GB2131855A - Fishplate joints - Google Patents

Abstract

In a bolted fishplate joint for railway or other structures, at least one of the bolts 17'' has conical portions such as 33, 34 engaging split expanding bushes in the respective apertures of the fishplates and (optionally) the rail to form a clearance-free joint. As shown the split bush 20' is loaded by a spring 26, the bush 21 has a flange 32, and the bush 20'' is loaded by a nut 25. The split bushes may be eccentric to allow adjustment. The joint may be further strengthened by adhesive insulation 15''. A shape of fishplate is disclosed having contact with the rail head and foot over only part of its length. <IMAGE>

Description

SPECIFICATION A strapped joint, in particular a rail joint This invention relates to a strapped joint to connect profiles, and it relates in particular to a rail joint to connect the unwelded ends of rails for railways, in which joint two fishplates are accommodated in the rail fishing surfaces which are formed between the head and foot on both sides of the profile or rail stems and they may be braced therein by several high-strength bolt connections which are inserted into holes of the profile or rail stems and of the fishplates, and they may also be boneded therein, if necessary.

During the erection of metal constructions using profiled rods, profiled supports or the like, it is not always possible or desirable to join the ends of two adjacent profiles together by welding. In such cases, typical strapped joints are used with high-strength bolts connections to connect the profiles.

Moreover, during the construction of track installations for railways, the ends of the rails cannot always be welded together. However, it is unavoidable in certain cases to join the ends, facing one another, of successive rails by a rail joint of the typical kind. So-called fishplates are used to form the rail joint which are accommodated on both sides of the rail stem in the rail fishing surfaces which are formed between the rail head and rail foot, and are braced by bolt connections which are inserted into holes of the rail stems and of the fishplates. Rail joints of this type are provided as a firm joint via an individual sleeper or a coupled sleeper, but they are also installed to lie as a suspended joint between two sleepers, i.e., inside the so-called sleeper field.Particular significance is attributed to a bonded insulated rail joint having highstrength bolt connections, because this joint ensures a continuous, buckle-free and densecurrent rail connection and thus, has become indispensible in modern signalling technique.

The known strapped joints, as they are used quite generally in the erection of structures in steel, bridge and railway construction, but in particular the typical rail joints for connecting the unwelded ends of rails for railways, suffer from the considerable disadvantage that they cannot permanently endure the dynamic effects which are unavoidable in the case of great fluctuations in temperature. Therefore, known expansion gaps result between the ends of the profiles or rails which are not welded together, which gaps are constantly changing in size. However, severe consequent damage results due to such expansion gaps between the ends of rails in railway tracks.

In order to avoid expansion gaps in track installations, the fishplates have hitherto been bonded into the fishing surfaces of the rails, in particular in the case of insulated rail joints which are indispensible in signalling technique. The longitudinal tensile forces which arise in track installations are not transmitted by the bolts, but by the surfaces of the rails and of the fishplates which are bonded together.

Formerly, bonded insulated joints were regularly produced in a length of several meters in the track construction workshop and were then, after the adhesive had been left to dry for a sufficient length of time, welded into the track on site. These bonded insulated joints having highstrength bolts have proved very efficient, because they ensure a continuous, non-breathing, bucklefree and dense-current rail connection.

However, the rail joints which are required for a gap-less, insulated connection, or even an uninsulated connection of the unwelded ends of rails for railways are presently fishplated and bonded on site for financiai reasons, i.e., so-called site insulated joints are produced. Consequently, the financial expense for welding-in which was unavoidable in the former type of production indeed no longer arises, but the site insulated joints which presently belong to the prior art have severe technical faults. The reason for this lies mainly the defective adaptability of the individual components of these insulated joints to the forces which arise in a separate stretch of rails. These faults are frequently further intensified by the selection of an incorrect positon of the strapped joint in the track and by said joint acting so-tospeak as an absorbing joint.Different crosssectional distorstions are then produced in the region of the two rail ends which cause the socalled jumping effect when a wheel passes thereover. However, this also leads to various faults which require a high maintenance expense and, particularly in the case of insulated joints, entail a considerable reduction in the serviceable life.

The jumping effect which is produced as the wheel passes over results in the fishplates and/or the rails breaking and leads to the formation of a burr on the joint and, in addition thereto, necessitates a frequent re-tamping of the joint sleepers.

The main reason for the lack of breathing of the joint is based on the fact that the adhesive connections on site are not effectively reproducible, because there it is often impossible to observe the relatively long setting and hardening time required for the adhesive, since the bonded insulated joints have to be travelled over during the setting time, i.e., shortly after they have been produced.

Another disadvantage which arises in the case of bonded strapped joints, in particular insulated joints is that a fishplate form and quality which is not adequately adapted to the forces which arise is used. It also happens that the fishplates in the fishing surface come to rest only on the head and foot of the rail, but not on the stem thereof, so that when the high-strength bolts are tightened, such a high expanding force is produced that it may lead to the rails breaking, particularly in the case of an irregular hole de-burring. Finally, the formation of burrs on the ends of the rail head is substantially promoted, when expansion gaps occur, by the use of insulating joint intermediate layers which have an inadequate compressive strength.

An object of the present invention is to eliminate the faults which are associated with strapped joints, in particular with insulated joints which are to be produced on site. Therefore, an object of this invention is to provide a strapped joint in particular an insulated joint of the initially mentioned type which ensures, with simple means, a permanently reliable, mutual mechanical locking between all the co-operating elements, i.e., which maintains a non-breathing, gapless connection between the adjacent profile or rail ends even when high tensile forces arise in the region of the strapped or insulated joint.

This object is mainly achieved according to the characterisation of claim 1 in that at least one of the bolt connections which engage on the adjacent profile or rail ends each consists of expanding bushes which may be inserted into the holes of both fishplates and optionally into the holes of the profile or rail stem and which have conical inside surfaces, and consists of a drawbolt penetrating these expanding bushes and having complementary conical peripheral sections.

It has proved to be particularly efficient, if according to claim 2, the drawbolt has at least two conical peripheral sections which taper towards the ends of the bolt in opposite directions, and if both ends of the bolt are provided with a thread for adjusting nuts.

According to claim 3, the present invention also provides that the two conical peripheral sections of the drawbolt differ in length and the longer peripheral secton may be made to engage with the expanding bush which sits in the profile or rail stem, and with the expanding bush which sits in one fishplate, whereas the shorter peripheral section engages only in the expanding bush which sits in the other fishplate.

A feature of an embodiment according to the present invention is seen according to claim 4 in that the expanding bush which may be inserted into the profile or rail stem has on its end of a larger internal diameter a supporting collar which is directed radially outwards and has a length which at least corresponds to the maximum stem thickness. On the other hand, according to claim 5, a feature of an embodiment of this invention is also seen in the fact that the length of the expanding bushes which may be inserted into the fishplates is less than the thickness of the fishplate and distance rings and/or spring elements are allocated thereto as an abutment towards the adjusting nuts which may be screwed on to the thread of the drawbolt.

According to claim 6 of the present invention, it has proved to be particularly effective to arrange the inside surface eccentrically to the outside surfaces on the expanding bushes which may be inserted into the fishplates and/or on the bushes which may be inserted into the profile or rails stems, because as a result of this measure, it is possible, for example to easily compensate for work tolerances in the holes and/or in the spacings between the holes.

According to claim 7, another inventive feature of the present invention is that the expanding bushes are provided with a slit which passes through the complete length of the bushes.

Another important feature of an embodiment according to the present invention is that, according to claim 8, the contact surfaces of the fishplates facing the fishing surfaces of the profiles have a coating of micro-encapsulated adhesive, in particular a two-component adhesive consisting of a hardener and a binder.

According to claim 9, a further measure which lies within the scope of the present invention is to provide the fishplates and/or the fishing surfaces of the profiles or rails on their contact surfaces with a layer of insulating material of a high compressive strength and either, according to the teaching of claim 10, to provide the fishplates with a layer of insulating material of a high compressive strength on their contact surfaces for the bolt connection, i.e., on the walls and edges of the holes, or, according to claim 11, to provide at least the expanding bush which may be inserted into the profile or rail stem on its conical inside surface and/or on its outside surface with a layer of insulating material having a high compressive strength.

According to this invention, the rail sections, which are preferably separated in the middle of the sleeper field, are connected by fishplates which should attain in their cross section at least about 50% of the moment of resistance of an unseparated rail, so that when travelling over the joint, the rail does not sag substantially any more than in the rest of the track. The position of the joint in the middle of the sleeper field is to prevent the two rail ends form arching differently with respect to one another and from becoming displaced vertically. As in an unseparated, normal track, the impacts which arise are to be taken up resiliently and are to be distributed half each to the sleepers lying upstream and downstream of the joint, so that no additional maintenance of the two joint sleepers is required by frequent tamping and straightening operations.

However, the designs of fishplates which are usually used generally attain only 30% of the moment of resistance of the unseparated rail, so that undesirable fishplates breaks often occur. The reason for the fishplates breaking is to be attributed primarily to the fact that the rail joint which is freely suspended and lies exactly in the middle of the sleeper field is bent vertically to a greater extent elastically at the ends, facing one another, of the two rails, than in the places where the free ends of the fishplates lie inside the fishing surfaces. Thus, a supporting width for the fishplates is produced between the fishplate ends which are directed away from each other, which width is equal to their maximum length and thus amounts to about 600 mm.Due to this considerable supporting width, excessive stresses arise in the outer lower stretch fibre region on the fishplates when they are unavoidably bent, which stresses lead to thefishplates breaking, in particular under a high strain.

In order to be able to effectively counter such fishplate breakages, the present invention provides, according to claim 12, that the fishplates rest supporting only over one longitudinal section on the lower side of the rail head with their contact surfaces on the fishing surfaces of the adjacent profiles or rail ends, which longitudinal section extends to half the fishplate length over a region which is defined by the two holes, lying closest together, on the adjacent rail ends, whereas they are supported with their contact surfaces on the top of the foot of both rails in each case only over longitudinal sections which lie in a region which is defined by the spacing between the two holes which are in the same rail and is in a longitudinally displaced position with respect to the longitudinal section which is in contact on the head side.

The fishplate design which is modified in this way results in a substantial reduction in the effective supporting width, in contrast to the known design, with an elastic sagging of the rail joint. Thus, a clear power flux is produced from the rail head to the rail foot, with a full cover of the moments of resistance and intertia which are required for the maximum strain. In this way, the fishplate breakages are effectively countered.

According to claim 13, the present invention further proposes that the longitudinal section of the fishplates, in contact on the head side is of a length which is adapted to the spacing between the circumferential regions, which are furthest apart from one another, of the two holes, which are closest together, of both profile or rail sections.

Furthermore, it has also proved effective according to claim 14 for the foot-side longitudinal section which is opposite the longitudinal section, in contact on the head-side, of the contact surface of the fishplates to be delimited by an indentation in order to ensure a precise power flux.

Moreover, it is provided according to claim 15 that the contact surfaces of the fishplates facing the rail head and the rail foot extend in each case converging from the supporting sections towards the fishplate ends and preferably lie on a circular arc of a large radius. In this case, according to claim 1 6 the greatest spacing between the contact surfaces of the fishplates and the head and foot surfaces adjacent thereto of the rail sections should amount to about 1 mm.

A strapped joint which has the features of claims 1 and 2, and optionally also the features of any of claims 5 to 10, and 12 to 16 may also be designed according to claim 17 so that the drawbolt between the two conical perpiheral sections has a cylindrical peripheral section which engages with a narrow tolerance in the hole of the rail stem. In this case, the cylindrical peripheral section may either be positioned according to claim 18, centrically to the longitudinal axis of the drawbolt, or it may be positioned according to claim 19, essentrically to the longitudinal axis thereof. According to claim 20, the cylindrical peripheral section may also be formed by a narrowly adapted bush which sits on the drawbolt.In this arrangement, it has been found to be an essential feature, according to claim 21, to delimit the cylindrical peripheral section on one side by a collar which has a greater diameter than the stem hole of the profile.

According to claim 22, an encircling groove for receiving a ring made of rubber, plastics or the like is appropriately provided on the side opposite the collar, which ring prevents the cylindrical periphery from unintentionally sliding out of the stem holes when the fishplates are assembled. It was also found to be important according to claim 23 to produce the intermediate layer of insulating material, provided between the joint ends of the rails, from a plastics material, the compressive strength of which is about the same as, or is higher than the yield point of conventional rail steel.

Since the critical region lies in the middle of the sleeper field, i.e., in the cut joint region of the two rail sections, the two fishplates should fully cover the moment of resistance as well as the moment of inertia, depending on the actual strain, in order to avoid fishplate breakages, even under maximum strains. Since the power flux from the travelling surface of the rail head is transmitted downwards from above 450, only the relatively short top supporting region of the fishplates absorbs the forces and deposits them on the rail foot exclusively over the two supporting regions which are provided at a spacing from one another.

Each of these two lower supporting regions takes up in each case only half of the load from the top supporting region. Moreover, the surface pressing which occurs on the supporting surface of the rail foor is, however, considerably reduced in these regions, because there is a small air gap thereabove between the contact surface of the fishplate and the rail head. Absolutely no vertical forces may be transmitted at the ends of the fishplates, because there is a sufficient clearance at this point towards the rail head as well as towards the rail foot. The ends of the fishplates are used only for transmitting the tensile forces which arise in a longitudinal direction at a low temperature.

The burr formation on the joint ends of the rails can be ruled out almost completely by inserting between these ends an insulating joint intermediate layer which, according to claim 23, consists of an insulating material which has a higher compressive strength than the yield point of the rail steel. Thus, it is possible to reduce the thickness of the joint intermediate layer to such an extent as is possible for ensuring a dense current connection, without the consideration of burr formation.

The essence of the present invention is to brace together three cooperating elements of the strapped or rail joint without a clearance by the bolt connections which are used for the mechanical locking, via each drawbolt, by causing an optimum surface pressing inside the hole soffit of the fishplate bores and optionally of the rail stem bore. The bush which may be inserted into the holes of the rail stem may also have a cylindrical inside surface, and the drawbolt may also be provided with a cylindrical peripheral section in the stem region It is possible to position the bore of the stem bush concentrically or eccentrically to the bush periphery. In the latter case, the bush bore accommodating the drawboit may be adjusted by turning the bush in the stem bore.

Since the expanding bushes which may be inserted into the fishplates are not only designed to be conical inside and cylindrical outside and are provided with a longitudinal sit, but also have an eccentricity of, for example 0.6 mm of their conical inside surfaces with respect to the cylindrical outside surfaces, a particularly advantageous possibility is provided to achieve a tolerance balance. By pushing the conical inside surfaces of the expanding bushes into the allocated, conical peripheral sections of the drawbolt, the external diameter thereof is adapted to the diameter of the fishpiate bores, depending on the pushing-on depth.The eccentric expanding bushes are installed in each case in a predetermined direction namely in the tensile direction of the forces, with their thicker wall thickness, stipulated by the prevailing eccentricity, so that a form locking initially occurs between bolt, eccentric expanding bush and fishplate, and thus a bracing which counteracts the tensile direction of the forces is built up. Since the conical inside surfaces of the expanding bushes and since the likewise conical peripheral sections of the drawbolt are designed so that they lie inside the self-locking region, the eccentric expanding bushes which are inserted into the fishplates cannot be automatically released, stipulated by the friction which is produced on the bolt and in the fishplate bore.Since, however, a varying strain is to be reckoned with, under the influence of temperature and wheel load, an initial tension is exerted on the system via the drawbolt, to prevent the eccentric expanding bushes from being able to become released from their working position on cold winter days, under a corresponding tensile stress of the rails. The initial tension to be produced is preferably measured on half the total strain which occurs in order to thus suppress from the beginning the part of the pulsating load which is produced. This initial tension may be produced by using an auxiliary adjusting nut which presses the expanding bushes into their working position via the drawbolt.In order to secure the expanding bushes in their working position, even in the event of an incorrect assembling, a spring element is provided between the adjusting nut or between the washer allocated thereto and the relevant expanding bush. The elastic force ensures that even incorrectly mounted eccentric expanding bushes are pushed into their intended position and remain therein. Since in all cases, the resisting force through the friction is greater than the axial component which acts on the expanding bushes, said bushes may be prevented from being pushed out of their working position even with a low elastic force.

The characteristic provision of the drawbolt with the conical peripheral sections allows at least the expanding bush sitting in a fishplate to be pre-stressed at the same time as the expanding bush sitting in the profile or rail stem, when the drawbolts are braced, whereas the second expanding bush located in the second fishplate may be pre-stressed independently thereof.

In order to be able to use identical expanding bushes in the two fishplates, the dimensions of the conical peripheral sections on the drawbolt are selected so that they are designed identically in the working region of the expanding bushes located in the two fishplates, whereas the region of the longer conical peripheral section located outside the fishplate-side expanding bush is designed so that it cooperates with the expanding bush sitting in the profile or rail stem.

The procedure of assembling drawbolts, expanding bushes and fishplates is to be carried out such that first of all, the side which is at the front in the insertion direction of the drawbolt is braced, so that a fixing of the bolt with respect to the profile or the rail is ensured. This applies to the tightening of an auxiliary adjusting nut to a predetermined torque, and also to the tightening of the adjusting nut which remains on the fishplate and which leads to a bracing of the drawbolts up to a tension of 30 t.Since the fishplates are braced in each case in the working direction of the expanding bushes via the adjusting nuts which are allocated thereto, an additional, firm bracing of the expanding bushes is achieved with respect to the conical peripheral sections of the drawbolt and with respect to the fishplate bores and thus the expanding bushes are prevented from being released from their working position.

To dismantle a strapped or rail joint, all the adjusting nuts sitting on the front ends of the drawbolts in the insertion direction of said bolts are unscrewed. The complete construction may then be closed out against the insertion direction of the drawbolts. It is thereby ensured that the strapped and rail joint may subsequently be released at any time, so that, for example in the event of a rail stem breaking, repairs may easily be carried out on the fishplates or even on the drawbolt.

Other features and advantages of the object of the present invention will now be described in the following using embodiments which are shown in the drawings.

Figure 1 shows in a top view and partially in section an insulated joint positioned in the middle of a sleeper field, in a first embodiment, the drawbolts being isolated with respect to the fishplates, Figure 2 shows a longitudinal section through the insulated joint according to Figure 1, along the line Il-Il, Figure 3 shows, on an enlarged scale, a cross section along the line Ill-Ill in Figures 1 and 2 through the insulated joint, Figure 4, again on an enlarged scale, shows a cross section through the insulated joint according to Figures 1 and 2 along the line IV IV, Figure 5 shows a view which corresponds to Figure 1, of a modified type of construction of an insulated joint having an insulated stem hole, Figure 6 shows, on an enlarged scale, a cross section along line VI--VI through the insulated joint according to Figure 5, Figure 7 shows a longitudinal section, corresponding to Figure 2, through an insulated joint having a modified design of the fishplates, Figure 8 shows, on an enlarged scale, a cross section along line VIlI-VIlI through the insulated joint according to Figure 7, Figure 9 shows a cross section, also on an enlarged scale, through the insulated joint according to Figure 7 along line IX-IX, Figure 10 shows a cross section, again on an enlarged scale, along line X-X through the insulated joint according to Figure 7, and Figure 11 shows a section, corresponding to Figures 6 and 8, through another modified insulated joint.

Two rail sections 3' and 3" are firmly joined together by an insulated joint 4 within the socalled sleeper field 1, preferably in the middle of this field 1, between two sleepers 2' and 2". This insulated joint 4 is formed on one side by the ends 5' and 5", facing each other, of the rail sections 3' and 3", and on the other side by two fishplates 6' and 6" which are in a mirror-inverted position with respect to one another and which each overlap half the ends 5' and 5" of the rail sections 3' and 3".

The two rail sections 3' and 3" are attached to the sleepers 2' and 2" in a conventional manner by means of so-called iron mountings 7 at a spacing from their ends 5' and 5" which face one another in the middle of the sleeper field 1.

It may be seen from Figure 1 that the fishplates 6' and 6" have such a longitudinal dimension for the production of the insulated joint that they cover the ends 5' and 5" of the two rail sections 3' and 3" beyond the sleeper field 1 into the region of the iron mounting 7 located on the sleepers 2' and 2", in that, according to Figures 3 and 4, they engage with their contact surfaces 8 in a form-locking manner into the fishing surfaces 9 on both sides of the rail sections 3' and 3" which are delimited on one side by the rail stem 10 and on the other side by the rail head 11 and the rail foot 12.

The fishplates 6' and 6" have in their centre region wings 13' and 13" which project laterally over a certain longitudinal section to increase their moment of resistance and which overlaps the rail foot 12, as may be seen in Figures 1 and 3.

To produce a dense-current rail connection inside the insulated joint 4, there is provided on the one side between the front surfaces which face each other, on the ends 5' and 5" of the rail section 3' and 3", an intermediate layer 14 of insulating material which has a high compressive resistance, as indicated in Figures 1 and 2.

However, on the other side, the form-locking contact surfaces 8 of the fishplates 6' and 6" engaging in the fishing surfaces 9 of the rail sections 3' and 3" and/or the appropriate surfaces of the fishing surfaces 9 on the rail sections 3' and 3" are provided with a layer of insulating material 15' and 1 5", as is indicated in Figures 1 and 2 and as may clearly be seen from Figures 3 and 4.

To produce a bonded strapped joint, in particular an insulated joint 4, it is appropriate to coat the contact surfaces 8 of the fishplates 6' and 6" with micro-encapsulated adhesive, if applicable on their insulating layer 15' and 15", which adhesive is preferably a two-component adhesive consisting of a hardener and a binder.

The microcapsules containing the hardener and binder are crushed when the fishplates 6' and 6" are fitted into the fishing surfaces 9 of the rail sections 3' and 3", and, in so doing, the hardener and binder are released in the provided mixture ratio and are capable of setting and hardening within a relatively short time. Due to the particular geometry of the contact surfaces 8 on the fishplates 6' and 6", when the microcapsules are crushed, the adhesive composition flows towards the upper and lower inclined surfaces on the rail head 11 and on the rail foot 12, as well as in a longitudinal direction, thus producing an intimate mixing of hardener and adhesive.

Several, for example four high-strength bolt connections 16', 17' and 16", 17" are used for the mechanical locking of each strapped joint, in particular insulated joint 4. These bolt connections each penetrate holes 18' and 18" in the two fishplates 6' and 6" and they also penetrate relevant holes 1 9 in the stems 10 of the rail sections 3' and 3", as may be seen in Figures 1 and 3.

At least the high-strength bolt connections 17' and 17" which are directly adjacent to the ends 5' and 5" of the rail sections 3' and 3", but preferably also the high-strength bolt connections 1 6' and 1 6" which are further away therefrom have a particular design which ensures a clearance-free, tolerance-bridging, mechanical locking between the two rail sections 3' and 3" and between the two fishplates 6' and 6", and thus ensure a non-breathing connection between the ends 5' and 5" of the adjacent rail sections 3' and 3", which connection also reliably withstands the considerable tensile forces which arise at very low temperatures, and is thus a permanently gapless connection.

As shown in Figure 1 with reference to the bolt connections 17' and 17" and in Figure 3, using the bolt connection 17", the clearance-free, tolerance-bridging, mechanical locking is substantially formed by three expanding bushes 20', 20", 21 and by one drawbolt 22 and two relevant adjusting nuts 23' and 238. Moreover, each bolt connection 17' and 17" used for the mechanical locking also comprises two washers 24' and 24", allocated to the adjusting nuts 23' and 23", a distance sleeve 25 and a spring element 26 which is designed as, for example a pressure spring.

The expanding bushes 20', 20" and 21 are each provided with a slit 27 which passes through their complete length, as shown in figures 1 and 5. The two expanding bushes 20' and 20" are of an identical design and are accommodated in the holes 18' and 18" of the fishplates 6' and 6". In this design, they have a cylindrical periphery 28' or 28" and a conical inside surface 29' or 29".

The expanding bush 21 is accommodated by the hole 19 in the stem 10 of the rail sections 3' and 3" and is provided with a cylindrical periphery 30 and with a conical inside surface 31. On its end having a greater internal diameter, the expanding bush 21 has a collar 32 which is directed radially outwards, with which it may be supported in an axial direction against the lateral surface of the rail stem 1 0. Deviating from the embodiments which are shown in the drawings, a bush having a cylindrical outer surface and a cylindrical inner surface may also be used, instead of the expanding bush 21.

The conical inner surface 31 of the expanding bush 21 is preferably positioned concentrically to the cylindrical outer surface 30 thereof. Theconical inside surfaces 29' and 29" of the expanding bushes 20' and 20" have an eccentricity with respect to their outer surface 28 or 28", and this eccentricity may amount to, for example 0.5 or 0.6 mm, and the direction of this eccentricity runs toward the longitudinal slits 27, so that the expanding bushes 20' and 20" have the greatest wall thickness in their curcumferential region which is diametrically opposite the longitudinal slit.

The drawbolt 22 is provided with two conical peripheral sections 33 and 34 which taper in opposite directions and towards the ends of the bolt. Each bolt ends is provided with a threaded section 35 and 36, onto which the adjusting nuts 23' and 23" may be screwed.

The two conical peripheral sections 33 and 34 of the drawbolt 22 have different longitudinal dimensions, and that is, the peripheral section 33 has a greater longitudinal dimension and the peripheral section 34 has a smaller longitudinal dimension. Whereas the conical peripheral section 33 may cooperate with the expanding bush 21 inserted into the hole 30 of the rail stem 10, and with the expanding bush 29" inserted into the hole 18" of the fishplate 6", the oppositely directed, conical peripheral section 34 is designed only for cooperation with the eccentric expanding bush 20' which is positioned in the hole 28' of the fishplate 6'. If, instead of the expanding bush 21, a. bush is used in which not only the outer but also the inner surface is cylindrical, the peripheral section 3 must of course also be cylindrical in the region of the rail stem 10.

When the strapped joint, in particular the rail joint which is designed as an insulated joint 4 is assembled, the expanding bushes 21 are initially inserted into the holes 30 of the rail joint 10.

While the drawbolt 22 is driven in, they are then braced against the soffit surfaces of the hole 1 9 in the rail stem 10 with their cylindrical outer surface 30, being spread out radially by the rear part of the conical peripheral section 33. The drawbolt 22 may either be driven in by hammering the end of the bolt which has the threaded section 36, or by using an auxiliary adjusting nut which may be screwed onto the threaded section 35 with a limitable torque, being supported on the rail stem 10 or the like. The expanding bush 21 is supported via its radial collar 32 on one side of the rail stem 10 against the axial force component exerted on the expanding bush 21 by the drawbolt 20 via the conical peripheral section 33, whereas it projects from the rail stem 10 to a slight extent on the other side.

The expanding bushes 20' and 20" inserted into the fishplates 6' and 6" have a longitudinal dimension which is smaller than the thickness of the fishplates 6' and 6". So that, nevertheless, a radial spreading-out movement of the expanding bushes 20' and 20" with their cylindrical outer surfaces 28' and 28" against the soffit surfaces of the holes 18' und 18" into the fishplates 6' and 6" is allowed in a reliable manner via the drawbolt 22 or the conical peripheral sections 33 and 34 thereof, an adjusting nut 25 is provided on the one hand between the washer 24" and the expanding bush 20" and a pressure spring 26 or in the form of a cup spring column is provided on the other side between the washer 24' and the expanding bush 20'.

The spreading-out movement of the expanding bushes 20' and 20" inside the holes 18' and 18" of the fishplates 6' and 6" is caused, independently, on the one hand by operating the adjusting nut 23' and on the other hand by operating the adjusting nut 23, in which case, by operating the adjusting nut 23", expanding forces are also simultaneously exerted on the expanding bush 21 in the hole 30 of the rail stem 10 over the conical peripheral section 33. Due to the cooperation of the drawbolt 22 via the rear part of its conical peripheral section 33 with the expanding bush 21, the latter is pressed, without a clearance, into the hole 30 of the rail stem 10.

Consequently, an ideal pressing fit is produced with a homogeneous hole soffit pressure which thereby allows an optimum power transmission in the elastic region of the material over the complete projected surface of the hole soffit. The bolt and/or the bush may be flattened in the critical region to avoid relatively high linear strains.

In order to achieve a form-locking and tolerance-bridging mechanical locking of the cooperating elements and, above all, a nonbreathing connection between the adjacent profile or rail ends, it is important for at least the expanding bushes 20 and 20" to have an eccentricity of their conical inside surfaces 29' and 29" relative to their cylindrical outer surfaces 28' and 28". As a result of this measure, they may be inserted, for example into the holes 18' and 1 8" of the fishplates 6' and 6" so that they lie with their greater wall thicknesses in the direction of the force absorption. The same effect may also be achieved by positioning the inside surfaces 31 of the expanding bushes 21 sitting in the rail stem 10 (or of the bushes used in their place having a cylindrical inside surface) eccentrically to the external surfaces 30.It is particularly advantageous if the expanding bushes 20' and 20" as well as the bushes 21 are designed as eccentric bushes, because in this case, not only the desired complete eccentricity may be distributed to the bushes 20' and 20" on the one hand and to the bushes 21 on the other hand, but it is also possible to compensate for displacements of the drawbolt 22 at a right angle to the rail. Such a vertical displacement of the drawbolt 2 or with respect to the rail takes place if the eccentric axes of the bushes 21 lie above or below the horizontal plane running through the centre axes of the stem bores 1 9. However, the fishplates 6', 6" are adjusted vertically with respect to the rail with the drawbolts 22, so that a form-locking contact on the walls of the fishing surfaces is no longer ensured.In this case, a vertical displacement of the fishplates may be avoided by a suitable twisting of the expanding bushes 20', 20".

By a suitable force effect on the expanding bushes 20' and 20" in an axial direction, and that is, either by an impact effect or by screwing an auxiliary adjusting nut onto the threaded sections 35 and 36 of the drawbolts 22, does not allow from the pairing of the drawbolt 22 with the expanding bushes under load, if the cone angle lies in the self-locking region and if a frictional force is produced between the cooperating surfaces of fishplates 6', 6", and expanding bushes 20', 20", on the one hand and between expanding bushes 20', 20" and drawbolts 20 on the other hand, which force is greater than the axial component, resulting from the cone angle, of the proportionate bracing force of the rail sections 3' and 3".

In order that the puisating load of the mechanical locking which results from temperature fluctuations on the one hand and from wheel loads on the other hand does not lead to a detachment of the expanding bushes 20', 20" and 21, a securing effect is exerted by the pressure spring 6. Said spring 26 takes over a securing action against the adjusting nut 23' from unscrewing on the threaded section 36 of the drawbolt 22, in addition to securing the position for the expanding bush 20'.

It has been found that the longitudinal tensile forces which occur on the rail sections 3' and 3" may be reliably absorbed via the hole soffit pressure in the holes 1 9 of the rail stems. In the case of a diameter of the holes 19 in the rail stem 10 of about 40 mm, a radial force of about 44 Mp may easily be transmitted, per hole, to the hble soffit surface, without a plastic deformation.This means that even during the producton of bonded strapped joints, in particular insulated joints 4, it is possible to travel over the rail joint during the setting and hardening time of the microencapsulated adhesive, and a rail longitudinal tensile force of about 90 Mp may be absorbed, without the hardened adhesive being destroyed by the longitudinal tensile forces acting on the rail during the setting time, or even later on.

It has already been pointed out that particular insulating material intermediate layers 14 and insulating material layers 1 5', 1 5" must be provided in the region of the fishplate to form the insulated joints which are indispensible in modern signalling technique. However, the dense-current rail connection must not be interrupted on any account by the installation of the mechanical locking in the region of the bolt connections 16', 16" and 17', 17".

Thus, in the embodiment shown in Figures 1 to 4 of a bonded insulated joint 4, the soffit surfaces of the holes 18' and 18" in the fishplates 6' and 6" and also the supporting surfaces for the washers 24' and 24" or the adjusting nuts 23' and 23" are provided with layers or sleeves of insulating material having a high compressive strength, as may be clearly seen in Fig. 3.

The embodiment, shown in Figures 5 and 6, of an insulated joint 4 to connect rail sections 3' and 3" has basically the same construction and the same method of operation as the embodiment according to Figures 1 to 4. It is only the ensuring of the dense-current connection in the region of the mechanical locking, achieved by the bolt connections which is provided in a different way.

In this case, the expanding bush 30 to be inserted into the hole 30 of the rail stem 10 is provided with a layer of insulating material having a high compressive strength at least on its conical inside surface, but optionally also on its cylindrical outside surface. This design ensures that not only the two fishplates 6' and 6", but also all the functional elements used for the mechanical locking of the rail joint have a dense-current separation with respect to the rail sections 3' and 3". Of course, it would also be possible to combine the embodiment according to Figures 5 and 6 with the embodiment according to Figures 1 to 4, to achieve a dense-current rail connection 4, i.e., in the embodiment according to Figures 1 to 4 to also provide the expanding bush 21 with an insulating layer according to Figures 5 and 6.

The object which is recognised may also be achieved, at least partly, if fitting bushes having cylindrical inside surfaces are used instead of the expanding bushes 20', 20" having conical inside surfaces 29', 29". However, in this case, it is absolutely necessary for the inside surfaces of the fitting bushes to be positioned eccentrically to the outer surfaces thereof. The non-breathing gapless connection between the adjacent profile or rail ends may then be achieved by a suitable eccentric adjustment.

Figs. 7 to 10 show an insulated joint 104, the basic construction of which conforms with the insulated joint 4, as it has been described above in more detail with reference to Figures 1 and 6.

Thus, the same parts having the same reference numerals are allocated to Figures 7 to 10, but the parts have each been increased by 100 to clarify the difference. The insulated joint 104 according to Figures 7 to 10 has been modified with respect to the insulated joint 4 according to Figures 1 to 6 practically only with respect to the design of the fishplates 106' and 106" which each overlap half the rail sections 103' and 103".

The fishplates 106' and 106" do not engage over their complete length in a form-locking manner with their contact surfaces 108 into the fishing surfaces 109 on both sides of the rail sections 103' and 103". Instead, the fishplates 106' and 106" lie, supporting, merely over a middle longitudinal section on the lower side of the rail head 111 with their upwardly directed contact surface 108', which middle longitudinal section extends over a region 1 37 which is defined by the two holes 11 9', closest together, in the stems 110 of the two rail sections 103' and 103".On the other hand, the fishplates 106' and 106" are supported in each case with their contact surfaces 108" on the top of the rail foot 112 of both rail sections 103' and 103" only over longitudinal sections which lie in regions 138' and 138", which are defined by the spacing between the two holes 119' and 11 9" located on the same rail section 103' or 103". These regions 138' and 138" are in a longitudinally displaced position with respect to the longitudinal section resting on the lower side of the rail head 111 over the region 137, and that is because the fishplates 106' and 106" have an indentation 1 39 on their contact surface 108", which indentation is opposite the region 137 of their longitudinal section in contact on the head side.

The contact surfaces 108' facing the rail head 111 and the contact surfaces 108", facing the rail foot 112 of both fishplates 106' and 106" are designed such that they extend converging towards the fishplate ends from the respective supporting sections 137 or 138' and 138", and that is because they each lie on circular arcs 140 or 141' and 141", as may be clearly seen in Figure 7.

The greatest spacing between the contact surfaces 108' or 108" of the fishplates 106' and 106" from the surfaces, adjacent thereto, of the rail head 111 and of the rail foot 112 should amount to about one millimeter.

It may be clearly seen from Figure 8 that in the case of the fishplates 106', 106" inserted into the fishing surfaces 109 of the rail sections, an air gap 142 is maintained in that longitudinal region where the contact surfaces 108' rest closely on the lower side of the rail head between the contact surfaces 108" and the adjacent surfaces of the rail foot 112.

On the other hand, it may be clearly seen from Figure 9 that in those longitudinal regions where the contact surfaces 108' of the fishplates 106' and 106" are closely supported on the adjacent surfaces of the rail foot 112, an air gap 143 is maintained in each case between the contact surfaces 108' and the adjacent surfaces of the rail head 111.

Finally, it may also be seen from Figure 10 that the air gaps 142 and 143 are located towards the ends of the fishplates 106' and 106", between the contact surfaces 108" and the adjacent surfaces of the rail foot 112, and also between the contact surfaces 108' and the adjacent surfaces of the rail head 111.

This design of an insulated joint 104 allows the forces which become effective in the critical region of the insulated joint 104, i.e., in the so cailed cut joint region, to be absorbed by the longitudinal section 1 37 of the two fishplates 106' and 106", and to be introduced into the rail foot 112 via their inner region through the two longitudinal sections 138' and 138". Therefore, from the travelling surface of the rail head 111, the power flux is further transmitted approximately under an angle of 450 into the rail foot 112 of the two rail sections 103' and 1 03n, so that each of the rail feet 112 has only to absorb half the force introduced at the top.The forces absorbed by the fishplates 106' and 106" in the longitudinal region 1 37 act via the longitudinal regions 138' and 1 38" on sections of the rail foot 112 of the rail sections 103' and 103" which have a relatively large spacing from the ends 105' and 105" of these rail sections and reach relatively closely up to the two joint sleepers 102' and 102". The presence of the air gaps 142 and 143 ensures that the end regions of the fishplates 106' and 106" cannot transmit any vertical forces from the rail head 111 into the rail foot 112, and are consequently protected against excessive strains which may lead to the fishplates breaking.

The cross section of the two fishplates 106' and 106" which may be seen in Figure 10 is used only for transmitting longitudinal forces which may be produced, for example by low rail temperatures. It is also mentioned that it is appropriate to seal the air gaps 142 and 143 on site using a permanent-plastic sealing composition in order to keep moisture and water away from these gap regions.

The strapped joints have been described above mainly in the form of rail joints for railway tracks.

However, it is quite possible to use such strapped joints in other areas of structural engineering as well. For example, they could be used for other structures which have to be erected using metal profiles.

Thus, for example strapped joints of the design which has been described but which are not insulated, could also be used in the case of rails, austenitic manganese steel core pieces, but also for masts, bridges, steel stuctures or similar supporting constructions, as they are often used in permanent ways, in the supply of electricity, and in steel structural engineering and bridge construction.

Figure 11 shows another embodiment of an insulated joint 4 which substantially differs from the insulated joints 4 and 104 which have been described above in that the drawbolt 22 has a cylindrical peripheral section 37 in the region between its two conical peripheral sections 33 and 34. This section 37 engages with a narrow fit into the hole 19 in the rail stem 11 so that it is in contact with the soffit surfaces of the hole 1 9 without practically any clearance. A predetermined seat may be achieved by delimiting the cylindrical peripheral section 37 on one side by a collar 38 which has a greater diameter than the hole 1 9 provided in the stem 10, and which is thus capable of being supported laterally against the joint.In order to prevent the drawbolt 22 from sliding unintentionally out of the hole of the stem during assembly, this cylindrical peripheral section is provided with an encircling groove 39, into which an O-ring 40 made of elastic material, for example plastics, rubber or the like is inserted so that it is positioned, being pre-stressed, against the hole 1 9 and thus fixes the drawbolt 22 during assembly. In order to achieve the desired narrow embracing of the peripheral section 37, it may be appropriate to prepare the holes 1 9 in the stems 10 so that they may be re-worked while still on site, for example by reworking with a reamer, to the desired close fit to the cylindrical peripheral section 37.A design of an insulated joint 4 of this type is particularly suitable for transmitting even greater expansive forces, without remaining deformations, because the cylindrical peripheral section 37 supports practically on half its circumference. In order to avoid plastic deformations in the hole 19 of the stem, the bolt is appropriately designed to be flattened in the region of the contact surface in order to prevent plastic deformations even in the case of very considerable tensile forces which have been absorbed. If the cylindrical peripheral section 37 is designed centrically to the longitudinal axis of the drawbolt 22, the bracing of the front surfaces of both rails against the insulating intermediate layer 1 4 is caused exclusively by turning the eccentric expanding bushes 20' and 20" and by bracing them axially in the fishplates.

In order to be able to transmit the desired tension forces via the insulating material as well, the insulating discs 41 charged with the tension force of the drawbolt 22 are produced from correspondingly strong and resistive insulating material. In order to be able to absorb the tensile forces which occur in the longitudinal direction of the rails, the insulating bushes 42 are each lined with a high-strength steel pipe 43. Said pipe 43 is appropriately pressed into the insulating bush 42 and is advantageously also bonded therein. The forces which are produced in the axial direction of the drawbolt 22 and which charge the clamping bushes are applied in a definite manner by the pressure springs 26.

In the case of the embodiment according to Figure 11 which has a fishplate insulation, it is indeed appropriate to produce the cylindrical peripheral section 37 in one piece with the drawbolt 22. However, it may also form a bush which is positioned and/or shrunk onto the drawbolt with a close fit, in particular, if it is intended to be able to exchange, if desired, a centric peripheral section for an eccentric section or an eccentric section for a centric section.

Claims (23)

Claims

1. A strapped joint for connecting profiles, in particular a rail joint for connecting the unwelded ends of rails for railways, in which two fishplates are accommodated in the fishing surfaces which are formed between the head and foot on both sides of the profile or rail stems and they may be braced therein by several high-strength bolt connections which are inserted into holes of the profile or rail stems and of the fishplate, and they may be additionally bonded therein, if necessary, characterised in that at least one of the bolt connections engaging on the adjacent profile or rail ends each consists of expanding bushes optionally which may be inserted into the holes of both fishplates and optionally into the holes of the profile or rail stem having conical inside surfaces optionally and consists of a drawbolt which penetrates these and has complementary conical peripheral sections.

2. A strapped joint according to claim 1, characterised in that the drawbolt has at least two conical peripheral sections which taper towards the ends of the bolt in opposite directions, and both ends of the bolt are provided with a thread for adjusting nuts.

3. A strapped joint according to claim 1 or 2, characterised in that the two conical peripheral sections of the drawbolt differ in length and the longer peripheral section may be made to engage with the expanding bush sitting in the profile or rail stem and with the expanding bush sitting in a fishplate, whereas the shorter peripheral section engages only in the expanding bush sitting in the other fishplate.

4. A strapped joint according to any one of claims 1 to 3, characterised in that the expanding bush which may be inserted into the profile or rail stem has on its end having a greater internal diameter a supporting collar which is directed radially outwards, and also has a length which at least corresponds to the maximum stem thickness (Figures 3 and 6).

5. A strapped joint according to any one of claims 1 to 4, characterised in that the length of the expanding bushes which may be inserted into the fishplates is less than the fishplate thickness and distance rings L -d/or spring elements are allocated thereto as an abutment towards the adjusting nuts which may be screwed onto the thread of the drawbolt (Figures 3 and 6).

6. A strapped joint according to any one of claims 1 to 5, characterised in that the inside surfaces optionally are positioned eccentrically to the external surfaces optionally on the expanding bushes which may be inserted into the fishplates and/or on the bushes which may be inserted into the profile or rail stems.

7. A strapped joint according to any one of claims 1 to 6, characterised in that the expanding bushes are provided with a slit (Figure 2) which passes through the complete length of the bushes.

8. A strapped joint according to any one of claims 1 to 7, characterised in that the contact surfaces of the fishplates, facing the fishing surfaces of the profiles or rail sections have a coating of micro-encapsulated adhesive, in particular a two-component adhesive consisting of hardener and binder.

9. A strapped joint according to any one of claims 1 to 8, characterised in that the fishplates and/or the fishing surfaces of the profiles or rails carry a layer of insulating material having a high compressive strength on their contact surfaces.

1 0. A strapped joint according to any one of claims 1 to 9, characterised in that the fishplates are provided with a layer of insulating material having a high compressive strength on their contact surfaces for the bolt connection i.e., on the walls of the holes and on the edges of the holes.

11. A strapped joint according to any one of claims 1 to 9, characterised in that at least the expanding bush which may be inserted into the profile or rail stem is provided on its conical inside surface and/or on its cylindrical periphery with a layer of insulating material having a high compressive strength (Figures 5 and 6).

12. A strapped joint for connecting profiles, in particular a rail joint for connecting the unwelded ends of rails for railways, in which two fishplates are accommodated in the fishing surfaces formed between the head and foot on both sides of the profile or rails stems and may be braced therein by several high-strength bolt connections which are inserted into holes of the profile or rail stems and of the fishplates, and may also be bonded therein, if necessary, in particular according to any one of claims 1 to 11, characterised in that the fishplates rest at the top, in a supporting manner, on the lower side of the rail head, in the fishing surfaces of the two profiles or rail sections with their contact surfaces, only over a longitudinal section which extends to half the fishplate length over a region which is defined by the two holes closest together, on the two ajdacent rail ends whereas they are supported with their contact surfaces on the top of the foot of both profiles or rail sections (103', 103"), in each case only over longitudinal sections which lie in a region which is defined by the spacing between the two holes located in the same rail and is in a longitudinally displaced position opposite the longitudinal section in contact on the head side.

13. A strapped joint according to any one of claims 1 to 12, characterised in that the longitudinal section of the fishplates, in contact on the head side has a length which is adapted to the spacing between the circumferential regions, furthest away from each other, of the two holes, closest together, of the two profiles or rail sections.

14. A strapped joint according to any one of claims 1 to 13, characterised in that the longitudinal section which is on the foot side and is opposite the longitudinal section, in contact on the head side, of the contact surfaces of the fishplates is delimited by an indentation.

1 5. A strapped joint according to any one of claims 1 to 14, characterised in that the contact surfaces of the fishplates facing the rail head and the rail foot each extend from the supporting sections, converging towards the ends of the fishplates, preferably lying on circular arcs having a large radius.

1 6. A strapped joint according to any one of claims 1 to 16, characterised in that the greatest spacing between the contact surfaces of the fishplates and between the surfaces, adjacent thereto, of the rail head and of the rail foot amounts to about 1 mm.

17. A strapped joint according to one of claims 1,2 and 5 to 10 and 12 to 16, characterised in that the drawboit has a cylindrical peripheral section between the two conical peripheral sections which section engages in the hole of the profile or rail stem with a narrow tolerance (Figure 11).

18. A strapped joint according to claim 17, characterised in that the cylindrical peripheral section is positioned centrically to the longitudinal axis of the drawbolt (Figure 11).

19. A strapped joint according to claim 17, characterised in that the cylindrical peripheral section is positioned eccentrically to the longitudinal axis of the drawbolt.

20. A strapped joint according to one of claims 1 7 to 19, characterised in that the cylindrical peripheral section is formed by a narrowly adapted bush which sits on the drawbolt.

21. A strapped joint according to one of claims 1 7 to 20, characterised in that the cylindrical peripheral section is delimited on one side by a collar which has a greater diameter than the hole which is provided in the stem of the rail section and which accommodates the collar.

22. A strapped joint according to one of claims 17 to 21, characterised in that the cylindrical peripheral section has an encircling groove on its side opposite the collar, for receiving an O-ring made of rubber, plastics or the like.

23. An arrangement according to one of claims 1 to 22, characterised in that the insulating intermediate layer provided between the joint ends of the rails consists of a plastics, the compressive strength of which is about the same as, or greater than the yield point of conventional rail steel.