WO2018006122A1

WO2018006122A1 - A trailer assembly

Info

Publication number: WO2018006122A1
Application number: PCT/AU2017/050689
Authority: WO
Inventors: Robert Hugh Bowman TAPLEY
Original assignee: Rhb Tapley Pty Ltd
Priority date: 2016-07-04
Filing date: 2017-07-03
Publication date: 2018-01-11
Also published as: AU2017293650A1; AU2017293650B2

Abstract

Provided is a trailer assembly (10) comprising a carriage (12) for operatively supporting a load (14), with two wheel mountings (16) each configured to support at least one wheel (18) for supporting the carriage (12), in use. Each wheel mounting (16) is arranged on opposite sides of the carriage (12) and includes a linkage (20) which is configured so that the mountings (16) are displaceable from and towards each other. In this manner, the wheels (18) are displaceable from the carriage (12) which is, in turn, lowerable or raiseable to facilitate loading thereof.

Description

A TRAILER ASSEMBLY

TECHNICAL FIELD

[0001] This invention relates to trailers for moving a load, in general, and specifically to a trailer assembly.

BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] In the known art, a number of trailers have been developed for the transporting of loads, such as boats, motorbikes, cars, etc. from one location to another. Where a boat is transported by trailer, the process of removing a boat from the water typically involves reversing the trailer down a shallow ramp into the water until the boat supporting members, typically in the form of a cradle, are immersed and the boat is guided over these supporting members by means of rollers and a winch. The boat is then secured in place and the trailer towed onto dry land, carrying the boat along with it. To launch the boat, the process is simply reversed.

[0004] Depending on the size of the boat, such an operation generally requires at least two or more people to perform safely. The conventional loading of other loads, such as a car onto a trailer, also often benefits from or even requires having more than one person involved. For this reason, a number of different trailer designs have been made over the years in an attempt to facilitate the loading of loads onto a trailer.

[0005] For example, US9,050,920 relates to improvements in a lowerable trailer that uses pneumatic cushions to provide both the cushioning of the trailer bed and raising and lower of the trailer bed to facilitate loading. It is mentioned that the lowerable trailer is ideal for the transportation of custom vehicles to and from an auto show where the custom vehicles may have limited ground clearance. The air in the pneumatic cushions can be vented to allow the bed of the trailer to lay flat on the ground. Another pneumatic cushion changes the angle of the bed to the tongue to ensure that both the front and the back of the bed come in contact with the ground. The pneumatic cushions can be filled with a standard hand pneumatic hand pump or with an air compressor that can be powered by a car battery or an electrical outlet.

[0006] Another example is given in US8,651,510 which describes a trailer including: i) a draw bar; ii) a trailer frame supporting a trailer bed; iii) an arm including a first pivot mount; iv) an axle pivotally connected to the arm at the first pivot mount; v) an actuating mechanism actuatable to exert a force on the arm relative to the trailer frame. The axle includes at least one associated wheel and the wheel has a plane of rotation in which the wheel rotates when traveling in a forward direction, and the actuating mechanism is located substantially in the plane of rotation. The trailer bed may be raised or lowered by exerting a force on the arm relative to the trailer frame. [0007] A further example in US6,857,643 is an elevating trailer for moving between a low, cargo-loading position and an elevated, cargo-transporting position. The frame of the trailer has opposing sides, each side carrying a pair of tandem wheels. An inflatable air bag is mounted on a supporting and pivotal frame above the trailer side. When the bags are inflated the arms of the supporting frames are spread apart, lifting the frame. When the bags are deflated, the arms pivot toward each other, lowering the frame and facilitating loading of cargo into a container mounted on the trailer frame.

[0008] Similarly, US5,810,544 describes a trailer having a load-bearing platform moveable between a ground-level loading position and a horizontal travel position supported on a U- shaped support frame, and having its wheels mounted on stub axles rather than a common axle. The stub axles are cantilevered on the support frame with suspension arms to keep the wheels in proper alignment with the support frame. The load-bearing platform is raised and lowered by a pivoting lever member, hinged at its rear end to the rear end of the platform, together with a block and tackle system which controls the lever member and raises and lowers the front end of the load platform.

[0009] A further example is US4,114,772 describing a trailer for loading, transporting and launching pontoon boats. A movable framework on the trailer bed is provided which can be lowered for loading the boat on land, elevated for transporting, and again lowered for launching a pontoon boat . [0010] The prior art solutions have shortcomings in that they only generally relate to raising or lowering of a loading bed of the trailer, which inherently limits the types of loads that can be carried, particularly boats. The present invention seeks to propose possible improvements, at least in part, in amelioration of the known shortcomings in the art.

SUMMARY OF THE INVENTION

[0011] According to a first aspect of the invention there is provided a trailer assembly comprising:

a carriage for operatively supporting a load;

two wheel mountings each configured to support at least one wheel for supporting said carriage, in use, said wheel mountings arranged on opposite sides of the carriage and including a linkage configured so that said mountings are displaceable from and towards each other;

a wheel mounting displacer configured to operatively displace said wheel mountings; and

a carriage actuating device configured to operatively lower or raise the carriage with respect to the wheels, wherein the wheels are displaceable from the carriage which is, in turn, lowerable or raiseable to facilitate loading thereof .

[0012] In one example, the carriage may comprise a framework configured to receive a particular type of load.

[0013] Typically, the carriage may be configured with a plurality of cradle members on which a boat is receivable, when in use. [0014] In one example, the carriage may comprise a platform for supporting a load.

[0015] Typically, the wheel mounting linkage may comprise a parallelogram linkage.

[0016] Typically, the parallelogram linkage may be configured such that, when the respective wheel mountings are displaced, the wheels on opposite sides of the carriage remain parallel to each other so that the trailer assembly remains easily towable.

[0017] Typically, the linkage may be rotatably cantilevered to the carriage at a proximal end of the linkage, with the at least one wheel arranged towards a distal end of said linkage.

[0018] In one example, the carriage is slidably mounted with respect to the wheels to allow dynamic balancing of the carriage when supporting a load.

[0019] In one example, the wheel mounting may include a slidable channel member arranged about at least a portion of the linkage, said channel member configured to support the at least one wheel so that the at least one wheel is slidable along the portion of the linkage to accommodate dynamic balancing of the carriage when supporting a load.

[0020] Typically, the channel member is configured to support two wheels. [0021] Typically, the linkage is configured to be displaceable in a plane of a load-supporting surface of the carriage .

[0022] Typically, the wheel mounting displacer may comprise a linear actuator, such as a hydraulic or pneumatic cylinder .

[0023] In one example, the wheel mounting displacer may include a hydraulic or pneumatic cylinder arranged between diagonally opposite ends of the parallelogram linkage.

[0024] In another example, the wheel mounting displacer may comprise an electromechanical actuator.

[0025] In one example, the wheel mounting displacer may be configured to displace the respective wheel mountings on opposite sides of the carriage from or towards each other by their respective cylinders respectively extending or contracting between diagonally opposite ends of the parallelogram linkages.

[0026] In one example, the carriage actuating device may comprise a linear actuator levered to the cantilevered linkage where such linkage is rotatably connected to the carriage, so that extension or contraction of the linear actuator rotates said linkage relative to the carriage.

[0027] Typically, the carriage actuating device may comprise a hydraulic or pneumatic cylinder. [0028] Typically, the carriage actuating device may comprise a shock-absorbing member for shock absorption between the wheels, via the rotatably cantilevered wheel mountings, and the carriage.

[0029] Typically, the shock-absorbing member may comprise a spring arranged coaxially about the linear actuator of the carriage actuating device.

[0030] In another example, the shock-absorbing member comprises a leaf spring arrangement between the wheels and the carriage.

[0031] In one example, the trailer assembly may comprise a hitch mechanism configured to hitch the carriage to a towing vehicle .

[0032] Typically, the hitch mechanism may comprise a hitch linkage configured to enable the carriage to be lowered or raised substantially in parallel with a surface on which the wheels rest .

[0033] Typically, the hitch linkage may comprise a parallelogram linkage.

[0034] In one example, the hitch mechanism may comprise a linear actuator, such as a hydraulic or pneumatic cylinder, configured to facilitate lowering and raising of the carriage . [0035] Preferably, the trailer assembly may include a fluid reservoir and pump configured to supply the hydraulic or pneumatic actuators.

[0036] Typically, the trailer assembly may include a remotely operable controller configured to control the linear actuators for controlling displacement of the wheel mountings and actuation of the carriage.

[0037] Typically, the trailer assembly may include a controller configured to slide the carriage with respect to the wheels to automatically balance the carriage when supporting a load.

[0038] In one example, the controller includes an inclinometer to allow automatic leveling of the carriage when supporting a load.

[0039] In a further example, the controller includes a water level sensor, said controller configured to sense a relative distance between the carriage and a water level in order to facilitate with raising and/or lowering the carriage relative to a desired water level for loading and/or unloading of a boat onto or from said carriage.

[0040] Typically, the controller is configured to automatically maintain the carriage at a predetermined level relative to a sensed water level.

[0041] According to a second aspect of the invention there is provided a method for loading a load onto a trailer assembly, said method comprising the steps of: providing a trailer assembly in accordance with the first aspect of the invention;

displacing the wheel mountings away from each other;

actuating the carriage to lower said carriage with respect to the wheels;

loading or unloading a load onto or from, respectively, the carriage;

actuating the carriage to raise said carriage with respect to the wheels; and

displacing the wheel mountings towards each other.

[0042] In one example, the steps of displacing the wheel mountings may comprise extending or contracting linear actuators arranged between diagonally opposite ends of each parallelogram linkage, so that the respective linkages are displaced in a plane of a load-supporting surface of the carriage so that the wheels on opposite sides of the carriage remain substantially in parallel.

[0043] In one example, the steps of actuating the carriage may comprise actuating the carriage actuating device which comprises a linear actuator levered to each respective cantilevered linkage where such linkage is rotatably connected to the carriage, so that extension or contraction of the linear actuator rotates said linkage relative to the carriage to lower or raise the carriage with respect to the wheels .

[0044] In one example, the method may include hitching the trailer assembly to a towing vehicle by means of a hitch mechanism . [0045] Typically, the steps of actuating the carriage actuating device may comprise extending or contracting a linear actuator within a parallelogram hitch linkage to enable the carriage to be lowered or raised substantially in parallel with a surface on which the wheels rest.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will be made with reference to the accompanying drawings in which:

Figure 1 is a side-view diagrammatic representation of an example of a trailer assembly, in accordance with an aspect of the invention, showing a carriage thereof in a raised position;

Figure 2 is a side-view diagrammatic representation of the trailer assembly of Figure 1, showing a carriage thereof in a lowered position;

Figure 3 is top-view diagrammatic representation of a wheel mounting of the trailer assembly of Figure 1, with said wheel mounting proximate the carriage;

Figure 4 is a top-view diagrammatic representation of the wheel mounting of Figure 3, with said wheel mounting displaced from the carriage;

Figure 5 is a top-view diagrammatic representation of the trailer assembly of Figure 1, showing the respective wheel mountings displaced toward each other; and Figure 6 is a top-view diagrammatic representation of the trailer assembly of Figure 1, showing the respective wheel mountings displaced from each other.

DETAILED DESCRIPTION OF EMBODIMENTS

[ 0046 ] In the figures, incorporated to illustrate features of an example embodiment or embodiments, like reference numerals are used to identify like parts. The following modes, given by way of example only, are described in order to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments.

[ 0047 ] Referring now to the accompanying drawings, there is shown one example of a trailer assembly 10. This example of a trailer assembly 10 comprises a carriage 12 for operatively supporting a load 14, with at least two wheel mountings 16 each configured to support at least one wheel 18 for supporting the carriage 12, in use.

[ 0048 ] As shown, each wheel mounting 16 is arranged on opposite sides of the carriage 12, and includes a linkage 20 which is configured so that the mountings 16 are displaceable from and towards each other. In particular, by the wheel mountings 16 being mounted on opposite sides of the carriage 12, they are also displaceable away from, or towards, the carriage 12 itself.

[ 0049 ] This arrangement is shown clearly in Figures 5 and 6. The wheel mountings 16 in Figure 5 are displaced towards each other and lie in close proximity to the carriage 12. However, Figure 6 shows the wheel mountings 16 displaced away from each other and, hence, the carriage 12.

[0050] The exemplified embodiment of the trailer assembly 10 further includes some manner of wheel mounting displacer 22 which is configured to operatively displace a wheel mounting 16. In the current example, each wheel mounting includes a wheel mounting displacer, as described in more detail below.

[0051] The trailer assembly 10 also includes a carriage actuating device 24 which is configured to operatively lower or raise the carriage 12 with respect to the wheels 18. The action of the carriage actuating device 24 is clearly shown in Figure 1 and 2. In Figure 1, the carriage actuating device 24 has the carriage 12 in a raised position, whereas Figure 2 shows the carriage actuating device 24 such that the carriage 12 is in a lowered position relative to the wheels 18.

[0052] In this manner, the wheels 18 are displaceable from the carriage 12 which is, in turn, lowerable or raiseable to facilitate loading thereof. The trailer assembly 10 accordingly enables easier loading of loads 14 onto the carriage 12, where the wheels 18 can be moved away from the carriage 12 and the carriage 12 lowered.

[0053] In one example, the carriage 12 comprises a framework which is configured to receive a particular type of load. For example, for general goods, the framework may comprise a cage-like structure for carrying general purpose loads. In another example, the carriage 12 may be configured with a plurality of cradle members (not shown) on which a boat is receivable, when in use. In a yet further example, the carriage 12 may comprise a specific platform for supporting a load 14, or the like. The current example shows the load as a boat 14.

[ 0054 ] Typically, each of the wheel mountings 16 comprises a parallelogram linkage 26, as shown, and also called a four- bar linkage. The parallelogram linkage 26 is generally configured such that, when the respective wheel mountings 16 are displaced, the wheels 18 on opposite sides of the carriage 12 remain in parallel, which allows the trailer assembly 10 to remain towable. It is to be appreciated that other types of linkages are possible, however.

[ 0055 ] The linkage 20 is typically rotatably cantilevered to the carriage 12 at a cantilever point 33 at a proximal end of the linkage 28. Similarly, the at least one wheel 18 is then arranged towards a distal end 30 of the linkage 20.

[ 0056 ] In a further example, the wheel mounting 16 may include a slidable channel member (not shown) which is arranged about at least a portion of the linkage 20. In such an example, the channel member is generally configured to support the at least one wheel 18 so that the at least one wheel 18 is slidable along the portion of the linkage 20 to accommodate dynamic balancing of the carriage 12 when supporting a load. Typically, the linkage 20 is configured to be displaceable in a plane of a load-supporting surface of the carriage 12.

[ 0057 ] In one example, the channel member is configured to support two wheels. It is to be appreciated that this type of arrangement can accommodate multiple wheels on each wheel mounting 16, which finds particular application where large loads are to be transported.

[ 0058 ] The wheel mounting displacer 22 generally comprises a linear actuator 32, such as a hydraulic or pneumatic cylinder. In another example, the wheel mounting displacer 22 may comprise an electromechanical actuator, or the like. In the current example, the wheel mounting displacer 22 includes a hydraulic or pneumatic cylinder 32 arranged between diagonally opposite ends of the parallelogram linkage 26, as shown. In this manner, extension of the cylinder 32 displaces the wheel mounting 16 away from the carriage 12.

[ 0059 ] Accordingly, the wheel mounting displacer 22 is typically configured to displace the respective wheel mountings 16 on opposite sides of the carriage 12 from or towards each other by their respective cylinders 32 respectively extending or contracting between diagonally opposite ends of the respective parallelogram linkages 26.

[ 0060 ] Similarly, the carriage actuating device 24 generally comprises a linear actuator levered to the cantilevered linkage 20 at the cantilever point 33 where such linkage 20 is rotatably connected to the carriage 12. In this manner, extension or contraction of the linear actuator 32 of the carriage actuating device 24 rotates the linkage 20 relative to the carriage 12. As above, the carriage actuating device 24 typically comprises a hydraulic or pneumatic cylinder 32, however other linear actuators are possible as well . [0061] In addition, in the current example, the carriage actuating device 24 includes a shock-absorbing member 36 for shock absorption between the wheels 18, via the rotatably cantilevered wheel mountings 16, and the carriage 12. The shock-absorbing member 36 generally comprises a spring arranged coaxially about the linear actuator 32 of the carriage actuating device 24, as shown, but suitable leaf springs or the like can also be used.

[0062] In this example, the trailer assembly 10 also comprises a hitch mechanism 38 which is configured to hitch the carriage 12 to a towing vehicle (not shown) . The hitch mechanism 38 comprises a hitch linkage which is configured to enable the carriage 12 to be lowered or raised substantially in parallel with a surface on which the wheels 18 rest. Accordingly, the hitch linkage 38 typically comprises a parallelogram linkage, however other arrangements are possible and within the scope of the present disclosure.

[0063] In the current example, the hitch mechanism 38 includes a linear actuator 32, typically a hydraulic or pneumatic cylinder, which is configured to facilitate lowering and raising of the carriage 12.

[0064] In addition, the trailer assembly 10 also includes a fluid reservoir and pump 40 which are configured to supply the respective hydraulic or pneumatic actuators 32.

[0065] The current example of the trailer assembly 10 also includes a remotely operable controller 42 which is configured to control the linear actuators 32 for controlling displacement of the wheel mountings 16 and actuation of the carriage 12, as described above. In this manner, a single person is able to manage loading of a load onto the carriage 12, such as loading and unloading a boat, or the like.

[ 0066 ] As mentioned above, one example sees the carriage 12 slidably mounted with respect to the wheels 18 to allow dynamic balancing of the carriage 12 when supporting a load. Accordingly, the controller 42 may be configured to slide the carriage 12 with respect to the wheels 18 to automatically balance the carriage 12 when supporting a load 14. Similarly, the controller 42 may include an inclinometer or similar levelling sensor to allow automatic levelling of the carriage 12 when supporting a load.

[ 0067 ] In a further example, the controller 42 includes a water level sensor (not expressly shown, but incorporated as part of the controller) . Such a water level sensor can be mounted on any suitable part of the trailer assembly 10, such as the carriage 12, the wheels 18, etc. The controller 42 is then configured to sense a relative distance between the carriage and a water level in order to facilitate with raising and/or lowering the carriage 12 relative to a desired water level for loading and/or unloading of a boat onto or from said carriage 12. Typically, the controller 42 is configured to automatically maintain the carriage 12 at a predetermined level relative to a sensed water level.

[ 0068 ] For example, such water level sensing and automatic maintenance of the carriage height with respect to the sensed water level find particular application in loading a boat onto the carriage 12. By maintaining the carriage 12 relative to a sensed water level generally allows a boat to be guided onto suitable cradle members without unnecessarily hitting other parts of the trailer assembly 10 or coming to rest skew on the cradle members .

[0069] The present invention provides for an associated method for loading a load 14 onto the trailer assembly 10. Such a method generally comprises the steps of providing the trailer assembly 10, displacing the wheel mountings 16 away from each other, actuating the carriage 12 to lower the carriage with respect to the wheels 18, loading or unloading a load 14 onto or from, respectively, the carriage 12, actuating the carriage 12 to raise the carriage with respect to the wheels 18, and displacing the wheel mountings 16 towards each other.

[0070] The steps of displacing the wheel mountings 16 typically comprises extending or contracting the linear actuators 32 arranged between diagonally opposite ends of each parallelogram linkage 26, so that the respective linkages 20 are displaced in a plane of a load-supporting surface of the carriage 12 so that the wheels 18 on opposite sides of the carriage 12 remain substantially in parallel.

[0071] The steps of actuating the carriage 12 typically comprise actuating the carriage actuating device 24 which comprises a linear actuator 32 levered to each respective cantilevered linkage 20 at the cantilever point 33 where such linkage 20 is rotatably connected to the carriage 12, so that extension or contraction of the linear actuator 32 rotates the linkage 20 relative to the carriage 12 to lower or raise the carriage 12 with respect to the wheels 18. [ 0072 ] The method also generally includes the step of hitching the trailer assembly 10 to a towing vehicle by means of the hitch mechanism 38.

[ 0073 ] The steps of actuating the carriage actuating device 24 generally comprises extending or contracting a linear actuator 32 within the parallelogram hitch linkage 38 to enable the carriage 12 to be lowered or raised substantially in parallel with a surface on which the wheels 18 rest.

[ 0074 ] Applicant believes it particularly advantageous that the present invention provides for a trailer assembly 10 that has wheel mountings 16 that is displaceable from the carriage 12 which is, in turn, lowerable and raiseable to facilitate loading and unloading of loads. In particular, the trailer assembly 10 finds particular application in loading and unloading of recreational watercraft, such as a boat. The displacement of the wheel mountings accommodate a slope of a boat's hull during loading and unloading, with displacement of the wheel mountings keeping the wheels parallel, so that the trailer assembly remains towable. This is particularly useful when the trailer assembly is driven into water to unload or load a boat, as the wheels can be displaced and driven into the water, before the carriage is raised or lowered .

[ 0075 ] Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. In the example embodiments, well- known processes, well-known device structures, and well known technologies are not described in detail, as such will be readily understood by the skilled addressee.

[0076] The use of the terms "a", "an", "said", "the", and/or similar referents in the context of describing various embodiments (especially in the context of the claimed subject matter) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open- ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. No language in the specification should be construed as indicating any non-claimed subject matter as essential to the practice of the claimed subject matter .

[0077] It is to be appreciated that reference to "one example" or "an example" of the invention, or similar exemplary language (e.g., "such as") herein, is not made in an exclusive sense. Various substantially and specifically practical and useful exemplary embodiments of the claimed subject matter are described herein, textually and/or graphically, for carrying out the claimed subject matter. [0078] Accordingly, one example may exemplify certain aspects of the invention, whilst other aspects are exemplified in a different example. These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention in any way unless the context clearly indicates otherwise. Variations (e.g. modifications and/or enhancements) of one or more embodiments described herein might become apparent to those of ordinary skill in the art upon reading this application. The inventor (s) expects skilled artisans to employ such variations as appropriate, and the inventor (s) intends for the claimed subject matter to be practiced other than as specifically described herein.

[0079] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

Claims

1. A trailer assembly comprising:

a carriage for operatively supporting a load;

2. The trailer assembly of claim 1, wherein the carriage comprises a framework configured to receive a particular type of load.

3. The trailer assembly of claim 2, wherein the framework comprises a plurality of cradle members on which a boat is receivable, when in use.

4. The trailer assembly of any of claims 1 to 3, wherein the carriage comprises a platform for supporting a load.

5. The trailer assembly of claim 1, wherein the wheel mounting linkage comprises a parallelogram linkage.

6. The trailer assembly of claim 5, wherein the parallelogram linkage is configured such that, when the respective wheel mountings are displaced, the wheels on opposite sides of the carriage remain parallel to each other so that the trailer assembly remains towable.

7. The trailer assembly of any of claims 1 to 6, wherein the linkage is rotatably cantilevered to the carriage at a proximal end of the linkage, with the at least one wheel arranged towards a distal end of said linkage.

8. The trailer assembly of any of claims 1 to 7, wherein the carriage is slidably mounted with respect to the wheels to allow dynamic balancing of the carriage when supporting a load .

9. The trailer assembly of claim 8, wherein the wheel mounting includes a slidable channel member arranged about at least a portion of the linkage, said channel member configured to support the at least one wheel so that the at least one wheel is slidable along the portion of the linkage to accommodate dynamic balancing of the carriage when supporting a load.

10. The trailer assembly of claim 1, wherein the channel member is configured to support two wheels.

11. The trailer assembly of claim 1, wherein the linkage is configured to be displaceable in a plane of a load-supporting surface of the carriage.

12. The trailer assembly of claim 1, wherein the wheel mounting displacer comprises a linear actuator.

13. The trailer assembly of claim 1, wherein the wheel mounting displacer comprises an electromechanical actuator.

14. The trailer assembly of either of claims 5 or 6, wherein the wheel mounting displacer includes a hydraulic or pneumatic cylinder or electromechanical actuator arranged between diagonally opposite ends of the parallelogram linkage .

15. The trailer assembly of claim 14, wherein the wheel mounting displacer is configured to displace the respective wheel mountings on opposite sides of the carriage from or towards each other by their respective cylinders or actuators respectively extending or contracting between diagonally opposite ends of the parallelogram linkages.

16. The trailer assembly of claim 7, wherein the carriage actuating device comprises a linear actuator levered to the cantilevered linkage where such linkage is rotatably connected to the carriage, so that extension or contraction of the linear actuator rotates said linkage relative to the carriage .

17. The trailer assembly of claim 1, wherein the carriage actuating device comprises a hydraulic or pneumatic cylinder.

18. The trailer assembly of claim 16, wherein the carriage actuating device comprise a shock-absorbing member for shock absorption between the wheels, via the rotatably cantilevered wheel mountings, and the carriage.

19. The trailer assembly of claim 18, wherein the shock- absorbing member comprises a spring arranged coaxially about the linear actuator of the carriage actuating device.

20. The trailer assembly of claim 18, wherein the shock- absorbing member comprises a leaf spring arrangement between the wheels and the carriage.

21. The trailer assembly of claim 1, wherein the trailer assembly comprises a hitch mechanism configured to hitch the carriage to a towing vehicle.

22. The trailer assembly of claim 21, wherein the hitch mechanism comprises a hitch linkage configured to enable the carriage to be lowered or raised substantially in parallel with a surface on which the wheels rest.

23. The trailer assembly of claim 22, wherein the hitch linkage comprises a parallelogram linkage.

24. The trailer assembly of claim 23, wherein the hitch mechanism comprises a linear actuator configured to facilitate lowering and raising of the carriage.

25. The trailer assembly of claim 1, wherein the trailer assembly includes a fluid reservoir and pump configured to supply hydraulic or pneumatic actuators.

26. The trailer assembly of claim 1, wherein the trailer assembly includes a remotely operable controller configured to control linear actuators for controlling displacement of the wheel mountings and actuation of the carriage.

27. The trailer assembly of claim 8, wherein the trailer assembly includes a controller configured to slide the carriage with respect to the wheels via suitable linear actuators to automatically balance the carriage when supporting a load.

28. The trailer assembly of claim 27, wherein the controller includes an inclinometer to allow automatic leveling of the carriage when supporting a load.

29. The trailer assembly of claim 26, wherein the controller includes a water level sensor, said controller configured to sense a relative distance between the carriage and a water level in order to facilitate with raising and/or lowering the carriage relative to a desired water level for loading and/or unloading of a boat onto or from said carriage.

30. The trailer assembly of claim 29, wherein the controller is configured to automatically maintain the carriage at a predetermined level relative to a sensed water level.

31. A method for loading a load onto a trailer assembly, said method comprising the steps of:

providing a trailer assembly in accordance with any of claims 1 to 30;

displacing the wheel mountings away from each other; actuating the carriage to lower said carriage with respect to the wheels;

loading or unloading a load onto or from, respectively, the carriage; actuating the carriage to raise said carriage with respect to the wheels; and

displacing the wheel mountings towards each other.

32. The method of claim 31, wherein the steps of displacing the wheel mountings comprise extending or contracting linear actuators arranged between diagonally opposite ends of each parallelogram linkage, so that the respective linkages are displaced in a plane of a load-supporting surface of the carriage so that the wheels on opposite sides of the carriage remain substantially in parallel so that the trailer assembly remains towable.

33. The method of claim 31, wherein the steps of actuating the carriage comprise actuating the carriage actuating device which comprises a linear actuator levered to each respective cantilevered linkage where such linkage is rotatably connected to the carriage, so that extension or contraction of the linear actuator rotates said linkage relative to the carriage to lower or raise the carriage with respect to the wheels .

34. The method of claim 31, which includes hitching the trailer assembly to a towing vehicle by means of a hitch mechanism .

35. The method of claim 31, wherein the steps of actuating the carriage actuating device comprises extending or contracting a linear actuator within a parallelogram hitch linkage to enable the carriage to be lowered or raised substantially in parallel with a surface on which the wheels rest .