Trailer comprising a level varying system

Abstract

In the field of trailers in which the level of a loading surface relative to ground level can be varied, a trailer (1) is provided in which this functionality is performed on the basis of varying the location of a wheel assembly (31) in the trailer (1), without a need for any other action aimed at lowering or lifting the loading surface (11). Advantageously, the wheel assembly (31) is displaceable in various directions including the direction of travel (T) of the trailer (1). By relying on displacement of the wheel assembly (31) for varying the level of the loading surface (11), a gradual and controlled vertical movement of the loading surface (11) is realized, wherein support by the wheel assembly (31) of a loading arrangement (10) of which the loading surface (11) is part is varied between full support and reduced support.

Description

[0001] Trailer comprising a level varying system

[0002] The invention relates to a trailer comprising:

[0003] - a loading arrangement having a loading surface configured to support one or more items as may be loaded on the trailer;

[0004] - a connection arrangement configured to connect the trailer to a vehicle;

[0005] - a wheel arrangement configured to support the loading arrangement on the ground at least in a drive status of the trailer, comprising at least one wheel assembly including a holder and a wheel rotatably arranged in the holder; and

[0006] - a level varying system configured to realize variation of a level of the loading surface relative to ground level in a range of levels delimited by a maximum level associated with the drive status of the trailer and a minimum level associated with a load status of the trailer.

[0007] The invention is in the field of trailers, particularly trailers in which the level of a loading surface relative to ground level can be varied.

[0008] It is generally known that a trailer is used to transport load, and that a trailer is intended to be connected to a vehicle so that the trailer can be towed by the vehicle. For the purpose of supporting the load, the trailer comprises a loading arrangement having a loading surface. In basic types of trailer, a level of the loading surface relative to ground level is fixed. In more sophisticated types of trailer, a level of the loading surface relative to ground level is variable, so that the loading surface can be lowered to enable easy loading / unloading of cargo, and can be lifted so as to have sufficient clearance during travel.

[0009] CA 2635066 A1 discloses a trailer comprising a platform supported by a hitch assembly and at least one wheel assembly. The hitch assembly is for rigid attachment to a vehicle. A vertical guide mechanism connects the platform to the hitch assembly. The vertical guide assembly includes a first vertical guide element capable of moving parallel to a second vertical guide element. The first vertical guide element is mounted to the platform and the second vertical guide element is mounted to the hitch assembly. A lifting mechanism is integrated with the vertical guide mechanism for raising and lowering the platform. When the platform is raised and lowered to the ground, the platform remains substantially parallel with the ground.

[0010] The wheel assembly of the trailer known from CA 2635066 A1 includes a block mount for mounting the wheel assembly. The wheel assembly further includes a block pivotably connected to the block mount by a first axle journaled in a first side of the block. A wheel is pivotably connected to a bottom of the block by a second axle journaled in the bottom of the block. When pivoting the block around the first axle, the wheel assembly can vertically collapse or extend. The wheel assembly is fully extended in a travel state of the trailer. During a platform lowering process, the wheel assembly collapses until it is horizontal with the ground.

[0011] GB 882502 A discloses a semi-trailer having a frame fitted with a forward coupling beam and legs provided with road wheels. The coupling beam and the road wheel legs are pivotally connected to the frame so that when the semi-trailer is uncoupled, the coupling beam and the wheel legs are in raised positions and the trailer frame rests on the ground. Further, the coupling beam and the wheel legs are operatively connected with a hydraulic jack on the trailer so that, when the beam is coupled and locked to a towing vehicle and the jack is operated, the beam and the wheel legs are lowered simultaneously to raise the trailer frame off the ground. The jack-operated mechanism and the coupling beam and wheel legs enable the frame to be raised and lowered parallel to the ground.

[0012] GB 2183559 A discloses a trailer comprising a base member, a tow bar pivoted to the base member, a wheel unit also pivoted to the base member at a point rearward of the tow bar pivot point, and hydraulic lift means for pivoting the wheel unit to raise or lower the base member.

[0013] It is an objective of the invention to provide a new design of a trailer in which the level of a loading surface relative to ground level can be varied, particularly to provide such a type of trailer that is compact, robust and reliable, and easy to handle by a user.

[0014] The invention provides a trailer as defined in the opening paragraph, namely, a trailer comprising - a loading arrangement having a loading surface configured to support one or more items as may be loaded on the trailer;

[0015] - a connection arrangement configured to connect the trailer to a vehicle;

[0016] - a wheel arrangement configured to support the loading arrangement on the ground at least in a drive status of the trailer, comprising at least one wheel assembly including a holder and a wheel rotatably arranged in the holder; and

[0017] - a level varying system configured to realize variation of a level of the loading surface relative to ground level in a range of levels delimited by a maximum level associated with the drive status of the trailer and a minimum level associated with a load status of the trailer; wherein:

[0018] - the connection arrangement is configured to allow free positioning of the loading surface relative to the vehicle in height direction, over the full range of levels of the loading surface relative to ground level;

[0019] - the wheel assembly is displaceable relative to the loading arrangement so as to enable variation of a location of the wheel assembly in the trailer; and

[0020] - the level varying system is configured to perform the functionality of realizing variation of the level of the loading surface relative to ground level through varying a location of the wheel assembly between a location at which the wheel assembly supports the loading arrangement on the ground with the loading surface at the maximum level and a location at which the wheel assembly enables the loading surface to be at the minimum level.

[0021] It follows from the above definition of the trailer according to the invention that the wheel assembly is displaceable relative to the loading arrangement, which means that the location of the wheel assembly in the trailer is variable, and which implies that placement of the wheel assembly relative to the loading arrangement is variable. In a practical embodiment of the trailer, the wheel assembly is displaceable relative to the loading arrangement by the holder of the wheel assembly being slidable relative to the loading arrangement. The displaceable arrangement of the wheel assembly is different from what is the case with known trailers, in which the wheel assemblies are pivoted relative to the loading arrangement without being moved to another location. In the case of the invention, it is possible to let the wheel assembly perform both a function of determining the level of the loading surface relative to ground level and a function of supporting the loading arrangement on the ground all the time during a process of lowering the loading surface, until the minimum level of the loading surface is reached.

[0022] In a practical embodiment, the trailer according to the invention comprises a guiding arrangement configured to guide displacement of the wheel assembly relative to the loading arrangement, which guiding arrangement is optionally integrated with the loading arrangement. The guiding arrangement can be designed in any suitable way. For example, it is possible that the guiding arrangement is configured to realize a guiding track of the wheel assembly including a first portion defining a displacement direction of the wheel assembly which is a horizontal direction relative to the ground. In such a case, it is a feasible option that the guiding track of the wheel assembly further includes a second portion defining a displacement direction of the wheel assembly which is a vertical or near-vertical direction relative to the ground, and an intermediate portion gradually defining transition displacement directions between the horizontal displacement direction and the vertical or nearvertical displacement direction. Further, it is advantageous if the displacement direction defined by the first portion of the guiding track coincides with the direction of travel of the trailer.

[0023] A practical position of the second portion and the intermediate portion of the guiding track of the wheel assembly is a position at a back side of the trailer, i.e. a side which is at a distance from a front side of the trailer as seen in the direction of travel of the trailer, wherein the front side is defined as the side where the coupling arrangement is present. In that case, starting from a situation in which the load surface is at the maximum level, lowering the loading surface is realized by moving the wheel assembly backwards in the direction of travel of the trailer and eventually upwards. A process of lifting the loading surface is then realizing by a reverse displacement of the wheel assembly, i.e. a downward displacement followed by a forward displacement in the direction of travel of the trailer. The invention covers an embodiment of the trailer in which the concept of varying the location of the wheel assembly in the trailer is further used to advantage in a situation in which one or more items are present on the trailer and the trailer is connected to a vehicle and in the drive status, namely, for the purpose of influencing a connection force exerted by the trailer on the vehicle at the position of the connection arrangement. In the field of trailers, this connection force is commonly referred to as nose weight. The connection force is related to the distribution of weight of the one or more items over the trailer, and therefore varies with the type of the items and the positioning of the items on the loading surface. In particular, the trailer may comprise a system configured to be activated in the situation as mentioned, and to determine the connection force through setting a location of the wheel assembly in the trailer. It is advantageous if the process of setting the location of the wheel assembly in the trailer is aimed at minimizing the connection force. The system may be of an electronic nature and may include a sensor arrangement for detecting forces acting at the position of the loading arrangement and / or the connection arrangement. In general, it is possible that the trailer is equipped with an electronic controller such as a microprocessor for controlling operation of at least the level varying system. In that case, assuming that the above-mentioned system for determining the connection force is present in the trailer, indeed, the controller may also be used for controlling operation of that system. The controller may comprise any type of user interface such as a touchscreen and / or may be configured to enable remote control of the trailer, such as by means of an app installed on a mobile phone.

[0024] It is practical if the loading arrangement comprises a load supporting structure and the loading surface of the loading arrangement is constituted by a top surface of the load supporting structure. In this respect, it is possible that the level varying system functions to have the wheel assembly located underneath the load supporting structure in the drive status of the trailer, and to let the wheel assembly be at least partially away from underneath the load supporting structure in the load status of the trailer. According to an advantageous yet non-essential option, the minimum level of the load surface is a level at which the load supporting structure rests on the ground. The load supporting structure may be a platform structure, for example. The level varying system can be designed in any suitable way. According to one feasible option, the level varying system comprises an actuator arranged to act on the wheel assembly for bringing about displacement of the wheel assembly. The invention covers any suitable type of actuator, and the actuator can be driven in any suitable way, such as by hand, hydraulically or electrically. For example, the actuator comprises at least one combination of a pulling cable connected to the holder of the wheel assembly, and a winch, or at least one combination of a piston and a cylinder, a spindle and a nut, or a rack and a pinion. Depending on the nature of the actuator, it may be advantageous to have one or more additional components in the trailer for locking the wheel assembly in place.

[0025] The trailer according to the invention is primarily intended for use with vehicles which are normally used as personal vehicles. Examples of loads to be placed on the trailer are one or more bicycles, a wheelchair and a mobility scooter. The loading surface can be adapted in any suitable way to enable secure and safe placement of the loads, and can be of any suitable shape and size. In one feasible example, the loading surface is provided with gutter-like wheel-receiving components, which can either be fixedly arranged or removably arranged so as to enable attachment and detachment of the components according to desire. For the purpose of enabling the wheel of the wheel assembly to smoothly follow all movements of a towing vehicle and to provide a user with an easy way of moving the trailer by hand when the trailer is not coupled to a vehicle, it is advantageous if the holder of the wheel assembly is configured to enable swivel movement of the wheel about a swivel axis.

[0026] In view of many possible applications of the trailer according to the invention, it is advantageous if the connection arrangement is configured to maintain a horizontal orientation of the loading surface relative to the ground. For example, the connection arrangement comprises a frame which is configured to be fixedly coupled to the vehicle and at least one pair of parallel rods, wherein each of the rods is pivotably coupled to the load arrangement at one end thereof and pivotably coupled to the frame at the other end thereof. Good lateral stability is obtained when the connection arrangement comprises two pairs of parallel rods, arranged at a distance from each other in a direction transverse to the direction of travel of the trailer.

[0027] Generally speaking, good lateral stability is obtained when the connection arrangement is configured to connect the trailer to a vehicle over more than a single small area, such as at least two areas at a distance from each other as is the case with the two pairs of parallel rods, or a single area covering a significant part of a dimension of the trailer in the transverse direction.

[0028] In a case that the connection arrangement comprises a frame, indeed, the frame can be used as a support of one or more components of the level varying system, such as the actuator mentioned earlier.

[0029] The invention will now be explained in greater detail with reference to the drawings, in which equal or similar parts are indicated by the same reference signs, and in which:

[0030] Figure 1 diagrammatically shows a perspective view of a trailer according to an embodiment of the invention, and illustrates how the trailer is connected to a vehicle; Figures 2 and 3 diagrammatically show a perspective view of the trailer and the back of a vehicle to which the trailer is connected, with the trailer in a drive status and a load status, respectively;

[0031] Figure 4 diagrammatically shows a side view of the trailer according to another embodiment of the invention and the back of a vehicle to which the trailer is connected, with the trailer in the load status;

[0032] Figure 5 illustrates a situation in which the trailer is moved over a bump in the ground; Figures 6 and 7 illustrate use of the trailer for supporting two bicycles;

[0033] Figure 8 illustrates use of the trailer for supporting a mobility scooter; and Figure 9 illustrates use of the trailer for supporting a cargo box.

[0034] The invention relates to a trailer which is intended to be connected to a towing vehicle, at the back of the vehicle, and which is thereby useful to transport load at a position behind the vehicle. Figures 1-3 show an embodiment of the trailer 1 according to the invention, wherein it is noted that this embodiment is just one of numerous embodiments which are feasible in the context of the invention. Apart from the trailer 1 , figure 1 further shows a towbar 2 of a vehicle 3 and an additional connection element 4, and figures 2 and 3 show a back of the vehicle 3.

[0035] With reference to figures 1-3, it is noted that the trailer 1 comprises a loading arrangement 10, a connection arrangement 20 and a wheel arrangement 30.

[0036] The loading arrangement 10 has a loading surface 11 configured to support one or more items as may be loaded on the trailer 1 , as will be explained later with reference to figures 6-9. In the present example, the loading arrangement 10 comprises a load supporting structure 12 including a pair of beams 13, and the loading surface 11 is constituted by a top surface of the beams 13.

[0037] The connection arrangement 20 is configured to connect the trailer 1 to the vehicle 3. In the present example, the connection arrangement 20 comprises a first standing frame 21 which is configured to be fixedly connected to the vehicle 3, a second standing frame 22 fixedly connected to front ends of the pair of beams 13 of the load supporting structure 12, and two pairs of parallel rods 23 extending between the frames 21 , 22 at opposite sides of the frames 21 , 22. Each of the rods 23 is pivotably coupled to the first frame 21 at one end thereof and pivotably coupled to the second frame 22, and thereby to the loading arrangement 10, at the other end thereof. As indicated in figure 1 , the first frame 21 is intended to be arranged on the towbar 2 of the vehicle 3, and also on the additional connection element 4 which is to be connected to the towbar 2. The use of an additional connection element 4 is not essential, but is beneficial to lateral stability of the trailer 1 during travel at the position behind the vehicle 3, given the fact that it extends in the transverse direction. Generally speaking, the connection to the vehicle 3 can be realized through other constructions, wherein use may be made of an existing structure of the back of the vehicle 3, with or without further adaption such as by adding a component.

[0038] A primary function of the wheel arrangement 30 is enabling a drive status of the trailer 1 , i.e. a status of the trailer 1 in which the trailer 1 is capable of moving over the ground on the basis of rolling contact of the wheel arrangement 30 to the ground, as illustrated in figures 1 and 2. In the present embodiment of the trailer, the wheel arrangement 30 comprises a single wheel assembly 31 including a holder 32 and a wheel 33 rotatably arranged in the holder 32. As indicated by means of arrows in figure 2, the holder 32 is configured to enable swivel movement of the wheel 33 about a vertical swivel axis As.

[0039] A further function of the wheel arrangement 30 is controlling processes of lowering and lifting the loading surface 11 and thereby varying a status of the trailer 1 between a drive status and a load status. Lowering the loading surface 11 is useful in situations in which one or more items are to be placed on the loading surface 11 or to be removed from the loading surface 11 . Lifting the loading surface 11 is useful in situations in which the trailer 10 is to be moved and is done for the purpose of having sufficient clearance underneath the load supporting structure 12 in such situations. In the present example, the wheel assembly 31 is slidably arranged on the pair of beams 13 of the load supporting structure 12, wherein sides of the beams 13 facing each other are open and the wheel assembly 31 is movable relative to the beams 13 by means of rollers 34 coupled to the wheel assembly 31 and positioned inside the beams 13. The beams 13 constitute a guiding arrangement 40 of the trailer 1 , particularly a guiding arrangement 40 defining a guiding track with a horizontal first portion 41 , a vertical second portion 42, and a curved intermediate portion 43 as a transition between the first portion 41 and the second portion 42.

[0040] Starting from a location of the wheel assembly 31 as shown in figure 2, i.e. a location at which the wheel assembly 31 is present underneath the load supporting structure 12 and at the first portion 41 of the guiding track, the loading surface 11 is lowered by displacing the wheel assembly 31 backwards in the direction of travel T of the trailer 1 and subsequently moving the wheel assembly 31 upwards. In the process, the wheel assembly 31 passes from the first portion 41 to the intermediate portion 43 of the guiding track, and from the intermediate portion 43 to the second portion 42 of the guiding track, until the end of the second portion 42 is reached. In the process, gradual lowering of the loading surface 11 is realized, which lowering takes place in a fashion that is very well controlled due to the supporting function of the wheel assembly 31 , which is only terminated when the wheel assembly 31 reaches the second portion 42 of the guiding track. The resulting configuration of the trailer 1 is shown in figure 3. Putting the trailer 1 from the load status back to the drive status is done by means of a reversed process in which the wheel assembly 31 moves back along the guiding track, wherein the wheel assembly 31 is lowered from the second portion 42 of the guiding track, moved through the intermediate portion 43 of the guiding track towards the first portion 41 of the guiding track and forwards through the first portion 41 until the wheel assembly 31 reaches an appropriate final location. In the process, the loading surface 11 is automatically lifted to a maximum level. The trailer 1 may comprise any suitable type of locking mechanism (not shown) for locking the wheel assembly 31 at the final location.

[0041] When it comes to moving the wheel assembly 31 from one location in the trailer 1 to another, various possibilities are available. Generally speaking, the trailer 1 comprises a level varying system 50 which is configured to perform the functionality of realizing variation of the level of the loading surface 11 relative to ground level through varying a location of the wheel assembly 31 between a location at which the wheel assembly 31 supports the loading arrangement 10 on the ground 5 with the loading surface 11 at the maximum level and a location at which the wheel assembly 31 enables the loading surface 11 to be at the minimum level. In the present example, said level varying system 50 comprises a combination of a pulling cable 51 connected to the holder 32 of the wheel assembly 31 , and a winch 52, as shown in figures 1-3. The winch 52 can be of the hand-driven type, as shown, or of the motor-driven type. Further, in the present example, the winch 52 is located on the first frame 21 of the connection arrangement 20. The shown combination of the pulling cable 51 and the winch 52 is useful to pull the wheel assembly 31 from the location associated with the load status of the trailer 1 to the location associated with the drive status of the trailer 1 . Additional and / or other actuators may be applied as well, such as an actuator for moving the wheel assembly 31 from the location associated with the drive status of the trailer 1 to the location associated with the load status of the trailer 1 . In general, it is possible that an electronic controller is present in the trailer 1 for enabling operation of the one or more components of the level varying system 50 in automated or semi-automated fashion on the basis of input of a user. An additional advantage of the possibility to move the wheel assembly 31 from one location in the trailer 1 to another is that this opens up another possibility, namely, a possibility to choose a location of the wheel assembly 31 in the drive status of the trailer 1 which is optimal in view of the center of gravity of cargo on the trailer 1 and the pressure exerted on the vehicle 3 by means of the connection arrangement 20. According to an interesting option, the trailer 1 is equipped with a system which is adapted to set the location of the wheel assembly 31 such that the pressure exerted on the vehicle 3 is minimized. An additional advantage of the possibility to move the wheel assembly 31 from underneath the load supporting structure 12 is that a compact configuration of the trailer 1 is obtained which enables easy storage of the trailer 1 when the trailer 1 is not in use.

[0042] In figures 4-9, an embodiment of the trailer 1 according to the invention is shown in which the first frame 21 of the connection arrangement 20 is lower than in the embodiment shown in figures 1-3. Figure 4 illustrates the fact that it is possible to realize the load status of the trailer 1 with the load supporting structure 12 resting on the ground 5 when the wheel assembly 31 is located at the second portion 42 of the guiding track. In this configuration, the loading surface 11 is at a minimum level which makes it very easy to place one or more items on the loading surface 11 , wherein items which are equipped with wheels can simply be driven from a position on the ground 5 at a side from the trailer 1 on to a position on the loading surface 11 .

[0043] Figure 5 serves to illustrate a specific function of the connection arrangement 20, namely, a function to maintain a horizontal orientation of the loading surface 11 relative to the ground 5. Figure 5 provides an illustration of the fact that the parallel rods 23 of the connection arrangement 20 account for unevenness in the ground 5 during travel. Due to the parallel arrangement of the rods 23, the frames 21 , 22 of the connection arrangement 20 are kept in a parallel positioning relative to each other. Hence, what happens when the wheel 33 of the wheel assembly 31 encounters a bump is that as the trailer 1 is pushed upwards by the bump, the rods 23 dictate a vertical movement of the second frame 22 of the connection arrangement 20, as indicated by arrows in figure 5, and thereby a horizontal orientation of the loading surface 11. Avoiding continual movement of the load on uneven ground 5 (uneven roads) in this way may be beneficial to many types of load and significantly reduces a risk that the load can get damaged or even fall off the trailer 1 .

[0044] The trailer 1 is suitable for use with many possible types of cargo. Figures 6 and 7 illustrate use of the trailer 1 for supporting load 60 in the form of two bicycles, figure 8 illustrates use of the trailer 1 for supporting load 60 in the form of a mobility scooter, and figure 9 illustrates use of the trailer 1 for supporting load 60 in the form of a cargo box. Figures 6-8 show the practical option of having gutter-like wheel-receiving components 14 on the loading surface 11 , which are useful to hold the bicycles and the mobility scooter, respectively, on the trailer 1. Further, straps or other appropriate components may be used to secure the bicycles and the mobility scooter to the trailer 1 . Use of the trailer 1 for various purposes is possible when the gutter-like wheel-receiving components 14 are removable from the loading surface 11 . Also, a possibility to remove the gutter-like wheel-receiving components 14 from the loading surface 11 may be helpful in a situation of storing the trailer 1 when the trailer 1 is not in use. In any case, as an advantageous result of the fact that the loading surface 11 can be lowered and lifted, it is not necessary to lift cargo for the purpose of placing it on the loading surface 11 . Instead, cargo can be placed on the loading surface 11 simply by rolling or sliding it on the loading surface 11 from a position on the ground 5, without a need for an additional ramp element or the like. For one thing, this is helpful in view of the fact that bicycles tend to get heavier and heavier, especially electric bicycles, and that in many countries, the group of elderly people who wish to transport their bicycles, mobility scooters or other means of transport from their own home by means of their own car is growing.

[0045] It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. It is intended that the invention be construed as including all such amendments and modifications insofar they come within the scope of the claims or the equivalents thereof. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The invention is not limited to the disclosed embodiments. The figures are schematic, wherein details which are not required for understanding the invention may have been omitted, and not necessarily to scale.

[0046] Notable aspects of the invention as described in the foregoing are generally defined as follows. In the field of trailers in which the level of a loading surface relative to ground level can be varied, a trailer 1 is provided in which this functionality is performed on the basis of varying the location of at least one wheel assembly 31 in the trailer 1 , without a need for any other action aimed at lowering or lifting the loading surface 11. Advantageously, the wheel assembly 31 is displaceable in various directions including the direction of travel T of the trailer 1. By relying on displacement of the wheel assembly 31 for varying the level of the loading surface 11 , a gradual and controlled vertical movement of the loading surface 11 is realized, wherein support by the wheel assembly 31 of a loading arrangement 10 of which the loading surface 11 is part is varied between full support and reduced support, wherein the latter can even be no support when a minimum level of the loading surface 11 is a level at which the loading arrangement 10 is supported on the ground 5. Further, it is possible to account for the fact that different loads 60 involve different distributions of weight over the trailer 1 , namely, by setting an appropriate location of the wheel assembly 31 in the trailer 1 , wherein a connection force exerted on a vehicle 3 by the trailer 1 can be minimized.

Claims

CLAIMS1. Trailer (1), comprising:- a loading arrangement (10) having a loading surface (11 ) configured to support one or more items (60) as may be loaded on the trailer (1);- a connection arrangement (20) configured to connect the trailer (1) to a vehicle (3);- a wheel arrangement (30) configured to support the loading arrangement (10) on the ground (5) at least in a drive status of the trailer (1), comprising at least one wheel assembly (31) including a holder (32) and a wheel (33) rotatably arranged in the holder (32); and- a level varying system (50) configured to realize variation of a level of the loading surface (11) relative to ground level in a range of levels delimited by a maximum level associated with the drive status of the trailer (1) and a minimum level associated with a load status of the trailer (1); wherein:- the connection arrangement (20) is configured to allow free positioning of the loading surface (11) relative to the vehicle (3) in height direction, over the full range of levels of the loading surface (11) relative to ground level;- the wheel assembly (31) is displaceable relative to the loading arrangement (10) so as to enable variation of a location of the wheel assembly (31 ) in the trailer (1 ); and- the level varying system (50) is configured to perform the functionality of realizing variation of the level of the loading surface (11) relative to ground level through varying a location of the wheel assembly (31) between a location at which the wheel assembly (31) supports the loading arrangement (10) on the ground (5) with the loading surface (11) at the maximum level and a location at which the wheel assembly (31 ) enables the loading surface (11 ) to be at the minimum level.

2. Trailer (1) as claimed in claim 1 , wherein the wheel assembly (31) is displaceable relative to the loading arrangement (10) by the holder (32) of the wheel assembly (31) being slidable relative to the loading arrangement (10).

3. Trailer (1) as claimed in claim 1 or 2, comprising a guiding arrangement (40) configured to guide displacement of the wheel assembly (31) relative to the loading arrangement (10).

4. Trailer (1) as claimed in claim 3, wherein the guiding arrangement (40) is integrated with the loading arrangement (10).

5. Trailer (1) as claimed in claim 3 or 4, wherein the guiding arrangement (40) is configured to realize a guiding track of the wheel assembly including a first portion (41) defining a displacement direction of the wheel assembly (31) which is a horizontal direction relative to the ground (5).

6. Trailer (1) as claimed in claim 5, wherein the guiding track of the wheel assembly (31) further includes a second portion (42) defining a displacement direction of the wheel assembly (31) which is a vertical or near-vertical direction relative to the ground (5), and an intermediate portion (43) gradually defining transition displacement directions between the horizontal displacement direction and the vertical or near-vertical displacement direction.

7. Trailer (1) as claimed in claim 5 or 6, wherein the displacement direction defined by the first portion (41) of the guiding track (40) coincides with the direction of travel (T) of the trailer (1).

8. T railer (1 ) as claimed in any of claims 1 -7, comprising an electronic controller configured to control operation of at least the level varying system (50).

9. Trailer (1) as claimed in any of claims 1-8, comprising a system configured to be activated when one or more items (60) are present on the trailer (1) and the trailer (1) is connected to a vehicle (3) and in the drive status, and to determine a connection force exerted by the trailer (1) on the vehicle (3) at the position of theconnection arrangement (20) through setting a location of the wheel assembly (31) in the trailer (1).

10. Trailer (1) as claimed in any of claims 1-9, wherein the loading arrangement (10) comprises a load supporting structure (12), and wherein a top surface of the load supporting structure (12) constitutes the loading surface (11) of the loading arrangement (10).

11. Trailer (1) as claimed in claim 10, wherein the wheel assembly (31) is located underneath the load supporting structure (12) in the drive status of the trailer (1), and wherein the wheel assembly (31) is at least partially away from underneath the load supporting structure (12) in the load status of the trailer (1).

12. Trailer (1) as claimed in claim 10 or 11 , wherein the minimum level of the load surface (11) is a level at which the load supporting structure (12) rests on the ground (5).

13. Trailer (1) as claimed in any of claims 1-12, wherein the level varying system (50) comprises an actuator arranged to act on the wheel assembly (31) for bringing about displacement of the wheel assembly (31 ).

14. Trailer (1) as claimed in claim 13, wherein the actuator comprises at least one combination of a pulling cable (51) connected to the holder (32) of the wheel assembly (31), and a winch (52).

15. Trailer (1) as claimed in claim 13 or 14, wherein the actuator comprises at least one combination of a piston and a cylinder, a spindle and a nut, or a rack and a pinion.

16. Trailer (1) as claimed in any of claims 1-15, wherein the holder (32) of the wheel assembly (31) is configured to enable swivel movement of the wheel (33) about a swivel axis (As).

17. Trailer (1) as claimed in any of claims 1-16, wherein the connection arrangement (20) is configured to maintain a horizontal orientation of the loading surface (11) relative to the ground (5).

18. Trailer (1) as claimed in claim 17, wherein the connection arrangement (20) comprises a frame (21) which is configured to be fixedly coupled to the vehicle (3) and at least one pair of parallel rods (23), and wherein each of the rods (23) is pivotably coupled to the load arrangement (10) at one end thereof and pivotably coupled to the frame (21) at the other end thereof.

19. Trailer (1) as claimed in claim 18, wherein the connection arrangement (20) comprises two pairs of parallel rods (23), arranged at a distance from each other in a direction transverse to the direction of travel (T) of the trailer (1 ).

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