WO2004062993A2

WO2004062993A2 - Single wheel trailer

Info

Publication number: WO2004062993A2
Application number: PCT/US2004/000286
Authority: WO
Inventors: Richard W. Miccoy; Jason R. Moldthan; Katherine A. Adams; John J. Kass
Original assignee: Cequent Towing Products Inc
Priority date: 2003-01-09
Filing date: 2004-01-08
Publication date: 2004-07-29
Also published as: WO2004062993A3; TW200500235A

Abstract

A trailer having a single ground-engaging wheel (22) includes a frame (20) having a load-supporting section (28) oriented between the ground-engaging wheel and the frame section (32) that is mounted to a towing vehicle. The load-supporting section defines a substantially horizontal plane substantially bisecting a centerpoint of the ground-engaging wheel. The frame (80) is mounted to the towing vehicle at fixed attachment points defined by cooperating receivers (104, 106) carried on the vehicle. The ground-engaging wheel is adapted to swivel around a substantially vertical axis.

Description

SINGLE WHEEL TRAILER

This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/438,868, filed January 9, 2003.

Technical Field

The present invention relates generally to the trailer towing field and, more particularly, to an improved trailer design having a single ground-contacting wheel.

Background of the Invention

Single- wheel trailers for towing behind a towing vehicle have long been known in the art. Single-wheel trailers are advantageous due to their lower weight, lesser cost, and smaller "footprint" in comparison to conventional multi-wheel trailers. Accordingly, the cargo-carrying capacity of smaller vehicles, such as small automobiles, motorcycles, and bicycles, may be significantly enhanced using single-wheel trailers. Examples of single- wheel trailers include those described in U.S. Patent Nos.6,042,138 to Shreck, 4,645,230 to Hammons, and 4,078,821 to Kitterman. Numerous other designs of single-wheel trailers, particularly for towing behind a bicycle or motorcycle, are also known in the art.

These single- wheel trailers are effective for their intended purpose. However, improvements are possible. Specifically, it is standard practice to design single wheel trailers for attachment to a towing vehicle via a conventional method, such as a ball and socket- type hitch, such as is shown in the ' 138 patent to Shreck. Accordingly, the connection between towing vehicle and trailer may pivot. This is particularly problematic in the situation where the operator desires to back the trailer up. A certain level of skill is required to accurately back a trailer, particularly a small, lightweight trailer attached to a vehicle with a ball and socket hitch, to prevent jack-knifing.

Existing single-wheel trailers also typically orient the load bearing portion above the midpoint of the ground-engaging wheel, thereby raising the center of gravity of the loaded trailer well above the wheel. This undesirably exacerbates the tendency of a lightweight trailer, which engages the ground at only a single point, rather than two or more points (wheels), to bounce or "buck" when operated over rough or uneven road surfaces. The risk of unbalancing the trailer and/or overturning the load is therefore increased.

There is accordingly a need in the art for a single-wheel trailer that tracks in a manner allowing ease of operation when backing. There is also a need for a single-wheel trailer with a lower center of gravity for increased stability when cornering and when traversing rough surfaces.

Summary of the Invention

In accordance with the need identified in the art as described above, the present invention provides a trailer for towing behind a vehicle, comprising a frame having a first section to which is mounted a single ground-engaging wheel, a second, load-supporting section defined by a pair of spaced-apart posts, and a third section distal to the first section for removably securing the frame to the vehicle. The load- supporting section is oriented between the ground-engaging wheel and the mounting section, and defines a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, wherein the second plane substantially bisects a centerpoint of the wheel. It will be appreciated that this feature lowers the center of gravity of a load placed on the trailer, thereby reducing undesirable "bucking" or bouncing during operation, which is a common phenomenon experienced by other, similar trailers having a small footprint and light weight.

The first frame section is typically closed, whereas the third frame section may be open. The third frame section is also adapted for removably mounting to fixed attachment points defined by a pair of cooperating receivers carried on the vehicle. Each post ends in a bracket carrying a pivoting bar adapted for removably mounting to a fixed attachment point defined by a pair of cooperating receivers carried on the vehicle.

The cooperating receivers on the vehicle may be any suitable means for removably securing the third frame section to the vehicle. As noted above, it is preferred to provide a fixed attachment point for the trailer, defined by a pair of cooperating receivers carried on the vehicle. The receivers carried on the vehicle may form either the male or the female portion of the completed assembly. Most desirably, the attachment system will be an embodiment of the Dual Port System (DPS) manufactured by Cequent Towing Products, Inc., which comprises a pair of accessory ports or receivers providing a relative orientation of the accessory ports or receivers which maximizes the ease of accessory alignment and mounting to the user. The cooperating receivers may form the female portion of the assembly, such as the accessory ports of the DPS systems manufactured by Cequent and described in detail in issued U.S. Patent No. 6,428,031 , in U.S. Patent Application Serial Nos. 10/332,869, 10/182,096, 10/182,105, and 10/415,062, and in PCT Patent Application Nos. PCT/US01/29012 and PCT/US01/10633, all incorporated herein in their entirety by reference. Still further, the cooperating receivers may comprise the male portion of the assembly, such as the DPS accessory receivers described in detail in U.S. Patent Application Serial Nos. 10/332,869 and 10/287,163, and in PCT Patent Application Nos. PCT/US01/29012, PCT/US03/30832, and PCT US01/30796, also incorporated in their entirety herein by reference. The ground-engaging wheel may be mounted to the first section in a manner allowing the ground-engaging wheel to swivel around a substantially vertical axis. This may be accomplished by a caster-type mechanism, typically being a swivelling assembly comprising a mounting plate including a central aperture for receiving a kingpin and a wheel-supporting bracket. The wheel-supporting bracket includes a top flange, a kingpin extending from a first surface of the top flange and rotatably received in the mounting plate central aperture, at least one first strut depending from an opposite surface of the top flange, and a second strut pivotally secured at one end to a distal end of the first strut and at the opposite end to an axle supporting the ground engaging wheel. A bearing is interposed between the top flange and the mounting plate, to allow the ground-engaging wheel to swivel around a substantially vertical axis. The ground-engaging wheel may also travel a predetermined distance along the substantially vertical axis. Typically, at least one shock dampener will be mounted at a first end to the wheel supporting bracket and at a second end to the wheel axle, thereby allowing the wheel to travel along the vertical axis and absorb the shock of road irregularities.

In another aspect, the present invention provides a trailer for towing behind a vehicle, the trailer comprising a frame having a closed end to which is mounted a single ground-engaging wheel, an open end defined by distal ends of a pair of spaced-apart frame posts, and an intermediate, load-supporting section defined by the pair of spaced- apart posts. The load-supporting section defines a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centerpoint of the wheel. The post distal ends are adapted for removably mounting to fixed attachment points defined by a pair of cooperating receivers carried on the vehicle. The ground-engaging wheel is secured to the closed end of the frame whereby the ground- engaging wheel swivels around a vertical axis, and may travel a predetermined distance along the vertical axis to cushion shock as described above. A shock dampener may also be provided as described above.

In yet another aspect, the present invention provides a trailer for towing behind a vehicle, comprising a frame, a single ground-engaging wheel, a swivelling assembly for attaching the wheel to the frame, and means for mounting the frame to the vehicle. The frame is characterized by having a load-supporting section oriented between the ground-engaging wheel and the mounting means, and defining a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, wherein the second plane substantially bisects a centerpoint of the wheel. The mounting means comprise a bracket carrying a pivoting bar attached to an end of the spaced-apart posts, the pivoting bar being adapted to be removably received by cooperating receivers carried by the vehicle.

In still yet another aspect of the present invention, a trailer and receiver attachment assembly are provided, comprising a trailer having a frame, a single swivelling ground-engaging wheel, and a pair of posts at an end of the frame opposite the ground-engaging wheel. The posts are adapted for releasably securing the trailer to the receiver attachment assembly. The receiver attachment comprises a pair of cooperating accessory receivers for releasably securing the trailer. As described above, the frame includes a load-supporting section which is oriented between the ground-engaging wheel and the frame end opposite the ground-engaging wheel, and which defines a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centerpoint of the wheel.

Each post may include a terminal bracket carrying a pivoting bar, the pivoting bar being adapted to be releasably received by a cooperating accessory receiver carried on the receiver attachment. The accessory receivers may be angled upwardly to define an included angle which is less than 90 degrees relative to a horizontal plane. Typically, the accessory receivers are angled upwardly to define an included angle of from about 10 degrees to about 45 degrees relative to a horizontal plane. In one embodiment, the accessory receivers may be ports defining an internal cavity as described in copending U.S. Patent Application S.N. 10/182,096. In this embodiment, the pivoting bars are adapted to be received in the port internal cavity, and may be secured by passing a pin through aligned apertures in the pivoting bars and ports. The pivoting bars may include an internal sleeve or slot. Accordingly, in another embodiment, the accessory receivers may be arms projecting from the receiver attachment, the arms terminating in a mating end. In this latter embodiment, the pivoting bar internal sleeve or slot is adapted to receive the accessory receiver arm mating end, and may be secured thereto bypassing a pin through aligned apertures in the pivoting bars and receiver mating ends. A similar structure is described in U.S. Provisional Patent Application S.N. 60/423,491, the entirety of which is incorporated by reference herein. The frame may be substantially U-shaped, with the closed end supporting the single ground-engaging wheel. However, it will be appreciated that other frame shapes may be desirable, such as rectangular, semicircular, or V-shaped. The load-supporting section may be provided with cross-bars or struts to support a load thereon, or specific flooring systems may be attached to the frame in accordance with the load to be carried. For example, in the art of trailering motorcycles it is known to support the motorcycle by providing rails corresponding to the width of the motorcycle tires.

As described above, the trailer of the present invention is designed to be attached to a vehicle at fixed attachment points defined by accessory receivers mounted to the vehicle. Those of skill in the art will appreciate that the features of fixed vehicular attachment points in combination with a single swiveling wheel provides an additional advantage to the present trailer. Ordinary trailers, which generally use single, pivoting attachment points such as common hitch and hitch ball, require a certain level of skill to operate when backing the vehicle. This is because the trailer tends to turn in a direction opposite to that expected for a given steering input. Attempting to back the trailer improperly may result in formation of an overly sharp angle between the trailer and the vehicle, or "jack-knifing." The tendency to jack- knife is exacerbated in small, lightweight trailers. In contrast to other trailer designs using a single, pivoting hitch attachment, the trailer of the present invention does not jack-knife when operated in the reverse direction. Rather, the two fixed attachment points in combination with the single swivelling wheel allow the trailer of this invention to function as an extension of the vehicle, so that the trailer always turns in the expected direction in accordance with the steering input provided. Thus, the level of operator skill and experience required to back the trailer to a desired point is reduced. In fact, the user need only back the vehicle and trailer into the desired position just as would be done for the vehicle alone, compensating only for the additional length of the trailer.

As should be appreciated, the embodiments shown and described in this patent application are an illustration of one of the modes best suited to carry out the invention. It will be realized that the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions herein must be regarded as illustrative in nature and not as restrictive.

Brief Description of the Drawings

The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain the principles of the invention. In the drawings:

Figure 1 is a perspective view of the single wheel trailer of the present invention;

Figure 2 is a side elevational view of the single wheel trailer shown in Figure 1 , showing the placement of the bracket and pivoting bar for securing the trailer to an accessory receiver;

Figure 3 is a perspective view showing one embodiment of the bracket and pivoting bar for securing the trailer to an accessory receiver of the invention in isolation; Figure 4 is an exploded perspective view of the single wheel trailer shown in Figure 1, showing a receiver assembly having ports for receiving the trailer pivoting bars; and

Figure 5 is an exploded perspective view of the single wheel trailer shown in Figure 1, showing a receiver assembly having receiver arms which are received in internal sleeves or slots in the trailer pivoting bars.

Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings.

Detailed Description of the Invention Reference is now made to drawing Figures 1 and 2 showing the single- wheel trailer 10 of the present invention. The trailer 10 includes a frame 20, a single ground-engaging wheel 22, and a wheel-supporting assembly generally designated by reference numeral 24. The frame 20 includes a first, closed section 26, an intermediate, load-supporting section 28 defined by two spaced-apart posts 29, 30, and a third, terminal section 32 comprising the ends 33, 34 of posts 29, 30 opposite the closed section 26. Frame 20 may be fabricated of a sufficiently heavy-duty tubing having any desired shape in cross-section, such as circular, oval, rectangular, square, and the like.

Typically, the frame may be substantially U-shaped, with the closed end 26 supporting the single ground-engaging wheel 22. However, it will be appreciated that other closed-ended shapes for frame 20 may be desirable, such as rectangular, semicircular, or V- shaped. The load-supporting section 28 may be provided with crossbars or struts (not shown) connecting posts 29, 30 to support a load thereon. Alternatively, posts 29, 30 may be provided with apertures 23 for removably securing specific flooring systems thereto in accordance with the load to be carried. For example, in the art of trailering motorcycles it is known to support the motorcycle by providing rails

(not shown) corresponding to the width of the motorcycle tires, and tie- downs (not shown) of known design to preserve an upright orientation of the motorcycle using ropes or straps. Other types of load may require a solid flooring system (not shown) secured to frame 20. The load-supporting section 28 of the frame 20 is spatially oriented to reside between the ground-engaging wheel 22 and the post ends 33, 34, and further to occupy a first substantially horizontal plane which may be coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centerpoint of the wheel 22 (see Figure 3). Typically, this is accomplished by including in frame 20 downwardly angled segments 36 extending from closed section 26 to each of posts 29, 30. Advantageously, this lowers the center of gravity of a load placed on the trailer 10, thereby increasing trailer stability when traversing rough surfaces and/or cornering at high speeds.

As described above, the trailer of the present invention is designed to be attached to a vehicle at fixed attachment points defined by accessory receivers mounted to the vehicle. As shown in Figures 2- 5, and discussed in greater detail below, a mounting bracket 21 may be secured to post ends 33, 34, for example by welding. Mounting bracket 21 includes bars 31 which may be removably received by female receivers on a towing vehicle. Of course, other securing methods are possible. For example, ends 33, 34 of posts 29, 30 (see Figure 1) may simply serve as the male portions of the securement system (without bracket 21), and may be configured to be removably received by female receivers having a corresponding cross-sectional shape, carried on a towing vehicle bumper or on a hitch receiver assembly mounted to the vehicle frame.

As best seen in Figure 3, mounting bracket 21 may include a U- shaped bracket 23 affixed to each of post ends 33, 34, for example by welding. Bracket 23 includes at least one aperture 25 for receiving a pin 27, which may be retained in place in bracket 23 using a clip 29. Assembly 21 further may include a bar 31 of any desired cross- sectional shape, which is configured to be removably received in accessory receivers (described in detail below) secured to a towing vehicle. Bar 31 includes apertures 35, 37 at its top and bottom end for receiving a pin 27. Bar 31 further may include an internal sleeve or slot 39, the purpose of which will be described in detail below. Accordingly, as best seen in Figures 2 and 3, pin 27 is passed through aligned apertures 25, 35 on bracket 23 and bar 31, and retained in place using a clip 29. Thus, bar 31 may pivot within bracket 23, thereby allowing the angle of bar 31 to be matched with that of the corresponding accessory receiver. Bar 31 may be secured to the accessory receiver, and retained in place using a pin and clip as described above.

The frame 20 further includes a swivelling assembly 38 for supporting the ground-engaging wheel 22, and a wheel supporting assembly 24. Swivelling assembly 38 is designed to allow swivelling of wheel 22 around a vertical axis, typically along a 360 ° circumference of travel. Referring to Figure 4, frame 20 includes a mounting plate 40 for supporting the swivelling assembly 38. Swivelling assembly 38 comprises a kingpin 44 rotatably supported in a bearing sleeve 46. A cap 50 retains kingpin 44 in bearing sleeve 46. It will be appreciated that cap 50 may be removable to allow access to kingpin 44 for purposes such as replacement or lubrication. Alternatively, a nipple (not shown) may be provided to allow lubrication of the interior of swivelling assembly 38.

Sleeve 46 includes a flange 48 which has apertures corresponding to similar apertures in mounting platform 40. Mounting platform 40 also includes a central aperture 52 configured to receive sleeve 46 merethrough. Accordingly, it will be appreciated that sleeve 46, with kingpin 44 rotatably installed therein, may be inserted through central aperture 52 in mounting platform 40 such that the upper surface of flange 48 and the bottom surface of mounting platform 40 abut, and such that corresponding apertures on mounting platform 40 and flange 48 are aligned. Sleeve 46 may then be secured to mounting platform 40 in any desired manner, such as cooperating threaded bolts and nuts.

Kingpin 44 includes a lower section 54 for securing wheel- supporting assembly 24 thereto. Typically, lower section 54 comprises a lip 56 and a shaft 58 configured to be received by wheel-supporting assembly 24. Shaft 58 may be secured to wheel supporting assembly 24 by any desired means, such as welding or threaded nuts and bolts (not shown). Wheel-supporting assembly 24 is an articulated assembly comprising a top flange 60, at least one first strut 63, a central pivot assembly 62, and at least one second strut 64. Second strut 64 attaches at a first end, via central pivot assembly 62, to first strut 63, and at a second end to axle 76 passing through a centeφoint of wheel 22. Top flange 60 includes an aperture 66 for receiving shaft 58 therethrough, thus allowing swivelling of wheel-supporting assembly 24, and a wheel 22 mounted thereto, around a vertical axis along the desired path of travel.

The wheel-supporting assembly 24 may further be provided with a shock dampener 68. Shock dampener 68 may be a coiled-spring or gas-filled shock absorber, a torsion spring, or any shock dampener known in the art. Shock dampener 68 is mounted at a first end to a pin 70 extending from frame 20 and passing through apertures 71 in first struts 63 of wheel-supporting assembly 24, and at a second end to axle 76. It will be appreciated that this feature allows wheel 22 to travel along a vertical axis, thereby dampening any shock incurred from rough road conditions and the like.

In one embodiment of the present invention, best seen in Figure 4, a receiver assembly 78 is provided which includes a cenfral frame member or cross member 80. Frame or cross member 80 may be formed from tubular steel sections 82, 84 welded to the opposing side walls 86, 88 of a centrally located receiver box 90 of conventional design so as to project outwardly in opposing directions. It will be appreciated that frame or cross member 80 may be formed with a rounded cross section as shown in Figure 4, a square cross section, or any other appropriate shape and material providing the necessary strength to function as a receiver assembly. A chain plate 92 may be welded to the receiver box 90 and tubular steel sections 82, 84 to strengthen the connection, and may include apertures 94 for engaging safety chains (not shown).

Vehicle mounting brackets 96 may be mounted adjacent the distal end of each tubular section 82, 84. The mounting brackets 96 may include a mounting flange 98 and an upwardly projecting mounting lug 100, both with apertures 102. Of course, suitable fasteners such as nut and bolt fasteners (not shown) may be extended through apertures 102 and aligned apertures (not shown) drilled in the frame of the towing vehicle to mount receiver assembly 78 thereto.

The receiver assembly 78 may also include a pair of accessory receivers 104 carried on the tubular sections 82, 84 of the central frame member 80. In the embodiment depicted in Figure 4, each of the accessory receivers 104 may be a port 105 extending from the sections 82, 84 such that one port 105 is positioned between the receiver box 88 and each mounting bracket 96. However, it will be appreciated that other configurations are possible without departing from the scope of the present invention as described herein. For example, accessory receiver 104 could be any desired shape in cross-section, in accordance with the cross-sectional shape of frame 20 as discussed above. One port 105 could also be configured as an accessory adapted to be received in and secured to receiver box 88.

Each port 105 includes a cavity 106 and cooperating aligned apertures 108 in the sidewall thereof to allow secure connection of bars 31 of trailer 10 thereto by means of a pin or clip of known design.

Cavity 106 maybe of any shape in cross-section suitable for receiving bars 31 therein. The accessory receivers 104 may be oriented as desired with respect to the central frame member 80 for the convenience of the operator. Typically, each port 105 will fall in a first plane which defines an included angle of less than 90 degrees with a second, horizontal plane which contains the longitudinal axis of the receiver box 88. More typically, each port 105 will fall in a first plane which defines an included angle of between about 10° to about 45 ° with a second, horizontal plane which contains the longitudinal axis of the receiver box 88. Accordingly, typically cavity 106 will open upwardly for better visibility and accessibility for easy connection of an accessory. Of course, as described above when a mounting bracket 21 is used to mount trailer 10 to the accessory receivers 104, bars 31 are capable of pivoting to match the angle of accessory receivers 104, thereby providing a secure attachment with reduced risk of inadvertent disengagement of frailer 10.

In the embodiment depicted in Figure 5, a. second receiver assembly 78' is provided wherein accessory receivers 104' comprise arms 107 projecting upwardly from the receiver sections 82, 84 at the included angles as described above. Arms 107 terminate in mating ends 109. As shown in Figure 3, bars 31 include an internal sleeve or slot 39, adapted for receiving arms 107 therein. Arms 107 may include apertures 110 which align with apertures 37 in bars 31. Accordingly, once sleeve or slot 39 in bar 31 receives arm 107, the assembly may be secured by a simple pin.

It will be appreciated that a fixed attachment system for mounting the trailer 10 of this invention to a towing vehicle is described which may comprise any number of embodiments. Of course, as described above the accessory receivers may comprise dedicated spaced-apart ports 105 or receiver arms 107 mounted to a vehicle bumper (not shown), directly to a vehicle frame (not shown), or to a hitch receiver assembly as shown in Figures 4 and 5. In the alternative, a towing accessory adapter for securing in a conventional receiver box of a trailer hitch assembly as described in Cequent Towing Product, Inc.'s U.S. Patent Application Nos. 10/415,062 and 10/287,163, and PCT Patent Application Nos. PCT/US03/30832 and PCT/USO 1/30796 (all incorporated herein in their entirety by reference) may be provided. The adapter includes a cross member, a mounting bar carried on the cross member for securing in the receiver box, and a pair of spaced accessory ports or receiver arms allowing two-point mounting of an accessory of a type incorporating multiple mounting posts or bars. Still further (embodiment not shown), posts 28, 30 may include downwardly angled ends 33, 34 for direct attachment to ports 105 or arms 107. Those of skill in the art will appreciate that the features of fixed attachment points in combination with a single swiveling wheel provide an advantage over conventional single wheel trailer designs. Conventional trailers using single, pivoting attachment points such as conventional hitch/hitch ball designs require a certain level of skill and experience when backing to effectively guide the trailer to a desired point. Attempting to back the trailer improperly may result in formation of an overly sharp angle between the trailer and the vehicle, or "jack-knifing." In contrast, the trailer of the present invention does not jack-knife when operated in the reverse direction. Rather, the dual fixed attachment points in combination with the single swivelling wheel allow the trailer of this invention to function as an extension of the vehicle, turning according to the steering input provided and reducing the level of operator skill required. The operator need only account for the additional length provided by the trailer when operating in the reverse direction.

It will also be appreciated that orienting the load-supporting section of the frailer of the present invention between the ground- engaging wheel and the dual fixed attachment points, whereby the load-supporting section occupies a first substantially horizontal plane which is substantially coplanar with or oriented beneath a second substantially horizontal plane which bisects the centerpoint of the wheel, provides additional advantages over conventional trailer designs. By so lowering the center of gravity of a load placed on the trailer, stability during operation, particularly when traversing rough surfaces and/or cornering, is increased. Thus, undesirable "bucking" or bouncing of the trailer during operation, which is known to occur with small, lightweight trailers, is reduced.

The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.

Claims

What is claimed is:

1. A trailer for towing behind a vehicle, comprising: a frame having a first section to which is mounted a single ground-engaging wheel, a second, load-supporting section defined by a pair of spaced-apart posts, and a third section distal to the first section for removably securing the frame to the vehicle; wherein the load-supporting section is oriented between the ground-engaging wheel and the mounting section, and defines a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centeφoint of the wheel.

2. The trailer of claim 1 , wherein the first frame section is closed and the third frame section is open.

3. The frailer of Claim 1, wherein the third section is adapted for removably mounting to fixed attachment points defined by a pair of cooperating receivers carried on the vehicle.

4. The frailer of Claim 3, wherein the third section is defined by the terminal ends of the spaced-apart posts, each post ending in a bracket carrying a pivoting bar adapted for removably mounting to a fixed attachment point defined by a pair of cooperating receivers carried on the vehicle.

5. The trailer of Claim 1, wherein the ground-engaging wheel is mounted to the first section whereby the ground-engaging wheel is adapted to swivel around a substantially vertical axis.

6. The trailer of Claim 5, wherein the ground-engaging wheel is mounted to the first section by a swivelling assembly comprising: a mounting plate including a central aperture for receiving a kingpin; a wheel-supporting bracket having a top flange, a kingpin extending from a first surface of the top flange and rotatably received in the mounting plate cenfral aperture, at least one first strut depending from an opposite surface of the top flange, and at least one second strut pivotally secured at one end to a distal end of the first strut and at the opposite end to an axle supporting the ground engaging wheel; and a bearing for rotation of the top flange relative to the mounting plate; whereby the ground-engaging wheel may travel a predetermined distance along the substantially vertical axis.

7. The trailer of Claim 6, further including at least one shock dampener mounted at a first end to the wheel supporting bracket and at a second end to the axle.

8. A trailer for towing behind a vehicle, the trailer comprising a frame having a closed end to which is mounted a single ground- engaging wheel, an open end defined by distal ends of a pair of spaced- apart frame posts, and an intermediate, load-supporting section defined by the pair of spaced-apart posts, the load-supporting section defining a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centeφoint of the wheel, and the post distal ends being adapted for removably mounting to fixed attachment points defined by a pair of cooperating receivers carried on the vehicle.

9. The trailer of Claim 8, wherein the ground-engaging wheel is secured to the closed end of the frame whereby the ground-engaging wheel swivels around a vertical axis.

10. The trailer of Claim 9, wherein the ground-engaging wheel is mounted to the first section by a swivelling assembly comprising: a mounting plate including a central aperture for receiving a kingpin; a wheel-supporting bracket having a top flange, a kingpin extending from a first surface of the top flange and rotatably received in the mounting plate central aperture, and at least one first strut depending from an opposite surface of the top flange; and a bearing for rotation of the top flange relative to the mounting plate.

11. The trailer of claim 10, further including at least one second strut pivotally secured at one end to a distal end of the first strut and at the opposite end to an axle supporting the ground engaging wheel; whereby the ground-engaging wheel may travel a predetermined distance along the substantially vertical axis.

12. The trailer of Claim 11, further including a shock dampener mounted at a first end to the wheel-supporting bracket and at a second end to an axle assembly passing through a centeφoint of the ground- engaging wheel.

13. A trailer for towing behind a vehicle, comprising: a frame; a single ground-engaging wheel; a swivelling assembly for attaching the wheel to the frame; and means for mounting the frame to the vehicle; wherein the frame is characterized by having a load- supporting section oriented between the ground-engaging wheel and the mounting means, and defining a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centeφoint of the wheel.

14. The frailer of Claim 13, wherein the mounting means comprise a bracket carrying a pivoting bar attached to an end of the spaced-apart posts, the pivoting bar being adapted to be removably received by a cooperating receiver carried on the vehicle.

15. A frailer and receiver attachment assembly, comprising: a trailer having a frame, a single swivelling ground- engaging wheel, and a pair of posts at an end of the frame opposite the ground-engaging wheel, the posts being adapted for releasably securing the trailer to the receiver attachment assembly; and a receiver attachment comprising a pair of cooperating accessory receivers for releasably securing the trailer to a towing vehicle; wherein the frame includes a load-supporting section which is oriented between the ground-engaging wheel and the frame end opposite the ground-engaging wheel, and defines a first substantially horizontal plane which is coplanar with or oriented beneath a second substantially horizontal plane, the second plane substantially bisecting a centeφoint of the wheel.

16. The trailer and receiver attachment assembly of claim 15, wherein each post includes a terminal bracket carrying a pivoting bar, the pivoting bar being adapted to be releasably received by a cooperating accessory receiver carried on the receiver attachment.

17. The trailer and receiver attachment assembly of Claim 15, wherein the accessory receiver is angled upwardly to define an included angle which is less than 90 degrees relative to a horizontal plane.

18. The trailer and receiver attachment assembly of Claim 17, wherein the accessory receiver is angled upwardly to define an included angle of from about 10 degrees to about 45 degrees relative to a horizontal plane.

19. The trailer and receiver attachment assembly of claim 17, wherein the accessory receiver is a port defining an internal cavity.

20. The trailer and receiver attachment assembly of claim 17, wherein the accessory receiver is an arm projecting from the receiver attachment, the arm term ating in a mating end.

21. The trailer and receiver attachment assembly of claim 19, wherein the pivoting bar is adapted to be received in the port internal cavity.

22. The trailer and receiver attachment assembly of claim 20, wherein the pivoting bar includes an internal sleeve or slot adapted to receive the accessory receiver arm mating end.