GB2425990A - Trailers for use on soft ground - Google Patents

Abstract

A first trailer (10) is suitable for use in transporting a second trailer. It comprises engaging means (18) for releasably engaging the second trailer and pulling means (19) operably connected to the engaging means (18) for pulling the second trailer onto a platform (11) of the first trailer. It may also have tracks (13) or other means that allow the pressure that would be exerted on the ground by the first trailer (10) with the second trailer loaded thereon to be less than the pressure that would be exerted on the ground by the second trailer alone prior to loading it onto the first trailer (10). This allows the first trailer (10) to be used to transport the second trailer with a reduced risk of it sinking into the soft ground. It also reduces soil compaction. The trailer may also include a tilting bed to facilitate loading, and may be adjustable in size. Skids or a smooth underside may also assist movement over soft ground.

Description

Improved Traijers The present invention relates to trailers. It relates

especially, hut not exclusively, to farm trailers.

A trailer is typically hitched behind a motor vehicle to provide a convenient way of transporting a load from one location to another. The trailer can be relatively simple in construction, typically cOfllprisirig a platform, two more wheels that support the platform and a hitch tbr hitching the trailer to the vehicle so that it can be towed. If desired. the trailer may also have one or more connectors for connecting to the vehicle SO that power can be supplied (e.g. to operate lights or indicators). The trailer may also be provided with raised sides/ends to prevent the Ic ad falling off.

In some cases the trailer may he enclosed.

Trailers arc particularly useful on a farm environment. l'hcy can he pulled by tractors or other farm vehicles and used to transport large amounts of farm produce or farm animals. I lowever tarm trailers often become stuck, especially if used on soil ground.

This is a significant problem. Many fanns are located on soft land, because of its fertility and/or because it may be relatively inexpensive. For example farms may include feii-land.

marsh-land, bogs or paddy fields. i'hey may even he on land reclaimed from the sea, from a lake or a river. This is well known in countries such as The Netherlands where many farms consist of reclaimed polders.

Even ground that is normally well drained can become soft clue to changes in weather conditions or environmental conditions. This can occur, fir example, after prolonged or intense rain fall.

Additionally, there is an increased risk of flooding in many countries associated with climate change, defbrcstation etc. This can also lead to softer ground and can therefhre accentuate the risk of trailers becoming stuck.

In some eases it may be possible for a farmer to wait until ground conditions have improved before using a trailer, SO that there is less risk, of the trailer becoming stuck. However this is noi always praci icable. especially if there is a significant risk of a crop spoiling if it is not harvested in ume. or if it must reach a marketplace by a particular date (e.g. to supply a supermarket).

In the. case of farm animals it may also he necessary to transport them at particular times. For example, it may he necessary to transport them to a cattle market, to an ahattoir. or for breeding, shearing or veterinary purposes. Thus it may again not he practicable to wait until ground conditions improve.

Indeed ii may be particularly necessary to move firm animals when ground conditions are poor so as to move them to better grazing land or to stables. Whatever the reason for transporting the animals, there is a risk of the trailer becoming stuck. ibis can he distressing to the animals. It tnay then be necessary to unload the animals until the trailer has been freed, but this can he a difficult and time-consuming operation. It will also be necessary 1c find a sale place where the animals can be kept without escaping, whilst, the trailer is freed.

Even if it is possible to wait until soil conditions improve before using a trailer, this generally results in a signi licant delay. Furthermore, it is not always possible to predict accurately when ground conditions will improve, because of possible changes in weather conditions, \!1riahi1ity of the water table. etc. In any event it will often he necessary to retain skilled labour until conditions improve and this can he expensive.

Ofeotirse 1ground conditions arc permanently soft, then delaying using a trailer until ground condjtions improve is simply not an option.

In the light of the foregoing considerations, ii. will be appreciated that in many cases a farmer may need to use a trailer even if there is a significant risk of the trailer becoming stuck. If the trailer doeS become stuck then it will normally be possible to remove it by various methods. l'hcy include removing a load from the trailer, using a more powerful tractor, placing planks or ramps under the wheels to aid in providing traction for the tyres, partially deflating lyres, using farm staff to help push the trailer, etc. liowever these methods tend to be very time-consuming afl(l tedious More recently, farmers have concentrated upon using modified tractors. For example, tractors with very large wheels have been used to try to obtain improved traction. i'wo or more such wheels may even he provided at each side of the tractor. However this can severely reduce the manoeuvrahilty of the vehicle, especially if it is desired to use the vehicle on narrow roads or tracks. It can also reduce the rear field of view of the driver of the tractor. Furthermore. this method is not always effective, especially if a trailer becomes firmly stuck. En such circumstances it may still he necessary to use an additional vehicle - e.g. to use an additional tractor either to push the trailer from behind or to provide additional towing force.

Another alternative is to use a tractor that has caterpillar tracks. Although this is generally an improvement over using tractors with large wheels, it can be a. very expensive option ii such tracks are to he tIlted onto all of the tractors that a 1umer might wish to use on soft ground.

Typically a Farmer will have several tractors and wish them all to he available for use.

Furthermore the provision of such tracks on a tractor does not necessarily prevent the trailer itself from sinking into solt ground, especially when the trailer is slow or stationary.

A further problem is that trailers can become stuck even if the ground conditions are not particularly soft. This can arise, for example, if a trailer is usd1 heavy and/or if it is used to carry a large load. lii these circumstances it may he possible to remove or reduce the load and/or to use some of the other approaches discussed above (e.g. to use a modified tractor). However none of these approaches are ideal. There is therefore a major need fbr an alternative approach to the problem of preventing trailers becoming stuck, or at least o reduce the likelihood thereof.

A further problem is that of soil compaction. Even if a trailer does not become stuck, if it is heavy or is carrying a heavy load then this can still result in significant soil compaction. Soil compaction is also a problem if trailers are run many limes over the same ground, as can occur with modern i ni ensivc farming techniques.

Soil compaction reduces the friability of soil and increases the risk of flooding. Compacted soil is also likely to he less Fertile and can therefore result in reduced yields of certain crops. It can lead to an increased risk of disease because of the poor soil conditions that may result. Although it is possible to plough compacted soil to try to restore soil quality this requires additional labour and therefbre incurs further costs and time. Furthermore if the soil is heavily compacted it may be difficult to plough and/or it may he necessary to]cave it fallow for Sonic time after ploughing.

l'hcre is therefore also a major need to avoid or reduce soil compaction.

The present invention seeks to address or at least to alleviate one or more of' the aforementioned problems. These problems are not trivial, but they are long-standing and no entirely satis1tctory solutions have been provided to date. This is despite the widespread use of trailers in many countries for well over a hundred years.

The present invention takes a radically different approach from the prior art in providing a modified trailer upon which another trailer can be conveniently transported.

According to the present invention there is provided a first trailer suitable fbr use in transpOrtiig a second trailer; the first trailer comprising engaging means for releasably engaging the second trailer and pulling means operably connected to the engaging means for pulling the second trailer onto a platform of the first trailer.

Preferably the pressure that would be exerted on the ground by the first trailer with the second trailer loaded thereon is less than the pressure that would he exerted on the ground by the second trailer alone (prior to loading it onto the first trailer).

l)esirahly this is achieved by providing the first trailer with caterpillar tracks. The pressure exerted by the first trailer with the second trailer mounted thereupon will be the ftrce applied due to the combined weight of the two trailers divided by the ground area that the caterpillar tracks are in contact with. Caterpillar tracks provide a convenient way of allowing the combined weight of the trailers to he distributed over a relatively large area SO thafthe pressure exerted at on the ground is less than the pressure that would have been exerted by the second trailer alone.

Although it is preferred fhr the first trailer to have caterpillar tracks, this is not essential. For example. the first trailer may he provided with more wheels than the second trailer, the wheels may be larger, and/or the wheels may he wider.

Many other alternatives are also possible. Ihus, for example the first trailer may he provided with one or more rollers to allow improved weight distribution and to reduce the pressure applied to the ground. These may extend across the full width of the trailer or across a substantial pid thereof.

The trailer may even be provided with skis or other low friction sliding supports that allow the trailer to be slid over sofi ground.

The precise nature of the ground-contacting parts of the first trailer is not crucial, hut it is desirable that they help in reducing the pressure applied to the ground (relative to the pressure that would be applied by the second trailer alone when not mounted on the first trailer).

JE is not even essential fbr ground contacting parts to be present when the first trailer is in use. In one embodiment of the present invention the first trailer may function as a hovercraft. llius it may have no ground contacting parts. It may he provided with a skirt and one or more fins fbr providing a downwards thrust. ibis embodiment of the present invention is useful for particularly wet ground. it can still be coupled to a tractor or other motor vehicle for steering/providing POWCI etc. hut the load pulled by the tractor can be considerably redLiced.

11 is however preferred that fhr most embodiments that the trailer has one or more rotatably mounted ground-contacting parts, such as caterpillar tracks, that assist in reducing pressure on the ground.

Preferably the platform of the first trailer is movably mounted so that it an he moved from a first position to a second, more downwardly sloping position at which it can serve as a ramp onto which the second trailer can be pulled by the pulling means. This can facilitate the pulling of the first trailer onto the second trailer. Desirably the platform is pivotally rnOWlte(l onto an axle of the trailer. l'he ground-contacting parts of the trailerare desirably mounted upon this axle. The first position is preferably a generally horizontal position, or is at least less inclined than the second position.

Any appropriate means can he used to move/pivot the platform. This may for example he achieved by using a lever. Preferably automated means are used. For example, one or more hydraulic arms may he used.

Conveniently, one hydraulic arm may he located at each side of the trailer, with one end of'cach arni being operably connected to the platform and the other one end being operably connected to a mounting for the axle. When the arms are hydraulically extended they cause pivoting of the platform about the axle so that the front of the trailer rises and the rear lowers towards ground level. An automatic stop may he provided that is actuated once a certain angle of pivot has been reached at which the rear of the platform is at or close to ground level. This can he a useful feature in preventing damage to the rear of the platform.

An alternative is to provide one or more hydraulic arms (or other extendable members) lsewherc on the trailer. For example they may he provided at close to the front of the trailer and function to lift the front of the trailer whilst the platform pivots about the axle so that its rear is lowered to / close to ground level. (Many dumper trucks have hydraulic arms that function in a similar manner).

Less prcfirably, the platform is not pivotally mounted hut is fixed (e.g. in a substantially horizontal position) and a ramp to the plalfbrm is provided. For example, the ramp may be pivolally mounted to the rear of the platform so that it can he dropped or lowered down towards the ground when needed and slowed away when not in use. It may he stowed under the platform and a catch or lock may be provided to hold it in place until needed.

As a further alternative, a separate ramp may he provided and moved into position when needed.

If desired th.e ramp may be releasably secured to the trailer when in use. I icre the trailer may be provided with engaging means to engage the ramp and prevent it from slipping when in use. For example, one or more slots, bolts or catches may be used.

A still further alternative is for the platform to he in a fixed position so that its rear is already close to ground level. It may therefore be fixed at a.n inclined position so that it already acts as a ramp without the need for pivoting. This alternative is however less preferred because ground clearance may be low when the trailer is used for transportation. l'his may cause difficulties if the trailer is used over uneven ground. It is therefore most prefiiTed that the platform is itself pivotally mounted, as aforesaid.

lurning now to the pulling means, any appropriate means for pulling the second trailer onto the first trailer may he used. For example a winch-, ratchet-, pulley-, belt-, piston- or chain-driven system may be used. Whatever system is used, it is prefirabiy automated. it may he provided with its own power source.

N'Iore preferably, however, it is powered by the vehicle to which the first trailer is attached. for example. it may he powered by the hydraulic system and/or by the electrical system of the vehicle.

It may also he controlled by a driver of said vehicle.

Farm vehicles such as tractors are frequently provided with hydraulic systems that are intended to drive a wide range of machinery. Such a hydraulic system can he connected to a trailer of the present invention and used to drive the pulling means of a trailer of the present invention. It can also be used to drive other parts such as the pivoting mechanism described previously.

The caterpillar tracks, wheels or other ground contacting members can he powered, if desired, especially if additional traction is desired. However in most cases this is not necessary.

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As indicated above, the pulling means of the first trailer can he in many different.föniis. However in a preferred embodiment it comprises a cross member. i'he cross member is desirably operably connected to a drive located at each side of the platform. The two drives are prelerably synchronised SO that the cross-member can be smoothly pulled towards the front of the first trailer For example, a chain-driven system may he used whereby a chain is located at each side C)Ithe platform and the crossmember is connected to each chain at an equivalent point along the chain, with the two chains being operated at the same speed.

Preferably the cross member is substantially at right angles to the sides of the first trailer and remains so whilst it is being moved by the chains. This helps in the even distribution of forces liie cross-member is desirably supported by OflC or more rotatable members that run along one oi more tracks. Although this is not essential, it can help in providing a smooth pulling operation. It is also useful in reducing the force on the chains (or other pulling means). [he rotatable riiembcrs may, br example, be wheels, bearings, castors, cogS or rollers. As an alternative to rotatable members, low friction slidable mountings may he used.

The tracks on which the rotatable members run are preferably substantially parallel with the sides of the trailer. i)esirahly they run along a substantial part olthe trailer. For example they may run for a distance that is at least 50%, at least 70%, at least 90%, of the length of the platform. More desirably they run for at least the full length of the platform.

in a preferred embodiment two parallel tracks are provided, with one located to each side of the platform. However there are many other possibilities. For example, a single central track may be provided, or a plurality of tracks may he located at regularly spaced intervals across the platform.

ha plura]ity of tracks is provided it is prelerred that the tracks are arranged symmetrically about a central longitudinal axis running along the length of the trailer. The tracks are preferably formed of a resilient material so as to reduce wear (e.g. they may be formed of a hard metal). They can he in any appropriate form. Thus for example they may he in the form of rails, grooves, channels, etc. It is possible to dispense with tracks and to run the rotatable members directly over the platform of the trailer. however this is less preferred because it can cause wear to the platform, especially if a The cross member desirably includes an engaging means for reicasably engaging the second trailer. The engaging means can he in any appropriate form, as will be determined by the part of the second trailer that it engages. For example, if it engages an eye present at the end of the second trailer then the engaging means may be in the fhrm of a hook, bolt. catch or protruding member that fits into the eye (or vice-versa).

There are of course many other possibilities and all are within the scope of the present invention provided that they allow the first and second trailers to be engaged in a manner so that the second trailer can be pulled onto the first trailer by the pulling means. Preferably the engaging means is a male or female member that engages a complementary member present on the towbar of the second trailer.

A securing means may he provided, if necessary, to prevent accidental disengagement of the engaging means. !his may for example he a locking mechanism (e.g. a pin that fits into a corresponding aperture). It may he a second cross-member that can he positioned over the engagement means or over another part of the towhar of the second trailer, as will he discussed later in further detail. I'he second cross-member may then be in contact with the engaging means or tow bar but this is not essential. Indeed a spacing is preferred.

l)csirahly a stop is provided that prevents the pulling means from pulling the second trailer beyond a given point. This may be electrical or mechanical. For example it may be a switch that switches off power to the pulling means at a certain point. Alternatively it may he a deformahie member, e.g. a pad, cushion, buffer or spring, that cushions impact.

It is preferred that the first trailer comprises a release means for releasing the second trailer from the platform. This may, for example, he operated once the first trailer has been used to transport the second trailer onto a relatively hard surface such as a road or drive. It can he used to release the second trailer and any load that it is carrying to ground level and without damage.

it is possible to provide a separate release means that is not part of the pulling means. For example, a separate ratchet system or other lowering system may be provided to gradually lower the second trailer from the first trailer. However it is preferred. that the release means comprises the pulling means when operated in reverse.

Thus, for example, if the pulling means is chain-driven, when a chain is operated in a given direction ii will pull the second trailer forwards onto the platlbrm trailer and when it is operated in the reverse direction it will move the trailer rearwards so that it can he released. Preferably two or more chains are used and are connected to a cross- member, as discussed previously.

Forward and rearward gears may be provided. Conveniently these are operably connected to the vehicle used to tow the trailer, so that a driver of the vehicle can conveniently change the gears without having to leave the vehicle.

Preferably the platform is pivotally mounted and the release means is designed to he operated once the platibrm has been pivoted to a position at which its rear end is at/close to ground level. The second trailer can then he gradually lowered down the platform under the control of the release means.

If desired, the release means may be provided with a braking system. This may operate automatically if the release means operates beyond a certain speed.

Preferably the release means comprises a stop that causes the release means to stop moving once the second trailer has reached a certain point. This is preferably an automatic stop. Desirably this point is reached once all of the wheels of the second trailer have reached ground level. The first and second trailers can then be conveniently disengaged from one another by unhitching the engaging means.

The first trailer can then be driven off for further use by a tractor or other towing vehicle, lithe platform is pivotally mounted, prior to being driven away it may be pivoted (e.g. by using the hydraulic arms) so as to increase ground clearance. It may be pivoted to a substantially horizontal position. l.lowever this is not essential. It may be pivoted to a lesser degree, or, if there is already sufficient ground clearance, pivoting may not he necessary.

(Indeed, as discussed previously, in some embodiments the platform need not be pivotally mounted.) 11 is only necessary to supply one trailer of the present invention (referred to herein as the "first trailer" for convenience) and this can he used as a shuttle to move many standard trailers ("second trailers") in turn from a first to a second location e.g. from relatively soft ground to harder ground.

A trailer of the present invention can of course he as large or small as desired. This will largely depend upon. the size of the trailer that it is intended to transport.

Preferably a trailer of the present invention is wide enough to transport a trailer that is at least I metre wide (measured across its maximum width). More preferably it is wide enough to transport a trailer that is at least 2 metres wide, or at least 3 metres wide.

in one variant the width of a trailer of the present invention is adjustable.

In some circumstances it may be desirable for the trailer to be relatively wide (e.g. where it is desired to transport wide loads). In other circumstances (e.g. for use on narrow roads, for other areas where it is difficult to manoeuvre, or for storing the trailer) it may he desirable to have a trailer that is relatively narrow.

By providing a trailer with an adjustable width, a single trailer can be used in all of these circumstances.

Various ways of achieving an adjustable width are possible.

One or more parts of the trailer platform may be movable relative to other parts in order to reduce/increase width, as appropriate.

For example, one or more parts of the trailer platform may he arranged SC) that they can be moved over/under/into other parts in order to reduce width, but can then he moved back towards their original position SO as to increase width. (Such arrangements are well.. .k()wi for example in order to increase/reduce the size of adjustable table tops.) Possibilities include telescopic arrangements, concertina arrangements, slidablc arrangements, stowa.hle arrangements. etc. In one embodiment a central part of the platform is kept stationary and side portions are movably mounted so that they can be moved inwards to reduce width or outwards to return to the original width. I-lowevcr other arrangements are possible.

The platform may he mounted upon an axle that is also adjustable in width (e.g. by a telescopic arrangement). This allows the distance between the caterpillar tracks or other supports fOr the platform to he varied, if necessary. in a less preferred embodiment a set of axles of differeni widths may he provided so that one width of axle can be replaced with another when desired. A quick release mounting may be provided to facilitate this, if desired.

in a further embodiment the axle and caterpillar tracks (or other supports) may be mounted underneath the platform and the outer edges of the caterpillar tracks (or other supports) may he positioned at some distance inwards of the outer edges of the platform (when the platform is at its maximum width).

In this embodiment the axle is not the limiting factor, because reducing the width of the platform reduces the width of the trailer from its maximum width. Thus a fixed axle can be used. (It is not necessary to reduce the width of the axle/to replace the axle with a shorter axle in this embodiment.) If a trailer of adjustable width is provided, it is preferred thai. a driver of the vehicle that lows the trailer can adjust the width whilst operating the vehicle. For example a hydraulic system may be operated to increase/reduce the width as desired.

Using such a system, one or more telescopic hydraulic arms may he retracted/expanded so as to decrease/increase the width of the trailer as desired. Preferably at least two such arms are provided. The ends of the arms may be operably connected with the sides of the trailer so as to J. ull the sides inwardly/push them outwardly as desired.

It is preferred that the width of the trailer is adjustable (by whatever means) so that it can be reduced by at least 1 O%, at least 20% or at least 30% from its maximum width. In some embodiments reductions of at least 40%, or at least 50% in width are possible.

Turning 110W to the length of the trailer of the present invention, desirably the platform is long enough to transport a trailer that is at least 2 metres long in total. More preferably ii is long enough to transport a trailer that is at least 5 metres long, or at least 7 metres long.

As with the width, it is possible for the length to he adjustable. For example the trailer may have a portion of its platibrm that can be extended/moved in a length-wise direction so as to accommodate elongate loads if necessary. Thus it may be possible to vary the length by at least 1 0%, at least 20%, at least 30%, at least 40%, or at least 50% in some embodiments if very large trailers are to he transported then the trailer of the present invention can he provided with additional means for distributing weight. For example further, longer or wider caterpillar tracks may be provided. A combination of caterpillar tracks and separate wheels may even he used, although this is less preferred.

As indicated previously it is preferred that the trailer of tile present invention is towed by aiiolher vehicle, e.g. a farm vehicle such as a tractor. Thus the trailer of the present invention desirably has engaging means that allows it to reieasab]y engaged to the vehicle. Any appropriate engaging means can he used, as is well known in tile art. Thus a standard towbar connection for connecting trailers to tractors may be used.

!hc trailer may also be adapted for connection to the electrical and/or hydraulic System of the vehicle. Thus one or more electrical and/or hydraulic connectors may be provided, as is well known in the art of farm machinery.

In addition to the trailer itself, the present invention also includes the combination of the trailer with another trailer supported thereon. Thus the combination of the first and second trailers is covered.

The present invention further comprises the combination of the first trailer (optionally with the second trailer supported thereon) and a motor vehicle to which the first trailer is connected.

The motor vehicle is preferably a farm vehicle and is most preferably atractor. Ihe tractor can be a standard tractor. Alternatively the tractor may be provided with extra large wheels, with caterpillar tracks, or other means for distributing load or improving traction.

In addition to the trailer of the present invention and the combinations discussed above, various methods arc also within the scope of the invention.

l'hus the present invention includes a method whereby a trailer of the present invention is used to pull a second trailer thereupon.

Preferably the method is performed on a farm. Thus farm produce may be loaded onto the second trailer. l)esirahly this is done once the second trailer has been loaded onto the first trailer. it may be done whilst the trailers are being transported by a vehicle, such as a tractor, that is attached to the first trailer. Ilius farm produce may he loaded whilst the trailers are in motion.

For example, a harvester may he run alongside the first trailer with the second trailer thereon and be used to deposit farm produce onto the second trailer. The second trailer may carry one or more containers into which the farm produce is loaded. However this is not essential, especially if the trailer has enclosed sides/ends to prevent produce falling off it.

The harvester may, for example, be a combine harvester. It may include a chute or conveyor that can he positioned over the second trailer or over a container carried by the second trailer so as to deposit farm produce as desired.

Alternatively farm produce may he manually loaded onto the second trailer. For example farm produce may be cut (or otherwise harvested) and placed in crates or other containers along a field.

A tractor pulling the first trailer, With the second trailer loaded thereon may then be slowly run alongside the filled containers SO that they can he conveniently he loaded onto the second trailer by farm workers.

There are different many ways in which a trailer of the present invention can he used. As indicated above it is preferably USCd fbr farming purposes. 1 lowever this is not essenlial. It can be used for any other purpose.

Indeed it is not even limited to transporting trailers. For example, it can be used to rescue a stranded vehicle. A vehicle may become stuck if overloaded, or if used on soft ground. It may simply be broken down. Such a vehicle can he conveniently pulled onto a trailer of the present invention using the pulling means and the trailer with the vehicle loaded thereon can then be towed away to a convenient location, where it can he unloaded.

The present invention is also useful on regions of sand, shale or mud. Tractors and trailers are o.Iten used by fishermen to transport equipment or catches over such areas, hut there is a risk that conventional trailers can become stuck. Thus the present invention provides a useful alternative, whereby a standard trailer containing any desired load can he carried by a trailer of the present invention SO as to reduce pressure on the ground. it is particularly useful in the cockling and shrimping industries. In these industries tractors and trailers are often used at low tide over very soft ground.

A further useful application of the present invention is that of loading / unloading boats. Boats are often carried by trailers hut these can he difficult to manouvre especially over soft ground and may themselves become stuck. A trailer of the present jnvention therefore provides a useful way of transporting boats.

As indicated earlier, a trailer of the present invention is useful in transporting farm animals.

However it may also he used to transport other animals. For example, it can he used to transport race horses on race courses (e.g. to stable or paddock areas). The conditions of race courses can vary significantly and, as indicated earlier, the present invention is particularly useful over soft ground. Similarly the fields in which the horses are normally kept may he on soft ground soft, so that there is again a risk of a conventional horse trailer becoming stuck. A conventional horse trailer can therefore be conveniently transported usin.g a trailer of the present invention.

A still further application of the present invention is in transportation over SflOW or ice.

Conventional trailers may become stuck under such conditions or may he dangerous to use (e.g. because of skidding). A conventional trailer or another load (e.g. a vehicle) can he pulled onto a trailer of the present invention SO as to reduce such risks. This application of the present invention is particularly useful fur extreme conditions, on mountainous ground or in polar/sub-polar regions.

Ildesired snow chains/spikes or other means may be used to provide improved traction conditions. However in most cases caterpillar tracks will he effective.

it will be appreciated from the foregoing analysis that the present invention has an almost infinite number of applications. It can be used for any application where a conventional trailer is used (as well as for many other applications). Conventional trailers can he Lised to transport a wide range of produce, animals, machinery, vehicles etc. Given that such trailers can be conveniently loaded and unloaded onto a trailer of the present invention, a trailer of the present invention can of course be used for the same purposes. The present invention allows another trailer to he transported in "piggy back" fashion and reduces the risks that might otherwise he associated with the conventional trailer being moved over certain ground conditions.

As indicated earlier, the present invention is particularly useful for reducing ground compaction and /or for reducing the risk that a conventional trailer might become stuck.

in a preferred embodiment of the present invention the underside of the platform is shaped SC) that ii can slide over ground when the trailer is moved (after the platlbrm has been pivoted to lower its rear end towards ground level). Thus the platfbrm can act as a sledge to further assist in weight distribution. This is also convenient because it means that the platftrm does not need to he raised whilst it is used over soft ground.

The platform may therefore have a lower surface that is angled relative to the upper surface over at least part of its length. Thus when the platform is pivoted towards ground level the angled lower surlhce moves to a position at which it is adjacent to and in contact with the ground. This aids in reducing pressure by increasing the ground contacting area. Preferably the angled lower surface is substantially smooth. It may he formed of a low friction material or may have a low friction coating if desired. Other alternatives are however possible. For example skis, wheels, rollers or even additional small caterpillar tracks may he present underneath the platform.

It will he appreciated from the foregoing description that many different embodiments of the present jnvention are possible.

In the most preferred embodiment the invention comprises at least a pivotally mounted platform $ one or more chains or drives (desirably one mounted at each side of the platform); and an engaging means that is operably connected to th.e chain(s)/drive(s) to allow a second trailer to he moved on/off the platform.

it is also most preferred that the underside of the trailer is shaped so that it can be slid over soft ground, as described above.

The present invention will now he described by way of example only with reference to the accompanying non-limiting drawings, wherein: Figure 1 is a perspective view ofa trailer of the present invention (referred to herein as the first trailer) when viewed from above and to the right hand side. In this view an engaging means is show in position at the rear olthe trailer ready to engage a towbar of a standard trailer.

Figure 2 is an expanded view of the engaging means that is shown iii Figure 1 and that is circled in said figure.

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Figure 3 is an expanded view of covered part of the first trailer that is circled in ligure 1, hut with the cover removed so as to expose a drive system.

Figure 4 is an expanded view of a part of the first trailer that is circled in Figure 1 showing wheels that run on side rails of the trailer.

Figure 5 shows the trailer that is shown in Figure 1 when the engaging means has been moved to a forward position on the trailer.

Turning now to Figure I, trailer 10 can he seen to comprise an elongate platform Ii, a metal frame 12 and caterpillar tracks 13. The platform 11 is pivotally mounted upon. an. axle (not shown) that is positioned underneath the platform ii and is located between the two sets of caterpillar tracks 13.

The trailer 1 0 also has two hydraulic arms 14; one being provided on each side of the trailer 1 0.

(In the view shown in Figure 1 only the lei hand hydraulic arm is visible, but a right hand hydraulic arm is also present.) Each arm 14 is connected atone end to the frame 12 of the trailer 10 and at the other end to a mounting for the caterpillar tracks 13. In the position shown in Figure 1 the hydraulic arms 14 have already been extended. Extension of the arms 14 causes the platform 11 to pivot about the axle so that the rear 1 5 of the trailer 1 0 pivots to a position that is at or close to ground level. This is the position that is shown in Figure 1. it serves as a useful ramp.

The platform ii can have an angled underside (not shown). It may he therefore he generally wedge or sledge shaped in longitudinal cross section towards its rear. This can he useful whilst its is being used as a ramp. This is not however essential. The platform 11 may, for example, have wheels (not shown) or other supports underneath it, to support it when it is lowered towards ground level. Of course if the iDiatform 1] is strong enough then no supports may he needed.

The trailer 1 0 comprises first and second cross members 1 6 and 1 7. The first CTOSS niember 1 6 carries a generally conical member 1 8. This is shaped to fit into a corresponding aperture present at the end of a towbar of a second trailer (not shown in Figure 1). The conical member 18 can best he seen in l'igure 2 and allows engagement of the first trailer with the second trailer.

The first and second cross members 16 and 17 are operably connected to side chains 19, which are located to each side of the platform 11. With the exception of the connections to the cross members 16 and 1 7, the side chains 1 9 are endless. They are driven hydraulically.

As can be seen from Figure 3, a hydraulic system 20 drives an upper sprocket 21 located at each side of the front of the trailer 10. The upper sprocket 21 is cormected by a small chain 22 to a lower sprocket 23. The lower sprocket 23 drives a shaft upon which a sprocket 24 for the side chain 19 lies. (A further sprocket for the side chain 19 is located towards the rear of the trailer 10 so that the chain can be held under tension between the two side chain sprockets.) Of course for safety reasons the drive system shown in Figure 3 would normally not he exposed when the trailer 1 0 is in use, but would be behind the protective cover 25 that is shown in Figure 1.

As can be seen from Figure 4, the first and second cross members 16 and 17 are supported by wheels 26. The wheels 26 run on rails 27 that are part of the frame 12. The wheels 26 and rails 27 help in directing the cross members 16 and 17 whilst they are being pulled by the side chains 1 9 1 9. They also prevent undue sagging of these chains 19.

Towards the rear of the trailer 1 0 the rails 27 are downwardly angled over a short distance. When the wheels run down this part 28 of the rails the first cross-member 16 pivots relative to the second COSS member 17. This XOSS the conical member 1 8 SC) that it is in a convenient position for engaging the tow bar of the second trailer (see Figure 1 and Figure 2) . The trailers can he engaged manually once the first trailer 1 0 is positioned close to the second trailer, with the conical member 1 8 close to a corresponding aperture provided in the tow bar of the second trailer.

When the first 1 0 and second trailers are so engaged, the side chains 1 9 can he operated in the opposite direction to the direction that was previously used to move the cross members 1 6 and 1 7 to the rear of the first trailer 10. Ihe second trailer is then pulled onto the platform ii. I)uring this operation the wheels 26 that run along the rails 27 run initially up the downwardly angled part of the rails 28. Thus the pivoting action described above for the first cross niember 16 relative to the second cross member 1 7 is reversed.

This causes part of the towbar of the second trailer (which is engaged by the conical member 18) to move underneath the second cross member 17 and into a position that physically prevents the towbar from disengaging the conical member 1 8. l'he second cross member may he in contact with the towbar / conical member 18. However this is not essential, because if there is on]y a small gap present between the towbar / conical member 18 and the bottom of the second cross member 17 this will not allow sufficient room for disengagement.

As the second trailer is pulled further onto the first trailer 10 by the action of the side chains 19, the rail contacting wheels move off the downwardly angled part of the rails 28 and onto the remainder of the rails 29, with the first and second cross-members 16 and 17 cooperating to prevent accidental disengagement of the second trailer from the first trailer 1 0, as described above.

This can be seen in Figure 5, which shows the first and second crossmembers 1 6 and 1 7 when they have most ol the distance to the front of the first trailer 10 and there is only a short distance remaining. An automatic stop prevents the cross-members 16 and 1 7 from damaging the front of the trailer 10. This may, fOr example, he a switch that is triggered when the cross-members 16 and 17 have moved a certain distance and which functions to stop the side chains 19 from moving.

The second trailer will then be in position so that it is fully loaded onto the first trailer 10.

When the second trailer is in this position the hydraulic arms 14 can he retracted, causing the platform 11 of the first trailer 10 to pivot to a generally horizontal position. The first trailer 10 can then he towed away by a tractor with the second trailer loaded on the platform 11.

The second trailer may already have a load upon it (e.g. farm produce or animals) when it is moved onto the first trailer. Alternatively it may he loaded once it has first been moved onto the first trailer 11. As described previously it may he loaded manually or by machine (e.g. by a harvesting machine). It may be loaded when stationary or when being pulled by the tractor.

Both trailers (together with any load) can then he transported to a convenient location at which the second trailer can be unloaded from the first trailer 10. Unloading is achieved by reversing th.e operalion. described above.

Thus, during ui-iloading, the hydraulic arms 14 are extended to pivot the platform 11 so that it slopes downwardly until its rear is at/close to ground level. The side chains 1 9 are then operated in the reverse direction to that used for loading the second trailer. ibis moves the first and second cross members 16 and 17 towards the rear of the first trailer 10, with the second trailer engaged t.o the conical member 18. As the wheels 26 move down onto the angled part of the rails 28, the first and second cross members 16 and 1 7 pivot relative to one another so that the second cross member 17 no longer physically prevents the first 10 and second trailers from being disengaged.

l'he second trailer can then be disengaged from the first trailer uniiitched by lulling its tow bar off the conical member 1 8.

During the operation described above an automatic stop can be provided to prevent the first and second cross members 16 and 17 moving beyond a certain distance when the second trailer is lowered towards ground level. A brake may also be provided and may be set to operate automatically if the side chains 19 operate above a certain speed.

Once the second trailer has been unhitched, the first trailer 10 can be towed away by the tractor to he used to load and unload further trailers. The rear of the platform 11 can be raised again by using the hydraulic arms 14 to pivot the platform ii before driving the tractor of 1 to load further trailers. However it need not he raised completely to a horizontal position. It only need be raised sufficiently to obtain adequate ground clearance. indeed if the platform 11 is not in contact with the ground and there is already sufficient ground clearance to prevent it being damaged when towed by the tractor then it need not he raised at all. In most cases, however, it is likely that the lower end of the platform Ii will be raised after a first trailer has been unloaded, prior to driving the tractor off to load further trailers onto the first trailer 10.

A single first trailer 10 can be used to load and unload many standard trailers over the course of a working day. It can he used over most soil conditions and can significantly reduce ground compaction relative to standard trailers. The trailer 1 0 is particularly effective when used in combination with a tractor that also has caterpillar tracks. 1-lowever it can also he used with tractors having standard wheels, because it is generally the trailer rather then the tractor that is most at risk from becoming stuck in soft ground. The trailer 10 of the present invention significantly reduces this risk.

Ti should he appreciated thai although in the preceding description and example the present Invention has been described with reference to a trailer that can he connected to a tractor or other vehicle, the features of the trailer can he integrated into a motor vehicle. Thus it is not essential to provide a separate towing vehicle and trailer. A motor vehicle including the features of a trailer of the present invention therefore represents a further aspect of the present invention and can he used (hr the same purposes as the trailer r* resent invention. Of course if a unitary vehicle is provided then there is no need to provide it with means for connecting it to a tractor or other towing vehicle.

Claims (43)

1. Claims 1. A first trailer suitable for use in transporting a second

   trailer; the first trailer comprising engaging means for releasably engaging the second trailer and pulling means operably connected to the engaging means fir pulling the second trailer onto a platform of the first trailer.
2. 2. A first trailer according to claim 1; wherein the pressure that would he exerted on the ground by the first trailer with the second trailer loaded thereon is less than the l)SSt11 that would he exerted by the second trailer alone.
3. 3. A first trailer according to claim I or claim 2 that comprises caterpillar tracks or other ground contacting members to improve weight distribution.
4. 4. A first trailer according to any preceding claim; wherein the platform of the first trailer is pivotally mounted so that it can he pivoted from a first position to a second position at which it can serve as a ramp onto which the second trailer can he pulled by the pulling means.
5. 5. A first trailer according to claim 4, wherein the platform can be pivoted by means of one or more hydraulic arms.
6. 6. A first trailer according to claim 5, wherein a hydraulic arm is located at each side of the trailer adjacent to the caterpillar tracks.
7. 7. A first trailer according to any of claims I to 6, wherein the pulling means is chain operated.
8. 8. A first trailer according to claim 7; wherein the pulling means comprises a cross member that interconnects first and second chains; wherein the cross member comprises the engaging means and can he moved towards the front of the first trailer when chains are operated so as to pull the second trailer onto the platform.
9. 9. A first trailer according to any preceding claim that comprises a retaining means that prevents the engaging means becoming accidentally disengaged when the trailer is in use.
10. 1 0. A trailer according to claim 9, wherein the retaining means is a further cross member to the cross member described in claim 8 and is arranged so that it can be moved over the engaging means and/or over a tow bar of the second trailer into a position preventing accidental disengagement.
11. 11. A first trailer according to any preceding claim comprising a stop that prevents the puilmg means pulling the second trailer beyond a given point.
12. 1 2. A first trailer according to any preceding claim comprising a release means br releasing

    I

    the second trailer from the platform once it has been transported to a desired location.
13. 13. A first trailer according to claim 12, wherein the release means is provided by the pulling means when operated in reverse.
14. 14. A first trailer according to claim 12 or claim 13, comprising a stop that prevents the release means from moving the second trailer beyond a certain point.
15. 15. A first trailer according to any preceding claim that can he used for transporting a second trailer that is at least one metre wide.
16. 16. A. first trailer according to any preceding claim that can he used for transporting a second trailer that is at least two metres long.
17. 17. A first trailer according to any preceding claim that has an engaging means for engaging it to a vehicle so that it can he towed by the vehicle.
18. 1 8. A first trailer according to claim 1 7 that is arranged to be connected to the hydraulic and/or electrical system of the vehicle.
19. 1 9. A first trailer according to claim 1 8; wherein the vehicle is a tractor.
20. 20. A first trailer according to any preceding claim; wherein at least part of the underside of the platborm is shaped so that it can slide over soft ground when the platform has been pivoted to contact the ground.
21. 21. A first trailer according to any preceding claim; wherein the underside of the platform is provided with one or more skis, wheels, rollers or other supporting members.
22. 22. A first trailer according to any preceding claim, wherein the trailer is arranged so that its width can he adjusted.
23. 23. A first trailer according to claim 22, wherein the trailer is arranged so that its width can he reduced by at least 1 0% from its maximum width.
24. 24. A combination of a first trailer according to any preceding claim with a second trailer supported Upon the first trailer.
25. 25. A combination comprising a first trailer according to any preceding claim, with a second trailer optionally mounted thereon, wherein the first trailer is operably linked to a vehicle.
26. 26. .A combination according to claim 25, wherein the vehicle is a tractor.
27. 27. A method comprising using a first trailer as described in any of claims 1 to 23 to pull a second trailer thereupon.
28. 28. A method according to claim 26 firther comprising loading.firrn produce onto the second trailer.
29. 29. A method according to claim 27, wherein fiirm produce is loaded onto the second trailer whilst the second trailer is on the first trailer.
30. 30. A method according to claim 29, wherein farm produce is loaded onto the second trailer whilst the second trailer is being transported by a tractor that is attached to the first trailer.
31. 31. A method according to any of claims 28 to 30, wherein the farm produce is loaded into th.e second trailer by a harvesting machine.
32. 32. A method according to claim 31, wherein the harvesting machine is a combine harvester.
33. 33. A method according to claim 31 or claim 32, wherein the harvesting machine is run alongside the second trailer.
34. 34. A method according to any of claims 28 to 30, wherein farm produce is manual]y loaded onto the second trailer.
35. 35. A method according to any of claims 27 to 34 that is performed on soft ground.
36. 36. The use of a trailer according to ally ol claims I to 23 to transport a vehicle.
37. 37. l'he use of a trailer according to any of claims I to 23 to transport a trailer containing one or more animals.
38. 38. I'he use of a trailer according to any of claims Ito 23 to transport flshing equipment, a catch of fish, or other seafood.
39. 39. The use of a, trailer according tO any of claims I to 23 to transport a boat.
40. 40. The use of a trailer according to any of claims I to 23 in firming.
41. 41. The use of a trailer according to any of claims I to 23 in harvesting.
42. 42. A motor vehicle having the features of a trailer according to any of claims I Ic) 23 integrated into tile vehicle.
43. 43. l'he present invention substantially as hereinbefbre described, with reference to the accompanying drawings.