Front end for a railway coupler comprising an energy absorber

Abstract

The present invention relates to a front end for a railway coupler, the front end (10) comprising a coupler head (11) and a coupler shank (12) attached to each other, wherein the coupler shank (12) also comprises a rear end (121) with a through-hole (13) for receiving a pivot pin (40), and wherein the front end (10) further comprises an energy absorber (30) arranged in said through- hole (13) for fitting around the pivot pin (40), wherein said energy absorber (30) comprises at least one deformable element (31) that is / are configured with a first threshold such that deformation of the at least one deformable element (31) takes place only when the energy absorber (30) is subjected to a force above the first threshold. The invention also relates to a coupler (100) with such a front end (10), an energy absorber (30), and a method for replacing an energy absorber (30).

Description

[0001] FRONT END FOR A RAILWAY COUPLER COMPRISING AN ENERGY ABSORBER

[0002] TECHNICAL FIELD

[0003] The present invention relates to a front end for a railway coupler, in particular a front end with an energy absorber for fitting around a pivot pin to decrease movement of the pivot pin in relation to the coupler shank.

[0004] BACKGROUND

[0005] Railway couplers generally comprise a front end formed by a coupler head attached to a coupler shank, and a draft gear for mounting on a railway vehicle. The front end is pivotably connected to the draft gear by a pivot pin that extends through a vertical through-hole in the rear part of the coupler shank. The pivot pin is held by a draw bar anchor that is attached to the draft gear.

[0006] That the front end is pivotable is necessary to enable interconnected railway vehicles to follow bends along the tracks, and for this purpose a clearance is provided between the rear end of the coupler shank and the draft gear. The pivoting movement is limited by rear edges of the coupler shank, since pivoting the coupler shank will bring the rear edge on one side towards the draft gear. At the point where the rear edge contacts the draft gear, no further pivoting is possible and the coupler has reached its maximum deflection.

[0007] It is also necessary to ensure that forces on the coupler due to acceleration or braking are applied along a longitudinal axis of the coupler. This in turn ensures that energy absorbers provided in the coupler (typically in the form of a reversible energy absorber in the draft gear for handling forces during normal operation and at least one irreversible energy absorber for handling excessive forces during a crash) are able to operate as intended. For this purpose, it is essential that buckling or bending or the coupler is reliably prevented in the event of a crash.

[0008] As long as the force is directed in the longitudinal direction, the crash management system of the coupler and the railcar itself are able to absorb the crash force and thereby avoid damage, injury or death to cargo or passengers travelling inside the railcar. The stabilization that ensures the longitudinal application of forces is achieved by the rear end of the coupler shank having a rearwardly facing contact surface that is perpendicular to the longitudinal direction and that is pushed against a counter surface on a back plate of the draft gear when subjected to a buff force (i.e. a force that pushes the front end towards the draft gear) . When the contact surface is in contact with the back plate, the front end is held securely in the neutral position and cannot pivot, thereby forming a stabilizing link to stabilize the coupler. Stabilization requires a large contact surface of the coupler shank to completely prevent pivoting.

[0009] The dual requirements of enabling pivoting of the front end and of stabilizing the coupler are typically met by increasing the clearance between the coupler shank and the draft gear so that the front end is free to rotate around the pivot pin despite the contact surface being large enough to ensure stabilization. There is also typically a clearance at the pivot pin, either between the pivot pin and the pivot anchor or, more commonly, between the pivot pin and the through-hole in the coupler shank. Thereby, the distance between the contact surface and the back plate increases during operation in particular when the coupler is subjected to a draft force so that the coupler shank is pulled away from the draft gear.

[0010] However, increasing the clearance in the coupler is also associated with drawbacks, in particular with a snatch effect that arises when couplers that are compressed to the stabilizing position with the coupler shank pressed against the draft gear are subjected to a draft force. In particular where multiple couplers are mounted in a set of interconnected vehicles, the draft force may cause a very large snatch for the last vehicles in the set, resulting in excessive wear to the components involved and also a discomfort for passengers and possible damage to cargo. The compression and expansion of the clearances also cause excessive noise that is undesirable, in particular in cities and other locations where many humans or animals are close to railway lines. At present, there are no efficient and convenient solutions for minimizing snatch and noise in railway couplers while at the same time allowing the necessary range for pivoting of the coupler shank as well as the stabilization of the coupler shank against the draft gear. There is therefore a need for improvements within this area.

[0011] SUMMARY

[0012] The object of the present invention is to eliminate or at least to minimize the problems discussed above. This is achieved by a front end for a railway coupler, a railway coupler, an energy absorber, and a method for replacing an energy absorber in a front end for a railway coupler according to the appended independent claims.

[0013] The front end for a railway coupler comprises a coupler head and a coupler shank attached to each other. The coupler shank comprises a rear end with a through-hole for receiving a pivot pin, and the front end further comprises an energy absorber arranged in said through-hole in a manner suitable for fitting around the pivot pin. The energy absorber comprises at least one deformable element that is / are configured with a first threshold such that deformation of the at least one deformable element takes place only when the energy absorber is subjected to a force above the first threshold.

[0014] By providing the energy absorber in the through-hole and by ensuring that the at least one deformable element is / are compressed only when subjected to a force above the first threshold, the front end largely prevents movement of the pivot pin in relation to the coupler shank and ensures that movements that do take place are dampened so that noise is avoided. This allows for a clearance provided between the pivot pin and the through-hole to enable pivoting of the coupler shank but prevents the snatch effect from causing sudden jerks in an interconnected set of railway vehicles where the front end is mounted during operation. Also, by selecting the first threshold the energy absorber can be unaffected by small forces or even by most forces during normal operation, so that compression only takes place at high forces or in the event of a crash. This is highly advantageous in controlling movements of the front end in relation to a draft gear.

[0015] That the energy absorber only absorbs forces above the first threshold also gives the advantage that the energy absorber returns to its neutral position when the force is lowered below the first threshold, such as when a set of interconnected railway vehicles comprising the front end is braked. At a high brake force, the energy absorber is compressed but as the buff force of the braking decreases, the energy absorber returns to its neutral position so that the pivot pin is held at a center of the through-hole when the set stops moving. This in turn prevents snatch from occurring as the set of interconnected vehicles start moving again, since the distance between the pivot pin and the inner circumference of the through-hole is taken up by the energy absorber. Also, it eliminates any noise stemming from the pivot pin contacting the inner circumference of the through-hole as the set of vehicles moves.

[0016] Suitably, the energy absorber has a first stroke length that corresponds to the deformable element having a maximum compression at a second threshold that is higher than the first threshold. Thereby, the energy absorber is able to absorb force by being compressed until the second threshold is reached. Since the energy absorber has then reached its maximum compression at the first stroke length, no further compression of the energy absorber is possible. This in turn renders the energy absorber highly efficient at absorbing a force between the first threshold and the second threshold but not outside of a range formed by these thresholds.

[0017] Also, the front end suitably comprises at least one mechanical stop for the energy absorber, said mechanical stop being configured to limit compression of the at least one deformable element to the first stroke length. Thereby, the mechanical stop acts as a protection for the energy absorber to prevent an excessive force from damaging it.

[0018] In some embodiments, the at least one mechanical stop is connected to one of an edge of the through-hole and an inner surface of the energy absorber, said at least one mechanical stop extending at least partially in a radial direction towards a counter surface connected to the other of the edge of the through- hole and the inner surface of the energy absorber. Thereby, the mechanical stop is provided in the coupler shank connected to an end of the through-hole and to the inner surface of the energy absorber where the pivot pin is to be placed. This means that the mechanical stop is provided in parallel with the at least one energy absorber. The mechanical stop can thereby be made available for inspection to allow an operator to verify that the mechanical stop is correctly placed and able to function as intended. In some embodiments, the mechanical stop may be provided as a protrusion from the inner circumference of the through-hole extending towards where the pivot pin is to be held. This means that the pivot pin itself can provide the counter surface for the mechanical stop, or alternatively that a counter surface may be extending from the inner surface of the energy absorber.

[0019] In such embodiments, a plurality of mechanical stops may also be provided and be distributed in a vertical direction, so that mechanical stops may be provided at an upper and a lower part of the through-hole with the energy absorber arranged between them. This is advantageous in providing a symmetrical stop for the compression of the energy absorber to ensure that the coupler shank is not tilted in a vertical direction in relation to the pivot pin.

[0020] Suitably, the energy absorber comprises an outer layer for contacting the inner circumference of the through-hole, an inner layer with an inner surface in the form of a sleeve for fitting around the pivot pin, and the at least one deformable element arranged between the inner layer and the outer layer. Thereby, a compact and efficient energy absorber is provided, with the inner layer and outer layer serving to securely mount the energy absorber in the through-hole and to distribute force evenly along the at least one deformable element. Another advantage is that the energy absorber is rendered particularly convenient when mounting and when removing for replacing, and that the at least one deformable element is securely held between the inner and outer layers. In some embodiments where the energy absorber comprises the inner layer, outer layer and deformable element provided therebetween, the mechanical stop is at least one protrusion in one of the inner layer and the outer layer, said protrusion extending at least partly in a radial direction in relation to the through-hole towards a counter surface on the other of the inner layer and the outer layer. Thereby, the mechanical stop is provided as the energy absorber is manufactured, ensuring that it can be dimensioned to fit precisely the desired length of the first stroke and that the energy absorber cannot be compressed beyond that first stroke length, thus protecting the at least one deformable element and ensuring a longer lifetime.

[0021] Also, in embodiments where the energy absorber comprises the inner layer, outer layer and deformable element provided therebetween, the deformable element may comprise an upper ring element and a lower ring element, each arranged between the inner layer and the outer layer at an upper position and a lower position, respectively, with a hollow portion therebetween, and wherein the at least one mechanical stop is arranged between the outer layer and the inner layer in the hollow portion between the upper ring element and the lower ring element. Thereby, the mechanical stop is provided inside the energy absorber and is protected from wear and dirt caused by the surroundings when the front end is in operation in a set of railway vehicles.

[0022] Suitably, there may be a plurality of mechanical stops arranged in the energy absorber, said plurality of stops being separated from each other in a circumferential direction of the through-hole. Thereby, compression of the energy absorber is limited to the desired stroke length in compression both in the forwards and backwards direction along the longitudinal extension of the front end. Furthermore, compression in a sideways direction, i.e. at an angle to the longitudinal direction may also be limited in this way.

[0023] Suitably, the second threshold is 30 kN - 250 kN, preferably 50-225 kN and more preferably 200 kN. Thereby, the maximum energy absorption of the energy absorber can be selected to correspond to a force experienced during normal operation at a lower end of the range, or to a force experienced only during particularly large draft or buff forces at a higher end of the range. By selecting the second threshold appropriately, the energy absorber is rendered highly beneficial since it enables compression to the first stroke length at a desired maximum force for absorption.

[0024] Also, the first threshold is suitably 20 - 120 kN, preferably 40 - 110 kN, more preferably 100 kN. Thereby, the first threshold where compression of the energy absorber starts can be selected as a level of force experienced during normal operation in the lower end of the range, or as a level of force experienced only at particularly large draft or buff forces in the higher end of the range. It is highly advantageous that the compression of the energy absorber can be selected to start as desired, since it enables control of the movement of the pivot pin in relation to the coupler shank.

[0025] In some embodiments, the deformable element comprises an elastomer, preferably rubber. This is an efficient yet cost-effective solution where stable and reliable operation is provided for a long lifetime of the energy absorber. It also enables a precise selection of the first threshold and of the first stroke length, either by selecting the elastomer to have a desired hardness or by pre-tensioning the elastomer so that compression below the first threshold is avoided.

[0026] In other embodiments, the deformable element instead comprises a mechanical spring, preferably a volute spring. Thereby, a reliable and highly robust solution is provided where the first threshold and the first stroke length are selected by choosing suitable properties of the mechanical spring. The mechanical spring also enables a longer lifetime and ensures reliable operation in all temperatures and other environment conditions.

[0027] In yet other embodiments, the deformable element comprises a gas- hydraulic damper. Thereby, properties of the deformable element can be selected with high precision to in turn select the first threshold and the first stroke length.

[0028] In some embodiments comprising any type of deformable element, the at least one deformable element is pre-tensioned to the first threshold. Thereby, compression of the at least one deformable element is reliably avoided below the first threshold.

[0029] The present invention also relates to a coupler for a railway vehicle. The coupler comprises a draft gear configured to be connected to a railcar, said draft gear comprising a second energy absorber for reversibly absorbing energy when subjected to a force in a longitudinal direction along the coupler. Also, said draft gear comprises a draw bar anchor and a pivot pin, and the coupler further comprises a front end according to the invention, said pivot pin being arranged in the through-hole of the coupler shank and held by the draw bar anchor for pivotably connecting the coupler shank to the draft gear.

[0030] Thereby, a coupler is provided that has the advantage of the energy absorber fitted around the pivot pin to minimize movement of the pivot pin in relation to the coupler shank when subjected to forces below the first threshold.

[0031] Suitably, the energy absorber is configured to fit around the pivot pin with a clearance of less than 1 mm in a radial direction, preferably less than 0.5 mm and more preferably less than 0.1 mm. Thereby, snatch is further minimized and any noise arising from movement of the pivot pin in relation to the coupler shank is also minimized.

[0032] Also, the second energy absorber may be configured to absorb energy below the first threshold of the energy absorber of the coupler shank. Thereby, the second energy absorber will act to absorb any forces on the coupler while the energy absorber will remain uncompressed until the first threshold is reached. This is advantageous in preventing forces below the first threshold from affecting other components of the coupler or the railway vehicle on which it is mounted during operation. It is particularly advantageous when the first threshold is high, so that energy absorption is provided by the second energy absorber during normal operation. Thereby, the lifetime of the energy absorber is also increased.

[0033] Alternatively, the second energy absorber is configured with a third threshold such that energy absorption takes place only when the second energy absorber is subjected to a force above the third threshold, and wherein the third threshold is higher than the first threshold. Thereby, the second energy absorber will only act to absorb forces that are high enough that compression of the energy absorber has already begun. This is particularly advantageous in embodiments where the first threshold is low, so that forces in normal operation are absorbed in the energy absorber whereas higher forces also affect the second energy absorber. In some embodiments, the third threshold may be selected to be close to or equal to the second threshold, ensuring that only very high forces are absorbed by the second energy absorber.

[0034] Suitably, the coupler shank comprises a rearwardly facing contact surface for contacting a back plate of the draft gear, said contact surface being arranged at a first distance from the back plate in a neutral position, and wherein the first distance is equal to or smaller than a first stroke length of the energy absorber of the front end, said first stroke length corresponding to a maximum compression of the deformable element of the energy absorber. Thereby, it is ensured that the stabilization of the coupler can take place as desired, since the contact surface of the coupler shank will be in contact with the back plate at least when the energy absorber is compressed the first stroke length.

[0035] In embodiments having the first distance from the contact surface to the back plate, the first distance may be 3- 15 mm, preferably 5- 15 mm and even more preferably more than 10 and less than 15 mm. Thereby, the first distance can be selected to fit the first stroke length and also to ensure that the required pivoting of the coupler shank can take place due to the combined clearance in a rotational direction provided by the first distance and the first stroke length.

[0036] Suitably, the draw bar anchor comprises the back plate. Thereby, the back plate is stiffly arranged with the draw bar anchor so that movement of the back plate in relation to the draw bar anchor is prevented. This ensures a cost efficient solution where the stabilizing of the coupler is particularly reliable. Also, the pivot pin is suitably fixedly arranged in a longitudinal direction in the draw bar anchor. Thereby, the risk of noise is further reduced, since movement of the pivot pin in relation to the draw bar anchor is prevented.

[0037] Suitably, the draw bar anchor comprises guiding means that at least partially enclose the second energy absorber. Thereby, the risk of angular movement of the draw bar anchor is reduced, thereby ensuring that the second energy absorber functions as intended, especially at high buff forces.

[0038] Also, the coupler suitably comprises a draft gear housing that in turn comprises means for connecting the draft gear housing to a bottom surface of a freight rail vehicle, wherein the draft gear is arranged at least partly inside the draft gear housing. Thereby, the draft gear can be firmly and stably attached to a freight rail vehicle.

[0039] The present invention also relates to an energy absorber that comprises an inner layer in the form of a sleeve with a circular cross-section and also comprises an outer layer arranged around the inner layer. The energy absorber further comprises at least one deformable element arranged between the inner layer and the outer layer, said at least one deformable element being configured with a first threshold such that deformation of the at least one deformable element takes place only when the energy absorber is subjected to a force above the first threshold.

[0040] By thereby ensuring that the at least one deformable element is / are compressed only when subjected to a force above the first threshold, the energy absorber is able to minimize snatch and excessive noise when used in a front end for a railway coupler.

[0041] Suitably, the energy absorber also comprises at least one mechanical stop formed by at least one protrusion in one of the inner layer and the outer layer, said protrusion extending at least partly in a radial direction towards a counter surface on the other of the inner layer and the outer layer, said at least one mechanical stop being configured to limit compression of the at least one deformable element to the first stroke length. Thereby, the mechanical stop acts as a protection for the energy absorber to prevent an excessive force from damaging it.

[0042] Also, the at least one deformable element may be pre-tensioned to the first threshold. Thereby, compression of the at least one deformable element is reliably avoided below the first threshold. The present inventors have realized that the lifetime of the deformable element 31 is increased when pretensioned to a first threshold that is above at least some forces that occur during normal operation.

[0043] Suitably, the at least one deformable element comprises an elastomer, preferably rubber. This is an efficient yet cost-effective solution where stable and reliable operation is provided for a long lifetime of the energy absorber. It also enables a precise selection of the first threshold and of the first stroke length, either by selecting the elastomer to have a desired hardness or by pre-tensioning the elastomer so that compression below the first threshold is avoided.

[0044] Alternatively, the at least one deformable element comprises a mechanical spring, preferably a volute spring. Thereby, a reliable and highly robust solution is provided where the first threshold and the first stroke length are selected by choosing suitable properties of the mechanical spring.

[0045] As yet another alternative, the at least one deformable element may comprise a gas-hydraulic damper. Thereby, properties of the deformable element can be selected with high precision to in turn select the first threshold and the first stroke length.

[0046] The present invention also relates to a method for replacing an energy absorber in a front end for a railway coupler, the method comprising the steps

[0047] - providing a front end for a railway coupler according to the invention and also providing an additional energy absorber,

[0048] - removing the energy absorber from the through-hole in the coupler shank - mounting the additional energy absorber in the through-hole in the coupler shank.

[0049] Thereby, the energy absorber of the front end may be replaced when worn or damaged.

[0050] Many additional benefits and advantages of the present invention will be readily understood by the skilled person in view of the detailed description below.

[0051] DRAWINGS

[0052] The invention will now be described in more detail with reference to the appended drawings, wherein

[0053] Fig. 1 discloses a perspective view of a coupler with a front end according to a first embodiment of the invention;

[0054] Fig. 2a discloses a cross-sectional view from above of the rear end of the coupler shank of the front end, together with a draft gear and a pivot pin;

[0055] Fig. 2b discloses a cross-sectional view from the side of the components of Fig. 2a;

[0056] Fig. 3a discloses schematically an energy absorber of the front end of Fig. 1 in a view from above;

[0057] Fig. 3b discloses schematically the energy absorber according to a second embodiment;

[0058] Fig. 4a discloses schematically the energy absorber of the first embodiment from the side;

[0059] Fig. 4b discloses schematically the energy absorber of a third embodiment from the side;

[0060] Fig. 5 discloses the rear end of the coupler shank and the draft gear of the first embodiment in a schematic view from above; Fig. 6 discloses the coupler from above in a neutral position with the coupler shank pivoted;

[0061] Fig. 7 discloses the coupler from above with the coupler shank pivoted to a maximum angle;

[0062] Fig. 8 discloses the coupler from above in a stabilized position with the coupler shank contacting the draft gear; and

[0063] Fig. 9 discloses schematically the method according to the invention.

[0064] All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the respective embodiments, whereas other parts may be omitted or merely suggested. Any reference number appearing in multiple drawings refers to the same object or feature throughout the drawings, unless otherwise indicated.

[0065] DETAILED DESCRIPTION

[0066] The invention will now be described according to a number of embodiments, firstly with the focus on a front end 10 and then on a coupler 100 as a whole. Throughout, there will be disclosure of an energy absorber 30 that distinguishes the present invention over the prior art and provides a number of advantages and benefits. It is in particular to be noted that the different embodiments vary mainly in the design of the energy absorber 30 as such and that the embodiments are similar or identical in other regards. Therefore, any embodiment disclosed herein is to be understood as similar or identical to the other embodiments except in features explicitly stated to be different.

[0067] The term ’’front end” as used herein is to be understood as an arrangement of components that are pivotable in relation to a draft gear of a coupler. In other words, the front end comprises a coupler shank, a coupler head, and any components that are non-pivotably attached to them. The front end may thus also be referred to as a coupler shank arrangement that encompasses the coupler shank and components attached thereto. Similarly, the term “draft gear” as used herein is to be understood as an arrangement of components that form a rear end of the coupler and that is configured to be attached to a railway vehicle.

[0068] Fig. 1 discloses the coupler 100 with the front end 10 according to a first embodiment of the invention. The front end 10 comprises a coupler head 11 (shown as an attachment of the coupler head 11 in Fig. 1) and a coupler shank 12 that is attached to the coupler head 11 as is well-known in the art. The coupler head 11 comprises a mechanical coupler for coupling to a front end of an opposing coupler as is likewise well-known in the art. Typically, electrical, pneumatical and / or other couplers are also provided in the coupler head to enable transmission of signals, electricity, pressurized air, etc. from one coupler to another when the front end 10 is in use. The coupler head is preferably an automatic coupler head according to EN 16019.

[0069] The coupler 100 also comprises a draft gear 20 that is configured to be mounted on a rail vehicle such as a freight rail vehicle. The draft gear 20 of the first embodiment comprises a second energy absorber 21 for reversibly absorbing energy when the coupler 100 is subjected to draft and / or buff forces during operation. The draft gear 20 also comprises a draw bar anchor 22 configured to hold a pivot pin 40 in a vertical position. Furthermore, a draft gear housing 23 is provided and at least partly surrounds the second energy absorber 21; the draft gear housing 23 also comprises means 231 for connecting the draft gear housing 23 to a bottom surface of a rail vehicle such as a freight rail vehicle. Such means 231 may be a bracket or holder that can be attached to the rail vehicle by known means such as bolting, screwing or welding. The second energy absorber may be in the form of a spring package, a gas-hydraulic damper, a hydraulic damper, or any other suitable device for reversibly absorbing energy in a railway coupler.

[0070] Suitably, the pivot pin 40 is fixedly arranged in a longitudinal direction along the coupler in the draw bar anchor 22. That the pivot pin 40 is arranged fixedly in the longitudinal direction is to be understood as the pivot pin 40 being arranged without a clearance in the longitudinal direction, so that a movement of the pivot pin 40 in a forwards or backwards direction in relation to the draw bar anchor 22 is prevented. For example, the draw bar anchor 22 may comprise an upper jaw, a lower jaw and holes in said upper and lower jaws, where said holes have a diameter or width that corresponds to a diameter of the pivot pin 40.

[0071] The draft gear 20 further comprises guiding means 221 comprised in the draw bar anchor 22 that at least partially enclose the second energy absorber 21. Such guiding means 221 may be elongated members that extend along at least one side of the second energy absorber 21.

[0072] Also provided in the draft gear 20 is a back plate 201 (see Fig. 5) that faces the front end 10 and that is suitably formed as a part of the draw bar anchor 22. On a rear part 121 of the coupler shank 12, a rearwardly facing contact surface 122 is arranged facing the back plate 201, as will be described in more detail further below.

[0073] Preferably, the guiding means 221 extend rearwards from the back plate 201 (see Fig. 6). An embodiment with the guiding means 221 preferably comprises also the draft gear housing 23 and the guiding means 221 that are arranged to interact directly or indirectly (i.e. with at least one intermediary component such as a wear plate) with an inner surface or surfaces of the draft gear housing 23.

[0074] To summarize, the coupler 100 comprises two main sections, namely the front end 10 and the draft gear 20. By attaching the draft gear 20 to a railway vehicle and coupling the front end 10 to a similar coupler attached to another railway vehicle, a set of interconnected railway vehicles is formed. The front end 10 is mounted on the draft gear 20 by the pivot pin 40 held by the draw bar anchor 22 extending through a through-hole 13 provided in the rear end 121 of the coupler shank 12. This enables a transmission of draft and buff forces from one section of the coupler 100 to the other, but it also enables the front end 10 to pivot in relation to the draft gear 20.

[0075] The coupler 100 also comprises the energy absorber 30 that is arranged in the through-hole 13 and configured to be fitted around the pivot pin 40. Thus, the energy absorber 30 is dimensioned to fit between an inner circumference 131 of the through-hole 13 and the pivot pin 40. This is shown in Fig. 2a-2b, where the arrangement of the shank 12, draft gear 20 and pivot pin 40 is shown in cross-section to reveal the energy absorber 30.

[0076] The energy absorber 30 is arranged in the through-hole 13 on the inner circumference 131 (or optionally with at least one intermediate object therebetween) and with an inner surface 301 in the form of a sleeve configured to fit around the pivot pin 40. The energy absorber 30 also comprises at least one deformable element 31 that absorbs energy by deforming when subjected to a force. That force may be a draft force, caused by the front end 10 being pulled away from the pivot pin 40, or may alternatively be a buff force caused by the front end 10 being pushed towards the pivot pin 40. Importantly, the energy absorber 30 is configured with a first threshold such that only forces above the first threshold cause a deformation of the at least one deformable element 31. This means that forces below the first threshold are unable to cause such deformation so that the pivot pin 40 is held immobile in relation to the coupler shank 12 by the energy absorber 30. The at least one deformable element 31 may be defined as a reversible energy-dissipating unit.

[0077] Fig. 2a also shows a circumferential direction CD that is defined in relation to the through-hole 13; thus, a movement in the circumferential direction CD is a movement around an axis A extending vertically through a center of the through-hole 13. Furthermore, Fig. 2b shows a radial direction R that is defined in relation to the same axis. A movement in the radial direction R is therefore a movement towards or away from the axis A.

[0078] The front end 10 also comprises at least one mechanical stop 14 for protecting the at least one deformable element 31 by preventing excessive compression of the energy absorber 30. In the first embodiment, the at least one mechanical stop 14 is connected to or provided on either an edge 131 of the through-hole (i.e. on the inner circumference 131) or the inner surface 301 of the energy absorber 30. The at least one mechanical stop 14 extends at least partially in the radial direction R towards a counter surface 141 that is connected to or provided on the other of the edge 131 of the through-hole and the inner surface 301. This means that either the edge 131 or the inner surface 301 either has a protrusion integrally formed with the part from which it protrudes or that a separate part acting as a mechanical stop 14 is attached to the edge 131 or the inner surface 301. Similarly, the counter surface 141 may be formed by the edge 131 or the inner surface 301 as such or by a protrusion integrally formed with or a part attached to the edge 131 or the inner surface 301. As an alternative, the mechanical stop 14 or the counter surface 141 may be connected to the inner surface 301 by being connected to the pivot pin 40 itself. When the energy absorber 30 is compressed by a force at or above the first threshold, a distance between the mechanical stop and the counter surface 141 decreases until finally they contact each other. At that point, the mechanical stop prevents further compression of the energy absorber 30 and the energy absorber has reached its maximum compression, denoted as a first stroke length SL1 (see Fig. 4b and 5). Providing the mechanical stop 14 therefore protects the energy absorber and prolongs its lifetime, while at the same time providing a well- defined first stroke length SL1 so that the maximum compression of the energy absorber 30 can be selected as desired.

[0079] That a component is connected to another is to be understood as the components being connected in such a way that a movement or force on one of the components is transferred to the other. This may mean that the components are joined together or attached to each other, or alternatively that they are both joined or attached to at least one intermediary component that serves to form a connection between them.

[0080] The mechanical stop 14 may be provided outside the energy absorber 30 as described above for the first embodiment. It may be provided either above the energy absorber 30 at an upper end of the through-hole 13, or below the energy absorber 30 at a lower end of the through-hole 13. Alternatively, it may be provided both above and below the energy absorber to ensure a protection of the at least one deformable element 31 even if the force applied to the energy absorber 30 is not horizontal. Also, it limits tilting of the front end 10, i.e. rotation about a horizontal axis that causes movement in a vertical direction. The maximum compression of the at least one deformable element 31 occurs when the force applied to the energy absorber 30 is at a second threshold that is higher than the first threshold. Absorption of energy therefore only takes place when the force on the energy absorber 30 is at the first threshold or the second threshold or between them. For lower forces, the energy absorber 30 maintains its uncompressed form and the pivot pin is held at the center of the through-hole 13. For higher forces, the energy absorber 30 is at its maximum compression with the pivot pin 40 moved the first stroke length SL1 in relation to the coupler shank 12. Advantageous selection of the first and second thresholds is described in more detail below.

[0081] Fig. 3a discloses the energy absorber 30 according to the first embodiment, with an outer layer 32, an inner layer 33 and at least one deformable element 31 between them. The at least one deformable element 31 may be designed as a sleeve fitting between the inner layer 33 and outer layer 32 and following an outer shape of the inner layer 33 and an inner shape of the outer layer 32, or may alternatively be designed a separate ring elements that are distributed in the vertical direction between them. As yet another alternative, a plurality of deformable elements 31 may be provided and be distributed in the circumferential direction CD, the radial direction R, the vertical direction, or any combination thereof.

[0082] The outer layer 32 has an outer surface 321 that is to be placed against the inner circumference 131 of the through-hole 13 when the energy absorber 30 is mounted in the front end 10. In the first embodiment, the outer surface 321 forms a circle so that the inner surface 301 of the inner layer 33 and the outer surface 221 of the outer layer 32 form concentric circles. This is advantageous in enabling a uniform thickness of the at least one deformable element 31 in the circumferential direction CD to in turn enable a highly advantageous absorption of force at deformation, i.e. when the inner layer 33 moves in relation to the outer layer 32. Shear forces are thereby minimized.

[0083] Fig. 3b discloses a second embodiment that differs from the first by the outer layer 31 being oval while the inner layer 33 is circular. This is particularly advantageous when fitting the energy absorber 30 in a coupler shank 12 with an oval through-hole 13, since it allows the energy absorber 30 to fit between the through-hole 13 and the pivot pin 40 without a clearance being formed between the outer layer 32 and the inner circumference 131 of the through-hole 13. Another advantage of the second embodiment is that the at least one deformable element 31 has an increased thickness in a longitudinal direction along the coupler shank 12 when mounted, so that energy absorption is improved.

[0084] Fig. 4a discloses the energy absorber 30 of the first embodiment from the side, showing the inner layer 33, the outer layer 32 and the deformable element 31 arranged between them. The inner layer 33 is shaped like a sleeve with the inner surface 301 forming a cylinder that is suitable for fitting around the pivot pin 40, and the inner layer 33 also has a curved outer surface 331. That the outer surface 331 is curved provides an advantage when stabilizing the coupler 100 since it provides increased control over force components on the coupler. It is also advantageous when compressing the energy absorber 30, since it distributes shear forces in the at least one deformable element 31 evenly and thereby improves wear resistance of the energy absorber 30. Advantageously, the curved outer surface 331 is curved to form part of a sphere to maximize the benefits mentioned above.

[0085] When the energy absorber 30 of the first embodiment of Fig. 4a is compressed, the inner layer 33 moves towards the outer layer 32 to compress the at least one energy absorber 31. The outer layer 32 suitably has a curved shape in at least one portion of an inner surface 322 that matches the shape of the curved outer surface 331 of the inner layer 33. This is advantageous in compressing the at least one deformable element 31 evenly and preventing excessive compression in a portion radially outwards from the outer surface 331 of the inner layer 33. It also improves stabilization of the energy absorber 30. Suitably, the outer surface 321 of the outer layer 32 is shaped to fit the inner circumference 131 of the through- hole 13 as explained above. Fig. 4b discloses a third embodiment that differs from the first and second embodiments in that the at least one mechanical stop 14 is provided inside the energy absorber 30. It is formed as at least one protrusion in the inner layer 33 and extends at least partially in a radial direction towards the outer layer 32 to meet the counter surface 141 provided on the inner surface 322 of the outer layer 32 when the at least one deformable element 31 is compressed to the first stroke length SL1. In some versions of the third embodiment, the at least one mechanical stop 14 can instead be provided in the outer layer 32 and extending in the radial direction towards the counter surface 141 on the inner layer 33. In the third embodiment as shown in Fig. 4b, two mechanical stops 14 are provided, one on either side of where the pivot pin 40 is to be placed in the front end 10. This means that the mechanical stop 14 is provided for both draft forces and buff forces to prevent excessive compression of the at least one deformable element 31 in both directions. Alternatively, a plurality of mechanical stops 14 can be provided distributed in the circumferential direction CD inside the energy absorber 30, or else the mechanical stop 14 can be provided as a collar extending around the inner layer 33 or outer layer 32 of the energy absorber 30.

[0086] In the third embodiment, the at least one deformable element 31 is provided as an upper ring element 311 and a lower ring element 312 that are arranged above and below the mechanical stop 14, respectively. A hollow portion 313 is formed between them, allowing the mechanical stop 14 to move towards and contact the counter surface 141 without damaging the deformable element 31. In some embodiments, for manufacturing reasons where the deformable element 31 comprises an elastomer, the upper ring element 311 and the lower ring element 312 may be joined by a joining section that extends across the hollow portion 313. The joining section forms a sacrificial portion that may then be excessively compressed or broken through by the mechanical stop 14 during use without decreasing performance of the energy absorber 30. For any of the embodiments described herein, the at least one deformable element 31 may comprise an elastomer. One particularly suitable elastomer for this purpose is rubber, but other elastomers such as polysiloxane may also be used. Elastomers have excellent energy absorbing properties and are comparatively easy to manufacture and handle. They are also cost efficient and have a suitable lifetime for use in a component such as the energy absorber 30 of the present invention.

[0087] As an alternative, the at least one deformable element 31 according to any embodiment herein may comprise a mechanical spring. One particularly suitable option is a volute spring, but other types of spring such as a ring spring may also be used. Using a mechanical spring has the advantage of a longer lifetime and ensuring reliable operation in all temperatures and other environment conditions.

[0088] As yet another alternative, the at least one deformable element 31 according to any embodiment herein may comprise a gas-hydraulic damper. This may be realized by providing a space inside the coupler shank 12 for housing a gas-hydraulic capsule operatively connected to the inner layer 33 of the energy absorber 30 so that a force from the pivot pin 40 on the inner surface 301 is transferred to the gas-hydraulic capsule for damping. Choosing this alternative provides the advantage of determining the first threshold and the first stroke length of the energy absorber 30 with high precision and providing a long lifetime and reliable operation of the energy absorber 30.

[0089] Enabling the energy absorber 30 to be compressed only by forces at the first threshold or above can be achieved by selecting a suitable material for the at least one deformable element 31 , such as an elastomer with a suitable hardness or a mechanical spring with a suitable spring constant. However, in one particularly advantageous design of the energy absorber 30 according to any embodiment disclosed above, the first threshold is achieved by pretensioning the energy absorber 30.

[0090] It is particularly advantageous to provide the energy absorber 30 with the at least one deformable element 31 held between the inner layer 33 and outer layer 32, since this renders the energy absorber 30 easy to handle and to mount and remove in the through-hole 13 of the coupler shank 12. Also, in particular when the at least one deformable element 31 is pre-tensioned, holding it securely between the inner layer 33 and outer layer 32 maintains the pre-tensioning and enables the at least one deformable element 31 to act as intended when subjected to a force above the first threshold.

[0091] The first threshold is suitably in the interval 20 - 120 kN, preferably 40 - 110 kN, and more preferablylOO kN. Choosing the first threshold at the lower part of the range means that at least some forces during normal operation are absorbed by the energy absorber 30, whereas choosing it at the higher part of the range would instead mean that only very high forces cause a compression of the energy absorber 30. Thus, depending on other available damping in the coupler 100 where the energy absorber 30 is to be used (such as the second energy absorber 21), selecting the first threshold determines how forces of different magnitudes should be handled in the coupler 100.

[0092] Similarly, the second threshold is suitably in the interval 30 kN - 250 kN, preferably 50-225 kN and more preferably 200 kN. Choosing the second threshold at the lower part of the range would mean that at least some forces during normal operation are left to other energy absorbers, such as the second energy absorber 21 of the coupler 100, to handle. Choosing it at the higher part of the range would mean that the energy absorber 30 operates alone or together with the second energy absorber 21 also for larger forces.

[0093] Of course, since the second threshold provides the upper limit for energy absorption, it follows that the second threshold must be higher than the first threshold and corresponds to a state where the at least one deformable element 21 has reached its maximum compression. Thus, if it is decided that the energy absorber 30 should operate only for small forces, the first threshold may be chosen as 20 kN and the second threshold as 30 kN. Alternatively, if it is decided that only very high forces should be absorbed, the first threshold may be chosen as 120 kN and the second threshold as 250 kN. As yet another alternative, if it is decided that only a small range of force should affect the energy absorber 30, the first and second threshold can be chosen close to each other anywhere in the ranges, such as e.g. 50 kN for the first threshold and 55 kN for the second threshold. If instead a large range should affect the energy absorber 30, the first threshold can be chosen as 20 kN and the second threshold as 250 kN. Thus, it is to be understood that the selection of the first and second thresholds may be freely made to suit any particular application for the energy absorber 30 and that it should be based on available energy absorption in the coupler 100 as a whole (reversible through the second energy absorber 21 and irreversible through a deformation tube or similar (not shown)).

[0094] In one embodiment, it may be desirable for the second energy absorber 21 of the draft gear 20 to absorb forces below the first threshold (such as starting from 0 N) up to very high forces (around 1500 kN that is typically an upper limit for reversible energy absorption in railway couplers) whereas the energy absorber 30 should only absorb force in a specific range in parallel with the second energy absorber 21. The present inventors have found that the range 100 - 200 kN would be highly suitable for the energy absorber 30 in such an embodiment, since this means that up to 70 % of all forces during normal operation are handled by the second energy absorber 21 so that the pivot pin 40 is held immobile in the longitudinal direction in relation to the energy absorber 30 except during large draft or buff forces (such as quick braking or acceleration) .

[0095] In another embodiment, it may instead be desirable for the second energy absorber 21 to have a third threshold that is higher than the first threshold. In such an embodiment, lower forces would only be handled by the energy absorber 30 whereas higher forces would be handled by both the energy absorber 30 and the second energy absorber 21 if the third threshold is lower than the second threshold. In some embodiments, the third threshold may be close to or equal to the second threshold, meaning that the energy absorber 30 and the second energy absorber 21 would not operate concurrently but only one at a time. Typically, however, the operating range is much larger for the second energy absorber 21 than for the energy absorber 30, meaning that very high forces (up to the limit where deformation tubes provided for irreversible energy absorption are activated) are handled by the second energy absorber 21 alone. Fig. 5 discloses the rear end 121 of the coupler shank 12 together with the draft gear 20 and the pivot pin 40 and energy absorber 30 and shows in particular the first stroke length SL1 of the energy absorber 30. This first stroke length SL1 limits the possible translational motion of the pivot pin 40 in relation to the coupler shank 12. Also, Fig. 5 shows the first distance D I from the rearwardly facing contact surface 122 of the coupler shank 12 to the back plate 201 if the draft gear 20, and how the first distance D I forms a second stroke length SL2 that limits the possible translational motion of the coupler shank 12 in relation to the draft gear 20.

[0096] It is an advantage that the first stroke length SL1 is equal to or larger than the first distance D I, since this ensures that a buff force on the coupler 100 causes the contact surface 122 to be pushed against the back plate 201, thereby activating the stabilizing function of the coupler to prevent buckling of the front end 10.

[0097] In some embodiments, the first distance D I is 3- 15 mm, preferably 5- 15 mm and even more preferably more than 10 and less than 15 mm. The first stroke length SL1 is therefore suitably equal to or larger than the ranges given for the first distance D 1. Choosing the first distance D 1 and the first stroke length SL1 is important since it determines how far the front end 10 may pivot in relation to the draft gear 20 without the contact surface 122 abutting the back plate 201. Being able to provide the first stroke length SL1 in the energy absorber 30 thereby enables the first distance D I to be smaller than in conventional couplers, since it is the combination of the first stroke length SL1 and the first distance D I that enables the full pivoting of the front end 10.

[0098] Fig. 6 discloses a pivoting of the front end 10 in relation to the draft gear 20 of 9.4 ° in a situation where no buff or draft forces act on the coupler. This may be a situation where the coupler 100 is in constant motion or when it is standing still. The available angle shown in Fig. 6 is a maximum angle based only on the first distance D I between the contact surface 122 and the back plate 201, i.e. there is no compression in the energy absorber 30.

[0099] Fig. 7 discloses a maximum pivoting of the front end 10 in relation to the draft gear of 17 °, also in a situation where no buff or draft forces act on the coupler but where the front end 10 is subjected to a pivoting force that causes the energy absorber 30 to be compressed so that further pivoting of the coupler shank 12 is enabled after the point where the contact surface 122 contacts the back plate 201. This shows the total maximum angle between the front end 10 and the draft gear 20 and highlights the particular advantage of providing the first stroke length SL1 in the energy absorber 30 in combination with the first distance D 1.

[0100] It is to be noted that the angles given above for the pivoting of the coupler shank 12 in relation to the draft gear 20 are given as examples only, and that they mainly serve to demonstrate that compressing the energy absorber 30 enables pivoting to a larger angle than when using only the first distance D I without compressing the energy absorber 30.

[0101] Thus, the main objective of the present invention of enabling a large pivoting movement of the front end 10 with only a small first distance D I is achieved by the energy absorber 30 with the first stroke length SL1 where the at least one deformable element 21 is compressed.

[0102] Fig. 8 shows the coupler 100 in a non-pivoted position subjected to a large buff force. This may be a situation where the set of interconnected vehicles in which the coupler 100 is mounted is braked to decrease its speed during operation. The buff force has caused the energy absorber 30 to be at least partially compressed to approach the first stroke length SL1 and this has brought the contact surface 122 into contact with the back plate 201, thereby stabilizing the coupler 100 so that the force applied to the coupler 100 propagates through the coupler in the longitudinal direction (i.e. along a symmetry axis B from the left to the right in Fig. 8) . In an embodiment where the first stroke length SL1 is equal to the first distance D I, the energy absorber 30 is compressed to the first stroke length SL1 when the coupler shank 12 is in contact with the back plate 201.

[0103] Thus, the second main objective of the present invention of enabling stabilizing of the coupler 100 when subjected to a large force is achieved by the energy absorber 30 where maximum compression to the first stroke length SL1 enables the contact surface 122 to be pressed against the back plate 201.

[0104] Returning now to Fig. 5, it shows how the energy absorber 30 is configured to fit around the pivot pin 40 without a clearance or with only a very small clearance. Suitably, the clearance (i.e. the play in which the pivot pin 40 is able to move in relation to the energy absorber 30 without compressing the at least one deformable element 30) is less than 1 mm, preferably less than 0.5 mm and more preferably less than 0.1 mm. A smaller clearance is advantageous since it prevents both snatch and excessive noise during operation, and since it enables the energy absorber 30 to maintain its position in relation to the pivot pin 40 to ensure that it operates as intended when subjected to a force above the first threshold. This fit between the energy absorber 30 and the pivot pin 40 is created by selecting dimensions of the energy absorber 30 to fit the diameter of the pivot pin 40, which is a standard dimension within the field of railway couplers. In other words, the energy absorber 30 has an inner diameter that corresponds to an outer diameter of the pivot pin 40 so that the energy absorber is configured to be arranged around the pivot pin with a clearance as small as that shown above.

[0105] The method for replacing the energy absorber 30 will now be described with reference to Fig. 9. In a first step, a front end 10 for a railway coupler 100 according to any embodiment of the invention disclosed herein is provided 1001, and the energy absorber 30 is then removed 1002 from the through- hole 13 in the coupler shank 12. This may be in a situation where the energy absorber 30 is damaged and needs to be replaced, or where planned maintenance to replace components that approach their expected technical lifetime takes place. An additional energy absorber 30 according to any embodiment of the invention disclosed herein is also provided 1001, and after removing 1002 the energy absorber 30 from the coupler shank 12 the additional energy absorber 30 is mounted 1003 in its place.

[0106] It is in particular to be noted that the energy absorber 30 that is removed and the additional energy absorber 30 with which it is replaced may be designed according to different embodiments of the present invention. For instance, the first threshold and second threshold may be different so that the old or damaged energy absorber 30 is replaced with one that has a higher or lower first or second threshold. Also, the at least one deformable element 31 may in one case comprise an elastomer and in the other a different elastomer, or a mechanical spring or gas-hydraulic damping element. As long as the new energy absorber 30 has the same outer dimensions to be able to fit into the through-hole 13 and the same inner dimensions to be able to fit around the pivot pin 40, any other aspects of the energy absorber 30 may be varied if desired. This may be because it has been found that a larger range for absorbing forces is desirable, so that the first and second thresholds are changed, or because it has been found that another type of deformable element 31 is more suited to the specific coupler 100 in which the energy absorber 30 is to be used (e.g. for use in heavy traffic such as freight vehicles or in colder climates such as during winter or in countries or regions with lower temperatures) .

[0107] It is to be noted that features from the various embodiments described herein may freely be combined, unless it is explicitly stated that such a combination would be unsuitable.

Claims

CLAIMS1. Front end for a railway coupler, the front end (10) comprising a coupler head (11) and a coupler shank (12) attached to each other, wherein the coupler shank (12) also comprises a rear end (121) with a through-hole (13) for receiving a pivot pin (40), and wherein the front end (10) further comprises an energy absorber (30) arranged in said through-hole (13) for fitting around the pivot pin (40), wherein said energy absorber (30) comprises at least one deformable element (31) that is / are configured with a first threshold such that deformation of the at least one deformable element (31) takes place only when the energy absorber (30) is subjected to a force above the first threshold.

2. Front end for a railway coupler according to claim 1, wherein the energy absorber (30) has a first stroke length (SL1) that corresponds to the deformable element (31) having a maximum compression at a second threshold that is higher than the first threshold.

3. Front end for a railway coupler according to claim 1 or 2, further comprising at least one mechanical stop (14) for the energy absorber (30), said mechanical stop (14) being configured to limit compression of the at least one deformable element (31) to the first stroke length (SL1).

4. Front end for a railway coupler according to claim 3, wherein the at least one mechanical stop (14) is connected to one of an edge (131) of the through-hole (13) and an inner surface (301) of the energy absorber (30), said at least one mechanical stop (14) extending at least partially in a radial direction towards a counter surface connected to the other of the edge (131) of the through-hole and the inner surface (301) of the energy absorber (30).

5. Front end for a railway coupler according to any previous claim, wherein the energy absorber comprises an outer layer (32) for contacting the inner circumference (131) of the through-hole (13), an inner layer (33) with an inner surface (301) in the form of a sleeve for fitting around the pivot pin (40), and the at least one deformable element (31) arranged between the inner layer (33) and the outer layer(32).

6. Front end for a railway coupler according to claim 5 when dependent on claim 3, wherein the mechanical stop (14) is at least one protrusion in one of the inner layer (33) and the outer layer (32), said protrusion extending at least partly in a radial direction in relation to the through-hole (13) towards a counter surface on the other of the inner layer (33) and the outer layer (32).

7. Front end for a railway coupler according to any of claims 5-6, wherein the deformable element (31) comprises an upper ring element (311) and a lower ring element (312), each arranged between the inner layer(33) and the outer layer (32) at an upper position and a lower position, respectively, with a hollow portion (313) therebetween, and wherein the at least one mechanical stop (14) is arranged between the outer layer (32) and the inner layer (33) in the hollow portion (313) between the upper ring element (311) and the lower ring element (312).

8. Front end for a railway coupler according to any of claims 3-7, further comprising a plurality of mechanical stops (14) arranged in the energy absorber (30), said plurality of mechanical stops (14) being separated from each other in a circumferential direction (CD) of the through-hole (13).

9. Front end for a railway coupler according to any of claims 2-8, wherein the second threshold is 30 kN - 250 kN, preferably 50-225 kN and more preferably 200 kN.

10. Front end for a railway coupler according to any previous claim, wherein the first threshold is 20 - 120 kN, preferably 40 - 110 kN, more preferably 100 kN.

11. Front end for a railway coupler according to any previous claim, wherein the at least one deformable element (31) comprises an elastomer, preferably rubber.

12. Front end for a railway coupler according to any of claims 1- 10, wherein the at least one deformable element (31) comprises a mechanical spring, preferably a volute spring.

13. Front end for a railway coupler according to any of claims 1- 10, wherein the at least one deformable element (31) comprises a gas- hydraulic damper.

14. Front end for a railway coupler according to any previous claim, wherein the at least one deformable element (31) is pre-tensioned to the first threshold.

15. Coupler for a railway vehicle, the coupler (100) comprising a draft gear (20) configured to be connected to a railcar, said draft gear (20) comprising a second energy absorber (21) for reversibly absorbing energy when subjected to a force in a longitudinal direction along the coupler (100), and said draft gear (20) also comprising a draw bar anchor (22) and a pivot pin (40), and the coupler (100) further comprising a front end (10) according to any of claims 1- 14, said pivot pin (40) being arranged in the through-hole (13) of the coupler shank (12) and held by the draw bar anchor (22) for pivotably connecting the coupler shank (12) to the draft gear (20).

16. Coupler according to claim 15, wherein the energy absorber (30) is configured to fit around the pivot pin (40) with a clearance of less than 1 mm in a radial direction, preferably less than 0.5 mm and more preferably less than 0. 1 mm.

17. Coupler according to claim 15 or 16, wherein the second energy absorber (21) is configured to absorb energy below the first threshold of the energy absorber of the coupler shank.

18. Coupler according to claim 15 or 16, wherein the second energy absorber (21) is configured with a third threshold such that energy absorption takes place only when the second energy absorber (21) is subjected to a force above the third threshold, and wherein the third threshold is higher than the first threshold.

19. Coupler according to any of claims 15- 18, wherein the coupler shank (12) comprises a rearwardly facing contact surface (122) for contacting a back plate (201) of the draft gear (20), said contact surface (122) being arranged at a first distance (D I) from the back plate (201) in a neutral position, and wherein the first distance (D I) is equal to or smaller than a first stroke length (SL1) of the energy absorber of the front end, said first stroke length (SL1) corresponding to a maximum compression of the deformable element (31) of the energy absorber (30).

20. Coupler according to claim 19, wherein the first distance (D I) is 3- 15 mm, preferably 5- 15 mm and even more preferably more than 10 and less than 15 mm.

21. Coupler according to any of claims 15-20, wherein the draw bar anchor (22) comprises the back plate (201).

22. Coupler according to any of claims 15-21, wherein the pivot pin (40) is fixedly arranged in a longitudinal direction in the draw bar anchor (22).

23. Coupler according to any of claims 15-22, wherein the draw bar anchor (22) comprises guiding means (221) that at least partially enclose the second energy absorber (21).

24. Coupler according to any of claims 15-23, further comprising a draft gear housing (23) that comprises means (231) for connecting the draft gear housing (23) to a bottom surface of a freight rail vehicle, wherein the draft gear (20) is arranged at least partly inside the draft gear housing (23).

25. Energy absorber for a railway coupler, said energy absorber (30) comprising an inner layer (33) in the form of a sleeve with a circular cross-section and also comprising an outer layer (32) arranged around the inner layer (33), and further comprising at least one deformable element (31) arranged between the inner layer (33) and the outer layer (32), said at least one deformable element (31) being configured with a first threshold such that deformation of the at least one deformable element (31) takes place only when the energy absorber (30) is subjected to a force above the first threshold.

26. Energy absorber according to claim 25, further comprising at least one mechanical stop (14) formed by at least one protrusion in one of the inner layer (32) and the outer layer (33), said protrusion extending at least partly in a radial direction towards a counter surface on the other of the inner layer (32) and the outer layer (33), said at least one mechanical stop (14) being configured to limit compression of the at least one deformable element (31) to the first stroke length (SL1).

27. Energy absorber according to claim 24 or claim 25, wherein the at least one deformable element is pre-tensioned to the first threshold.

28. Energy absorber according to any of claims 24-26, wherein the at least one deformable element (31) comprises an elastomer, preferably rubber.

29. Energy absorber according to any of claims 25-27, wherein the at least one deformable element (31) comprises a mechanical spring, preferably a volute spring.

30. Energy absorber according to any of claims 25-27, wherein the at least one deformable element (31) comprises a gas-hydraulic damper.

31. Method for replacing an energy absorber in a front end for a railway coupler, the method comprising:- providing (1001) a front end (10) for a railway coupler (100) according to any of claims 1- 14 and also providing an additional energy absorber (30),- removing (1002) the energy absorber (30) from the through-hole (13) in the coupler shank (12),- mounting (1003) the additional energy absorber (30) in the through-hole (13) in the coupler shank (12).

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