EP4045715A1 - Articulated assembly of two links, and associated removal chain - Google Patents

Abstract

Disclosed is an articulated assembly (10) of two links (100, 101, 102) for a ballast removal chain (8), a first (101) of the two links (101, 102) comprising a single-piece member (101') having two flanges (110a, 110b) which are parallel to one another and each of which has a through-hole (111), a second (102) of the two links comprising a single-piece member (102') comprising a guide flange (120) that is inserted between the two parallel flanges (110a, 110b) of the first link (101), the guide flange (120) being penetrated by a guide hole (112), the articulated assembly (10) further comprising a hinge pin (160) that is inserted into the guide hole (112) and the through-hole (111) in each of the two parallel flanges (110a, 110b). The guide hole (112) is reinforced by a bushing (113) designed to receive the hinge pin (160) and rotatingly guide the hinge pin (160) relative to the single-piece member (102') of the second link (102). The through-hole (111) in one (110b) of the two parallel flanges comprises a flat portion (105) cooperating with a flat section (161) of the hinge pin (160) so as to prevent the hinge pin (160) from rotating relative to the single-piece member (101') of the first link (101).

Description

DESCRIPTION

TITLE: ARTICULATED ASSEMBLY OF TWO LINKS AND EXCAVATION CHAIN

ASSOCIATE

TECHNICAL FIELD OF THE INVENTION

The invention relates, in general, to the technical field of clearing or excavation chains.

The invention relates more specifically to an articulated assembly of two links intended to equip an excavation chain for a ballast clearing device below a railway track, to an excavation chain comprising such a link assembly and a method of manufacturing such links.

STATE OF THE PRIOR ART

Known in the prior art are work trains equipped with machines responsible for removing the ballast located under the sleepers of a railroad track, and sorting it for possible reuse by dumping it on the track. These machines are commonly called "stripping machines". In a known manner, such work trains generally further comprise a machine responsible for screening the ballast to keep, on the one hand, the healthy part of the ballast for its reuse, and on the other hand, to evacuate the worn part of the ballast in wagons provided for this purpose. In this way, the stripper-screener makes it possible to remove and sort the used ballast and replace the entire ballast layer with the sorted healthy ballast as well as a possible additional supply of new ballast.

[0004] Such work trains are equipped with excavation chains consisting of a succession of articulated links, at least part of which is equipped with shovels intended to excavate the ballast. This chain is arranged in a movable or adjustable manner in height, on the chassis of the rail vehicle. The chain is endlessly moved by a driving mechanism. The chain path is configured so that it has a rectilinear excavation portion located under the railway sleepers, the chain working on this excavation portion transversely to the orientation of the rails of the railway track. by training and carrying the ballast with them. On either side of this rectilinear excavation portion are arranged brackets forming return members for the excavation chain. These brackets are located at the ends of the rectilinear excavation portion, the portion along which the ballast is withdrawn, and are generally formed of a fixed bent wall on which the chain links slide successively. The chain circulates along a longitudinal arrival path then circulates on the rectilinear excavation portion after having passed through a first bent portion formed by one of the brackets. The chain which continues on its way then leaves said rectilinear excavation portion to circulate on the longitudinal outlet portion after having passed through a second bent portion formed by the other of the brackets. The shovels arrive on this rectilinear excavation portion while being unloaded and come out loaded with ballast towards the longitudinal exit portion. The longitudinal inlet and outlet portions are connected, in an area located high above the rail vehicle, by a transverse discharge portion where the ballast is discharged onto conveyor belts. The shovels unloaded from the ballast then continue their way towards the arrival longitudinal portion, then repeating these operations.

[0005] Document EP 2 848 735 A1 describes an example of shovels of the prior art.

[0006] These shovels are designed to respond to many problems. In particular, they must be strong enough to ensure a certain number of predetermined cycles in order to ensure the excavation and the transport of ballast while requiring a minimum of maintenance. These shovels must also allow the efficient transport of the ballast to its dumping for the screening operation, this to improve the efficiency of the stripper by the excavation of the ballast as well as that of the screen to improve the performance. healthy ballast reuse rate.

[0007] In addition to these constraints, the excavation chain itself must also be strong enough to transport these excavators in order to ensure the excavation and the transport of ballast while requiring a minimum of maintenance. In particular, the assembly of links articulated between them must not constitute a point of weakness for the chain and must allow sufficient pivoting to be able to pass the return members arranged in its path and without constraint.

DISCLOSURE OF THE INVENTION

The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular an articulation between two links, configured to limit their wear so as to be able to reduce maintenance operations and guarantee a duration of greater life of the links and the associated chain.

To do this is proposed, according to a first aspect of the invention, an articulated assembly of two links for an excavation chain for a ballast excavating device, a first of the two links comprising a one-piece body comprising two flanges parallel to each other and to a reference plane of the articulated assembly, each traversed by a through hole aligned with a geometric axis of articulation of the articulated assembly, perpendicular to the reference plane, a second of two links comprising a one-piece body comprising a guide flange inserted between the two parallel flanges of the first of the two links, the guide flange being traversed by a guide hole aligned with the geometric axis of articulation, the articulated assembly comprising in in addition to a hinge inserted in the guide hole and the through hole of each of the two parallel flanges, the articulated assembly being remarkable in that: - the guide hole is reinforced by u bush configured to receive the hinge and guide the hinge in rotation relative to the one-piece body of the second link; and in that - the through hole of one or the other of the two parallel flanges, called the hinge rotational locking flange, comprises a flat cooperating with a flat part of the hinge so as to block the hinge in rotation relative to the one-piece body of the first link.

Such a combination of characteristics is particularly advantageous in that it makes it possible to limit the wear of the hinge and of the two links of the assembly. Indeed, on the one hand, the assembly is locked in rotation with respect to the first of the two links comprising the two flanges parallel to each other limiting the friction between these two parts and, on the other hand, the assembly allows the rotation of the second of the two links at the level of its guide flange reinforced by a bush with the hinge of the hinge assembly. In addition, it allows particularly simple assembly and disassembly.

Preferably, the flat and the flat are located in a plane parallel to the geometric axis of articulation. The very simple shapes which result therefrom facilitate the manufacture of the hole comprising the flat, and in particular make it possible to envisage manufacturing the corresponding link by molding without reworking by machining. [0012] According to one embodiment, one or the other of the two parallel flanges of the first of the two links, called the translational locking flange of the hinge, comprises a translational locking interface configured to accommodate a locking means in translation of the hinge in at least one direction parallel to the geometric axis of articulation. Preferably, the locking means is removable with respect to the locking interface. In this way, the maintenance operation consisting in removing the hinge from the assembly between the two links is facilitated.

Preferably, the translational locking interface and the translational locking means of the hinge do not block the hinge in rotation around the geometric axis of articulation. According to one embodiment, the locking interface is an annular groove inside the associated through hole of one of the two flanges of the first of the two links, the locking means preferably comprising an internal elastic ring . Such an annular groove is a relatively simple shape to be machined and allows the elastic ring to be accommodated therein so that the hinge is blocked in translation with respect to the geometric axis of articulation.

More specifically, the hinge is blocked in translation with respect to the geometric axis of articulation in a first direction by being in abutment against said elastic stop ring and, on the other hand, by being in abutment against a side surface of the dish. According to one embodiment, the inner elastic ring has a quadrilateral axial section, preferably rectangle, and more preferably a square section. Such a section of the elastic ring aims to increase its resistance to loads. [0017] According to one embodiment, the flange for blocking the hinge in translation is distinct from the flange for blocking the hinge in rotation.

[0018] According to one embodiment, the first of the two links comprises a second distinct geometric axis of articulation, perpendicular to the reference plane. The flat of the through-hole is oriented so that it is contained in a plane. This plane is preferably perpendicular to a plane containing the two geometric axes of articulation and is preferably located between the two geometric axes of articulation. Such an orientation of the plate makes it possible to improve the locking in rotation of the hinge in question, the force being applied to the flat part of the hinge.

According to one embodiment, the body of each of the two links is made of cast steel, the flat of the through-hole of one of the two parallel flanges of the first of the two links being made with the body of the associated link so not to be machined. In this way, the one-piece link body can be made very easily and the flat is obtained at the same time.

According to one embodiment, the hinge comprises, on one of its two ends, an anchoring interface, for example a tapped hole coaxial with the geometric axis of articulation, so as to allow its engagement with a tool for its manipulation. Such a feature further facilitates maintenance of the assembly. Preferably, the anchoring interface is a removable fixing interface to ensure cooperation of the tool with the hinge, the time only for a maintenance operation.

According to another aspect of the invention, it relates to an excavation chain having an excavation portion for a ballast excavating device below a railway track, the chain of excavation being remarkable in this that it comprises a succession of chain links connected in pairs by an assembly as described above to form an endless chain.

According to one embodiment, the excavation chain is formed by an alternating succession of links forming the first link of an assembly with each of the two adjacent links and of links forming the second link of an assembly with its two adjacent links . Each link includes a body which extends longitudinally between a front end and a rear end. In the case where the excavation chain is formed by such a successive alternation of links, each of the two ends of the same first link forms a first of the two links for an assembly with an adjacent second link, and each of the two ends of the same second link forms a second of the two links for assembly with an adjacent first link.

[0023] Alternatively, the same link has an interface such as a first link at one of its front and rear ends, and forms an interface such as a second link at the other of its front and rear ends.

According to another aspect, the invention also relates to a method of manufacturing a link intended to equip an excavation chain as described above, remarkable in that it comprises a molding step consisting in casting a metal or a liquid or pasty alloy, preferably steel, in a mold. According to one embodiment, the flat of the through-hole of one of the two parallel flanges of the first of the two links is produced with the body of the associated link during the molding step, so as not to be machined .

According to one embodiment, the manufacturing method comprises a machining step, on one or the other of the two flanges of the first of the two links, preferably separate from the flange for locking the hinge in rotation, d a locking interface configured to accommodate a means for locking the hinge in translation, for example an annular groove inside the associated through hole. BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will emerge on reading the following description, with reference to the appended figures, which illustrate:

[Fig. 1]: a simplified side diagram of a work train equipped with a stripper-screen;

[Fig. 2]: a partial diagram of an excavation or clearing device, seen from the front without an excavation chain;

[Fig. 3]: a perspective view of a portion of an excavation chain according to one embodiment; [Fig. 4]: a front view of a portion of an excavation chain according to this embodiment;

[Fig. 5]: a sectional view A-A of FIG. 4;

[Fig. 6A]: an exploded view of a succession of links assembled according to this embodiment; [Fig. 6B]: a detail of FIG. 6A illustrating a perspective view of an elastic ring according to one embodiment;

[Fig. 7]: a top view of a succession of assembled links intended to equip an excavation chain;

[Fig. 8]: a partial view of section B-B of FIG. 7; [Fig. 9]: a partial view of section C-C of FIG. 8;

[Fig. 10]: a side view of a first link according to one embodiment;

[Fig. 11]: a top view of FIG. 10;

[Fig. 12]: a DD section view of FIG. 10. For greater clarity, identical or similar elements are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

Referring to Figure 1, there is illustrated a railway vehicle 1 such as a stripper-screen equipped with a clearing or excavation device 4 for cleaning the ballast of a railway track 2. This clearing or excavation device 4 is arranged between two bogies 3 of train 1.

The ballast clearing device 4 comprises an excavation chain 8 moved endlessly by a drive mechanism 9 and guided by conduits including a transverse conduit 5 located under the track 2 in the working position , along which the chain runs on a substantially rectilinear excavation portion 8A. The clearing device 4 also comprises upward and downward ducts 6, 7 connected on either side of the transverse duct 5 to which they are connected by bent portions forming angle references 40 also called "brackets" (see figure 2). It is understood that the excavation portion is generally rectilinear, even though the excavation is provided in a part of the curve of each of the angle transmitters.

The drive device 9 is arranged in height relative to the railway vehicle 1, above the railroad track 2, on a side longitudinally opposite to the transverse duct 5, and between the ascending duct 6 and the duct descent 7. The drive device 9 is placed on the path of the excavation chain 8 and comprises a drive wheel 9 'locally engraining with links 100 of the excavation chain 8 so as to move it. An endless path is thus formed to guide the excavation chain 8. Arrows illustrated in FIG. 2 indicate the direction of movement of the chain 8. At the upper ends of the ascent 6 and descent 7 ducts, on the side of the drive device, idle wheels 41 forming return members 40 are provided for ensure the correct movement of chain 8 at these bent areas. Once the ballast is transported high in the riser pipe 6, it is unloaded on a conveyor belt 10 and then transported to a screening unit 11 in order to sort the healthy ballast from the used ballast.

The vehicle 1 further comprises a lifting unit 13 of the railway track 2 which is connected to a frame 14 of the vehicle 1 and which is located upstream of the clearing or excavation device4 with respect to a working direction 12 of the vehicle 1. A height adjustment device 16 is also provided and connected to the frame 14 of the vehicle 1, which is configured to move the clearing device 4, by drive means 15, from an elevated position to a position. lowered under the railway track 2 and can be connected for example removably to the transverse duct 5 by a connector (not visible in the figures).

Figures 3 and 4 illustrate a portion of an excavation chain 8 according to one embodiment. The excavation chain 8 is formed by a succession of links 100 articulated in pairs until the two ends of the chain 8 are connected end to end to form a closed chain 8, of the endless chain type.

Each of the links 100 are articulated in pairs at their respective ends. More precisely, each assembly of two articulated links is produced between a first link 101 and a second link 102. Each articulation between two links is produced by an assembly 10, details of which are illustrated in particular in FIGS. 5 and 9.

The first 101 of the two links comprises a one-piece body 101 'comprising two flanges 110a, 110b parallel to each other and to a reference plane P of the articulated assembly 10. The two flanges 110a, 110b are each crossed by a through hole 111 aligned on a geometric axis of articulation X of the articulated assembly 10, perpendicular to the reference plane P. Figures 10, 11 and 12 illustrate views of a link having articulation means at each of its longitudinal ends, each end of the link of which is provided with two flanges 110a, 110b parallel to one another, that is to say that the link is a first link to both with respect to the assembly 10 which links it to the adjacent front link and also with respect to the assembly which links it to the adjacent rear link. The second 102 of the two links comprises a one-piece body 102 'comprising a guide flange 120, preferably single, inserted between the two parallel flanges 110a, 110b of the first 101 of the two links, the guide flange 120 being crossed by a guide hole 112 aligned with the geometric axis of articulation X.

The articulated assembly 10 further comprises a hinge 160 inserted into the guide hole 112 and the through hole 111 of each of the two parallel flanges 110a, 110b. In this way, the hinge 160 allows the connection between the first and second links 101,102 so as to form a hinge between these two links. The first 101 of the two links forms a female interface with its two flanges 110a, 110b to receive between the two, the guide flange 120 of the second 102 of the two links 101, 102 forming a male interface coming to interlock and mate, with the hinge 160 with the associated female interface.

In order to limit the wear between the second link 102 and the hinge 160, the guide hole 112 is reinforced by a sleeve 113 configured to receive the hinge 160 and guide the hinge 160 in rotation relative to the body 102 'of the second link 102. Preferably the sleeve 113 is shrunk, for example cold shrunk, in the guide hole 112 of the body 102 'of the second link 102 made of manganese steel. In this way, the sleeve 113 is arranged coaxially with the geometric axis of articulation X and configured to be in a pivot connection with the hinge 160, said sleeve 113 being held fixed in the body 102 'of the second link, in particular in the guide hole. 112. The bush is housed entirely in the guide hole 112 of the guide flange 120, so as not to protrude, which makes it possible to limit the friction between the parts of the assembly10. In other words, the sleeve 113 is preferably either flush with or slightly set back from the laterally emerging ends of the guide flange 120, in the guide hole 112, to avoid such a projection.

In order to further limit the wear of the joint 10, between the first link 101 and the hinge 160, the through hole 111 of one 110b of the two parallel flanges comprises a flat 105 cooperating with a flat 161 of the hinge 160 to lock the hinge 160 in rotation relative to the one-piece body 101 'of the first link 101 (see for example Figures 8 and 9). The rotation around the geometric axis of articulation X being blocked, friction is limited. The pivot articulation between the first and second links 101, 102 of the assembly 10 is for its part always allowed by the degree of freedom in rotation of the second link 102 with the hinge 160.

A link 100 of the chain 8 comprises a front end and a rear end. In this way, the first link 101 of the assembly comprises a second distinct geometric articulation axis, parallel to the first, and perpendicular to the reference plane P. The plate 105 of the through hole 111 is oriented so as to be contained in a perpendicular plane Pp to a plane containing the two geometric axes of articulation X and perpendicular to the reference plane P. Such an orientation promotes the resumption of forces as a function of the direction of advance of the chain 8 and of the direction of rotation of the links between them when they pass certain obstacles such as the return members40.

In order to maintain the hinge in the articulated assembly, and in particular to prevent its mobility in translation along the geometric axis of articulation X, the latter is blocked in both directions. Indeed, the hinge 160 comprises a substantially cylindrical body, one end of which is provided with a flat 161. In such a configuration, an intermediate part of the hinge 160 is cylindrical to ensure the pivot connection with the second link 102 in the guide hole. 112 of the guide flange 120. The cylindrical part is separated from the flat 161 along the axis of the hinge 160 by a step 163 extending in a plane perpendicular to the geometric axis of articulation X of the assembly 10.

In the assembled position, the recess 163 of the hinge 160 comes into contact and bears against an inner face 110b 'of the flange 110b on a side edge 105' of the plate 105 which allows locking of the hinge 160 in a first direction.

To ensure the locking of the hinge 160 in translation in the opposite direction, un110a of the two parallel flanges of the first link 101 comprises a locking interface 103 configured to accommodate a locking means 104 in translation of the hinge 160. In particular, the locking interface 103 is a machined annular groove, here bored, inside the associated through hole 111. The locking means 104 comprises an internal elastic stop ring which is received in the annular groove 103 and a part of which is positioned on the path of the hinge 160 to obstruct it and block its translation. In particular to allow better holding of the elastic ring 104 in the bored groove 103, said elastic ring 104 has a quadrilateral section, preferably rectangle. To ensure optimum locking of the hinge 160, each means for locking the hinge 160 in translation in a given direction is carried by two separate flanges of the two parallel flanges 110a, 110b, that is to say that the flange 110a of the first 101 of the two links comprising the annular groove 103 is distinct from the flange 110b of the first 101 of the two links comprising the plate 105.

An elastic stopper ring 104 is illustrated in more detail in FIG. 6B. The elastic ring 104 comprises a body 104a extending annularly over a certain angular sector, preferably greater than 240 ° delimiting an interior space 104c. The body 104a has at each of its ends ears 104b which extend radially inwardly 104c of the body 104a and are configured to be taken by a tool such as a pliers. The elastic ring 104 is formed in one piece, that is to say in one piece. The elastic ring 104 is formed of a solid material, that is to say which does not have holes, either on its body 104a or its ears 104b. The elastic ring 104 is formed, for example, of steel.

The ears of the elastic ring 104 each have an elbow 104d so that the end part is directed in the direction of a distance from the other ear. This makes it possible to stiffen and strengthen the resistance to loads.

The elastic ring 104 is designed to fit and cooperate in a groove 103 to stop the hinge 160 in a direction of translation along the geometric axis of articulation X. The elastic ring 104 is dimensioned so that it is in contact and in support radially with respect to the geometric axis of articulation X against a bottom of the circular groove when it is positioned in said groove 103.

The hinge 160 comprises an anchoring interface 162 such as a threaded hole coaxial with the geometric axis of articulationX, so as to allow its engagement with a tool for its handling. This anchoring interface 162 is located on the side of the assembly where the elastic ring 104 is mounted in one 110a of the two parallel flanges of the first link 101, namely the side where the operator must access to proceed with the assembly and disassembly of the assembly 10. At the level of the hinge 160, the anchoring interface 162 is located at one of its ends, opposite to the one with the flat161. To carry out the maintenance of each assembly 10, the operator can act on the same side of the chain 8, using pliers to remove the elastic ring on the one hand, and using a suitable tool, for example a hammer. inertia, to cooperate with the threaded hole 162 opening onto one face of the end of the hinge 160 on the other hand.

Each of the links 100, 101, 102 comprises a body 101 ', 102' which extends longitudinally between a front end and a rear end. The longitudinal direction is understood here as the direction of movement of the link 100. Each link 100, 101, 102 is hingedly connected to two other adjacent links of the chain 8 at each of its front and rear ends. Each link is articulated at its two front and rear ends with an adjacent link so that the same link is articulated by two separate assemblies 10 on either side of its body.

Each articulation between two links is formed by an assembly 10 as described in detail above. It emerges from this that each end of the link is here configured either as a first 101 of the two links of the assembly considered, or as a second 102 of the two links of the assembly considered. In particular here: - a first group of links of the chain 8 has, for each of the links, on one side, a first end forming a first link 101 of an assembly and, on the other hand, a second end, opposite to the first, also forming a first link 101 of another assembly; and - a second group of links of the chain 8 has, for each of the links, on one side, a first end forming a second link 102 of an assembly and, on the other hand, a second end, opposite to the first, also forming a second link 102 of another assembly Preferably, each link body 101 ', 102' has symmetry with respect to a plane of symmetry perpendicular to its longitudinal axis and perpendicular to the reference plane P, but also perpendicular to a plane containing the two geometric axes d 'X joint. In other words, and for each of the links of the chain 8, the front end is substantially symmetrical with respect to the rear end.

As already mentioned, the first 101 of the two links of a given assembly forms a so-called "female" interface with its two flanges 110a, 110b to receive between the two, the guide flange 120 of the second 102 of the two links 101,102 forming a so-called “male” interface which interlock and mate, thanks to the hinge 160 with the associated female interface. Also, in the embodiment as illustrated, each link body has the same similar interface, female or male, at its two ends, hence the simplified name of the link which can be given to it in chain 8, i.e. female chain link or male chain link.

Of course, the arrangement of the assemblies in the chain 8 can be different. For example, the same link may have, on one side, a first end forming a first link 101 of a first assembly and, on the other hand, a second end, opposite to the first, forming a second link 102 d 'another assembly.

As illustrated in particular in Figures 3, 4, 6A and 7, the excavation chain 8 is composed of a succession of links 100 among which the links are of three different types although they each have a configured body either as a male link 102 or as a female link 101.

The excavation chain comprises links 100 of the type comprising a shovel 130, the links 100 of the type comprising a counter-stop 140 and links 100 of the type without protruding part, that is to say formed essentially from their body 101.

The function of such links 100 without protruding part is mainly to lighten the excavation chain 8. Another function is to better adapt the volume ballast excavated to the maximum capacity of the screen and this without losing too much of its own capacity which is reduced by an order of magnitude of 20%, and not by 50% as a person skilled in the art might think because of the substantially doubled spacing between two scoops 130 in such a configuration. This is notably made possible by virtue of the geometry of the shovel 130 similar to that described above, and in particular of its inclination.

In this embodiment, each of the links 100 of the type comprising a shovel 130 is disposed between two links 100 of the type comprising a counter-stop 140. In addition, each link 100 of the type without protruding part is also disposed between two Links of the type comprising a counter-stop 140. Every other link is therefore provided with a counter-stop 140, the other links being alternately a link of the type comprising a shovel 130 and a link of the type without protruding part.

A pattern of the chain 8 is therefore formed by a link 100 of the type without protruding part interposed between two links of the type comprising a counter-stop 140, and a link 100 of the type comprising a shovel 130 at a front end or back of this set of three links: these four links 100 together form, in this order, a pattern which is repeated successively along the chain 8.

According to the examples illustrated, the links 100 of the type comprising a shovel 130 and of the type without projecting part are female links and the links 100 of the type comprising a counter-stop 140 are male links.

Such a configuration has several advantages. Each link 100 comprising a shovel 130 comes directly in front of a link comprising a counter-stop 140 so, as already described, to limit a relative rotation of the link carrying the shovel 130. In addition, such a configuration makes it possible, on the one hand, to guarantee a sufficiently small space between the links comprising a shovel 130 to ensure the excavation and the transport of ballast in an efficient manner, and on the other hand, to guarantee a space large enough to ensure the correct movement of the chain with the necessary flexibility to pass the return bodies 40. To ensure effective and durable protection of the joints of the links 100 of the chain 8 against wear by abrasion by the ballast and against the action of dust, thus giving a longer life of the links 100 of the chain 8, the front and rear ends of the bodies 101 ', 102' of the links 100, 101, 102 each have a curved convex portion, for example a rounded longitudinal end in the form of an arc of a circle, so as to be free of stops. Each curved portion preferably extends over an envelope having a generatrix parallel to the associated geometric axis of articulation X. These curved convex portions forming rounded ends are carried by each of the parallel 110a, 110b and guide 120 flanges. Furthermore, for the same assembly, the curved convex portions of each of the parallel 110a, 110b and guide flanges 112 traversed by the same hinge 160 have a substantially identical radius of curvature so that when the joint passes a return member, the contact of the joint on the return member is distributed over the first and second links 101, 102 articulated together.

To further reduce the risk of premature wear of the assembly, and therefore of the joint, the guide flange 120 has play with the other two parallel flanges 110a, 110b between which it is placed which is sufficient for avoid friction during their relative rotation and but low enough to avoid allowing the ballast to get lodged in the joint.

Along the rectilinear excavation portion 8A, the links 100 run transversely with respect to the railway track 2 which corresponds to the longitudinal direction of the bodies 101 of the links 100 on this portion. The links 100 are oriented so that the geometric axes X of each of the joints 10 are substantially vertical with respect to the ground, the reference plane P then being horizontal, and the shovel 130 or the counter-stop 140 extending substantially radially towards the outside of the body of the associated link 100. The outer side of the links is the side where the ballast is excavated and transported. An inner side of the bodies 101 ′, 102 ′ of the links is for its part configured to come into contact and bear against the return members 40 on the path traveled by the chain 8. Taking into account the orientation, vertical of the geometric axes X, we understand the interest that the hinges 160 are fully housed in the space delimited by the through holes 111 and of the guide 112 so as not to protrude vertically, below or above, the bodies of the links. Such a configuration in fact avoids the wear of the hinges 160 of each assembly 10. In this embodiment, the links 100 are made for example of manganese steel and made in one piece. An example of a method of manufacturing this link 100 obtained by foundry comprises at least one metal injection step, and in particular a molding step in a mold formed for example of a form and an associated counter-form. Preferably, the body 101 ', 102' of each of the links 100,101,102 is made of cast steel, the flat 105 of the through hole 111 of one 110b of the two parallel flanges of the first 101 of the two links being made with the body 101 of the associated link so as not to be machined. In this way, the only machining required on the bodies of the links 100 participating in the assembly concerns the bore 103 configured to receive the elastic ring 104.

Naturally, the invention is described in the above by way of example. It is understood that a person skilled in the art is in a position to produce various variant embodiments of the invention without however departing from the scope of the invention.

Claims

1. Articulated assembly (10) of two links (100, 101, 102) for a chain (8) for excavating a ballast excavating device (4), a first (101) of the two links (101, 102) comprising a one-piece body (101 ') comprising two flanges (110a, 110b) parallel to each other and to a reference plane (P) of the articulated assembly (10), each traversed by a through hole (111 ) aligned on a geometric axis of articulation (X) of the articulated assembly (10), perpendicular to the reference plane (P), a second (102) of the two links comprising a one-piece body (102 ') comprising a flange of guide (120) inserted between the two parallel flanges (110a, 110b) of the first (101) of the two links (101, 102), the guide flange (120) being crossed by a guide hole (112) aligned with the geometric articulation axis (X), the articulated assembly (10) further comprising a hinge (160) inserted in the guide hole (112) and the through hole (111) of each of the two flanges ( 110a, 110b) parallel, the articulated assembly (10) being characterized in that: the guide hole (112) is reinforced by a bush (113) configured to receive the hinge (160) and guide the hinge (160) in rotation relative to the one-piece body (102 ') of the second link (102); and in that the through hole (111) of one (110b) or the other of the two parallel flanges, called the hinge rotational blocking flange, comprises a flat (105) cooperating with a flat (161) of the hinge (160) so as to block in rotation the hinge (160) relative to the body (101 ') in one piece of the first link (101). 2. Assembly (10) according to claim 1, characterized in that the flat (105) and the flat (161) are located in a plane parallel to the geometric axis of articulation (X). 3. Assembly (10) according to any one of the preceding claims, characterized in that one or the other (110a) of the two parallel flanges of the first (101) of the two links, said flange for locking in translation of the hinge , comprises a translational locking interface (103) configured to accommodate a translational locking means (104) of the hinge (160) in at least one direction parallel to the geometric axis of articulation (X). 4. Assembly (10) according to claim 3, characterized in that the translational locking interface (103) and the translational locking means (104) in translation of the hinge (160) do not block the hinge in rotation ( 160) around the geometric axis of articulation (X). 5. Assembly (10) according to claim 4, characterized in that the translation locking interface (103) is an annular groove inside the hole (111) passing through the flange (100a) for locking the hinge in translation. , the translational locking means (104) preferably comprising an internal elastic ring. 6. Assembly (10) according to claim 5, characterized in that the inner elastic ring (104) has a quadrilateral axial section, preferably rectangle. 7. Assembly (10) according to one of claims 3 to 6, characterized in that the flange (100a) for locking the hinge in translation is distinct from the flange (100b) for locking the hinge in rotation. 8. Assembly (10) according to any one of the preceding claims, characterized in that the first (101) of the two links comprises a second distinct geometric axis of articulation, perpendicular to the reference plane (P), the flat (105 ) of the through-hole (111) being preferably oriented so as to be contained in a plane (Pp) preferably situated between the geometric axis of articulation (X) of the articulated assembly (10) and the second geometric axis d 'distinct articulation, preferably perpendicular to a plane containing the two geometric axes of articulation (X). 9. Assembly (10) according to any one of the preceding claims, characterized in that the body (101 ', 102') of each of the two links (101, 102) is made of cast steel, the flat (105) of the through hole (111) of one (110b) of the two parallel flanges of the first (101) of the two links being produced with the body (101 ') of the associated link so as not to be machined. 10. Assembly (10) according to any one of the preceding claims, characterized in that the hinge (160) comprises, on one of its two ends, an anchoring interface (162), for example a coaxial threaded hole to the geometric axis of articulation (X), so as to allow it to be gripped with a tool for its manipulation. 11. Excavation chain (8) having an excavation portion for a device (4) for excavating ballast below a railway track (2), the excavating chain (8) being characterized in that it comprises a succession of links (100) of chain (8) connected in pairs by an assembly (10) according to any one of the preceding claims to form an endless chain (8). 12. Excavation chain (8) according to claim 11, characterized in that it is formed by an alternating succession of links forming the first link (101) of an assembly (10) with each of the two adjacent links and links. forming the second link (102) of an assembly (10) with its two adjacent links. 13. A method of manufacturing a link (100, 101, 102) intended to equip an excavation chain (8) for a ballast excavating device (4) according to claim 11 or 12, characterized in that ' it comprises a molding step consisting in casting a metal or a liquid or pasty alloy, preferably steel, in a mold. 14. A method of manufacturing a link according to claim 13, characterized in that the flat (105) of the through-hole (111) the rotational locking flange of the hinge of the first (101) of the two links is produced with the body. (101 ') of the associated link (101) during the molding step, so as not to be machined. 15. A method of manufacturing a link according to claim 13 or 14, characterized in that it comprises a machining step, on one or the other (110a) of the two flanges of the first (101) of the two links, preferably separate from the flange (110b) for locking the hinge in rotation, a locking interface (103) configured to accommodate a locking means (104) in translation of the hinge (160 ), for example an annular groove inside the through hole (111) associated.