Sliding ring and housing as well as mechanical ring seal

Abstract

Sliding ring (2) for a mechanical seal (40), comprising an end face running surface (4) which preferably extends substantially in a radial plane of the sliding ring (2), and further comprising a radially inner, conical, first contact surface (6), which is preferably strongly conical, for a first seal (20) which is intended to seal the sliding ring (2) with respect to a housing or a hub on the one hand and to support it in the axial direction as well as in the radial direction, characterized in that either the sliding ring (2) further has a radially outer second contact surface (12) for a further second seal (22) and a further third seal (24) or that the sliding ring (2) further has a radially outer second contact surface (12) for a further second seal (22) and a further radially outer third contact surface (16) for a further third seal (24).

Description

The present invention relates to a mechanical seal, such as those known primarily from the undercarriages of construction machinery. Mechanical seals are also known as those used in pumps and valves, for example, to seal shafts and pivots. The present invention relates to mechanical undercarriage seals, such as those used in the drives of excavators and crawler drives as well as bulldozers, but also in axle bearings of loaders and the like. Mechanical seals of this type are used to protect the wheel and axle bearings of tree and forestry machinery from wear and tear caused by soil and mud. A mechanical seal typically comprises two sliding rings, each with essentially flat, annular sliding surfaces that rub against each other during operation. The sliding surfaces of the rings can be lubricated. The sliding rings are usually held and pressed against each other by rubber or elastomer bearings. The rubber bearings allow for slight axial and radial misalignment, as well as a slight tilting of the sliding rings relative to each other. The sliding rings can also be equipped with anti-rotation devices to prevent two sliding rings from sticking together and one of them from twisting relative to its rubber bearing.The sliding ring bearings, with their smooth sliding surfaces and hard material, are highly resistant to wear from soil, sand, and mud. However, rubber bearings present a problem, as clay-rich soil, sand, or mud can significantly restrict the axial and radial movement of the seal. Furthermore, internal and external pressure can displace the elastomers and / or adversely affect the surface pressure of the sliding rings. It is known to reinforce the rubber bearings of the sliding rings. It is also known to use rubber bearings with special cross-sections, but this has not proven sufficiently effective. Mechanical seals in drive systems are susceptible to damage from mud that accumulates in the gap between the seal ring and the housing or shaft section. Depending on its viscosity and dryness, this mud can cause the seal ring to seize against the housing or shaft section. Seal rings that are stuck due to mud or encrustation and can no longer move will not provide uniform surface pressure on the running or sealing surfaces. This leads to the ingress of sand, soil, and mud between the running surfaces, resulting in significantly increased wear and ultimately the failure of the seal ring and the associated bearings. A proposal to make a mechanical seal more resistant to the ingress of dirt and thus to increased wear is shown in the German patent DE 10 2008 036489 B3, whereby a special sealing shape is intended to protect a mechanical seal from dirt-related wear. A similar solution to protect a mechanical seal from the ingress of dirt is disclosed in German patent application DE 3523485 A1, where a special sealing form is also used. German patent application DE 3141512 A1 discloses a mechanical seal whose sliding ring comprises a conical outer contact surface for a rolling element and wherein the sealing ring is further provided either with a further contact surface for a single additional elastomer seal or a rubber bead is vulcanized to the sliding ring, as shown in Fig. 4 of this document. American patent application US 3547452 A discloses the subject matter of the present Fig. 7, wherein two sliding rings are provided for two elastic rolling bodies each, which each bear against an outer conical surface or an inner conical surface of the sliding ring. German patent DE 10 2008 036 489 B3 relates to a mechanical seal which, instead of a known elastic rolling element, has an elastic element with a substantially H-shaped cross-section. It is therefore desirable to improve the sliding ring bearings of drives by enhancing the rubber bearing of the sliding rings and preventing or at least hindering the ingress of dirt between a sliding ring and its associated housing. Furthermore, the outer small elastomers should be better protected against wear through design than has been the case in the past. Mechanical seals consist of sliding rings that glide against each other while lubricated and are used in many different technical applications. One particularly noteworthy application is the sealing of axles and undercarriages of construction machinery, agricultural vehicles, and tracked vehicles, especially those operating in environments with high wear. A mechanical seal would not be suitable for standard passenger car axles, for example, as conventional radial shaft seals are usually sufficient in these cases. According to a first aspect of the present invention, a sliding ring for a mechanical seal is provided, which has the features of the independent claim. Preferred embodiments are described in the dependent claims. Such a sliding ring for a mechanical seal, particularly for drive units, comprises an end-face running surface that preferably extends substantially in a radial plane of the sliding ring and is configured to run on a running surface of another sliding ring. The sliding ring further comprises a radially inner, conical, first contact surface, which is preferably strongly conical, for a first seal that is configured to seal the sliding ring against a housing or hub and to support it axially as well as radially. The first sliding ring is provided with the first contact surface to center and align the sliding ring relative to the housing or hub, and also to generate a contact force that presses the sliding ring against an opposing sliding ring.The sliding ring is further provided with a radially outer second contact surface for two further seals, a second and a third seal, wherein the second contact surface is configured to bear against the second and third seals, respectively. In an alternative embodiment of the sliding ring, it comprises a radially outer second contact surface for a second seal, wherein the second contact surface is configured to bear against the second seal, and further a radially outer third contact surface, which is configured to bear against a further third seal. The sliding ring for a mechanical seal has a running or sealing surface on its end face. The first O-ring seals a gap between the sliding ring and a housing or hub and also provides axial and radial support for the sealing ring. The seal is considered a static seal, even though the first O-ring is designed to allow the sliding ring a small degree of axial movement, displacement in a radial plane, and tilting relative to the radial plane. The sliding ring according to the present invention further comprises a radially outer sealing surface for a second and third O-ring. These O-rings are designed to seal a gap between the sliding ring and the housing or hub to prevent mud and sludge from penetrating this gap and hardening there to such an extent that the mobility of the sliding rings and mutual contact between the sliding, running, and sealing surfaces of the two sliding rings can no longer be ensured. The design of a conventional mechanical seal is supplemented here with another seal, for example with an O-ring, a trapezoidal ring, a diamond ring, or an X-ring, to protect a gap between the sliding rings and a housing or hub part from penetrating dirt. The seals are numbered consecutively, with the first seal always located radially inside the sliding ring, supporting and centering it. The second seal is always located radially outside the sliding ring and seals a gap between the sliding ring and a housing or hub. A third seal is also always located radially outside the sliding ring and additionally seals a gap between the sliding ring and a housing or hub. In one embodiment of the sliding ring, the radially inner contact surface, which is designed to bear against the first seal, is further designed to bear against a first O-ring or a diamond, trapezoidal or Z-ring. In an additional embodiment of the sliding ring, the radially outer second contact surface, which is provided for at least one further second seal, is further provided to bear against at least one second O-ring and / or at least one second X-ring. In another embodiment of the sliding ring, the radially outer third contact surface is configured to bear against the radially outer third seal and is further configured to bear against a third O-ring or a third X-ring. In another additional embodiment of the sliding ring, the contact surfaces of the guide ring are configured to bear against the first O-ring, the second O-ring, and preferably the third O-ring. This embodiment relates to a sliding ring designed to be used only with O-rings. In a further additional embodiment of the sliding ring, the contact surfaces of the guide ring are preferably configured to bear against the first diamond or Z-ring, the second X-ring, and more preferably the third X-ring. This embodiment relates to a sliding ring that is supported and centered from the inside by a Z-ring or diamond-ring, and wherein further X-rings are provided to seal a gap between a housing or a hub. In this case, a sliding ring has a substantially triangular cross-sectional profile in a cross-section along a plane that includes an axis of rotation or rotational symmetry of the sliding ring, wherein one side is determined by the running surface which lies substantially in a radial plane, a second radially inner side is determined by the contact surface of the first O-ring, and a third radially outer side includes a contact surface for the second O-ring. It has been described that a preferably "strongly conical" first contact surface is provided for a first O-ring. Here, "strongly conical" is understood to mean a cone angle between 16° and 50°, preferably between 20° and 40°, and more preferably between 26° and 34°. Expressed, this corresponds to half a cone angle or slope angle (or half a cone angle) of the conical surface relative to the axis of rotation or rotational symmetry between 8° and 25°, preferably between 10° and 20°, and more preferably between 13° and 17°. In the case of a design for a diamond or Z-seal, the radial contact surface for this type of seal would be essentially cylindrical, with an additional contact shoulder being necessary to support the sliding ring in the axial direction as well. In an exemplary embodiment of the sliding ring, the radially outer contact surface has an inclination angle between 0.5° and 2.5°, and more preferably between 1.0° and 2.0°, relative to a rotational symmetry axis of the sliding ring. This embodiment is designed to prevent the second O-ring from contributing to an axial force exerted on the sliding ring, or to contribute only to a very limited extent. Essentially, the purpose of the second O-ring, which is to bear against the radially outer contact surface, is to prevent sand, mud, sludge, and other wear-promoting materials from reaching the area where the sliding ring is supported and sealed by the first O-ring. In another exemplary embodiment of the sliding ring, the radially outer second and third contact surfaces have an inclination angle of between 0.5° and 2.5°, and preferably between 1.0° and 2.0°, relative to a rotational symmetry axis of the sliding ring. This embodiment is designed in which the second and third O-ring (or X-ring) cannot contribute to an axial force exerted on the sliding ring, or can only do so to a very limited extent. Essentially, the purpose of the second and third O-rings or X-rings, which are intended to bear against the radially outer first and / or first and second contact surfaces, is to prevent sand, mud, sludge, and other wear-promoting materials from reaching the area where the sliding ring is supported and sealed by the first O-ring. In another exemplary embodiment of the sliding ring, the radially outer contact surface has a cone angle between 16° and 50°, preferably between 20° and 40°, and more preferably between 26° and 34°. Expressed, this corresponds to half a cone angle or an angle of inclination of the conical surface to the axis of rotation or rotational symmetry between 8° and 25°, preferably between 10° and 20°, and more preferably between 13° and 17°. Here, the two contact surfaces for the first and second O-rings are designed to center the sliding ring in the radial plane and to press it axially against a respective opposing sliding ring. Contact surfaces with such cone angles are particularly suitable for O-ring seals, since an O-ring seal can roll between the contact surfaces when the sliding ring moves relative to the housing or a hub element.It is also possible to design the two O-rings with similar dimensions, since, due to their shape, O-rings with larger cord diameters exhibit a more uniform force distribution under load than O-rings with smaller cord diameters. A smaller cord diameter O-ring is less compressible than an O-ring made of the same material with a larger cord diameter. To mitigate the effect of the different dimensions of the O-rings, it is possible to use O-rings with similar or identical cord diameters. This way, the first O-ring with the greater absolute deformation capacity is complemented by a corresponding O-ring with a similar deformation capacity to prevent the ingress of dirt.Another solution could involve using O-rings made of materials with different degrees of softness, with the material of the first (inner) O-ring being significantly stiffer than the material of the second, outer O-ring. Currently, it is envisaged that the second, outer O-ring has a modulus of elasticity that is at least twice and at most ten times, preferably at least three times and at most eight times, and more preferably at least four times and at most six times, that of the modulus of elasticity of the material of the second, outer O-ring. According to a further embodiment of the present invention, a sliding ring according to one of the preceding claims is provided, which has a radially inner contact shoulder that extends axially outwards to the radially inner first contact surface. The contact shoulder forms an abutment for the seal in the axial direction to increase compression of the seal in the axial direction. The shoulder is intended to prevent the sealing ring from coming into contact with the housing or a hub component. The radially inner contact shoulder has a radial dimension that is between 35% and 70%, preferably between 40% and 60%, of an axial dimension of the inner contact surface. Only the radial and axial projections of the shoulder and the contact surface are to be compared here. The shoulder should extend approximately half as high in the radial direction as the radially inner first contact surface extends in the axial direction. In an additional exemplary embodiment of the sliding ring, at least one radially outer contact shoulder is provided, which extends axially outwards to the radially outer contact surface. Here, two radially outer contact shoulders, a radially outer second contact shoulder, and a radially outer third contact shoulder can also be provided, provided that two radially outer contact surfaces, the radially outer second contact surface, and the radially outer third contact surface are also present. The radially outer contact shoulder has a radial dimension that is between 35% and 70%, preferably between 40% and 60%, of an axial dimension of the outer contact surface. It is specified here that a stop shoulder should be approximately half the height of the width of an associated second or third contact surface. In another embodiment of a sliding ring, the radially inner contact surface and the outer contact surface of the sliding ring overlap axially by 40% to 100%, preferably by 50% to 90%, and more preferably by 60% to 80%. This embodiment ensures that there is at least one radial plane that intersects both contact surfaces. In this configuration, the first and second O-rings of an assembled mechanical seal are staggered in the radial direction. Here, the axial overlap rate is considered with respect to a projection of the axial dimensions of the contact surfaces onto the axis of rotation or rotational symmetry, whereby the percentage overlap is considered with respect to the shorter of the projected axial dimensions. Any overlap where one axial dimension lies completely within another axial dimension is considered 100%. If the smaller axial dimension lies halfway within the larger axial dimension, the overlap is 50%. In another exemplary embodiment of a sliding ring, the radially inner contact surface and the outer contact surface of the sliding ring overlap axially between 0% and 40%, preferably between 5% and 35%, and more preferably between 10% and 30%. This embodiment relates to a situation in which the first O-ring and the second O-ring of an assembled mechanical seal are staggered in the axial direction. According to a further embodiment of the present invention, the sliding ring is provided with an anti-rotation device in the form of at least one bore, at least one recess, and / or at least one projection, wherein the anti-rotation device preferably has a rotational symmetry of 180°, 120°, 90°, 72°, 60°, 45°, 36°, 30° to 10°. A sliding ring with an anti-rotation device exhibiting rotational symmetry has the advantage that it can be mounted in several installation positions. Furthermore, a rotationally symmetrical anti-rotation device is expected to have a lesser influence on the sealing properties in the event of radial displacement, tilting, or other deviations. According to a further aspect of the present invention, a mechanical seal service set is provided, comprising a sliding ring as described above with an associated inner first seal, an associated outer second seal and preferably an additional outer third seal, wherein the service set further comprises two sliding rings with the associated two inner first seals, two associated outer second seals and preferably two additional outer third seals. According to a further aspect of the present invention, a mechanical seal service kit is provided for servicing mechanical seals according to the invention, in particular for replacing worn sliding rings and sealing rings. Such a mechanical seal service kit comprises a sliding ring as described above, as well as an associated inner first seal, an associated outer second seal, and preferably an additional outer third seal. It is also provided that a mechanical seal service kit comprises two sliding rings as described above, each with the associated two inner first seals, associated two outer second seals, and preferably the associated two outer third seals. This is considered a preferred commercially viable unit, since many more mechanical seals require maintenance than are newly manufactured.According to a further aspect of the present invention, a mechanical seal is provided which comprises at least one sliding ring as described above. The at least one sliding ring as described above is held in a respective housing and / or hub component by at least two O-rings. In another exemplary embodiment, the mechanical seal has an anti-rotation device for the sliding rings, which prevents the sliding rings from rotating circumferentially within the housing and / or hub component. In this basic version, at least one sliding ring, as described above, is used in a mechanical seal. An anti-rotation device is particularly preferred when using diamond, Z-, trapezoidal, or X-ring seals. Furthermore, the mechanical seal preferably comprises a first sliding ring and a second sliding ring, as described above, wherein the first sliding ring and the second sliding ring contact each other with their running surfaces, and wherein the first and second sliding rings are each held in a respective housing or hub component by at least two O-rings. In this embodiment, two sliding rings as described above are used at a sealing gap. In another embodiment of the mechanical seal, the first, and therefore inner, O-ring has a cord diameter that is 1.5 to 3, preferably 2 to 2.7, and more preferably 2.2 to 2.5 times greater than the cord diameter of the second, and therefore outer, O-ring. Here, the second O-ring essentially serves as a gap seal to prevent dirt, mud, sand, and sludge from penetrating the sealing gap and thus reaching the first O-ring. This design is particularly suitable for applications where the mechanical seal is subjected to axial forces, allowing a thinner O-ring to seal a gap even with greater axial movement, since the O-ring is not subjected to particularly strong radial stress or unstress. In another exemplary embodiment of the mechanical seal, the first (inner) O-ring has a cord thickness that is between 0.7 and 1.5, preferably 0.8 and 1.3, and more preferably 0.9 and 1.1 times greater than the cord thickness of the second (outer) O-ring. Here, both O-rings are approximately the same size, and both contribute to applying the contact forces of the mechanical seal's sliding rings and to centering them to a comparable extent. The outer, second O-ring is thicker here, not only to prevent dirt from reaching the first O-ring, but also to distribute the centering and sealing loads. In this configuration, both O-rings can have a smaller cord thickness than an inner O-ring in a conventionally constructed mechanical seal. Another embodiment of a mechanical seal is a mechanical seal in the drive or running gear of an agricultural machine or vehicle, a construction machine, or a tracked or crawler vehicle. Mechanical seals are particularly necessary in technical applications where abrasive media such as sand, mud, slush, or soil are present in the environment, which preclude the use of conventional radial shaft seals due to excessive wear. The present invention is described below with reference to schematic representations of preferred embodiments. Fig. 1 shows a sectional view through a conventional mechanical seal. Figs. 2, 3, 4 to 5 show sectional views through further embodiments of the mechanical seal according to the invention. In the following, the same or similar reference symbols are used in both the description and the figures to refer to identical or similar components and elements. Fig. 1 shows a sectional view through a conventional mechanical seal 98, such as those found in agricultural machinery. The conventional mechanical seal 98 is arranged between a housing 44 and a shaft or hub element 46. The housing 44 and the shaft or hub element 46 each have a recess in which the conventional sliding rings 42 are inserted. O-rings 52 are clamped between the conventional sliding rings 42 and the recesses, centering the conventional sliding rings 42 relative to the recesses and pressing the two conventional sliding rings 42 against each other. The wavy line indicates a shortened distance to an axis of rotation or axis of rotational symmetry 60 represented by the dashed-dotted line 48. Here, the O-rings 52 lie radially outside the conventional sliding rings 42. When the shaft or hub element 46 rotates, the O-rings 52 are held in place by the O-rings 52.As the hub rotates, the conventional sliding rings 42 can slide against each other on the running surface with which they contact. The conventional sliding rings 42 are made of a wear-resistant material. The running surfaces of this type of seal must be lubricated to prevent the conventional sliding rings 42 from overheating and welding together. The O-rings 52 center the conventional sliding rings 42 and press them against each other. Under a load that bends or axially displaces the shaft or hub 46 relative to the housing 44, the suspension via the O-rings 52 allows for compensation, preventing the two conventional sliding rings 42 from separating and thus preventing leakage of the mechanical seal.However, the conventional design has the disadvantage that contaminants can also get between the O-rings 52 and the respective contact surfaces, which can cause the O-rings to shift axially and / or lead to a restriction of the axial mobility of the sliding rings. Fig. 2 shows a sectional view through a first embodiment of a mechanical seal 40 according to the invention. The mechanical seal 40 according to the invention is also arranged between a housing 44 and a shaft or hub element 46. The housing 44 and the shaft or hub element 46 are each provided with a recess, which here is annular in shape. The recesses each have two contact surfaces 48, 50, namely a radially outer and a radially inner contact surface, for a seal 20, 22 in the form of an O-ring 80 / 82. A first seal 20, designed as a first O-ring 80, rests against the radially inner contact surface 48. The cord thickness of this O-ring essentially corresponds to that of an O-ring in a conventional mechanical seal. Due to its dimensions, the first O-ring 80 serves to center the sliding ring 2 radially and to press it axially against an opposing sliding ring 2. In contrast to the conventional mechanical seal 98 of Fig. 1, the seal 20, or rather the O-ring 80, is arranged radially further inward. The profile of the sliding ring is inverted compared to Fig. 1, so that the large O-ring supports the sliding ring from the inside, and not from the outside as in Fig. 1. The first seal 20, here the first O-ring 80, is arranged between the inner O-ring contact surface 48 of the recess and the inner contact surface 6 of the sliding ring 2 according to the invention.The first O-ring 80 serves to center the sliding ring 2 and to generate the forces to press the two sliding rings 2 against each other with their sliding, running, or sealing surfaces 4. For centering purposes, the contact surfaces of the first seal or the first O-ring 80 are conical. According to the invention, the gap is closed by two further seals: a radially more outwardly arranged second seal 22, here designed as a second O-ring 82, and a further outwardly arranged third seal 24, here designed as a third O-ring 82, which essentially only seals the gap. In the embodiment of Fig. 2, the sliding ring 2 is provided with an outer sealing surface 12, and the shaft or hub component 46 is provided in a recess with an outer sealing contact surface, between which the second and third outer seals 22 / 24, i.e., the O-rings 82 / 84, are clamped. The outer sealing contact surface 12 of the sliding ring and the outer sealing (or O-ring) contact surface of the shaft or hub component 44 are essentially cylindrical or only slightly conical (less than 2°), which is why the second and third outer seals 22 / 24 are Seal 22 / 24, like the second and third outer O-rings 82 / 84, can hardly contribute to increasing the contact forces between the two sliding rings 2. Due to the shape of the contact surfaces, the second seal 22 or the second O-ring 82 can contribute slightly to centering the sliding rings. The outer contact surfaces 12 of the sliding ring 2 and the housing 44 are further provided with contact shoulders that axially secure the third outer seal 24 or the O-ring 84 and prevent the second outer seal or the O-ring 84 from slipping inwards or outwards from the gap. The inner sealing contact surface 6 of the sliding ring extends towards the sealing surfaces into a contact shoulder 14. The second seal 22 or the second O-ring 82 reduces or prevents dirt from penetrating the gap, thus extending the service life of the mechanical seal, as the axial mobility of the sliding rings is maintained even under heavy mud-picking. Additionally, wear on the second seal 22 or the second O-ring 82 can be reduced by freely selectable labyrinth design or by an axially offset seal to the rear or inside. The position of the axis corresponds to that of Fig. 1, whereby the axis is again assumed to be located below the illustration, outside the drawing area. In Fig. 2, a third seal 24 or third O-ring 84 is arranged next to the second seal 22 or second O-ring 82. The third O-ring serves here as a series-connected O-ring and reinforces the sealing effect. Fig. 3 shows a modification of the embodiment of Fig. 2 in which the second and third seals 22, 24 and the second O-ring 82 and the third O-ring 84 are separated from each other in the axial direction by a separate bridge. In the embodiment of Fig. 4, the second and third seals 22, 24 and the second O-ring 82 and the third O-ring 84 are separated from each other by a step in both the axial and radial directions. Fig. 5 shows an embodiment similar to Fig. 4, wherein instead of the O-rings a diamond or Z-shaped sealing ring 90 is used as the first seal 20, together with X-rings 92 and 94 which are used as the second and third seals. Reference symbol list 2 Sliding ring 4 Sliding, running or sealing surface of the sliding ring 6 Inner radial first sealing contact surface of the sliding ring 8 Contact shoulder of the inner sealing contact surface of the sliding ring 12 Outer radial second sealing contact surface of the sliding ring 14 Contact shoulder of the outer sealing contact surface of the sliding ring 16 Outer radial third sealing contact surface of the sliding ring 18 Contact shoulder of the outer third sealing contact surface of the sliding ring 20 Inner first seal 22 Outer second seal 24 Outer third seal 40 Sliding ring seal according to the invention 42 Conventional sliding ring 44 Housing 46 Hub / Shaft 48 Inner O-ring contact surface of the recess 50 Outer O-ring contact surface of the recess 60 Axis of rotation / Axis of rotational symmetry 70 Conventional sliding ring seal 80 First inner O-ring 82 Second outer O-ring 84 Third outer O-ring 90 First inner diamond- or Z-ring 92 outer second X-ring 94 outer third X-ring

Claims

Sliding ring (2) for a mechanical seal (40), comprising an end face running surface (4) which preferably extends substantially in a radial plane of the sliding ring (2), and further comprising a radially inner, conical, first contact surface (6), which is preferably strongly conical, for a first seal (20) which is intended to seal the sliding ring (2) with respect to a housing or a hub on the one hand and to support it in the axial direction as well as in the radial direction, characterized in that either the sliding ring (2) further has a radially outer second contact surface (12) for a further second seal (22) and a further third seal (24) or that the sliding ring (2) further has a radially outer second contact surface (12) for a further second seal (22) and a further radially outer third contact surface (16) for a further third seal (24). Sliding ring (2) according to claim 1, wherein - the radially inner contact surface (6), which is configured to bear against the first seal (20), is configured to bear against a first O-ring (80), and - the radially outer second contact surface (12), which is configured to bear against two further seals, is configured to bear against at least two O-rings (82 / 84). Sliding ring (2) according to claim 1, wherein the sliding ring preferably additionally comprises the radially outer third contact surface (16), the radially inner contact surface (6) which is configured to bear against the first seal (20), is configured to bear against a first O-ring (80) or a diamond or Z-ring (90), and the radially outer second contact surface (12) which is configured to bear against at least one further second seal, is configured to bear against at least one second O-ring (82) and / or at least one second X-ring (92), and thirdly, the radially outer third contact surface (16) which is configured to bear against a third O-ring (84) or a third X-ring (94). Sliding ring (2) according to claim 1, 2 or 3, wherein the radially inner conical contact surface (6) has a slope angle between 8° and 25°, preferably between 10° and 20°, and more preferably between 13° and 17°. Sliding ring (2) according to claim 1, 2, 3 or 4, wherein the radially outer second contact surface (12) has an inclination angle between 0.5° and 2.5° and more preferably between 1.0° and 2.0°, or wherein preferably the radially outer second contact surface (12) and the radially outer third contact surface (16) each have an inclination angle between 0.5° and 2.5°, and more preferably between 1.0° and 2.0°. Sliding ring (2) according to one of the preceding claims, characterized by a radially inner contact shoulder (8) which adjoins the radially inner contact surface (6) in the axial direction outwards, wherein the radially inner contact shoulder (8) has a radial dimension which is between 35% and 70%, preferably between 40% and 60%, of an axial dimension of the inner contact surface, and / or characterized by a radially outer contact shoulder (14) which adjoins the radially outer contact surface (12) in the axial direction outwards, wherein the radially outer contact shoulder (14) has a radial dimension which corresponds to between 35% and 70%, preferably between 40% and 60%, of an axial dimension of the outer contact surface (12). Sliding ring (2) according to one of the preceding claims, characterized in that the radially inner contact surface (6) and the outer contact surface (12) of the sliding ring (2) overlap in the axial direction between 40% and 100%, preferably between 50% and 90%, and more preferably between 60% and 80%. Sliding ring (2) according to one of the preceding claims, characterized in that the radially inner contact surface (6) and the outer contact surface (12) of the sliding ring (2) overlap in the axial direction between 0% and 40%, preferably between 5% and 35% and more preferably between 10% and 30%. Mechanical seal service set comprising a sliding ring according to any one of the preceding claims 1 to 8, and an associated inner first seal, an associated outer second and third seal, and preferably comprising two sliding rings according to any one of claims 1-8, each with the associated two inner first seals, associated two outer second and two outer third seals. Mechanical seal (40) comprising at least one sliding ring (2) according to any one of the preceding claims 1 to 8 wherein each of the two sliding rings (2) is held in a respective housing and hub component (44, 46) by three seals, an inner first seal and an outer second and an outer third seal, preferably O-rings (20, 22), wherein the mechanical seal (40) is preferably provided with an anti-rotation device. Mechanical seal (40) according to claim 10, characterized in that the inner first seal (20) is formed by a first O-ring (80) and the outer two seals (22) are each formed by a second and third O-ring (82, 84), and wherein the inner first O-ring (80) has a cord thickness that is between 1.5 and 3, preferably 2 and 2.7, more preferably 2.2 and 2.5 times greater than the cord thickness of the outer second O-ring (22, 24). Mechanical seal (40) according to claim 10, characterized in that the inner first seal (20) and the outer two seals (22, 24) are each formed by a first O-ring (80) and a second and third O-ring (82, 84), respectively, and wherein the inner first O-ring (80) has a cord thickness that is between 0.7 and 1.5, preferably 0.8 and 1.3, and more preferably between 0.9 and 1.1 times greater than the cord thickness of the outer second or third O-ring (22, 24). Mechanical seal (40) according to one of claims 10, 11 or 12, characterized in that the mechanical seal (40) is a mechanical seal of a drive or running gear of an agricultural machine or agricultural vehicle, a construction machine, or a tracked or crawler vehicle.

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