NL2017968B1

NL2017968B1 - Assembly of a tow hitch and a tow hitch coupling

Info

Publication number: NL2017968B1
Application number: NL2017968A
Authority: NL
Inventors: Martinus Plat Harm
Original assignee: Brink Towing Systems B V
Priority date: 2016-12-09
Filing date: 2016-12-09
Publication date: 2018-06-19

Abstract

The invention relates to an assembly of a tow hitch and an accessory for carrying a load onto the tow hitch, wherein the tow hitch comprises a tow hook with a straight cylindrical neck at its end, and a tow ball at the end of the neck, and wherein the accessory comprises a tow hitch coupling that engages onto the tow hitch, wherein the tow hitch coupling comprises a ball clamp that engages at least the tow ball, and a forked support that engages the tow hook below the neck and spaced apart from the engagement by the ball clamp, wherein the forked support comprises a support body with a confinement aperture to receive the tow hook in a confinement direction, wherein the confinement aperture is bounded by two opposite side surfaces along which it diverges towards the tow hook.

Description

Assembly of a tow hitch and a tow hitch coupling BACKGROUND

The invention relates to an assembly of a tow hitch and an accessory with a tow hitch coupling that engages the tow hitch to carry a load. The tow hitch is then used to carry a load instead of towing a trailer. Known tow hitch couplings comprise a clamp that tightly clamps the ball of the tow hitch. The shape of the ball and the adjacent neck of the tow hook are standardized according to directive 94/20/EG for mechanical couplings for towing vehicles. In order to further enhance the carrying capacity, for example to carry electric bikes, the known clamps clamp or fixate both the ball and the directly adjacent part of the neck by using a counter-shaped clamp that clamp or fixate these components tightly. However, due to the short length of the standardized neck, the maximum, momentum that can be safely transferred to the tow hitch remains limited. In the past, the carrying capacity of known tow hitch couplings was enhanced by mounting additional couplers to the tow hitch. These couplers needed to be bolted to the tow hitch in advance, which is a long and complex mounting operation.

It is an object of the present invention to provide a tow hitch coupling which allows the transfer of a greater momentum to the tow hitch that comes with the ever increasing demand in carrying capacity.

SUMMARY OF THE INVENTION

The invention provides an assembly of a tow hitch and an accessory for carrying a load onto the tow hitch, wherein the tow hitch comprises a tow hook with a straight cylindrical neck at its end, and a tow ball at the end of the neck, and wherein the accessory comprises a tow hitch coupling that engages onto the tow hitch, wherein the tow hitch coupling comprises a ball clamp that engages at least the tow ball, and a forked support that engages the tow hook below the neck and spaced apart from the engagement by the ball clamp, wherein the forked support comprises a support body with a confinement aperture to receive the tow hook in a confinement direction, wherein the confinement aperture is bounded by two opposite side surfaces along which it diverges towards the tow hook, wherein the side surfaces are convex towards the tow hook, wherein the support body engages the tow hook in the confinement aperture at local opposite contact areas of the opposite side surfaces.

The assembly according to the invention comprises a tow hitch coupling with a ball clamp that confines the tow ball, and in addition thereto a forked support that engages the tow hook between its opposite diverging side surfaces. The side surfaces are convex towards the tow hook, whereby the contact areas are clearly defined at the apexes thereof independent on the local shape of the tow hook. As the side surfaces are diverging towards the tow hook, the engagement at the local contact areas is free of play. This engagement is independent of the local shape of the tow hook, and can therefore take place below the standardized neck to have a larger distance with respect to the ball. This allows the transfer of a larger momentum to the tow hitch. The forked support forms part of the tow hitch coupling, whereby no additional parts need to be mounted in advance to the tow hitch.

In an embodiment the local contact areas are in the confinement direction under a first angle between 5 degrees and 45 degrees. This particular first angle ensures that on one hand the engagement is free of play while on the other hand the engagement is self-releasing.

The play-free and self-releasing engagement is in particular obtained when the first angle is between 10 and 35 degrees.

In a further embodiment thereof the first angle is between 15 and 30 degrees.

In a further embodiment thereof the first angle is between 17 and 25 degrees.

In an further embodiment thereof the first angle is about 20 degrees.

In an embodiment the side surfaces are at the local contact areas symmetrical with respect to the plane of symmetry of the tow hitch to ensure that the accessory remains straight positioned behind a passenger car.

In an embodiment is in the confinement direction at a first position the distance between the side surfaces perpendicular to confinement direction larger than the distance between the contact areas, and is at a second position further away from the tow hook, the distance between the side surfaces perpendicular to the confinement direction smaller than the distance between the contact areas. This ensures that the side surfaces are continued on both sides of the contact areas, for example to be able to compensate wear over the years of use of the tow hitch coupling.

In an embodiment the side surfaces are straight in a first plane that extends in trie confinement direction.

In an embodiment the side surfaces are bounded by an upper edge and a lower edge that is located below the upper edge with respect to the tow ball.

In an embodiment thereof that is easy to manufacture, the upper edge and the lower edge are straight edges that extend parallel to each other.

In an embodiment the contact areas are located at or along the upper edges of the side surfaces, whereby the distance of the contact areas with respect to the ball, and therefore the maximum momentum that can be transferred to the tow hitch, are well defined.

In an embodiment the support body is plate shaped.

In an embodiment that can be installed with oversight, the support body comprises two fingers having the side surfaces that define the confinement aperture. The engagement of the tow hook can then easily be checked visually by verifying that the tow hook has come between the fingers.

In an embodiment the confinement direction is perpendicular to the center line of the neck.

In an embodiment the forked support comprises a holder for the support body, wherein the support body is slidably guided by the holder to be slid between the engaging position and a retracted position. In this embodiment it is possible to activate the ball clamp in a first stage of coupling, whereafter in a second stage the support body is slid to the tow hook.

In an alternative embodiment the forked support comprises a holder for the support body, wherein the support body is hingeably connected with the holder to be swung between the engaging position and a retracted position.

In an embodiment the tow hitch coupling comprises an operating mechanism for operating the ball clamp between the engaging position and a retracted position, wherein the support body is operatively connected with the operating mechanism for synchronous operation. The ball clamp and the forked support can then be operated by one single operation, for example by manually swinging a lever.

In an embodiment the tow hitch coupling comprises a housing having the ball clamp inside, wherein the forked support comprises a holder for the support body, wherein the holder is mounted below the housing. The holder with the support body may be a universal solution for any tow-hitch coupling to enhance their carrying capacity.

In an embodiment the tow ball and the neck comply with directive 94/20/EG for mechanical couplings for towing vehicles, and wherein the support body engages the tow hook below the prescribed neck.

In a practical implementation thereof the tow ball has a spherical outer surface with a diameter of 50 millimeters, wherein the support body engages the tow hook at a distance along the center line of the cylindrical neck of at least 32 millimeters with respect to the center of the tow ball.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which:

Figure 1 is an isometric side view of a bike carrier that is coupled to a first tow hitch by means of a tow hitch coupling according to the invention;

Figures 2A and 2B are isometric bottom views of the tow hitch coupling of figure 1 in a first and a second stage of coupling, respectively;

Figures 3A and 3B are isometric bottom views of the tow hitch coupling in the first stage of coupling as shown in figure 2A, wherein subsequently some parts have been taken away to show the internal components thereof;

Figure 4 is an orthogonal side view of the first tow hitch as engaged by the engaging part in the second stage of coupling as shown as shown in figure 2B;

Figures 5A-5C are orthogonal top views with cross sections of the first tow hitch as engaged by the engaging part in the second stage of coupling as shown in figures 2B and 4, and cross sections of engaged second and third alternative tow hitches;

Figures 6A-6C are orthogonal front views of the first tow hitch as engaged by the engaging part in the second stage of coupling as shown in figures 2B and 4, and engaged fourth and fifth alternative tow hitches; and

Figures 7A and 7B, 8A and 8B, and 9A and 9B are alternative configurations of the engaging part of the tow hitch coupling as shown in the previous figures.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 4 show a known first tow hitch 1 at the back of a passenger car that is not shown. The first tow hitch 1 comprises a tow ball 2 at the end of an elongate tow hook 7. At the other side the tow hook 7 is connected with a tow bar 13 that is mounted to the passenger car.

The first tow hitch 1 complies with directive 94/20/EG for mechanical couplings for towing vehicles, which prescribes specific dimensions of a tow hitch with a tow ball of 50 millimeters. In conformity this directive, the tow ball 2 has a spherical outer surface 3 with center C and a diameter D of 50 millimeters, and a circular flat top surface 4 with a diameter of 17 millimeters and an annular bottom surface 5 that in use both extend horizontally, wherein the distance E of the annular bottom surface 5 with respect to the center C of the tow ball 2 is more than 15 millimeters. The bottom surface 5 merges via a toroidal bottom surface 6 into a straight cylindrical neck 8 of the tow hook 7. The neck 8 has a diameter A of 29 millimeters over a length F with respect to the center C of the tow ball 2 of at least 32 millimeters.

Further to the parts with the prescribed specific dimensions, the tow hook 7 comprises in this example a curved section 9 and a thicker and straight section 10. The straight section 10 merges into a wider base section 11 having opposite and parallel straight surfaces 12 at which the first tow hitch 1 is mounted to the cross bar 13. Beyond the specified parts, many other shapes and configurations are possible for the tow hook, such as a straight, or curved over more than 90 degrees. The tow hook 7 may be a fixed tow hook that is bolted to the tow bar 13, or it be a detachable tow hook having a releasable coupling to disconnect it from the tow bar 13, or it may be a retractable tow hook that can be retracted it behind the bumper of the passenger car. The first tow hitch 1 is in this example made of steel.

Figure 1 shows a tow bar accessory for carrying loads behind the passenger car in this non-limiting example a bike carrier 20. Alternative tow bar accessories are a luggage box or a luggage carrier. In contrast with trailers that are towed, the suspended accessories exert a relatively high momentum. M onto a tow hitch. The bike carrier 20 comprises in this example basically two frame bars 29 and multiple wheel supports 19 for supporting bikes. The bike carrier 20 is coupled to the first tow hitch 1 by means of a tow hitch coupling 30 according to the invention, of which the embodiments are described in detai1 hereafter.

As best shown in figures 2A and 2B, the tow hitch coupling 30 comprises an outer housing 21 with a generally rectangular shape that in this example is formed out of a steel plate. The outer housing 21 comprises two parallel side walls 22, a back wall 23 connecting the side walls 22 with each other, and bottom flanges 24 along the bottom sides of the side walls 22 that are inwardly directed to define a bottom passage 25 for the tow ball 2. As best shown in figures 3A and 3B, the tow hitch coupling 30 comprises a front housing 4 0 that is complementary to the outer housing 21. The front housing 4 0 comprises a front wall 42 that in this example is formed out of a steel plate. The front wall 42 comprises multiple projecting notches 43 that are inserted in mounting slots 26 in the side walls 22, and a spherical section 4 4 with an inner shape that corresponds with the outer curvature of the tow-ball 2 and the adjacent part of the neck 8. The front housing 40 furthermore comprises a reinforcement 27 along the spherical section 44, The assembly of the outer housing 21 and the front housing 40 are covered by a cover wall 41 that in this example is made of plastic.

As best showm in figures 3A and 3B, the tow hitch coupling 30 comprises a ball clamp 50 that is in this example made of steel. The ball clamp 50 is hingeably connected to a hinge pin 51 that extends through holes 28 in the side walls 22 as shown in figures 1A and IB, At the opposite side the ball clamp 50 comprises a spherical section 52 with an inner shape that corresponds with the outer curvature of the tow ball 2 and the adjacent part of the neck 8 to cooperate with the spherical section 4 4 of the front housing 40. The ball clamp 50 is hinged in direction G between an open position in which the tow ball 2 can be inserted in the tow hitch coupling 30 via the bottom passage 25, and a clamping position in which the tow ball 2 and the adjacent part of the neck 8 are firmly engaged and confined without play. This confinement provides sufficient carrying capacity for an average bike carrier. The ball clamp 50 is hinged by means of a manually operated knee mechanism 53 of which only some parts are shown as such mechanisms are known per se for tow hitch couplings .

In order to further increase the carrying capacity of the bike carrier 20 or to improve its stability, the tow hitch coupling 30 is at the bottom provided with a supplementary support 60. As best shown in figure 3B, the supplementary support 60 comprises a holder 61 that in this example is made of steel. The holder 61 has a base 62 with a straight bottom surface 63 and two parallel lugs 64 extending from the base 62. At the free ends the lugs 64 are provided with a hole through which mounting screws 65 extend that are screwed into the bottom side of the outer housing 21. At the bottom side the supplementary support 60 comprises two parallel side walls 66 with straight first sliding surfaces 67 that are symmetrically directed obliquely inwards facing the bottom surface 63 for slideably enclosing a first forked support 70. The first forked support 7 0 is shown in more detail in figures 4, 5A and 6A.

The first forked support 70 is in this example made of steel, and comprises a plate shaped support body 71 with a substantially rectangular outline. The support body 71 is provided with two straight second sliding surfaces 72 that are parallel to the first sliding surfaces 67 and in abutment therewith to be confined by the holder 61 while providing guidance of a sliding movement of the support body 71 in a confinement direction H towards and away from the neck 8. The confinement direction H is parallel to the main plane of the plate shaped support body 71.

The first forked support 70 comprises a nut 90 that is in this example made of steel and that merges into a wider square flange 91. This flange 91 is recessed in the support body 71 and faces the bottom surface 63 of the holder 60. The first forked support 70 comprises a locking bolt 93 that is in this example made of steel and that is screwed through the nut 90. The locking bolt 93 is engaged by a plastic knob 94 for manually tightening the locking bolt 93 against the bottom surface 63 of the holder 61 to fixate the position of the first forked support 7 0 in trie confinement direction H with respect to the holder 61.

As best shown in figures 5A and 5A, the support body comprises a confinement aperture 75 between two projecting fingers 74. The confinement aperture 75 is bounded by two side surfaces 80 that are in this example symmetrical with respect to the plane of symmetry S of the tow hitch 1. The side surfaces 80 merge into a curved back surface 81. At the ends of the fingers 74, trie side surfaces 80 merge over curved front surfaces 85 into straight front surfaces 86 of the support body 71. The side surfaces 80 are in this example each bounded by a straight upper edge 82 and a straight lower edge 83 that each diverge towards the tow hitch 1. In a first plane perpendicular to the plane of symmetry S and parallel to the confinement direction H, the side surfaces 80 are in this example under an angle L of 20 degrees. The upper edges 82 extend parallel to the lower edges 83 under this same angle L, wherein the upper edges 82 are inwardly shifted with respect to the lower edges 83. In a second plane perpendicular to the plane of symmetry S and perpendicular to the first plane, the side surfaces 80 are convex.

As best shown in figure 5A, the upper edges 82 have a spacing J at the merger into the curved front surfaces 85 of in this example 40 millimetres, which is larger than the standardized diameter A of 29 millimetres of the neck 8. At the merger into the curved back surface 81, the upper edges 83 have in this example a spacing K of 26 millimetres, which is smaller than the standardized diameter A of 29 millimetres of the neck 8. As best shown in figure 4, the upper edges 83 engage below the neck 8 at a distance G which is larger than abovementioned standardised length F of at least 32 millimetres. The tow hook 7 of the first tow hitch 1 is in this example engaged above its curved section 9.

When the bike carrier 20 is installed onto the first tow hitch 1, the ball clamp 50 and the first forked support 70 are released and set in their retracted positions in directions G, H. Subsequently the tow hitch coupling 30 is placed onto the first tow hitch 1, wherein the tow ball 2 is inserted via the bottom passage 25. Then, the ball clamp 50 is hinged towards the tow ball 2 in direction G by manually tightening the knee mechanism 53. At that moment the tow hitch coupling 30 is in its first stage of coupling, 'wherein the position of the bike carrier 20 with respect to the first tow hitch 1 is fixed. The second stage of coupling is reached - by sliding the support body 71 in confinement direction H towards the tow hook 7 until it is engaged at local contact areas of the side surfaces 80, which in this example are located on the upper edges 82. The locking bolt 93 is manually tightened with the knob 91 to secure this position. Due to the V-configuration of the side surfaces 80 under angle L, and thereby the tangents of the opposite local contact areas or contact planes under this angle L, this engagement is free of play while it remains releasable. This first angle L may be between 5 degrees and 45 degrees.

Figures 5B, 5C, 6B and 6C show the engagement of alternative tow hitches 101, 201, 301, 401 by the tow hitch coupling 30 according to the invention. Like the first tow hitch 1, these alternative tow hitches 101, 201, 301, 401 have the same tow ball 2 and neck 8 that comply with directive 94/20/EG for mechanical couplings for towing vehicles as the first tow hitch 1. Beyond these identical specified parts, the second tow hitch 101 as shown in figure 5B has a tow hook 107 having at the distance G with respect to the centre C of the tow ball 2 a generally frustoconical cross section, and the third tow hitch 201 as shown in figure 5C has a tow hook 207 with a generally I shaped cross section at that distance G. The fourth tow hitch 301 as generally indicated with broken lines in figure 6B has a tow hook 307 that in its elongate cross section is tapering towards the ball 2 at the distance G with respect to the centre C of the tow ball 2, and the fifth tow hitch 401 as generally indicted with broken lines in figure 6C has a tow hook 4 07 that is in its elongate cross section even more tapering at that distance G. Abovementioned sections may be combined. It is clear that all these alternative tow hooks 107, 207, 307, 4 07 are confined by the first forked support /0 free of P-^Y- ihe operation of the tow hitch coupling 30 remains the same. -,7. Ppd 7B 8A and 8B, and 9A and 9B show

Figures ΙΆ ,u> on α ' „„nrf, ino 970 970 for the tow hook alternative forked supP°-LS ' ,- , ,. to fho -invention» wherein tne same coupling 1 according t j.n\ , Aed with the same reference numbers as parts have peen provi^e^ "iU1 the first forked support 70. The alternative forked supports 170, 270, 370 all comprise a plate shaped support body 171, 271, 371 with the second sliding surfaces /2, the straight front surfaces 86, the two fingers 74 and the nut 90. The operation of the tow hitch coupling 30 remains the same .

As shown in rigures /A and 7B, the confinement aperture 7 5 of the supporr body j-71 of the x_cond forked support 170 is bounded by two side surfaces 180 that merge into a curved back surface 181. The side surfaces 180 are each bounded by a straight upper edge 182 and a straight lower edge 183 parallel thereto that each diverge towards the tow hitch 1. The side surfaces 180 have a straight and sharp corner line 184 forming the apex towards the tow hook 7. Xn the first plane perpendi-^uxcir '...o ti*e pxans of symmetry S and parallel to the confinement direction n, the side surfaces 180, and therefore also the ouraignt upper edges 182, the straight lower edges i83 and the straight corner lines 184 are under abovementioned angle L of 20 degrees .

As shown in figures 8A and 8B, the confinement aperture 7 5 of the support body 271 of the second rorked support 270 is bounded by two side surraces 280 that merge into a curved back surface 281. The side surfaces 280 are cylindrically curved and merge fluently into the top surface 282 and the bottom surface 283 of the support body 271. The cylindrically curved side surfaces 280 have straight apexes 284. In the first plane perpendicular to the plane of symmetry S and parallel to the confinement direction H, the side surfaces 28 0, and therefore also the straight apexes 284 are under abovementioned angle L of 20 degrees .

As shown in figures 9A and 9B, the confinement aperture 75 of the support body 371 of the third forked support 37 0 is bounded by two side surfaces 380 that merge into a curved back surface 381. The side surfaces 380 are-each bounded by a straight upper edge 382 and a straight lower edge 383 parallel thereto that each diverge towards the tow hitch 1. The side surfaces 380 each comprise two straight surfaces 385,. 387 that symmetrically merge into a cylindrical or curved surface 386 having a straight apex 384. In the first plane perpendicular to the plane of symmetry S and parallel to the confinement direction H, the straight side surfaces 380, and therefore also the straight upper edges 382, the straight lower edges 383 and the straight apexes 384 are under abovemeritioned angle L of 20 degrees .

It will be clear that the alternative forked supports 170, 270, 37 0 can each engage the different tow hooks 7, 107, 207, 307, 407 in the same play free manner as described for the first forked support 70, and that according to the invention any combination of forked support 70, 170, 270, 370 and tow hook 7, 107, 207, 307, 407 is possible.

The forked supports 70, 170, 270, 370 each provide an additional engagement of the tow hitches 1, 101, 201, 301, 401 below the tow ball 2. This engagement below the normalized adjacent neck 8 is at sufficient distance with respect to the centre C to transfer the downwardly directed momentum M in the plane of symmetry S that is exercised by the bike carrier 20 to the tow hitches 1, 101, 201, 301, 401. The forked supports 70, 170, 270, 370 may selectively be applied within a product range of equivalent accessories to qualify for a higher carrying capacity.

In above described examples the bike carrier 20 is uninstalled by releasing the ball clamp 50 only, wherein the first hook clamps 70, 17 0, 27 0, 370 disengage when the to vi hitch coupling 30 is lifted from the tow hitches 1, 101, 201, 301, 401. There is no need to slide the support body 71 backwards in direction H to be able to take off the tow hitch coupling 30 from the tow hitches 1, 101, 201, 301, 401. The position of the different clamping bodies 71, 171, 271, 373 need to be set only once for one specific tow hitch 1, 101, 201, 301, 401. The diverging side surfaces 80, 180, 280, 380 under the angle L always ensure that the engagement of this unspecified part of the tow hook 7, 107, 207, 307, 407 at the contact areas is free of play, while this engagement is self-releasing at the contact areas. Alternatively, the clamping bodies 71, 171, 271, 373 are operatively connected with the ball clamp 50, whereby it is slid towards its engaging position and back in the direction H when the ball clamp 50 is operated.

In above described examples the clamping bodies 71, 171, 271, 371 are translated in the confinement direction H towards the tow hook 7. Alternatively, these clamping bodies are hingeably connected with the holder 61 or the hoiasings 21, 4 0 to be swung into its engaging position, for example in the main plane of the fingers 74. For this purpose, the side surfaces 80, 180, 280, 380 that are in V-configuration may not be symmetrical with respect to the plane of symmetry S of the tow hitch 1, but the V-configuration may be slightly curved with respect to the point of rotation of the hinging clamping bodies 71, 171, 271, 371.

In above described examples the clamping bodies 71, 171, 271, 371 are made of steel. They can be of any other suitable metal, such as aluminium, or any other suitable plastic.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.

Claims

Assembly of a tow bar and an accessory for carrying a load on the tow bar, the tow bar being provided with a tow bar rod with a straight-cylindrical neck at its end, and a tow ball at the entire end of the neck, and wherein the accessory is provided with a towbar coupling that engages the towbar, the towbar coupling being provided with a ball clamp that engages at least the tow ball, and a forked support that engages the tow bar rod below the neck and at a distance from the engagement by the ball clamp, the forked support comprises a support body with a receptacle opening to receive the towbar rod in a receptacle direction, the receptacle opening being delimited by two opposite side surfaces along which it diverges toward the towbar rod, the side surfaces being convex to the towbar, the support body engaging the towbar rod on opposite local contact surfaces of the opposite side surfaces.

2. Assembly as claimed in claim 1, wherein the local contact surfaces in the receiving direction are at a first angle between 5 degrees and 45 degrees.

The assembly of claim 2, wherein the first angle is between 10 degrees and 35 degrees.

The assembly of claim 3, wherein the first angle is between 15 degrees and 30 degrees.

The assembly of claim 2, wherein the first angle is between 17 degrees and 35 degrees.

The assembly of claim 5, wherein the first angle is approximately 20 degrees.

Assembly as claimed in any of the foregoing claims, wherein the side surfaces at the local contact surfaces are symmetrical with respect to the plane of symmetry of the towing hook.

8. Assembly as claimed in any of the foregoing claims, wherein in distance at a first position the distance between the side surfaces perpendicular to the direction of pick-up is greater than the distance between the contact surfaces, and at a second position further away from the towing hook position, the distance between the They are surfaces perpendicular to the pick-up direction that is smaller than the distance between the contact surfaces.

An assembly according to any one of the preceding claims, wherein in a first plane extending in the receiving direction the side surfaces are straight.

10. Assembly as claimed in any of the foregoing claims, wherein the sense surfaces are bounded by an upper edge and a lower edge which is located below the upper edge relative to the towing ball.

The assembly of claim 10, wherein the top edge and the bottom edge are straight edges that extend parallel to each other.

12. Assembly as claimed in claim 10 or 11, wherein the contact surfaces are situated on or at the upper edges of the side surfaces.

Assembly as claimed in any of the foregoing claims, wherein the support body is plate-shaped.

Assembly as claimed in any of the foregoing claims, wherein the support body has two fingers with the side surfaces defining the receiving opening.

An assembly according to any one of the preceding claims, wherein the receiving direction is directed perpendicular to the axis of the neck.

An assembly according to any one of the preceding claims, wherein the forked support comprises a holder for the support body, wherein the support body is slidably guided by the holder to be slid between an engaging position and a retracted position.

17. Assembly as claimed in any of the foregoing claims, wherein the forked support comprises a holder for the support body, the support body being hingedly connected to the holder to be pivoted between the engaging position and a retracted position,

18. Assembly as claimed in claim 17 or 18, wherein the towbar coupling is provided with an operating mechanism for operating the ball clamp between the engaging position and a retracted position, the supporting body being operatively connected to the operating mechanism for synchronous operation,

19. Assembly as claimed in any of the foregoing claims, wherein the towbar coupling is provided with a housing with the ball clamp therein, and wherein the forked support comprises a holder for the support body, the holder being mounted under the housing,

An assembly according to any one of the preceding claims, wherein the tow ball and the neck comply with Directive 94/20 / EC for mechanical couplings for towing vehicles, and wherein the support body. the tow bar engages under the prescribed neck,

An assembly according to any one of the preceding claims, wherein the tow ball has a spherical outer surface with a diameter of 50 millimeters, the support body engaging the tow bar rod at a distance along the axis of the cylindrical neck of at least 32 millimeters from the center of the tow ball.

A computer-readable medium with computer-executable instructions adapted to cause printing of a tow hitch coupling or forked support according to any one of the preceding claims, -o-o-o-o-o-o-o-o-