GB2067970A - Trailers - Google Patents

Abstract

A trailer has a load carrying platform 10, means 11 for attaching the front end of the platform 10 to the towing device of a towing vehicle, and a wheeled suspension unit 12 for the platform 10. The unit 12 is normally positioned as shown, with the wheels 20 lying between the front end and rear end of the platform 10 to support the platform 10. However the unit 12 can be moved to the rear of the platform, the wheels initially travelling along a rearwardly extending path and then along an upwardly extending path so that the rear of the platform 10 is lowered to the ground. <IMAGE>

Description

SPECIFICATION Trailers The invention relates to trailers and particularly, but not exclusively, to agricultural draw-bar trailers.

The invention provides a trailer having a load carrying platform, means for attaching the front end of the load carrying platform to the towing device of a towing vehicle, and a wheeled suspension unit for the load carrying platform, the suspension unit normally being positioned such that the wheels of the suspension unit lie between the front end and the rear end of the load carrying platform to support the load carrying platform, but the suspension unit being movable such that the wheels travel along a rearwardly extending path to bring the wheels to the rear of the load carrying platform and then move along an upwardly extending path such that the rear end of the load carrying platform can be lowered to the ground.

When the trailer is towed by a vehicle having means to lower the front end of the load carrying platform e.g. an agricultural tractor having a conventional three point linkage or some other vertically movable towing device, both ends of the trailer can be lowered so that the load carrying platform lies flat upon the ground, to facilitate access to the load carrying platform, e.g. to load or unload the platform.

The suspension unit is preferably arranged to move along the said rearwardly extending path and the said upwardly extending path by locating devices (e.g. rollers) which travel along appropriately shaped guide tracks.

For example there may be a track at each side of the trailer, the tracks each having a front portion which extends horizontally and a rear portion which is inclined upwardly at an angle to the horizontal, the suspension unit being fitted with rollers which engage in the tracks.

The tracks may comprise channel members.

The movement of the suspension unit may be controlled by a hydraulic ram.

Preferably the suspension unit is supported in each track by a pair of rollers spaced apart with respect to the longitudinal axis of the trailer.

Preferably only each of the rear rollers travels up the inclined rear portion of the associated track, so that the suspension unit, when the wheels move upwardly, pivots about the axis of rotation of the front rollers, the hydraulic ram being pivotally connected to the suspension unit at a point which lies on the axis of rotation of the front rollers.

The suspension unit may have support means (e.g. additional rollers) which engage underneath the tracks or underneath other parts of the load carrying platform when the suspension unit is in its forwardmost position to provide additional support for the load carrying platform when the trailer is being used to transport loads.

By way of example, a specific embodiment of trailer according to the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a side view of the embodiment of trailer with the suspension unit in the forwardmost position, ready to transport a load; Figure 2 is a view similar to Figure 1 but showing the suspension unit in its rearmost position, with the load carrying platform flat on the ground, ready for loading or unloading; Figure 3 is a perspective view of the rear of the trailer, with the wheels of the suspension unit omitted for clarity; and Figure 4 is a perspective view of the suspension unit, with the wheels omitted.

The trailer forming the subject of this embodiment is an agricultural draw-bar trailer having a flat load carrying platform 10, a draw bar 11 at its front end for attaching the trailer to a towing vehicle, and a wheeled suspension unit 12.

As best seen in Figure 3, the trailer has an upwardly inclined rear portion 13 and at each side of the trailer there is a downwardly extending skirt 14. At each side of the trailer, but spaced inwardly from the skirt 14, there is a channel member having a first portion 1 5 which extends horizontally along the underside of the load carrying platform 10 and a second portion 16 which extends in an upwardly inclined manner underneath the portion 1 3 of the trailer. The mouth of each channel member faces outwardly to provide a track. Extending along the centre line of the trailer underneath the load carrying platform 10 there is a further channel member 1 7 which faces downwardly.

The suspension unit is best shown in Figure 4.

The suspension unit has a box section beam 18 through which an axle 1 9 extends. The wheels 20 of the trailer are mounted one at each end of the axle 19. At each end of the beam 18, on its upper side, a short box section member 21 is welded and welded to each box section 21 is an elongate plate 22 which extends longitudinally of the trailer and supports two roners 23.

The plates 22 are welded to the inner faces of the box section members 21. Welded to the outer face of each box section member 21 is a longer plate 24 which extends from the beam 1 8 in an upwardly inclined manner towards the front of the trailer. Inbetween the ends of the plates 24 they are interconnected to one another by a second box section beam 25a welded between them. The beams 18 and 25a are joined together by a short connecting beam 26 welded therebetween. A further beam 27 is welded to the beam 25a and projects forwardly in an upwardly inclined manner.

The beam 27 is supported by two struts 28 welded between the transversely extending beam 25a and the forwardly extending beam 27.

Pivotally mounted at the front end of each plate 24 is roller 25. The rollers 25 have the same axis of rotation 26 and this axis of rotation 26 passes through the front end of the beam 27.

Inbetween the ends of the plates 24 there is an upwardly projecting lug 29 and each lug 29 carries a roller 30.

When the suspension unit is fitted on to the trailer the horizontal portions 1 5 of the channels rest on and are hence supported by, the rollers 23.

The rollers 25 and 30 engage within the tracks formed by the channel members.

The position of the rollers 25 and 30 when the trailer is in the load carrying condition is best shown in Figure 1. Lying within the downwardly facing channel 17 there is a hydraulic ram 31. The front end of the cylinder 32 is secured within the drawbar 11 and the piston rod 33 of the ram is pivotally connected to the front end of the beam 27.

When the suspension unit is in the position shown in Figure 1 the wheels 20 efficiently support the trailer and any load thereon and because the wheels lie inbetween the ends of the trailer, and not at one end thereof, the trailer is relatively manoeuvrable and can readily be towed through narrow openings such as the gates of fields.

If it is desired to unload the trailer, or load the trailer, it is merely necessary to supply hydraulic fluid to the ram 31, for example from the hydraulic power unit of an agricultural tractor used to tow the trailer. Extension of the ram pushes the suspension unit rearwardly. Initially the suspension unit moves horizontally, the rollers 23 running along the underside of the channels and the rollers 25 and 30 running within the channels.

However when the rollers 30 reach the end of the cnannel portions 1 5 they start to follow an inclined path, moving up the channel portion 16, and the suspension unit pivots upwardly about the axis 26. When the rollers 25 and 30 reach the position shown in Figure 2 the wheels 20 have risen to such an extent that the rear end of the load carrying platform is resting upon the ground.

The front end of the trailer can be lowered using the conventional three point linkage of the towing tractor, or any other vertically movable towing coupling, so that the trailer assumes the position shown in Figure 2.

In the rearmost position of the suspension unit the rollers 23 have moved clear of the channel portion 1 5 but their support is unnecessary when the load carrying platform is resting on the ground.

The rollers 23 are merely provided to give additional support to the load carrying platform to cope with the stresses imposed when the trailer is being used to transport a load.

Once the trailer has been loaded or unloaded, it is only necessary to retract the ram 31 to return the suspension unit to the position shown in Figure 1.

One particular use to which the trailer can be put is to transport an item of agricultural equipment, such as a seed drill, which is, itself, too wide to be towed on public roads. Such an item of equipment can be loaded on to the trailer with the transverse axis of the item of equipment extending along the longitudinal axis of the trailer. The fact that the load carrying platform of the trailer can be laid flat on the ground make its very easy to roll an item of equipment such as a seed drill on and off the platform when required. If desired the load carrying platform may be provided with inclined side portions or with ramps to further assist in wheeling items of agricultural equipment on and off the load carrying platform.

While the trailer is particularly suitable for carrying bulky items of farm equipment it may of course be used to carry any desired load whatsoever.

The invention is not restricted to the details of the foregoing embodiment.

Claims (9)

1. A trailer having a load carrying platform, means for attaching the front end of the load carrying platform to the towing device of a towing vehicle, and a wheeled susperision unit for the load carrying platform, the suspension unit normally being positioned such that the wheels of the suspension unit lie between the front end and the rear end of the load carrying platform to support the load carrying platform, but the suspension unit being movable such that the wheels travel along a rearwardly extending path to bring the wheels to the rear of the load carrying platform and then move along an upwardly extending path such that the rear end of the load carrying platform can be lowered to the ground.

2. A trailer as claimed in Claim 1, in which the suspension unit is arranged to move along the said rearwardly extending path and the said upwardly extending path by locating devices (e.g. rollers) which travel along appropriately shaped guide tracks.

3. A trailer as claimed in Claim 2, in which there is a track at each side of the trailer, the tracks each having a front portion which extends horizontally and a rear portion which is inclined upwardly at an angle to the horizontal, the suspension unit being fitted with rollers which engage in the tracks.

4. A trailer as claimed in Claim 3, in which the tracks comprise channel members.

5. A trailer as claimed in Claim 3 or Claim 4, in which the movement of the suspension unit is controlled by a hydraulic ram.

6. A trailer as claimed in Claim 5, in which the, suspension unit is supported in each track by a pair of rollers spaced part with respect to the longitudinal axis of the trailer.

7. A trailer as claimed in Claim 6, in which only each of the rear rollers travels up the inclined rear portion of the associated track, so that the suspension unit, when the wheels move upwardly, pivots about the axis of rotation of the front rollers, the hydraulic ram being pivotally connected to the suspension unit at a point which lies on the axis of rotation of the front rollers.

8. A trailer as claimed in any one of the preceding claims, in which the suspension unit has support means which engage underneath the tracks or underneath other parts of the load carrying platform when the suspension unit is in its forwardmost position to provide additional support for the load carrying platform when the trailer is being used to transport loads.

9. A trailer constructed and arranged substantially as herein described, with reference to the accompanying drawings.