Coupling socket with solid lubricant

Abstract

Coupling socket (10; 110) of a ball coupling for train operation, wherein the coupling socket (10; 110) is designed to couple with a coupling ball (18) for the purpose of forming a coupled train and for this purpose has a concave coupling section (20; 120) which, in the coupled state of the coupling socket (10; 110), is opposite a convex counter-coupling section (22) of the coupling ball (18) and contacts it in a contact area (24a, 24b), wherein at least one lubrication area (30; 130) is provided in the coupling section (20; 120) of the coupling socket (10; 110), which is designed to receive lubricant (26; 126), wherein a solid lubricant component (26;126) is included, which exists as a solid body at least in a reference state with a temperature of 20°C, an air pressure of 1 bar and is mechanically loaded only by its own weight, characterized in that the coupling socket (10; 110) is formed in one piece and in this one-piece design has a coupling element (14; 114) on which the concave coupling section (20; 120) is formed, as well as a drawbar section (12; 112) projecting from the coupling element (14; 114) for connection with a trailing vehicle, wherein the solid lubricant component is held on the coupling socket (10; 110) by positive locking.

Description

[0001] The present invention relates to a coupling socket of a ball coupling for a train operation according to the preamble of claim 1.

[0002] Such a coupling socket is known from DE 84 29 103 U1. The coupling socket known from this publication is designed in multiple parts. A solid lubricant is applied to it, but only as a surface coating.

[0003] The idea underlying the present invention can also be implemented on the component of a ball coupling that is complementary to the coupling socket, namely on a coupling ball. However, this is not included in the present invention. In such a case, at least one lubrication area is provided in a convex mating section of a coupling ball of the ball coupling, which is designed for coupling with a coupling socket and for this purpose has the mating section that, in the coupled state of the coupling ball, faces a concave coupling section of the coupling socket and contacts it in a contact area. This lubrication area is designed to receive lubricant.

[0004] In the present application, a ball coupling comprising a coupling ball and a ball socket is described to illustrate the coupling ball according to the invention. The coupling ball and the ball socket are couplingable to one another, the ball socket having a concave coupling section which, in the coupled state of the ball coupling, faces a convex counter-coupling section of the coupling ball and contacts it in a contact area. At least one lubrication area is provided in the coupling section of the coupling socket, which is designed to receive lubricant.

[0005] A ball coupling and its individual parts, the coupling socket and the coupling ball, are known from DE 201 16 970 U1. This publication discloses a ball coupling whose coupling socket and / or coupling ball is designed with recessed lubrication pockets in its coupling section and mating section, respectively, into which lubricating grease can be introduced and which can thus serve as a grease reservoir. The lubricating grease can be applied by hand or with a suitable tool before coupling the coupling socket to the coupling ball, or, as is known, for example, from WO 2006 / 122 807 A1, it can also be introduced into the coupling section and mating section, respectively, via a grease nipple provided on the coupling socket or coupling ball, even when the coupling socket and coupling ball are coupled.

[0006] Documents US 6,382,656 B1 and US 3,679,234 A disclose only coupling balls. US 6,382,656 B1 teaches the arrangement of a multi-layered flexible pad, preferably made of HDPE, between the coupling ball and the coupling socket that receives it. This pad is simply inserted between the coupling ball and the coupling socket without any special securing measures.

[0007] Provided that the publication US 6 382 656 B1 in its Fig. Figure 7 reveals a coupling socket, which is clearly not a single piece, but is constructed like the coupling socket of DE 84 29 103 U1.

[0008] US patent 3,679,234 A discloses a coupling ball coated with a low-friction layer.

[0009] DE 22 35 874 C3 discloses a detachable ball joint, such as those used for control linkages of motor vehicles. DE 22 35 874 C3 does not disclose a ball coupling for constructing a coupled train with a trailing vehicle. Consequently, DE 22 35 874 C3, with the connecting piece shown therein, does not disclose a drawbar section suitable for connection to a trailing vehicle.

[0010] EP 1 564 033 A1 discloses only a coupling ball. This ball has a lubrication device located outside its axis of symmetry and penetrating its contact surface.

[0011] WO 02 / 086 339 A1, similar to DE 22 35 874 C3, discloses an angle joint and consequently not a ball coupling with a drawbar section. In the manufacture of the angle joint known from WO 02 / 086 339 A1, the ball joint is first inserted into a lining part and locked into place. The lining part, with the ball joint locked into it, is then inserted into the socket and again locked into place. The ball joint is then self-locking to the socket of WO 02 / 086 339 A1. Disassembly of the ball joint by sufficiently high tensile forces is only possible by destroying the socket or the threaded stud used to secure the ball joint.

[0012] As an alternative to the destructive disassembly of the angle joint, WO 02 / 086 339 A1 offers the slotting of the ball socket, whereby the angle joint, once manufactured, can be levered apart by the fastening means of the ball socket and the coupling ball.

[0013] Consequently, the angle joint disclosed in WO 02 / 086 339 A1 is not to be understood as a ball coupling for constructing a coupled train with a trailing vehicle. Such a ball coupling must be sufficiently strong and easy to detach, since its purpose is precisely to connect different coupling balls with different coupling sockets in a way that transmits tensile force.

[0014] The object of the present invention is to improve the generic coupling socket in such a way that the maintenance work required, in particular for lubrication, is reduced compared to a conventional coupling socket of the prior art.

[0015] This problem is solved according to the present invention by means of a coupling socket with all the features of claim 1. In the at least one lubrication area of ​​the coupling socket, a solid lubricant component is incorporated, which exists as a solid at least in one reference condition with a temperature of 20°C, an atmospheric pressure of 1 bar and is mechanically loaded only by its own weight.

[0016] By arranging a solid lubricant component in at least one lubrication area, frequent refilling or loading of the lubrication area with grease, as was necessary with the ball coupling of DE 201 16 970 U1, is eliminated. The solid lubricant component provides a sliding surface against which the mating coupling section of the coupling ball, when the coupling socket and coupling ball are coupled, can slide with reduced friction compared to the direct, unlubricated contact between the coupling socket and coupling ball. This prevents the sliding contact from pumping or distributing the solid lubricant more or less uncontrollably into the gap between the coupling section and the mating coupling section.The lubrication situation created by at least one solid lubricant component remains essentially unchanged over a long period due to the higher dimensional stability of the solid lubricant component compared to a formless powdered lubricant such as graphite, or a pasty or liquid lubricant such as grease or oil. The maintenance effort required to restore a predetermined lubrication situation, as is necessary when using powdered graphite, pasty grease, or liquid oil, can therefore be eliminated or is significantly reduced.

[0017] Since materials can generally exist in different states of matter under different predetermined conditions, to determine whether a lubricant used is a solid within the meaning of this application, a reference state of the lubricant with a temperature of 20°C, an atmospheric pressure of 1 bar (normal atmospheric pressure), and a lubricant component unloaded except by its own weight, shall be used. If the lubricant component in the relevant state is a solid with a predetermined shape, i.e., neither liquid, nor pasty, nor powdery, nor even gaseous, then such a lubricant component shall be considered a solid lubricant component within the meaning of this application.

[0018] The fact that the lubricant component exists as a solid in the relevant reference state should in no way preclude it from also being a solid at higher or lower temperatures or at higher and lower atmospheric pressures. This will generally even be the case. However, to determine whether a lubricant component is a solid-state lubricant component within the meaning of the present application, the lubricant component should be considered in the reference state defined above. The term "temperature" refers both to the temperature of the lubricant component and to the temperature of the atmosphere surrounding it.

[0019] In order for the solid lubricant component to develop its effect in the best possible way, it is advantageous if it has a contact surface on which, in the coupled state of the coupling socket and coupling ball, the coupling ball is in contact engagement with the solid lubricant component in the coupling socket according to the invention.

[0020] To avoid undesirably high surface pressures between a coupling ball and the contact surface of the solid lubricant component, it is preferred if the contact surface is curved, and particularly advantageously curved about two mutually orthogonal spatial axes. Since the coupling area as well as the mating coupling area are at least partially designed as a spherical cap surface, the contact surface of the solid lubricant component is also preferably designed as a spherical cap surface. This is a concave spherical cap surface in the arrangement of the solid lubricant component in the coupling socket according to the invention.

[0021] To ensure that a coupling ball comes into contact with the contact surface of the solid lubricant component when coupled, it may be provided that the contact surface of the solid lubricant component protrudes from a surface of the coupling section adjacent to the solid lubricant component.

[0022] According to the invention, the solid lubricant component is held in place on the coupling socket by a positive fit. For example, the solid lubricant component can be inserted into a complementary recess in the coupling section of the coupling socket, preferably with the radial thickness of the lubricant component being greater than the radial dimension of the recess into which it is inserted, in order to ensure that the contact surface projects beyond an adjacent surface of the coupling section. The solid lubricant component can be secured in position on the coupling socket by a positive-locking engagement of a groove in a component consisting of the solid lubricant component and the coupling socket with a detent formed in the other component. Additionally or alternatively, the solid lubricant component can be bonded to the coupling socket.

[0023] A positive-locking retention of the solid lubricant component on the coupling socket according to the invention can be achieved in a particularly simple manner by forming a shoulder behind the insertion opening in an insertion direction in which the coupling ball is inserted along an insertion track into an insertion opening of the coupling socket during coupling. This shoulder is engaged by the solid lubricant component. Preferably, the shoulder is a shoulder circumferential around the insertion track, so that the contact area of ​​the solid lubricant component engaging behind the shoulder is as large as possible, and so that the engagement situation is as independent as possible from the circumferential location around the insertion track. The shoulder can be the end face of a shoulder component, such as a pipe section, that can be removed along the insertion track from an insertion area of ​​the coupling socket containing the insertion opening. For example, the shoulder component can be...The pipe section must have an external thread, allowing it to be screwed into and unscrewed from the insertion area of ​​the coupling socket by means of an internal thread provided there.

[0024] However, other means of securing a separate component of the coupling socket forming the shoulder, such as screws screwed into the coupling socket from the outside up to the shoulder component, and the like, should not be excluded.

[0025] Such a detachable step component can significantly facilitate the replacement of a worn or excessively contaminated solid lubricant component with a ready-to-use solid lubricant component.

[0026] Preferably, the step described above is part of the previously described groove, which can be formed in the coupling section. The groove or step preferably runs continuously around the entire insertion path, so that a fastening condition that is as uniform as possible around the circumference of an insertion area of ​​the coupling socket or coupling ball can be achieved.

[0027] Preferably, the detent projection is formed on the solid lubricant component, although this is not mandatory. However, forming the groove on the solid lubricant component would generally result in a thin spot, which is not advantageous compared to the thickening caused by forming a detent projection.

[0028] Advantageously, the detent projection can be formed at one end of the solid lubricant component, so that the solid lubricant component terminates at one end with the detent projection. This prevents or reduces gaps between the solid lubricant component and the coupling socket in the assembled state, in which dirt can undesirably accumulate. The end of the solid lubricant component is preferably the inlet end through which the coupling ball is inserted to engage the solid lubricant component fixed to the coupling socket.

[0029] To ensure that the mating coupling section of the coupling ball is in contact with the contact surface of the solid lubricant component in as many or even all operating situations of the ball coupling discussed here, it is advantageous if the entire coupling section of the coupling socket is formed by the solid lubricant component. Thus, the entire coupling section can be formed by the contact surface of the solid lubricant component, thereby ensuring that the contact area between the coupling ball and coupling socket described above is always located within the contact surface of the solid lubricant component.

[0030] Then the solid lubricant component is advantageously formed in one piece, or exactly one solid lubricant component is provided for each coupling socket to facilitate its assembly. However, it should also not be excluded that the coupling socket has a plurality of solid lubricant components distributed over the coupling section.

[0031] For example, solid lubricant components can be provided, which can be arranged equidistantly around the insertion path in the coupling socket. This also ensures a continuous contact surface of the solid lubricant components in all or at least most operating situations when coupled, provided the angular width of the solid lubricant components is appropriate. Likewise, 4, 5, 6, or more solid lubricant components can be distributed across the coupling section. In the case of an arrangement of multiple solid lubricant components, three components are preferred, as this requires the least assembly effort when using multiple components, while still providing sufficient coverage of the coupling section with the contact surface of the solid lubricant components.

[0032] “Lubricant” within the meaning of the present application is any material or combination of materials whose intermediate arrangement between the coupling ball and the coupling socket reduces the friction occurring between these ball coupling components compared to their direct unlubricated contact.

[0033] As a solid lubricant, a polymer is generally suitable, with semi- or highly crystalline polymers being preferred due to their wear resistance. Polymers with a degree of crystallinity of 20 to 95% are preferred. The degree of crystallinity is the ratio of the crystalline polymer mass to the total polymer mass.

[0034] One advantage of polymer solid lubricant components lies in the material's elasticity. This allows the solid lubricant component to be formed in its final, predetermined shape and positioned on the supporting coupling socket by deformation during assembly, without requiring disassembly. For example, the solid lubricant component, with its integrated detent projection, can be moved over the step described above into the coupling socket by deformation until a final assembly position is reached. When the detent projection aligns with a groove on the supporting coupling component, i.e., the coupling socket, the solid lubricant component, due to its elasticity, will expand into the groove, thus creating the desired positive locking engagement.The same applies if the detent projection is formed on the coupling socket and the associated groove on the solid lubricant component, but this is not preferred for the reasons mentioned above, but also because of the increased manufacturing effort of a detent projection to be provided in a concave coupling section.

[0035] According to the invention, the coupling socket is formed in one piece, for example, forged from a single piece, and in this one-piece state, according to the invention, comprises at least one coupling element on which the concave coupling section is formed and a drawbar section projecting from the coupling element. This one-piece design is not intended to preclude the possibility of further components being mounted to the one-piece coupling socket thus formed, which merely extend the functionality of the coupling socket but are not necessary to establish its basic coupling function.

[0036] Due to its particularly high wear resistance combined with good lubricating properties, polyamide, or even more so aromatic polyamide, is preferred as a solid lubricant. Polyaramid has demonstrated the best overall performance in terms of lubricity combined with high wear resistance and durability, and is therefore the most preferred solid lubricant in the ball coupling application described here.

[0037] It can also be considered, in principle, to equip both of the aforementioned components of a ball coupling with solid lubricant components, although this is not preferred due to the effort required in relation to the effect achieved.

[0038] In addition to the above-mentioned polyamides, aromatic polyamides and the particularly preferred polyaramides, at least partially fluorinated plastics such as polytetrafluoroethylene or polyvinylidene fluoride can also serve as solid lubricants, although their expected service life in the highly stressful clutch operation is likely to be lower than that of aromatic polyamides or even polyaramides.

[0039] Furthermore, in certain applications, polymers with a molecular weight exceeding 500,000 g / mol can also be considered as solid lubricants. Possible examples include high-molecular-weight polyethylene (HNPE) or ultra-high-molecular-weight polyethylene (OHMPE). Other polyolefins with a correspondingly high molecular weight are also suitable.

[0040] Other possible polymeric solid lubricants are aliphatic polyethers, such as polyacetal, or aromatic polyethers, such as aromatic polyeterketones (PEEK). Aromatic polyesters, such as polyethylene terephthalate, are also suitable as polymeric solid lubricants, although all of these will have a shorter service life in the mechanically demanding operation of a ball coupling, which is particularly common in agricultural vehicles, than the preferred aromatic polyamides or even polyaramides.

[0041] All the polymers mentioned can contain fillers that enhance their lubricity. Suitable fillers include oils, molybdenum disulfide, graphite, polytetrafluoroethylene particles and / or fibers, or strength-enhancing fillers such as glass.

[0042] The present invention will be described below with reference to the accompanying figures. It represents: Fig. 1 a perspective partial view of a coupling socket according to the invention, looking into the concave coupling section of the coupling socket, Fig. 2a a longitudinal section view through the coupling socket of Fig. 1, Fig. 2b one with the coupling socket of Fig. 2a coupling ball and Fig. 3 one of the perspectives of Fig. 2a corresponding longitudinal section view through an alternative embodiment of a coupling socket according to the invention.

[0043] In the illustrated embodiments, the present invention is demonstrated using the example of a coupling socket. However, the present invention can additionally or alternatively be implemented on a coupling ball of a ball coupling.

[0044] In Fig. 1 is a first embodiment of a coupling socket according to the invention, generally designated by 10. The coupling socket, which is in Fig. Figure 1, shown in a partial perspective view from a low angle, initially shows a section of a drawbar 12 and a coupling element 14 of the coupling socket 10, which is rigidly connected to the drawbar 12. Preferably, the drawbar 12 and the coupling element 14 are forged in one piece from a blank in order to achieve the highest possible component strength through the resulting cold forming. The drawbar 12 can be connected to a vehicle, usually a trailing vehicle, in the usual manner.

[0045] The coupling device 14 has an insertion opening 16 through which a coupling ball, such as the one in Fig. 2b shows that the coupling ball 18 can be inserted along an insertion path E in the insertion direction K. For the sake of simplicity, the insertion path E, which can be straight and / or curved, is assumed to be straight in the example shown here.

[0046] In the insertion direction K behind the insertion opening 16, a concave coupling section 20 is located, which in the coupled state of the coupling socket 10 engages with a concave counter-coupling section 22 of the coupling ball 18 (see Fig. 2b) can be engaged in the system and touches it in a contact area. The contact area can change in its position and / or extent depending on the load case occurring at the coupled ball coupling. For example, in accelerated train operation, the contact area may be located closer to the longitudinal end of the coupling section 20 furthest from the drawbar, as in Fig. 2a is indicated by the dashed contact area 24a.

[0047] In contrast, when the coupled train decelerates, the contact area may be located closer to the longitudinal end of the coupling section near the drawbar, as in Fig. 2a is indicated by the dashed contact area 24b. Both contact areas 24a and 24b are preferably mirror-symmetrical to the section plane of the longitudinal section when the coupled train is traveling straight ahead. Fig. 2a.

[0048] To reduce the friction occurring between the coupling ball 18 and the coupling socket 10 in the coupled state, the following is provided in the Fig. In the example shown in Figures 1 to 3, a friction-reducing component 26 is provided in the coupling socket 10, which in the illustrated embodiments extends essentially over the entire coupling section 20 of the coupling socket 10.

[0049] The friction-reducing component 26, which is referred to as a lubricant component because of its friction-reducing effect, exists as a solid body with a predetermined shape in a reference state with a temperature of 20°C, an atmospheric pressure of one bar, and a purely mechanical load due to its own weight. Therefore, the friction-reducing component 26 is referred to in the present application as a solid lubricant component 26.

[0050] The solid lubricant component 26 is advantageously a polymer component which, due to the material properties, can be easily manufactured in the desired shape.

[0051] Regarding the possible materials for forming the solid lubricant component 26, or at least its contact surface 26a facing the coupling ball 18, reference is made to the descriptions in the preceding introductory section. For reasons of a particularly advantageous combined effect of high durability and low friction, the solid lubricant component 26 is made of aromatic polyamide or, even more preferably, of polyaramid. At least the contact surface 26a of the solid lubricant component 26 can be made of the aforementioned materials.

[0052] In the Fig. 1 and Fig. Figure 2a shows the solid lubricant component 26 as a single-piece component, which advantageously covers the entire concave coupling section 20. For this purpose, the solid lubricant component 26 can have an opening 28 to facilitate assembly. This opening allows air present between the solid lubricant component 26 and the concave surface 30 of the coupling element 14 during assembly to escape, so that the solid lubricant component 26 can be mounted in essentially full contact with the concave surface 30 of the coupling element 14. Preferably, the solid lubricant component rests against the concave wall of the coupling element 14 with a large proportion of its outer surface 26b opposite the contact surface. Particularly preferably, the entire outer surface 26b opposite the contact surface 26a rests against the concave surface 30 of the coupling element 14.

[0053] In principle, it is possible to bond the surfaces 26b and 30 of the solid lubricant component 26 on the one hand and the coupling design 14 on the other hand together.

[0054] However, to facilitate the repair and maintenance of the solid lubricant component 26, in particular its easier replacement in the event of damage, it is advantageous if the solid lubricant component 26 is only held in the coupling design 14 by means of a positive locking mechanism.

[0055] For this purpose, the coupling design 14 can have a shoulder 32 in the insertion direction K behind the insertion opening 16, which preferably runs continuously around the insertion track E. This shoulder 32 can be part of a groove 34, which also preferably runs completely around the insertion track E.

[0056] Preferably, the paragraph 32 and / or the groove 34 lies in a plane in the coupling design 14 to facilitate the assembly of the solid lubricant component 26, which is particularly preferably oriented parallel to the insertion opening 16 or orthogonal to the insertion track E.

[0057] For the purpose of engaging the groove 34, a projecting detent 36 can be formed radially outside on the solid lubricant component 26, which preferably runs continuously around the solid lubricant component 26.

[0058] To avoid undesirable gaps pointing away from the coupling section 20 between the solid lubricant component 26 and the coupling section 14, in which dirt can accumulate during operation of the coupling discussed here, the detent projection 26 is preferably provided at an end of the solid lubricant component 26 that is closest to the insertion opening 16 in the assembled state of the solid lubricant component 26.

[0059] Depending on the design of the coupling assembly 14 and the concave recess provided therein, a cylindrical or generally only one curved area can be connected to the end section of the solid lubricant component 26 that is closest to the insertion opening 16 in the assembled state, to which a dome-shaped section, i.e. a section curved about two mutually orthogonal axes of curvature, preferably a spherical cap-shaped section or a section with at least one spherical cap-shaped contact surface 26a, is connected further inwards in the insertion direction K.

[0060] Contrary to the insertion direction K in front of the groove 34, an insertion section 38 of the coupling socket 10 or the coupling assembly 14 can also be provided, which may preferably be designed with a cylindrical surface and the insertion track E as a cylinder axis to facilitate the insertion of the coupling ball 18 into the coupling section 20.

[0061] In Fig. Figure 3 shows a second embodiment of a coupling socket according to the invention.

[0062] The second embodiment, in which identical and functionally equivalent components or component sections are used as in the first embodiment, Fig. 1 and Fig. 2a, which has the same reference numerals but increased by the number 100, will only be described below insofar as it differs from the first embodiment, to whose description explicit reference is otherwise made. In contrast to the first embodiment, in which the coupling element 14 is formed in one piece, in the embodiment described in Fig. In the second embodiment of a coupling socket according to the invention, the insertion opening 116 and preferably also the insertion section 138 are provided on a ring component 140 which is formed separately from the coupling design 114.

[0063] The ring component 114 can, as in Fig. 3 is shown, fastened by fasteners, such as screws 142 to the coupling assembly 114. In the Fig. In the example shown, the only screw 142 depicted is screwed into the coupling device 114 with its screw axis parallel to the insertion path E, passing through the ring component 140. For a greater axial length relative to the insertion path E of the ring component 140, an alternative or additional screw can be used. Fig. The solution shown in 3 also considers radial screwing of fastening screws with respect to the insertion track E.

[0064] To ensure the most uniform application of a fastening force for attaching the ring component 140 to the coupling assembly 114, a plurality of screws 142 are advantageously provided, of which only one is located in the cross-sectional plane of Fig. 3 is located. Particularly preferably, the screws 142 are arranged equidistant from each other in the circumferential direction around the insertion track E.

[0065] The in Fig.3 The embodiment shown, with the ring component 140 detachably fixed to the coupling form 114, facilitates the replacement of the solid lubricant component 126 in the event of damage or when its service life has been reached.

Claims

[1] Coupling socket (10; 110) of a ball coupling for train operation, wherein the coupling socket (10; 110) is designed to produce a coupled train for coupling with a coupling ball (18) and for this purpose has a concave coupling section (20; 120) which, in the coupled state of the coupling socket (10; 110), lies opposite a convex counter-coupling section (22) of the coupling ball (18) and touches said convex counter-coupling section in a contact area (24a, 24b), wherein in the coupling section (20; 120) of the coupling socket (10; 110) at least one lubrication area (30; 130) is provided, which is designed to receive lubricant (26; 126), wherein in the at least one lubrication area (30; 130) a solid lubricant component (26; 126) is received, which is arranged at least in a Reference state with a temperature of 20°C, an air pressure of 1 bar and mechanically loaded only by its own weight as a solid body, characterized byin that the coupling socket (10; 110) is formed in one piece and, in this one-piece design, has a coupling formation (14; 114) on which the concave coupling section (20; 120) is formed, and a drawbar section (12; 112) projecting from the coupling formation (14; 114) for connection to a trailing vehicle, wherein the solid-state lubricant component is held on the coupling socket (10; 110) by positive engagement. [2] Coupling socket according to claim 1, characterized by that the solid lubricant component (26; 126) has a contact surface (26a; 126a) for contact with the coupling ball (18) in the coupled state. [3] Coupling socket according to claim 2, characterized by that the contact surface (26a; 126a) of the solid lubricant component (26a; 126a) protrudes from a surface of the coupling section adjacent to the solid lubricant component (26; 126). [4] Coupling socket according to claim 2 or 3, characterized bythat the contact surface (26a; 126a) has the shape of a spherical cap. [5] Coupling socket according to one of the preceding claims, characterized by that the solid lubricant component (26; 126) is glued to the clutch socket (10; 110). [6] Coupling socket according to one of the preceding claims, characterized by in that the coupling socket (10; 110) has an insertion opening (16; 116) into which the coupling ball (18) is inserted along an insertion path (E) during coupling, wherein in the insertion direction (K) behind the insertion opening (16; 116) a shoulder (32; 132), preferably a shoulder (32; 132) running around the insertion path (E), is formed in the coupling socket (10; 110), which is engaged behind by the solid lubricant component (26; 126). [7] Coupling socket according to one of the preceding claims, characterized by that the entire coupling section (20; 120) is formed by the solid lubricant component (26; 126). [8] Coupling socket according to one of the preceding claims, characterized by that it has a plurality of solid lubricant components which are provided distributed over the coupling section (20; 120). [9] Coupling socket according to one of the preceding claims, characterized by that the solid lubricant (26; 126) comprises a polymer, preferably a partially or highly crystalline polymer, in particular polyamide, more preferably aromatic polyamide, even more preferably polyaramid.

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