 11 of the trailer. The pivot 19 is at the top of the slot 28 in the rear link 17 and the ram 22 is in a somewhat extended condition.

In order to detach the trailer 10 from the tractor unit, the platform 11 must firstly be lowered to the ground. This is done by contracting the ram 22 as shown in Figure 4 of the drawings. Since the pin 25 is still in position, locking the front link 16 in relation to the platform 11, ther effect of contracting the ram is to bring the pivot 19 towards the lower end of the slot 28 in the rear link 17. The gooseneck 12 therefore pivots about the "fixed" pivot 18 at the top of the forward link and hence the platform is lowered to the ground. The forward end of the gooseneck 12 tilts upwardly. Once the trailer platform 11 is resting on the ground 26, further contraction of the ram 22 will detach the king pin from the tractor, which can then be driven away, leaving the trailer lying on the ground.

In the next stage (not shown), the ram 22 is again extended somewhat to bring the gooseneck 12 into a more or less horizontal condition and to take up the lost motion in the coupling between the pivot 19 and the slot 28, that is to bring the pivot 19 again to the top of the slot 28. The locking pin 25 is removed.

In Figure 5 of the drawings, with the pin 25 removed, the ram 22 is again contracted and the quadrilateral linkage tends to flatten, lowering the gooseneck 12 to the ground. This operation can only take place once the pivot 20 with the front link 16 becomes operational, by removing the locking pin 25.

Figure 6 shows the final lowered condition of the gooseneck 12, in which it is more or less aligned with the platform 11, the rear link 17 now lying on top of the front link 16. The back of the rear link and the upper surface of the gooseneck are provided with suitable deck-plates so that they can cooperate to provide a ramp for removing the machinery loaded on the platform.

After loading or unloading, the trailer may need to be re-connected to a tractor unit. This is done in the way illustrated in Figures 7 to 10 of the drawings. With the locking pin 25 still removed from the front link 16, and the pivot 19 at the top of the slot 28 in the rear link, the ram 22 is again extended, raising the gooseneck 12 from the ground while it remains generally parallel to the ground level 26 (Figure 7).

When the locking pin apertures in the front link 16 and platform 11 come into alignment, the locking pin 25 is re-introduced, thereby retaining the front link 16 at the predetermined angle in relation to the platform 11. The ram is then reversed and contracted, raising the gooseneck 12 at its forward end with the pivot 18 as fulcrum. The pivot 19 moves down the slot 28 in the rear link 17 (Figure 8).

The configuration is similar to that shown in Figure 4 of the drawings. The trailer can then be backed in under the gooseneck 12 and the king pin attached in conventional manner as shown in Figure 9.

The ram 22 is extended to straighten the gooseneck to a horizontal condition. In so doing, the ram lifts the platfrom 11 off the ground 26, the load being transmitted to the tractor through the gooseneck 12 as shown in Figure 10. During extension of the ram, the pivot 19 acts at the top of the slot in the rear link until the trailer returns to its normal running condition shown in Figure 1 of the drawings.

It will be appreciated that the linkage 15 is a quadrilateral linkage with, effectively, a variable length rear link, provided by the lost motion coupling between the pivot 19 and the slot 28 at the top of the rear link. The geometry of this linkage enables the single ram 22 to power the whole sequence of loading and unloading the trailer and attaching it to, and detaching it from the tractor.

Only the pivot points and locking pin apertures need to be provided in the side walls of the load carrying platform 11, together with the welded on attachment for the base of the ram 22. This means that the strength of the platform is not reduced.

Similarly, only the pivot points 18 and 19 need to be provided in the gooseneck so that it, too is not weakened significantly. The lost motion coupling is provided at a position well spaced from the road surface and always remains well spaced above ground level, to reduce the amount of dirt and debris which it may pick up. In any case, the pivot running through a slot is less prone to build up of debris than for example an enclosed slideway. It will be seen that each of the elements of the quadrilateral linkage is rigid in use and that the trailer avoids the need for, for example bell crank levers, folding or toggle linkages and the like, which have been proposed in quadrilateral linkages of previous folding gooseneck trailers.

The ability of the forward end of the gooseneck 12 to tilt upwardly relative to the horizontal, in contrast to a pure parallelogram linkage with no lost motion coupling, means that the links 16, 17 themselves do not have to be made excessively long to lift the king pin out of engagement with the tractor.

Where a pure parallelogram linkage is provided, the length of the front and rear links has to be increased substantially and the "Construction and Use" regulations governing trailers then require that the length of the load carrying platform 11 be reduced because of the extra length of the gooseneck assembly in the ramp or loading condition.

Claims (6)

1. A trailer comprising a load carrying platform; a gooseneck for connection to a tractor vehicle; and a linkage linking the gooseneck and the platform; the linkage comprising at least one front link and at least one rear link, each link being pivotally connected to both the gooseneck and the platform to define a quadrilateral linkage, and power means disposed generally diagonally of the quadrilateral linkage, wherein a lost motion coupling is provided between the upper end of the rear link and the gooseneck.

2. A trailer according to Claim 1 wherein the lost motion coupling comprises a slot in the upper end of the rear link cooperable with a pivot on the gooseneck.

3. A trailer according to Claim 1 or Claim 2 wherein locking means are provided for locking the front link in a pre-determined angular relationship with the platform.

4. A trailer according to any preceding claim wherein the power means comprise a hydraulic piston and cylinder assembly.

5. A trailer according to any preceding claim wherein the power means are connected to the gooseneck and the platform.

6. A trailer substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.