EP3894243A1

EP3894243A1 - Trailer hitch and method for producing same

Info

Publication number: EP3894243A1
Application number: EP19829447.2A
Authority: EP
Inventors: Kai ANGERMANN; Martin Wyrwich
Original assignee: Westfalia Automotive GmbH
Current assignee: Westfalia Automotive GmbH
Priority date: 2018-12-12
Filing date: 2019-12-11
Publication date: 2021-10-20
Also published as: DE102019106223A1; CN113453920A; US20220024267A1; WO2020120621A1

Abstract

The invention relates to a trailer hitch (10) for a motor vehicle (80), wherein the trailer hitch has a coupling arm (20), on one end region (25) of which a coupling body (30), in particular a coupling ball (31), is arranged for hitching a trailer (90) or coupling a load carrier to the motor vehicle (80). At least one support element forming at least part of an outer surface of the coupling body (30) and/or of the coupling arm (20) is provided on the coupling body (30) and/or on the coupling arm (20), said support element having a greater strength and/or hardness than an in particular metal basic material (41) of a main body (28, 38) of the coupling body (30) or coupling arm (20) on which the support element (60, 61, 70) is arranged or which bears the support element.

Description

Trailer coupling and method for their production

The invention relates to a trailer coupling for a motor vehicle, the trailer coupling having a coupling arm, on one end region of which a coupling body, in particular a coupling ball, for attaching a

Trailer or coupling a load carrier to the motor vehicle is arranged.

The coupling arm is in use for example to the rear in front of the

Motor vehicle ahead so that a load carrier or trailer can be coupled. As a rule, the coupling piece is a coupling ball, around which the trailer swivels in a ball-and-socket manner with its so-called pull-ball coupling. The

In practice, the trailer coupling must have a wide variety of loads

withstand, e.g. dynamic vibrations, high tensile or compressive loads and the like. Accordingly, the base material of the coupling arm and the coupling ball is chosen so that there is a certain ductility or elasticity. On the other hand, there is a requirement to have a high load capacity, in particular a high load capacity

To provide friction loads, which is why it is advantageous in itself, the

Manufacture dome body, especially the coupling ball, from a harder, more brittle material. With higher wear resistance, however, there is a risk that a harder or stronger material will break when the load drops

exceeds predetermined size, large.

It is therefore the object of the present invention to provide a mechanical

provide more resilient trailer coupling. To achieve the object, it is provided in a trailer coupling of the type mentioned at the outset that on the coupling body and / or the coupling arm at least one at least part of a respective outer surface of the coupling body and / or the coupling arm is provided, which, in particular the material thereof, is a towards one in particular

metallic base material of a base body of the dome body or

Coupling arm on which the support section is arranged or which supports the support section has higher strength and / or hardness.

The invention therefore also relates to a trailer coupling with a coupling arm, on the free end region of which a coupling piece for coupling a trailer or a load carrier is arranged, the coupling piece being one

Coupling body and the coupling arm one

Have coupling arm base body, characterized in that the coupling piece and / or the coupling arm at least one firmer

Has surface area, the strength of which is higher than that of a base material, in particular a metal, the coupling piece base body and the coupling arm base body.

The coupling arm has the coupling body at one end region, for example one at an opposite end region

Attachment section for attachment to the motor vehicle. The fastening part comprises, for example, means for releasable fastening to the motor vehicle, for example a plug-in projection which can be plugged into a plug-in receptacle of a holder which is fastened or can be fastened to the motor vehicle. Furthermore, the attachment section on a bearing for movably supporting the

Coupling arm between a position of use and one

Be arranged not in use position or have a bearing part of such a bearing. In the position of use, the coupling arm projects for example further in front of the rear of the motor vehicle than in the non-use position. The position of use is intended for coupling a load carrier or trailer. The coupling arm is preferred in the non-use position hidden behind and / or under a bumper of the motor vehicle or at least essentially hidden.

The trailer coupling preferably comprises a carrier arrangement for

Attachment to a body of the motor vehicle. The carrier arrangement comprises, for example, a cross member, which is preferably connected to the motor vehicle by side members. On the cross member or the carrier arrangement, the coupling arm is, for example, fixed or detachable, for example by means of a plug-in holder, or movably arranged, for example between the

Use position and the non-use position swiveling. It is a basic idea of the present invention that not the base body of the coupling body or the coupling arm or both have to consist of a solid or hard material, but that specifically where high

Loads, for example wear due to friction, in particular a coupling device of the trailer or of the load carrier on the

Dome body, or the like, occurs, one or more support sections are provided. The base body of the coupling arm and coupling ball can consist, for example, of metal, in particular of a metal with a predetermined ductility and / or strength and / or hardness. Compared to the main body of the coupling arm and coupling ball, the support section has e.g. lower ductility and / or higher strength and / or greater hardness. The invention thus provides that a harder and / or firmer material than the base material of the base body is used specifically at those points which are exposed to particularly high loads, namely in the region of the at least one support section. Of course, several support sections are possible at the desired locations.

Furthermore, different configurations are possible in the support sections, which will become clear in more detail. To form the support section, for example, the base material is solidified and / or hardened in the area of the at least one support section. This means that there is virtually no change of material, but the basic material of the

The base body of the coupling arm and / or coupling body is selectively solidified or hardened, or both.

The base material is hardened, for example, in the area of the at least one support section, thermal hardening, inductive hardening, laser hardening or the like being readily possible individually or in combination.

The base material is in the area of the at least one support section

for example, first heated and then cooled, in particular cooled suddenly. The initially heated support section is reduced to a predetermined time, for example by water or oil

Temperature cooled. After the cooling phase, the area of the at least one support section is then heated again by a predetermined amount, which is also referred to as tempering.

It is advantageously provided that the base material in the area of the at least one support section starting from an initial temperature or

Normal temperature, for example a typical room temperature of about 15-35 ° C, is heated to a first temperature which is higher than the initial temperature and cooled to a second temperature which is lower than the first temperature. The second temperature is

for example again as high as the room temperature or slightly higher. Thus, for example, the base material is heated and then cold quenched again, thereby hardening. The first temperature is in the range of, for example, several 100 ° C, for example 500-1300 ° C, the third temperature e.g. in the range of 200-350 ° C.

It is preferably provided that the base material of the support section is a material which, after cooling to the second temperature, has a third temperature which is higher than the second temperature, but which is lower than that first temperature is, has been heated. The last step of reheating corresponds to the tempering mentioned above, for example.

A consolidation or hardening of the at least one support section can, however, also by mechanical action, in particular an impulse or

striking mechanical action to form the support section. It is particularly favorable if the support section is formed by shot peening, rolling, rolling or combinations thereof. Individual parts of the base body of the coupling body or coupling arm are thus mechanically solidified in a targeted manner. The at least one support section can be solidified, for example, by cold working and / or hot working.

The support section can be produced not only by machining the base material of the base body, but also by using a support body that is separate from the base body, so to speak.

The at least one support section can be provided, for example, on a support body which is connected to the base body of the coupling arm or

Coupling body is firmly connected and is formed from a material which has a higher strength and / or hardness than the base material of the base body of the coupling arm or coupling body. Thus, the support body can consist of a completely different material than the base material of the base body, for example of a different metal, in particular of a metallic alloy with higher hardness and strength than the base material of the base body. Ceramics or the like can also be readily used in the support body.

The support body preferably comprises or is a wall body, which is arranged in the manner of an outer wall on the base body and / or surrounds the base body in the manner of a shell. Furthermore, it is possible that the support body as a

Shell body is designed. The shell body can in particular be shaped in the manner of a spherical shell. So it is possible, for example, that the coupling body is a coupling ball, the jacket of which is wholly or partly of that Support body is formed. The at least one support body can thus form a spherical jacket segment, for example.

The at least one support body is accommodated, for example, in a recess in the base body.

The at least one support body and the base body of the coupling body or coupling arm preferably form the complementary outer surface of the coupling body or coupling arm. The outer surface parts of the

The support body and the base body are arranged, for example, next to one another and / or adjoin one another. In particular, they go

Outer surface portions of the support body and base body preferably over one another in a stepless manner. The outer surface parts of the support body and base body are preferably aligned with one another. For example, the

Outer surfaces of the dome body and support body have a spherical surface.

The base body of the dome body and the support body can also form the dome body complementarily. For example, the support body and the base body of the dome body can have disc sections,

Be or have spherical segment sections. For example, it is possible for the base body of the coupling body to have a neck section or holding section for connection to the coupling arm, in particular a coupling body neck of the coupling arm. A partial sphere or a spherical segment is then arranged on this base body, for example. For example, the

Form the base body of the dome body and the support body spherical body parts. For example, a ball upper part can be provided by the support body, while a ball lower part is provided by the base body. Both the upper ball part and the lower ball part can have flats. For example, there may be no spherical cap on the upper spherical part or a flattened portion may be provided on the upper spherical part. Even in the transition of

A step, for example a flat surface or a flat surface, can be provided for the coupling body to the coupling arm. This step or plane surface is preferably arranged on the base body. The coupling body can easily be designed as a coupling ball, but also other geometries, for example polygonal geometries

Have a load carrier attached.

The support body is preferably integrally connected to the base body, for example glued, soldered or welded.

The support body is furthermore preferably connected to the base body in a form-fitting manner, for example on the basis of undercuts, pins or the like. It is also easily possible to screw the base body and support body. For example, it is possible for a screw to pass through the support body and the base body and to be connected to the coupling arm.

The support body is preferably connected to the base body by means of at least one retaining projection or retaining pin, which is, for example, from the

Support body or protrudes from the base body and engages in a receptacle on the base body or support body. If, for example, one or more retaining pins or retaining projections protrude from the supporting body, they engage

expediently in corresponding holding receptacles on the base body. The reverse configuration is also possible for one or more

Protruding protrusions protrude from the base body and engage in the support body.

The support body is expediently held on the base body by means of at least one undercut. The undercut is on one, for example

Recording provided for a holding projection. The undercut can

For example, be formed by a bottom region of the receptacle for the holding projection, which has a larger cross section than an insertion opening of the receptacle. The undercut is preferably provided at an edge region between the support section and an outer surface section of the base body, so that the support body and the base body engage in one another in a form-fitting manner.

For example, the undercut comprises a groove into which a tongue or another projection of the support section engages. The support body or the at least one support section can also be formed by coating the base body. The coating can be applied, for example, by thermal spraying, a casting process or the like. For example, a liquid ceramic material can be cast onto the base body of the dome body or the body in a casting process

Coupling arm are applied.

The support section preferably comprises a ceramic material, for example from the field of technical ceramics. The ceramic material can be fiber-reinforced, for example. However, the support section can also comprise or be formed from a metallic alloy, in particular based on nickel-chromium.

The coupling device of the trailer or load carrier is advantageously adjustable between a locked or closed closed position and an open position. The open position is for removing the

Coupling device of the trailer or load carrier provided by the coupling body. The closed position is provided for holding the coupling device on the coupling body for the motor vehicle to operate with the trailer or load carrier. For example, the coupling device has a closing body that is adjustable between the closed position and the open position or release position.

For a permanent, firm hold of the coupling device of the trailer or load carrier, it is advantageous if the base material of the coupling body has a minimal cross section, which means that the locked or removed

locked coupling device prevented by the coupling body.

For example, an equatorial area of a spherical dome body is provided so that the coupling device of the trailer or load carrier cannot be removed. In particular, the coupling device with the

Dome body in the case of the load carrier rotatably and / or fixedly connected or in the case of the trailer form a ball joint connection.

It is advantageous for the underhand grip or underhand grip of a coupling member

Coupling device provided with the coupling body. The dome of the Trailer coupling can no longer be removed from a coupling receptacle of the coupling device when the coupling member is in its closed position or holding position, for which purpose the minimum holding cross section is provided.

The at least one support section expediently does not extend to the minimum holding cross section. Thus, for example, the hardened or firmer area is provided outside the minimum holding cross section, so that it prevents or minimizes corresponding wear of the coupling body. The minimum holding cross section, however, which is made of the base material of the base body, is less hard or hard, so it tends to

Frictional load to higher wear, but is on the other hand more ductile or elastic, so that it ensures a reliable hold of the coupling device of the trailer or load carrier even if, for example, the support section is completely or partially worn. For example, a coating of the base body providing the support section can be removed or a support body configured as an insert can break. Also in this one

Situation, a reliable hold of the coupling device on the coupling body is possible.

The base material of the dome body base forms in the area of the

Minimal holding cross section expediently the outer surface of the

Dome body. Thus there is therefore no support section, not even a section of the support section.

However, a configuration is also possible in which the support section is also in the region of the minimum holding cross section or on the outside

at least partially covered. This ensures optimal wear resistance of the coupling body. In this situation, however, it is advantageous if the support section has the dome body in the region of the minimum holding cross section

covered on the outside with such a material thickness that the coupling body has a maximum holding cross-section, in which the coupling device of the trailer or load carrier into one for holding the trailer or

Load carrier for coupling operation provided coupling position is adjustable in which the coupling body is received in a coupling receptacle of the coupling device, for example rotatably in the case of the trailer or fixed in a fixed manner in the case of the load carrier. For example, in a so-called standard ball coupling according to the standard “ECE-R 55

Connection devices “the maximum diameter 50 mm, while the minimum diameter must be 49 mm. The material thickness of the support section in this case is, for example, a maximum of 0.5 mm. However, it is advantageous if the base body of the coupling body has a minimally larger cross-section than the minimum dimension or as necessary for the minimum holding cross-section, so that even with maximum wear of the support section, the coupling device of the trailer or load carrier remains reliably held on the

Dome body is possible.

The at least one support section advantageously comprises an upper support section at one of a connection point of the coupling body with the coupling arm

top of the dome body facing away, for example above a maximum cross section of the dome body, in particular the aforementioned holding cross section. The connection location is, for example, the transition from a coupling body neck or neck section of the coupling arm into the coupling body.

Also advantageous is a lower support section on an underside facing from a connection point of the coupling body to the coupling arm,

for example below a maximum cross section or holding cross section of the dome body.

One or more supporting parts can be provided both on the top and on the bottom of the dome body. A single upper-side support section and a single lower-side support section are preferred

intended.

It is preferably provided that the upper support section and the lower one

Support section on the dome body depending on an intended Installation position of the coupling arm, in particular its fastening section, are arranged on the motor vehicle.

In practice it has proven to be useful if the upper support section on one

Attachment to the motor vehicle provided longitudinal end of the coupling arm is facing. The upper support section is thus, for example, in

Vehicle longitudinal direction or forward direction of travel of the motor vehicle at the front. The lower support section is advantageously from one for attachment to

Motor vehicle facing away from the longitudinal end of the coupling arm.

However, it is also possible for the upper support section to face away from the longitudinal end of the coupling arm provided for attachment to the motor vehicle or to be oriented towards a free side of the trailer coupling. In this situation, it is advantageous if the lower support section faces the longitudinal end of the coupling arm provided for fastening to the motor vehicle. Such an arrangement is advantageous, for example, if the installation location of the

Trailer coupling on the motor vehicle is high, so that a drawbar of a trailer attached to the trailer coupling has an oblique orientation with an increasing sense away from the motor vehicle when the combination consisting of the towing vehicle or motor vehicle and trailer stands or drives on a common flat surface.

It can be provided that only a single upper and / or only a single lower support section of the aforementioned type are provided. It is particularly preferred if a single upper and a single lower support section are present, the one support section being arranged above the equator and the other support section being arranged on a transverse central plane of the coupling body and / or below the equator of the coupling ball.

The at least one support section expediently comprises a support section on the coupling body, which extends over an angular range of at most 70 ° to the side next to a longitudinal central axis or longitudinal central plane, which is parallel to a main longitudinal axis of the coupling arm or in the motor vehicle assembled state of the trailer coupling to the vehicle's longitudinal axis

Motor vehicle is parallel. The longitudinal center plane is, for example, at right angles to the equatorial plane in which an equator or equator area of the coupling ball lies. The longitudinal center plane is, for example, a vertical plane, the equatorial plane is a horizontal plane in the position of use of the trailer coupling, for example when it is attached to a motor vehicle which is on a horizontal plane. The main longitudinal axis of the coupling arm is, for example, that axis which runs approximately between the longitudinal end regions of the coupling arm, the coupling body being arranged on one longitudinal end region and the other longitudinal region serving for fastening to the motor vehicle. The main longitudinal axis of the coupling arm and / or the longitudinal central axis and / or the longitudinal central plane of the coupling body extends, for example, in the so-called X direction. The angular range extends from the X direction or X axis in the direction of an in the Y axis, which extends, for example, in the transverse direction of the motor vehicle and / or transverse to the main longitudinal axis of the coupling arm, in the aforementioned angular range. The angular range is preferably provided symmetrically, i.e. that the support section laterally next to the longitudinal center axis of the dome body with the same

Angle range extends, for example, 70 °. However, the angular range can also be smaller, for example a maximum of 50 °, preferably a maximum of 40 ° or only 30 °. It is therefore preferred if the at least one support section or all support sections is or are symmetrical with respect to the longitudinal central axis or longitudinal central plane of the dome body. For example, such a support section extends at the same angles to opposite sides of the central longitudinal axis on the dome body.

In particular, for example, the aforementioned upper support section, like the lower support section, can extend laterally alongside the longitudinal central axis over such an angular range.

It is advantageous if the support section or the plurality of support sections is first

Portions of the outer surface of the dome body, for example the

Coupling ball, provide when operating or using the Trailer coupling are in contact with the coupled coupling device of the load carrier or the trailer, that is to say with a coupling ball

for example, their spherical surface, while other portions of the

The outer surface of the dome body, for example the coupling ball, is formed by the base material or base body of the dome body. Thus, for example, parts of the spherical surface are reinforced by the support parts, while other parts are not reinforced.

It is advantageously provided that the first partial surfaces one when using the

Trailer coupling in contact with the load carrier or trailer standing area of the outer surface of the coupling body, in particular the

Coupling ball, are formed from the base material of the base body of the coupling body, in particular the coupling ball, and second partial surfaces of the area of the outer surface of the coupling body, in particular the coupling ball, which is in contact with the load carrier or trailer when using the trailer coupling, of the at least one supporting part or an arrangement a plurality of support sections comprising at least one support section are formed. The first partial areas can of course only be formed by a single first partial area. Likewise, the second partial surfaces can also be formed by only a single second partial surface, for example if on one

Coupling ball only a single support section is arranged.

A maximum of six, in particular a maximum of four, particularly preferably a maximum of two support sections are preferably provided on the dome body.

In principle, it is possible that the at least one support section

is punctiform or linear. In practice, however, it is advantageous if the support section or support sections have a minimum surface area or are flat. For example, the at least one support section has a flat shape and provides at least 10%, preferably at least 20%, in particular at least 30%, of an area of the outer surface of the coupling body, in particular the coupling ball, which is in contact with the load carrier or trailer when the trailer coupling is in use. The total area of the support sections can be larger or smaller than that

Total area of the base material of the dome body

Outer surface. For example, it can be provided that an entire surface area of the second partial areas is smaller or larger than a total surface area of the first partial areas. It is advantageous, for example, if the total surface area of the second partial areas is a maximum of 75%, in particular a maximum of 60%, further preferably a maximum of 50% of the total surface area of the first partial areas.

The coupling arm advantageously has an arm body and a fial section or dome body neck, which is arranged between the arm body and the dome body. The dome body neck has, for example, an essentially circular cylindrical cross section and / or a cylinder shape. Furthermore, the already mentioned attachment part is provided on the coupling arm. The

Fixing part is used, for example, for the fixed attachment of the

Trailer coupling on the motor vehicle, e.g. for screwing, welding or the like. The fastening part is, for example, firmly connected to a cross member, which is to be mounted on the spot of the motor vehicle, is pluggably connected by a plug-in connection, or is movably supported by means of a bearing arrangement.

It when the coupling arm between a

Use position, in which he is behind the stain of a motor vehicle

Attaching the trailer or coupling the load carrier protrudes, and is adjustable, in particular pivotable, a non-use position, in which it protrudes less far from the spot of the motor vehicle than in the

Position of use. The coupling arm is in the non-use position

for example, completely or essentially hidden behind a stain apron, a bumper or the like of the motor vehicle.

As has already been made clear, the at least one support section can also be provided on the coupling arm. The particularly stressed areas of the coupling arm are preferably reinforced by one or more support parts. For example, the at least one support section is located on the dome body neck and / or on an end region of the arm body that supports the dome body neck.

The support section can have different material thicknesses. For example, it is advantageous if it is in a transition area to a

Outer surface of the base body of the coupling arm or coupling body is less than at a greater distance from the transition area. For example, a particularly stressed area, for example an area of the support section along the longitudinal central axis of the dome body, can be larger

Have material thickness than that area of the support section which is further away from the longitudinal central axis. For example, in the case of the aforementioned angular areas, the outer areas, as it were outer or angular or most distant from the central longitudinal axis, can have a lower material thickness than the central section of the support section in the area of the central longitudinal axis of the dome body.

It is also possible for the coupling arm to have one or more support sections. A support section on the coupling arm is, for example, harder or stronger in the area of its outer surface than in the direction of a cross-sectional center of the coupling arm, for example in the area of a neutral fiber of the

Clutch arm. Thus, the coupling arm is somewhat softer in the area of its neutral fiber or cross-sectional center, so to speak, while it is in the

Outdoor area is harder and firmer.

The base body of the coupling arm and coupling body, which can also be in one piece, are, for example, castings and / or forgings or through

Forged components.

It is preferred if the arm body and dome body neck and / or the

Coupling arm and the coupling body and / or the coupling body neck and the coupling body are made in one piece and / or from a common blank. While it is advantageous for the dome body neck to have an annular cross section or to be cylindrical, it is possible for the arm body to have a substantially non-annular cross section. For example, the arm body has ribs, support structures or the like, which are not provided for the dome body neck.

It is also advantageous that the arm body immediately next to the

Dome body neck has a larger cross-sectional area than the dome body neck.

The coupling ball is expediently flattened at its area facing away from the dome body neck.

The coupling ball can expediently be designed as a spherical segment ball, each of which has a flattened portion, in particular a flat surface, on its region facing away from the coupling body neck and facing towards the coupling body neck. The flats can serve, for example, as a placement aid or support surfaces for a load carrier.

The coupling ball and / or the coupling body neck and / or the coupling arm are expediently produced by forming. Forming is particularly suitable for forging, upsetting, rolling or profiling. As mentioned, the forming expediently takes place in the warm, in particular in the hot, state of a blank for producing the

Clutch arm instead.

However, it is also easily possible to cut or forge a blank, at least in sections, to produce the coupling body and / or the coupling arm.

The coupling arm, in particular the dome body neck, and the coupling ball preferably consist of metal, in particular of steel or aluminum. In particular, it is advantageous if the coupling arm as a whole consists of steel or aluminum, at least in the section where it is connected to the coupling body neck and the coupling ball or is in one piece. For example, so-called structural steel, higher strength materials, for example from the group of tempered steels or precipitation hardening, are preferred

ferritic-pearlitic steels or AFP steels. Bainitic steels are also advantageous.

Exemplary embodiments of the invention are explained below with reference to the drawing. FIG. 1 shows a partially schematic side view of an arrangement

comprising a motor vehicle and a load carrier which is arranged on a trailer coupling according to the invention,

Figure 2 is a side view of a coupling arm and a coupling body of the trailer coupling according to Figure 1, Figure 3 shows a longitudinal cross section through a front part of the

Coupling arm and the coupling body according to FIG. 2,

Figure 4 is a side view corresponding approximately to Figure 1, but with a coupling device coupled to the coupling body of a trailer, Figure 5 is a plan view from above of a front part of the

Trailer coupling according to the above figures,

Figure 6 is an exploded view of the trailer coupling according to

above figures with support bodies not yet assembled,

Figure 7 is a side view of another embodiment of a

trailer coupling according to the invention, Figure 8 is a side view of a third embodiment of a trailer coupling according to the invention.

A trailer coupling 10 is, for example, on a motor vehicle 80

arranged. A load carrier 90 or a trailer 190 (shown schematically in FIG. 4) can be coupled to the trailer coupling 10, so that, for example, a load, in particular bicycles F, or also on a

Trailer 190 loads to be transported by the motor vehicle 80

can be transported. The motor vehicle 80 is, for example, a

Motor vehicle with an internal combustion engine, electric motor or hybrid motor In any case, the loading capacity or transport capacity of the motor vehicle 80 can be increased by the load carrier 90 or a trailer 190.

The trailer coupling 10 comprises, for example, a carrier arrangement 11 which can be fastened to a body 81 of the motor vehicle 80. The carrier arrangement 11 comprises, for example, a cross member and side members or side members which can be fastened, for example screwed, to the body structure of the body 81.

A holder 12 of the trailer coupling 10 is fastened to the carrier arrangement 11. The holder 12 carries a clutch arm 20 or holds a clutch arm 20. The clutch arm 20 is based on a bearing 13 between a use position G shown in FIG. 1, in which the clutch arm 20 essentially protrudes in front of a bumper 83 of the motor vehicle 80, and one

Non-use position N adjustable, where it is in particular hidden behind the bumper 83 on the motor vehicle 80.

In the use position G and preferably in the non-use position N, the coupling arm 20 can be locked using a locking device 15, for example using a positive lock or the like. The locking device 15 has, for example, form-fitting elements which can engage in a form-fitting manner in form-fitting receptacles 18 on the bearing body 14. Using a drive 16, the coupling arm 20 can be unlocked in order to be adjusted between the use position G and the non-use position N, for example to be pivoted or to be shifted linearly or both. Thus, the bearing 13 is, for example, a swivel bearing,

Sliding bearing or swivel sliding bearing. But that is not the main thing.

The coupling arm 20 can also be held firmly on the holder 12, for example by means of a screw connection, or releasably connectable to the holder 12 using a plug connection.

For adjustment between the use position G and the

When not in use N, a drive 17 is preferably provided, which can also be referred to as a swivel drive.

The coupling arm 20 has an arm body 26 with a longitudinal end 21 which is provided for connection to the holder 12, that is to say forms a fastening part 21 A or on which a fastening part 21 A is arranged.

For example, the arm body 26 is firmly connected to a bearing element 14, for example a bearing head, in particular in one piece. The bearing element 14 is pivotally and / or displaceably mounted on the holder 12, for example by means of a bearing pin.

A curvature section 22 adjoins the longitudinal end 21. Of the

Curvature section 22 serves, so to speak, so that the coupling arm 20 can protrude upward under the bumper 83 in the use position G. The curvature section 22 is adjoined by an essentially straight arm section 23 which merges into a further curvature section 24. It can be seen that through the curved sections 22, 24 a

Adaptation to an outer contour of the motor vehicle 80 is realized, so that ultimately a coupling body 30, in particular a coupling ball 31, is arranged on the curved section 24 of the coupling arm 20, the end region 25 of the coupling arm 20, an upwardly oriented and for Attaching a trailer or coupling a load carrier, for example the load carrier 90, has a suitable orientation. The curved section 22 serves, for example, to adapt to a bumper contour 84 of the motor vehicle 80.

A coupling device 93 of the load carrier 90, with which the load carrier 90 is fastened to the trailer coupling 10, in particular the coupling body 30, acts with great force on the coupling arm 20 when the motor vehicle 80 is coupled with the load carrier 90 coupled, in particular in the region of the

End region 25. There is essentially a dome body neck 50

cylindrical shape is provided, which is not necessary in this so to speak slim or narrow version for operation with the load carrier 90, but for operation with a trailer 190 or a coupling device 193 of the trailer 190, for example a so-called ball coupling.

So that the coupling device 193 namely sufficient

Has rotational mobility in the manner of a ball joint on the coupling ball, there is a corresponding free space below the coupling body 30, which is given by the coupling body neck 50, the outer diameter of which is smaller than that of the coupling body 30.

The coupling device 193 has a receiving space 194, into which the coupling body 30 engages when the trailer 190 is coupled to the motor vehicle 80. The receiving space 194 can be closed by a locking jaw 195 of the coupling device 193, so that the coupling body 30 is fixed in the receiving space 194 but is rotatably or pivotally received.

The locking jaw 195 is adjustable between an open position O, which is provided for removing the coupling device 193 from the coupling body 30, and a closing position S, in which the coupling device 193 for

Ferry operation of motor vehicle 80 is closed or locked with the trailer 190. Then the dome body 30 in the receiving space 193 is articulated

added. In the case of the load carrier 90, one or more bicycles F, which can also be, for example, electric bicycles, are fastened or can be fastened to the supporting structure 91, for example a carrying frame. There are also load carriers that can carry up to four bicycles. The load that loads on the load carrier 90 and acts on the coupling arm 20, in particular the coupling body neck 50 and the transition between the coupling body neck 50 and the coupling body 30, is correspondingly heavy. The effect is further enhanced by the fact that the load carrier 90 protrudes far in front of the rear 82 of the motor vehicle 80, for example because the coupling device 93 is arranged on a correspondingly elongated support projection 92. In practice, this can result in the coupling body 30 or the coupling ball 31 breaking off from the coupling body neck 50, for example.

The coupling ball 31 has a spherical surface 32, however

Has flattenings, for example a flat 33 on its upper side 34 and on its underside 35 a further flat 36, where the coupling ball 31 or the coupling body 30 is connected to the coupling body neck 50, for example is integrally connected to it or is screwed to it.

The ball surface 32 forms an outer surface of the coupling body 30 or the coupling ball 31 when the coupling body 30 or the coupling ball 31 is in contact with the coupling device 93 or 193. The flat 33 and the flat 36 are not in regular contact with, for example, the coupling device 193.

A connection location 51 with the dome body neck 50 is provided on the flattened area 36. Between the flats 33 and 36, so to speak at the equator AQ of the coupling ball 31, which runs parallel to the flats 33, 36, the coupling body 30 or the coupling ball 31 has a holding cross section 37. With the closing jaw 195 closed, the coupling device 193 of the

Trailer 190 can not be moved over this holding cross section 37, ie the closing jaw 195 engages under the coupling ball 31 on its underside 35, so to speak. This represents a safety measure.

It is accordingly advantageous if the base material is a

Base body 38, which forms the coupling ball 31, in the area of

Holding cross section 37 is present and / or forms parts of the outer surface, in particular the spherical surface, of the coupling ball 31, that is to say, for example, none of the reinforcements or support parts explained below are provided there.

The holding cross section 37 is, for example, a maximum of 50 mm and a minimum of 49 mm for a standard ball for the European area.

For example, the base material of the base body 38 is in an equatorial region AB around the equator AQ without one of the reinforcements explained below and / or extends to the outer surface of the

Dome body. The equatorial region AB of the outer surface of the coupling body 30 or of the coupling body 130 to be explained extends above and / or below the equator AQ, in particular in an angular range AW1 above the equator AQ and / or AW2 below the equator AQ. A respective angle on which the angular range AW1 or AW2 is based is, for example, 15 ° to 20 ° with respect to a center Z of the coupling body 30, 130 or

Coupling ball 31.

In practice, however, it was found that the coupling ball has 31 typical wear zones. These wear zones extend, for example, in an angular range W1 with respect to a longitudinal center axis L and one

Angular range W2 with respect to the longitudinal center axis L of the coupling body 30. The longitudinal center axis L runs parallel to the forward direction of travel V des

Motor vehicle 80 or to its longitudinal axis direction when the coupling arm 20 is in the use position G. The longitudinal central axis L runs in one

Longitudinal center plane LM of the dome body 30. The longitudinal center plane is LM for example at right angles to an equatorial plane AE, in which the equator of the coupling body 30 or the coupling ball 31 lies.

The front wear zone in the direction of travel V is located on the upper side 34 of the coupling body 30, where corresponding forces act on the coupling body 30 when the trailer 190 is subjected to tensile loads or a tensile load. There is coupling body 30 in the sense of a pulling and supportive contact in the receiving space 194 of the coupling device 193, which leads to increased

Wear leads. In the direction of travel, i.e. opposite to

Forward driving direction V, the further wear zone is on the underside 35 of the coupling body 30, where the locking jaw 195 acts. In practice, this has shown a partial wear of the coupling ball, which is counteracted with the following measures.

On the front part of the top 34, that is, on the front 39 of the

Coupling ball 31, a support section 60 is provided, while in the direction of travel, a support section 61 is provided at the rear, ie on the underside 35 or rear side 40 of the coupling body 30. Thus, a reinforced support section is provided wherever there is particular wear during operation or pulling of the trailer 90.

The support sections 60, 61 extend, for example, in whole or in part over the angular ranges W1 and W2, starting from the longitudinal central axis L of the dome body 30. The angular ranges W1 and W2 are between 30 and 60 degrees, for example.

It is advantageously provided that the support sections 60, 61 are provided precisely at those points at which particularly high loads and high wear occur in practice or during ferry operation or trailer operation. For example, the support parts 60, 61 are for a first installation position

Fastening section 21 A of the coupling arm of the trailer coupling 10 on

Motor vehicle 80 is provided, for example at a first distance from a road surface, as alternative support parts 60A, 61A for a second Installation position of the fastening part 21 A are provided, which is higher or lower than the first installation position, for example. For example, the support sections 60A,

61 A is provided for an off-road vehicle or an SUV (Sports Utility Vehicle), while the support sections 60, 61 for a less high one

Motor vehicle, for example a sedan or a combination motor vehicle, are provided.

However, there are no reinforcement measures or support parts on the right angle at right angles to the longitudinal central axis L, that is to say in the region of a transverse axis Q.

Dome body 30 is provided. There is the holding cross section 37 of the

Base body 38 of the dome body 30, so to speak, directly for support or

Holding the coupling device 93, 193 of the load carrier 90 or the

Trailer 190 available.

The support section 60 and / or 61 is formed, for example, by a support body 62. The support body 62 can, for example, be adhesively bonded to the base body 38 of the dome body 30, welded on or in another manner integrally connected to it, for example also soldered.

On the base body 38 there are recesses 42 for example

Support body 62 available.

Outer surfaces 45 and 65 of the base body 38 and the support body 62 merge continuously into one another and / or are flush with one another at the edge region 43, so that they together form the homogeneous spherical surface 32.

The support bodies 62 are made of ceramic, for example, while a base material 41 of the dome body 30 is a metallic base material.

At the edge regions 43 of the recesses 42, undercuts 44, shown schematically and in an enlarged manner, for example undercuts 44 extending transversely to the bottom surface of the respective exception 42, into which a respective support body 62 engages, can be provided, so that a positive support of the support body 62 in the recess 42 and thus on the coupling body 30 is given.

The support bodies 62 can, however, also be attached or arranged in the recesses 42 by injection molding, in particular thermal spraying or the like.

A further exemplary embodiment according to FIG. 7 in the case of a coupling body 130 which is designed as a coupling ball 131 provides a support body 162 which extends over the entire ball surface 32 of the coupling ball 131. The support body 162 is provided, for example, as a coating on the base body 138 of the dome body 130.

Alternatively, it is also possible for the support body 62 to extend, for example, only over the equatorial region AB. In this case, it is advantageous if the equatorial region has a larger extension or extension above and / or below the equator AQ. For example, in this case the angles AW1 and / or AW2 are not only 15 ° to 20 °, but advantageously approximately or at least 30 °, approximately or at least 35 °, particularly preferably approximately 45 °.

The base body 138 is in itself a spherical body with a diameter which is also provided at its equatorial region AB. As a result, the base body 138 has a minimum holding cross section 137A. In particular, it is advantageous if the entire or essentially the entire spherical surface 32 is provided with the support body 162. It is possible that the upper flat 33 and / or the lower flat 36 is also provided with the support body or the support section which is formed by the support body. But it is also sufficient if, for example, only that

Spherical surface 32 is provided with the support body 62.

The support body 162 can engage with one or more holding projections 163 in holding receptacles 145 of the base body 138. The holding receptacles 145 have floor areas 145A with a cross section that is larger, for example is its penetration opening 145B for the holding projections 163 so that undercuts 144 are formed there.

The material thickness of the support body 162 now ensures that the dome body 130 has an additional coating in the region of the holding cross section 137A, so that the base body 138 including the supporting body 162 forms a maximum holding cross section 137B. The maximum cross section 137B is, for example, 50 mm, while the minimum holding cross section 137A is 49 mm or somewhat more, for example 49.2 mm.

If the support body 162 is now worn or destroyed in the area of the holding cross section 137, the minimum holding cross section 137A of the base body 138 is still available for holding the coupling device 93 or 193, so that it is in the closed state or fastened to the trailer coupling 110 is not removable from the dome body 130.

Of course, the coupling arm 20 can also be reinforced in the manner according to the invention. It is particularly advantageous if, for example, the

Dome body neck 50, in particular in the area of the connection location 51, has a support section 70. The support section 70 is formed, for example, by shot peening, hardening or by the like otherwise compressing or hardening a base material 29 of a base body 28 of the coupling arm 20. The dome body neck 50 has, for example, an essentially circular cylindrical cross section.

The support section 70 can comprise zones of different hardness, for example zones 70A, 70B. For example, zone 70A faces a longitudinal end 21 of coupling arm 20 provided for attachment to motor vehicle 80, and zone 70A faces away from this longitudinal end 21. Zone 70A may be harder than zone 70B or vice versa. It is also readily possible that only one of the zones 70A, 70B is provided, ie that no support section or support measure is provided in the region of the zones 70A or 70B shown. Furthermore, it is possible for a support section to extend only over a predetermined length of the coupling body neck 50 with respect to its longitudinal extent LH between the coupling arm 20 and the coupling body 30,

for example only over a longitudinal section LH1 or a longitudinal section LH2. For example, the support section 70 as a whole can only extend over the longitudinal section LH1 or the longitudinal section LH2. Zones 70A, 70B can only extend over part of the longitudinal extent LH of the

Dome body neck 50 extend.

A support section, for example a support section 170, may also be provided in the area of the arm body 26 in the area of one of the two curved sections 22 and / or 24 which are particularly stressed during operation. For example, the base material 29 of the coupling arm 20 is in the region of the

Curved section 24 is compressed by shot peening or the like, another hardening measure for producing the support section 170.

It would be readily possible to insert support bodies in the manner of the support bodies 62 or 162 into the coupling arm 20. It is also possible to use the

To provide the coupling arm 20 with a coating, for example in the region of the coupling body neck 50.

A coupling body 230 of a trailer coupling 210 is, for example, in several parts.

A base body 238 forms, for example, a lower part of the coupling body 230, in particular a lower part of the coupling ball 231, which is complementarily formed by a supporting body 262. The support body 262 is with the

Base body 238 firmly connected, for example welded, glued or the like.

Also both the support body 262 and the base body 238

connecting element 275, for example a screw, can be used to fasten the support body 262 to the base body 238. The

Connecting element 275 can be used, for example, to connect the support body 262 and the base body 238 with a schematically illustrated coupling arm 220 of the trailer coupling 210.

The material of the support body 262 is harder and / or stronger than the base material 241 of the base body 238. For example, the support body 262 consists of a ceramic material, while the base body 238 consists of metal. It is also possible for the support body 262 to be made of a harder metal than the base body 238.

Although the support body 262 may be somewhat more brittle or fragile than the base body 238, the coupling device 193 or 93 is firmly held on the coupling body 230 even if the support body 262 is damaged. Of the

Base 238 namely extends from the connection point 251 of the

Coupling arm 220 with the coupling body 230 up to a maximum

Holding cross section 237 of the dome body 230.

Claims

Expectations

1. Trailer coupling for a motor vehicle (80), the trailer coupling (10) having a coupling arm (20), on one end region (25) of which a coupling body (30), in particular a coupling ball (31) for attaching a trailer (90) or Coupling a load carrier to the motor vehicle (80) is arranged, characterized in that on the coupling body (30) and / or the coupling arm (20) at least a part of a respective outer surface of the coupling body (30) and / or the coupling arm (20 ) forming support section (60, 61, 70) is provided, which, in particular the material thereof, is one compared to an in particular metallic base material (41)

Base body (28, 38) of the coupling body (30) or coupling arm (20), on which the support section (60, 61, 70) is arranged or which supports the support section (60, 61, 70), has higher strength and / or hardness .

2. Trailer coupling (10) according to claim 1, characterized in that the base material (41) in the region of the at least one support section (60, 61, 70) for

Formation of the support section (60, 61, 70) is solidified or hardened.

3. Trailer coupling according to claim 1 or 2, characterized in that the base material (41) in the region of the at least one support section (60, 61, 70) hardened, in particular thermally and / or inductively and / or by

Laser exposure is hardened.

4. Trailer coupling according to one of the preceding claims, characterized in that the base material (41) in the region of the at least one support section (60, 61, 70) by mechanical action, in particular pulsed mechanical action, to form the support section (60, 61, 70) is solidified or hardened.

5. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) through

Shot peening and / or rolling and / or rolling is formed.

6. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) is provided on a support body (62, 162) which with the base body (28, 38) of the coupling arm (20) or Dome body (30) is firmly connected and is formed from a material which has a higher strength and / or hardness than the base material (41) of the base body (28, 38).

7. Trailer coupling according to claim 6, characterized in that the support body (62, 162) is a wall body which is arranged in the manner of an outer wall on the base body (28, 38) and / or surrounds the base body (28, 38) in a shell-like manner and / or that the support body (62, 162) is designed as a shell body, in particular shaped in the manner of a spherical shell.

8. Trailer coupling according to claim 6 or 7, characterized in that the at least one support body (62, 162) and the base body (28, 38) of the coupling body (30) or coupling arm (20) complement each other

Form the outer surface of the dome body (30) or coupling arm (20), the outer surface parts of the support body (62, 162) and the base body (28, 38) being arranged next to one another and / or adjoining one another and / or continuously merging.

9. Trailer coupling according to one of claims 6, 7 or 8, characterized

characterized in that the base body (28, 38) of the dome body (30) and the support body (62, 162) complementary form the dome body (30) and / or have a disk section and / or a spherical segment section, and / or as a spherical segment and / or are designed as spherical body parts.

10. Trailer coupling according to one of claims 6 to 9, characterized in that the support body (62, 162) with the base body (28, 38) is integrally connected, in particular glued and / or soldered and / or welded. 11. Trailer coupling according to one of claims 6 to 10, characterized

characterized in that the support body (62, 162) on the

Main body (28, 38) held and / or with the main body (28, 38)

is screwed.

12. Trailer coupling according to one of claims 6 to 11, characterized

characterized in that the support body (62, 162) is connected to the base body (28, 38) by means of at least one holding projection (163) or holding pin which protrudes in front of the support body (62, 162) or the base body (28, 38) a receptacle (145) on the other of the support body (62, 162) and

Basic body (28, 38) engages. 13. Trailer coupling according to one of claims 6 to 12, characterized

characterized in that the support body (62, 162) using at least one

Undercut (44, 144) is held on the base body (28, 38).

14. Trailer coupling according to claim 13, characterized in that the undercut is provided at an edge region (43) between the support section (60, 61, 70) and an outer surface section of the base body (28, 38), so that the support body (62, 162) and the base body (28, 38) interlock positively.

15. Trailer coupling according to one of claims 6 to 14, characterized

characterized in that the support body (62, 162) or the at least one

Support section (60, 61, 70) is formed by a coating of the base body (28, 38).

16. Trailer coupling according to claim 15, characterized in that the coating is formed by thermal spraying and / or a casting process.

17. Trailer coupling according to one of the preceding claims, characterized in that the support section (60, 61, 70) comprises a ceramic material, in particular from the field of technical ceramics, and / or a metallic alloy, in particular based on nickel-chromium is thereby formed.

18. Trailer coupling according to one of the preceding claims, characterized in that the base material (41) of the base body (28, 38) of the coupling body (30) has a minimum holding cross-section (137A) which is provided in particular on its equatorial region (AB) and which has a Removal of a coupling device (93, 193) of the trailer (90) or load carrier from the coupling body (30) is prevented when the coupling device (93, 193) assumes its locked and / or closed position (S) provided for driving the trailer with the motor vehicle.

19. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) does not extend to the minimum holding cross section (137A) and / or the base material (41) of the base body (28 , 38) in the area of

Minimum holding cross-section (137A) forms the outer surface of the dome body (30). 20. Trailer coupling according to one of the preceding claims, characterized in that the support section (60, 61, 70) covers the coupling body (30) on the outside in the region of the minimum holding cross section (137A) with a material thickness such that the coupling body (30) has a

Maximum holding cross-section (137B), in which the coupling device (93, 193) of the trailer (90) or load carrier in one for holding the trailer

(90) or load carrier for a coupling operation is adjustable, in which the coupling body (30) in a coupling receptacle (20) of the coupling device (93, 193), in particular rotatable in a ball joint,

is included.

21. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) an upper support section (60, 61, 70) at one of a connection point of the coupling body (30) with the coupling arm (20) top of the dome body (30) facing away, in particular above a maximum cross section of the dome body (30), and / or a lower support section (60, 61, 70) at an underside facing a connection point of the dome body (30) to the coupling arm (20), in particular below a maximum cross section of the dome body (30). 22. Trailer coupling according to one of the preceding claims, characterized in that the upper support section (60, 61, 70) faces a longitudinal end (21) of the coupling arm (20) provided for attachment to the motor vehicle (80) and / or the lower support section ( 60, 61, 70) from one to the other

Attachment to the motor vehicle (80) provided longitudinal end (21) of the

Coupling arm (20) is facing away.

23. Trailer coupling according to claim 21 or 22, characterized in that the lower support section (60, 61, 70) faces a longitudinal end (21) of the coupling arm (20) provided for attachment to the motor vehicle (80) and / or the upper support section ( 60, 61, 70) by one for attachment to

Motor vehicle (80) provided longitudinal end (21) of the coupling arm (20) faces away

24. Trailer coupling according to one of claims 21 to 23, characterized

characterized in that they only have a single upper support section (60, 61, 70) on the upper side of the dome body (30), in particular above the maximum

Cross section of the dome body (30), and / or only a single lower support section (60, 61, 70) on the underside, in particular below the maximum

Cross section of the dome body (30).

25. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) comprises a support section (60, 61, 70) on the coupling body (30), which extends over an angular range of a maximum of 70 °, preferably a maximum of 50 °, in particular a maximum of 40 ° or 30 °, extends laterally next to a longitudinal central axis which is parallel to a main longitudinal axis of the coupling arm (20) and / or when the trailer coupling is mounted on the motor vehicle (80) is parallel to the longitudinal axis of the motor vehicle (80).

26. Trailer coupling according to one of the preceding claims, characterized in that the first partial surfaces of a region in use when the trailer coupling is in contact with the load carrier or trailer

The outer surface of the coupling body (30), in particular the coupling ball (31), is formed by the base material (41) of the basic body (38) of the coupling body (30), in particular the coupling ball (31), and second partial surfaces of the contact coupling are in use when using the trailer coupling with the load carrier or trailer standing area of the outer surface of the coupling body (30), in particular the coupling ball (31), of the at least one support section (60, 61, 70) or an arrangement of several, the at least one support section (60, 61, 70)

comprehensive, support sections is formed.

27. Trailer coupling according to claim 26, characterized in that a total surface area of the second partial areas is smaller or larger than a total area size of the first partial areas, in particular that the total surface area of the second partial areas is a maximum of 75%,

is in particular a maximum of 60%, more preferably a maximum of 50%, of the total area of the first partial areas.

28. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) has a flat shape and at least 10%, preferably at least 20%, in particular at least 30% of one in contact with when using the trailer coupling the area of the load carrier or trailer

Provides the outer surface of the coupling body (30), in particular the coupling ball (31).

29. Trailer coupling according to one of the preceding claims, characterized in that the coupling arm (20) has an arm body (26) and a coupling body neck (50) which is arranged between the arm body (26) and the coupling body (30). 30. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) has a support section (60, 61, 70) on the neck section and / or on an end region (25) carrying the coupling body neck (50) ) of the arm body (26).

31. Trailer coupling according to one of the preceding claims, characterized in that a material thickness of the at least one support section (60,

61, 70) in a transition area to an outer surface of the base body (28, 38) of the coupling arm (20) or coupling body (30) is less than at a greater distance from the transition area.

32. Trailer coupling according to one of the preceding claims, characterized in that the at least one support section (60, 61, 70) comprises a support section (60, 61, 70) on the coupling arm (20), the support section (60, 61, 70 ) has a greater hardness and / or strength in the area of its outer surface than in the direction of a cross-sectional center of the coupling arm (20), in particular a neutral fiber of the coupling arm (20). 33. Trailer coupling according to one of the preceding claims, characterized in that the coupling body (30) and the coupling arm (20) are in one piece or that the coupling body (30) is a separate component from the coupling arm (20), which is on the coupling arm (20 ) based on

Fasteners is attached. 34. Method for producing a trailer coupling for a motor vehicle (80), the trailer coupling (10) having a coupling arm (20), on one end region (25) of which a coupling body (30), in particular a coupling ball (31), for attaching a trailer (90) or coupling a load carrier to the motor vehicle (80) is arranged, characterized by manufacture at least one at least part of a respective outer surface of the coupling body (30) and / or the coupling arm (20) forming support section (60, 61, 70) on the coupling body (30) and / or the coupling arm (20), the supporting section (60 , 61, 70), in particular their material, one in relation to an in particular metallic base material (41) of a base body (28, 38) of the coupling body (30) or coupling arm (20) on which the support section (60, 61, 70) is arranged or who carries the support section, has higher strength and / or hardness.