SE526056C2 - Collision protection for rail vehicle couplings and a linkage device designed for such a connection for permanent coupling of two rail vehicle units - Google Patents

Abstract

The invention relates to a collision protection for couplings the rail-mounted vehicles of the type that comprises a coupling element (1) in which two parts (6, 7) translationally movable in relation to each other are included, between which one or more energy-extincting elements (23, 24) of deformable character are arranged. Characteristic of the invention is that the energy-extinction elements (23, 24) consist of tubes, which are deformable by radial compression as a consequence of having a first, tapering end portion inserted into a thinner bore (25, 26) in one of the parts (7) and an opposite, free end distanced from the second part (6) in order to, upon displacement of the two parts (6, 7) in the direction of each other, be pressed axially into the bores. The invention is particularly suitable for use in link devices of the type that is used for permanently connecting two rail-mounted vehicle units.

Description

un »no u .... .- u u o» ao 10 U 20 25 30 35 526 056 w 2 joint connected link head. More specifically, said deformation tube at its front end is formed with a forwardly widening, conical collar in which a partially conically shaped ring is inserted on the rear end of the male element. More specifically, the conical surface of this ring is pressed tightly or play-free against the collar of the deformation pipe already in the initial position of the device, ie without a collision occurring. When the individual link is applied an axial force in addition to a predetermined limit value, the male element can be penetrated axially into the deformation pipe during radial widening thereof, whereby the material in the pipe is plastically deformed during simultaneous heat generation; all for the purpose of converting kinetic energy into heat energy and thereby alleviating or reducing the effect of axial impact forces between two interconnected rail vehicle units.

In practice, however, this type of crash protection is associated with a number of disadvantages. A disadvantage is due to the fact that the deformation work and the energy conversion take place by radial expansion of the deformation pipe to the extent that this requires a certain available space around the pipe.

In this way, the designer's opportunities to reach the desired limit are limited. The fact that the deformation takes place by radial expansion results in increased compactness of the link device as a whole. in addition, there is a latent risk that the material in the deformation pipe will rupture before the male element has had time to cover its entire stroke. In this way, the energy conversion process can cease prematurely, as a result of which the impact protection effect of the pipe is lost too quickly. In addition, the construction's general energy absorption capacity is rather limited even in the case where the pipe is holding.

OBJECTS AND FEATURES OF THE INVENTION In its broadest aspect, the present invention aims to eliminate the disadvantages of prior art crash guards in general and to create improved crash guards.

A primary object of the invention is thus to create a crash protection which can be realized in a compact design by not requiring any special receiving space for radially expanding components. An additional purpose is to create a crash protection whose energy-extinguishing elements do not risk rupture and which therefore do not risk prematurely losing their energy-converting and shock-absorbing ability.

According to the invention, at least the primary object is achieved by means of the features stated in the characterizing part of claim 1. Advantageous embodiments of the crash protection according to the invention are further defined in the dependent claims 2-15.

In a second, narrower aspect, the invention also relates to a linking device of the type indicated in the preamble. The features of this linking device are set out in the characterizing part of claim 16.

Summary of the invention The invention is based on the idea of using as energy quenching element one or more pipes or pieces of pipe, which are plastically deformable by radial compression as a result of having a first, tapered end portion inserted in a thinner bore in one of the two parts of a coupling element and an opposite, free end spaced from the other part so that when the two parts are displaced in the direction of each other - in connection with a collision - is pushed axially into the barrel. This means that the deformable element can never be destroyed radially and take up space in the surroundings outside it. There is also no risk of the element failing prematurely as a result of material breakage. Another feature characteristic of the invention is that the front, free end of the deformation tube or tubes is spaced from one part of the coupling element via a certain gap. This ensures that the deformation pipe can never be affected by the normal, moderate stresses that occur in the link device. Only after such considerable impact forces which occur in connection with collisions or the like have released the translationally movable part does it come into contact with the deformation tube and trigger the crash protection function. Fig. 10 U 20 25 30 35 526 056 4 Brief description of the accompanying drawings In the drawings: Fig. 1 is a side view of a link device intended for permanent connection in which a collision protection according to the invention is included, Fig. 2 is a plan view from above of the link device according to Fig. 1, Fig. 3 a longitudinal section through the same link device, Fig. 4 a perspective exploded view of two links included in the link device, Fig. 5 a perspective exploded view of only one link, Fig. 6 an enlarged longitudinal section through a carrier included in the link, Fig. 7 a first longitudinal section through a back piece included in the carrier, Fig. 8 a second longitudinal section through the same back piece, Fig. 9 a side view of a first type of deformation pipe included in the crash protection, Fig. 10 a longitudinal section through the same pipe, Fig. 11 a side view of another type of deformation pipe, Fig. 12 a longitudinal section through the pipe according to Fig. 11, and Fig. 13 a simplified, perspective exploded view showing the link device in connection with partly two rail vehicle units in the form of a chassis or wagon baskets, partly one with these cooperating Jakobs-boggi.

Detailed description of a preferred embodiment of the invention Below, the invention will be described with reference to a special form of rail vehicle coupling, namely a link device or link coupling, which is used in practice for permanent coupling of two rail vehicle units, eg two wheeled chassis or wagon baskets, which together form a railway wagon, which can be inserted into arbitrary trainsets by being connected to other wagons or locomotives, usually via automatic couplers or the like. It should be pointed out, however, that the invention is not limited to a link device of the type shown in the drawings, but can also be applied to arbitrary connecting elements for coupling elements for to connect rail vehicles, such as automatic couplings, other permanent couplings or the like.

The link device selected as an exemplary embodiment illustrated in Figs. 1-4 comprises two components, namely a first, complete link 1 and a part denoted by 2, which is included in a second link. More specifically, the part 2 is insertable into a box-like frame 2 'shown in Fig. 13, which forms a second link part which is attachable to a vehicle unit or car body other than the link 1. The two links are interconnected via a in its entirety with 3 designated joints. This joint comprises in a conventional manner partly a 2 to pivot vertical pin 4, which allows the links 1, relative to each other in the horizontal plane, as indicated by the angular area in Fig. 2, and partly a spherical bearing body 5, which allows the links to pivot in the vertical plane relative to each other , as indicated by the angular range ß in Fig. 3.

Each link 1, 2 is attachable to a rail vehicle unit or as indicated in Fig. 13. In the example, only the one with a crash protection is a chassis, one link, namely the link 1, according to the invention, so the other link 2, 2 'is not more to be touched upon.

As best seen in Fig. 4 in combination with Figs. 1-3, the link 1 comprises a front link head 6 and one to a rear carrier, which cooperating vehicle unit permanently connectable, is designated in its entirety 7. composed of two assembled components, namely an In the example this carrier is a co-shaped body 8, partly a back piece 9 located in the area of its rear end. The body 8 comprises partly a bottom plate 10, partly a vertical front plate 11 from which extend two vertical side pieces l2, which are rigidly connected to both the front plate and the bottom plate, for example by being welded to them. The side pieces are oriented at right angles to the front plate 11 and spaced apart from each other, while each of them is located at a certain distance inside the opposite side edges of the bottom plate 10. In practice, the frame 8 is made of strong steel sheet (thickness in the range 25-50 mm). Even stronger is the back piece 9, which can advantageously be made in the form of a solid cast steel body, which is connected to the side pieces 12 of the body 8 via a plurality of strong connecting elements 13, for example coarse screws or pins. Connection of the carrier 7 to the associated rail vehicle unit takes place via the bottom and front plates 10, 11 of the frame 8, which are shown connecting elements which are applied in holes 14 in travel, more precisely via non-respective plates.

Referring now to Figures 5 and 6, the nature of the link 1 is illustrated. It can be seen from Fig. 5 that, in more detail, the link head 6 at a rear end has a crosspiece 15, which extends at a right angle to the geometric longitudinal axis of the link head. More specifically, the crosspiece 15 has a rectangular basic shape, in its opposite short side edges are grooves grooved 16. In assembled condition, the link head 6 projects through a central opening 17 in the front plate 11 of the frame 8, the crosspiece 15 abutting the back of the front plate 11. The crosspiece 15 is formed four threaded holes 18 for receiving the same number of screws or bolts 19 (see Fig. 6), which have the task of holding the link head in place. In the area between the hanging thread of the individual screw and the head 20, the shaft of the screw is slightly weakened via a waist 21 whose diameter determines the strength of the screw. By giving the waist 21 a suitable diameter, it can be predetermined at which stress the screw will burst. Thus, to the extent that the linkage device would be subjected to extreme, axial shock forces of the kind that occur in connection with collisions and the like, the link head 6 can be released from the body 8 by breaking the screws 19, and then set in an axial, translational movement relative to the body.

Arranged on the inside of the individual side piece 12 is an axially oriented guide strip 22, which engages in a cooperating groove 16 in the crosspiece 15 of the link head. During translational movement of the link head relative to the frame, the link head is thus guided by the guide strips 22.

Connected to the back piece 9 are three pipes or pipe pieces serving as crash protection, namely a central pipe 23 of a first type, and two side-by-side pipes 24 of a different type. The nature of these pipes, which in practice are called deformation pipes, will be described in more detail below with reference to Figs. 9-12. The most conspicuous nano; away; 10 15 20 25 30 35 526 us in 7 the difference between the two types of pipes is that they have different diameters. More specifically, the central tube 23 has a larger diameter than the two side tubes 24. The tubes cooperate with through-runs 25, 26 in the rear piece 9.

Referring now to Figures 7 and 8 which illustrate the nature of the aforementioned bore 25, 26 of the deformation tubes 23, 24. Although the central bore 25 of the central deformation tube 23 and the lateral bores 26 of the tubes 24 have different diameters, they are formed in basically the same way. Thus, the individual barrel has a cylindrical basic shape and is formed with a funnel-shaped mouth 27 which widens in the forward direction towards the front surface 28 of the back piece 9. In the example, each barrel is divided into three different sections with different diameters, namely a front section 29, which has a smallest diameter and is located in immediate connection with the mouth 27, an intermediate section 30 with a slightly larger diameter, and a rear section 31, which has a larger diameter than the intermediate section 30. An annular shoulder surface 32 is formed between the two latter sections. of the orifice 27 is in this case genuinely conical, ie the surface delimiting the orifice is rotationally symmetrical and generated by a rectilinear generator. In this context, however, it should be pointed out that the tapered shape of the funnel mouth 27 can also be determined by surfaces other than a genuinely conical surface, for example a convexly curved surface (= the arcuate generator).

Fig. 6 shows a special insert ring 33, which is not shown in Figs. 7 and 8, but which after manufacture of the body forming the back piece 9, is mounted in the annular space adjacent to the barrel. This insert ring 33 consists of a different material than the material in the back piece in general. For example, the ring 33 may consist of a high-strength and heat-resistant steel, while the body 9 may, for example, consist of cast steel.

A common feature of both types of pipes 23, 24 (see Figs. 9-12) is that they have a first, rear end portion 34, which tapers in the rearward direction from the long, front portion 35 of the tube. In the example, the portion 35, which extends along most of the length L of the tube, genuinely 'ø-n. coon: 10 15 20 25 30 '535 526 056 8 cylindrical shape, i.e. its mantle surface 36 is cylindrical and generated by an imaginary rectilinear generator which is parallel to the center axis C (see Figs. 11, 12). The shape of the tapered end portion 34 is determined by an outer circumferential surface 37, which in the example is genuinely conical, i.e. generated by an imaginary generisis which is rectilinear. In the example, the conical end portion 34 has the same thickness T as the cylindrical portion 35, more specifically as a result of the inner surface 38 of the end portion 34 having the same conicity as the outer surface 37.

This conicity, which is determined by angle v, is of great importance for the functionality of the deformation pipe. In the example, the angle V amounts to 15 °. Although the conicity can vary both upwards and downwards from this value, however, the cone angle in question should amount to at least 5 ° and not more than 20 °, and suitably be in the range 10-166 °. Experiments which form the basis of the invention have been most successful as the cone angles have varied within the range ll-l5 °. In this context, it should be emphasized that it is the cone angle of the outer mantle surface 37 that is most critical. Adaptation and variation of the energy absorption capacity of the deformation tube to desired characteristics can thus take place by varying the wall thickness in the end portion 34. By reducing the cone angle of the inner surface 38, the end portion 34 can thus be gradually thinned towards the smallest opening of the tube.

The wall thickness of the cylindrical tube portion 35 is defined as D1-D2 / 2, where D1 is the outer diameter and D2 the inner diameter. In the example, the pipe 24 of the thinner type has an outer diameter D1 of 60 mm and an inner diameter D2 of 42 mm, ie the wall thickness amounts to 9.0 mm. The total length L is at the same time 249 mm. In this context, it should be noted that the front end of the tube 24 is constituted by an annular, flat surface 39 extending at right angles to the center axis C.

At its rear end, the tube 24 has a seat in which a washer 40 with a nut 41 is welded.

The differences between the embodiment described above and shown in Figs. 8 and 9 and the coarser pipe 23 shown in Figs. 10 and 11 are few. However, the outer diameter D1 in the tube 23 is larger and in the example amounts to 134 mm, at the same time: the inner diameter D2 amounts to 120.2 mm, ie the wall thickness of the tube amounts to in this case to 6.9 mm (compared to the thickness 9.0 mm of the thinner tube 24). When several pipes with different diameters are used in combination with each other, it has been found that the wall thickness of the pipe sections should be inversely proportional to the diameter insofar as a coarser pipe should have a smaller wall thickness than each smaller pipe and vice versa.

The total length L of the coarse tube 23 amounts to 266 mm.

In other words, the tube 23 is slightly longer than the tube 24.

Otherwise, the tube 23 is similar to the tube 24 in that it includes a welded washer 40 and a nut 41, and the conical end portion 34 has the same wall thickness 1 as the cylindrical portion 35.

Reference is now made again to Figs. 7 and 8, which - in the concrete exemplary embodiment - illustrate the dimensions of the bores 25, 26 which cooperate with the deformation pipes 23, 24. For the coarse bore 25, the inner diameter D3 of the section 29 amounts to 120 mm. This dimension corresponds to the smallest inner diameter of the insert ring 33 (see Fig. 6) at the rear end of the ring. As pointed out above, the deformation tube 23 has an outer diameter D1 of 134 mm. This means that the diameter of the hole section 29 amounts to only about 90% of the outer diameter of the pipe and that the outer diameter of the pipe will be reduced by 14 mm when the pipe is pressed into the bore.

Otherwise, the diameter D4 for the middle section 30 is = 222 mm, while the rear section 31 has a diameter D5 of 127 mm. The axial length L1 of the back piece amounts to 160 mm. Otherwise, the length measurements L2 are 95 mm, L3 45 mm and L4 26 mm. The mouth's 27 largest outer diameter D6 amounts to 146 mm.

The cone angle Å corresponds to the cone angle V according to Fig. 12 (the retrofitted insert ring 33 is evenly thick and therefore has the same cone angle as the seat of the mouth).

For the smaller bore 26 according to Fig. 8, the following vital dimensions apply: Ib = 52 mm, D4 = 54 mm, L2 = 105 mm, L3 = 45 mm, L4 = 18 mm and D6 = 72 mm. Also in this case the cone angle Å corresponds to the cone angle Å of the tube 24.

From the above it appears that the inner diameter D3 (52 mm) of the hole section 29 amounts to about 87% of the outer diameter D1 of the pipe 24 "= ss 526 056 10 diameter D1 (60 mm). In this case the diameter of the pipe 24 is thus reduced. with 8 mm in case of deformation.In general, the degree of reduction should be in the range 80-95%, preferably 85-90%.

Reference is now made again to Fig. 6 which illustrates how a deformation pipe 24 is mounted in the back piece 9. More specifically, the mounting takes place by means of a bolt 42 provided with a skull 42 'whose male thread is screwed into the female thread 41 of the nut 41.

The skull 42 'is fastened to a stop element in the form of a washer 43, which is abutment against the aforesaid shoulder 32. Between the washers 40, 43 serving as stop elements, a spacer 44 extends whose length determines the tightening force with which the conical end portion of the tube 24 is clamped fixed in the mouth or seat 27 in the rear piece 9.

Reference is now made to Fig. 2, which shows that the tubes 23, 24 protrude different distances in the forward direction from the back piece 9. More specifically, the coarse, central tube 23 protrudes slightly further than the two smaller, laterally arranged tubes 24. Between the tube 23 and the crosspiece 15 of the link head 6 thus forms a gap 45 which is slightly smaller or shallower than the gap 46 between the front end surfaces 39 of the side tubes 24 and said crosspiece 15. In practice the gap 45 may have an axial length in the range 5-15 mm and the gaps 46 a length within the range 10-20 mm. This means that one of the pipes, namely the central pipe 23, will be hit by the crosspiece 15 slightly before the same crosspiece hits the other pipes in connection with a possible release of the crash protection.

The choice of material in the deformation tubes 23, 24 is of vital importance. In general, the pipes should be made of steel, more specifically carbon steel. After a variety of tests, it has been found that a commercially available steel of the type OVAKO 280 has particularly suitable properties. This steel is characterized by the following directional analysis: C: 0.17-0.20%, Si: 0.30-0.45%, Mn: 1.45-1.60%, P: max 0.030%, S: 0.020- 0.035%, Cr: 0.202-0.30%, Ni: max 0.30%, Mo: max 0.10%, Cu: max 0.30%, V: 0.08-0.12%, Ca: max 15 ppm, Ti: max 30 ppm, O: max 15 ppm and N: 70-150 ppm. another uv-a; 10 15 20 25 30 35 526 056 11 Function and advantages of the invention Under normal circumstances, ie when the carriages or vehicle units in a train set are subjected to the usual tensile, compressive and torsional stresses, the crash protection formed by the three deformation tubes is ineffective in that the screws 19, the link head 6 is fixed in the position shown in the drawings in which the crosspiece 15 is kept tightly pressed against the back of the front plate 11. In this condition, the crosspiece does not have any contact with the deformation tubes 23, 24 due to the presence of the gaps 45, 46. However, should a collision occur and the carriages or vehicle units be subjected to extreme shock forces which strive to propagate through a train set, the crash protection is activated.

This is done by the screws 19 breaking, whereby the link head 6 is released so that this and the back piece can move towards each other. In this case, the crosspiece 15 first hits the central tube 23 and shortly thereafter the two leaner side tubes 24, all tubes being pressed into the associated bore in the back piece up to a point where the cross piece 15 is stopped against the front surface 28 of the back piece 9. pressed into the associated barrel, the same will be gradually deformed by being compressed or compressed in the radial direction all the while the outer diameter of the pipe is reduced to the same inner diameter as the front section 29 in the barrel (= the smallest inner diameters of the insert ring). During this deformation work, which takes place essentially in the area of the conical insert ring 33, the kinetic energy in the released link head is converted into heat in both the deformation tubes and the back piece 9. This means that a substantial part of the kinetic energy is extinguished before it transferred from one wagon or vehicle unit to the other.

The above-mentioned screws 19 extend axially, i.e. parallel to the longitudinal extent of the link or parallel to the relative direction of movement between the link head 6 and the body 7. Rupture therefore occurs when the material in the screws, more specifically the screws' waists, reaches the tensile strength. In this case, the screws serve as release means, which - by suitable selection of the diameter of the screws or waists - can be dimensioned so that they activate the crash protection at a very precise, predetermined limit value for the impact forces that the link coupling is to take up. In addition, the screws also participate in the shock-absorbing and kinetic energy-extinguishing work to the extent that the material in them is deformed during elongation and heat development up to the point where the tensile strength limit is reached. In this context it may also be mentioned that the elongation of the screws is possible due to the presence of the gaps 45, 46 between the crosspiece 15 of the link head and the free ends of the deformation tubes 23, 24, i.e. due to the deformation tubes not being clamped at their opposite ends. The fact that the screws are stretched and elongated a bit before they break also means that the crosspiece 15 of the link head is in the immediate vicinity of the ends of the deformation pipe (the gap 45 between the deformation pipe 23 and the crosspiece 15 is reduced to one or a few millimeters) when the screws defects and triggers the actual crash protection. The preload of the screws 19 further provides a play-free and fatigue-resistant joint for normal vertical, lateral and longitudinal operating loads. In this connection it should further be pointed out that the link head and its crosspiece are guided axially without turning due to the guide strips 22 engaging in the guide grooves 16. Although it would be conceivable to use only a deformation tube which can be compressed radially, It is preferred to use two or more different lengths of tubes in which the deformation work is initiated at different lengths after the link head has been released from its locked position. In this way, a smoother energy quenching process is obtained. In addition, the use of several pipes with a limited diameter instead of a single pipe with a large diameter means an improved utilization of the available height space in the link device or coupling. In other words, a crash protection of several side-by-side deformation pipes suitable for a given requirements specification takes up considerably less space in the vertical joint than a single pipe for the same requirements specification.

By modifying the deformation forces of the release screws 19 and the tubes 23, 24 and combining them in another suitable manner, a progressive force course can be achieved during the entire stroke in the event of a collision.

Possible modifications of the invention The invention is not limited only to the embodiment described and shown in the drawings. As already pointed out earlier, the general inventive idea can thus be applied in any couplings for rail vehicles, for example in automatic couplings or permanent couplings of a kind which do not form linking devices of the permanent type described above. In detail, the crash protection can be modified in various ways, in particular with regard to the geometry of the deformation pipes and the receiving barrels. Thus, the tapered portion of the deformation tube does not necessarily have to have a genuinely conical shape, nor does the receiving, tapered mouth. .vnøn 10 ß 20 25 30 526 056 14 List of reference numbers | _x I- * KOCOQOWLTIbUJRJRJ @ \ | - '| -'} - 'l \) PJ (A) lJ »ß F- * UW UJ ® | - * \ l FJ (D P4 kO l \) CD l \) IJ {\) l \) l \) U) l \) »bl \) Uï l \) ON l \) \ 1 l \) CD l \) KO U.) O LU IJ b) | \ J b) u.) B) »b- bd UW bl) O fi b) \ 1 link link part link part joint pivot bearing body link head carrier carrier frame back piece bottom plate front plate side pieces connecting element hole crossbar guide groove opening holes screws screw head waist guide strip middle deformation pipe side-shaped deformation pipes flea flea flea mouth front surface front flea section middle flea section rear flea section shoulder surface insert ring conical pipe end portion main pipe section pipe shell surface conical shell surface 38 39 40 41 42 43 44 45 46 internal gap gap surface

Claims (16)

10 U 20 25 30 35 526 056 15 Patent claim Collision protection for rail vehicle couplings of the type comprising a coupling element (1) which comprises two translationally movable parts (6, 7) between which at least one energy-extinguishing or absorbing element (23, 24) of deformable nature is arranged , characterized in that the energy extinguishing element consists of a tube (23, 24), which is deformable by radial compression as a result of having a first, tapered end portion (34) inserted in a thinner bore (25, 26). ) in a first part (7) and an opposite, free end (39) spaced from the second part (6) so that when the two parts (6, 7) are displaced in the direction of each other, they are pushed axially into the barrel, more precisely after rupture of one or more release means (19), which initially holds said parts together in a fixed state in which the deformation tube (23, 24) is completely inactive. Crash guard according to claim 1, characterized in that the bore (25, 26) is formed with a funnel-shaped mouth (27), which widens in the direction of the deformable tube and in which its rear end portion (34) is pressed. Crash protection according to Claim 1 or 2, characterized in that the deformable tube (23, 24) has a cylindrical basic shape. Crash guard according to Claim 2 or 3, characterized in that the end portion (34) of the pipe (23, 24) inserted into the mouth (27, 26) of the bore (25, 26) has a conical outside (35). Crash guard according to claim 4, characterized in that the funnel-shaped mouth (27) of the barrel is conical and has a cone angle (Å) which is at least equal to the cone angle (V) of the rear end portion (34) of the tube (23, 24) ), which amounts to a minimum of 5 ° and a maximum of 20 °. N Ü 20 25 30 35 526 056 16 Crash guard according to one of the preceding claims, characterized in that the free end of the deformable tube (23, 24) consists of an annular, flat surface (39) which extends at a right angle to the geometric center axis of the tube. (C). Crash protection according to one of Claims 4 to 6, characterized in that the deformable tube (23, 24) is fixedly pressed into the mouth (27) of the barrel (25, 26) by means of a clamping element (43). which is accessible from a rear end of the barrel (25, 26). Crash guard according to claim 7, characterized in that the clamping element consists of a nut (41) and bolt (42) extending between two stop elements (40, 43), one of which (40) is fixed in the tube (40). 23, 24) clamped end and the other is abutted against an annular shoulder (32) in the transition between a rear section (31) of the bore having a larger diameter than a front section (30). Crash protection according to one of the preceding claims, characterized in that the distance between the free end of the deformation pipe and said second part (6) amounts to at least 5 mm. Collision protection according to one of the preceding claims, characterized in that several deformable pipes (23, 24) are associated with said first part (7), the free ends (30) of which are located at different great distances from the second part (6) for initiating deformation of the pipes at different times after an initial displacement of the two parts (6, 7) towards each other. Crash protection according to Claim 10, characterized in that at least two different pipes (23, 24) have different outer diameters (D1). 10 15 20 25 30 35 526 056 17 Crash protection according to Claim 10 or 11, characterized in that the pipes (23, 24) have different wall thicknesses (T). Crash protection according to Claims 11 and 12, characterized in that the wall thickness (T) of the tubes is inversely proportional to the diameter (D1) in that a coarser tube (23) has a smaller wall thickness (T) than each leaner pipes (24). Collision protection according to one of the preceding claims, characterized in that said release means (19) consist of one or more screws (19), which extend parallel to the relative direction of movement between said parts (6, 7) in order to burst by reaching a predetermined tensile strength after stretching. Crash guard according to claim 14, characterized in that the individual screw (19) is formed with a waist (21) whose diameter determines the tensile strength of the screw. Linking device for permanent interconnection of two rail vehicle units, comprising two links or link parts (1, 2) connected via a common joint (3), of which at least one (1) is divided into two translationally movable parts, namely a front link head (6) connected to the joint (3) and a rear carrier (7) which can be fixedly connected to a vehicle unit, wherein between these parts (6, 7) an energy extinguishing or absorbing element serving as a crash protection is arranged. deformable nature, characterized in that a collision protection device constructed in accordance with any one of claims 1-12 is used as the impact protection, the energy extinguishing element of which consists of a tube (23, 24), which is deformable by radial compression as a result of having a rear, tapered end portion (34) inserted in a narrower bore (25, 26) in a back piece (9) included in the carrier (7), and which at an opposite, front end (39) is spaced from the link head (6) ).