ARTICULATED ASSEMBLY OF TWO LINKS, AND ASSOCIATED REMOVAL CHAIN

Abstract

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

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates, in a general manner, to the technical field of clearance or excavation chains.

The invention relates more specifically to an articulated assembly of two links which are intended to equip an excavation chain for a device for clearing ballast under a railroad, to an excavation chain comprising a link assembly of this kind, and to a method for manufacturing links of this kind.

PRIOR ART

In the prior art, work trains are known which are equipped with machines intended for removing the ballast located under the sleepers of a railroad, and for sorting it for possible re-use by tipping into onto the track. These machines are commonly referred to as “ballast clearing machines.” In a known manner, work trains of this kind more generally comprise a machine intended for screening the ballast in order on the one hand to keep the sound part of the ballast for re-use, and on the other hand to remove the spent part of the ballast, in trucks provided for this purpose. In this way, the ballast clearing machine/cleaner attachment makes it possible to remove and sort the spent ballast, and replace the entire ballast layer with the sorted sound ballast, as well as optional additional supply of new ballast.

Work trains of this kind are equipped with excavation chains made up of a succession of links which are articulated to one another, at least some of which are equipped with shovels intended for excavating the ballast. Said chain is arranged on the chassis of the rail vehicle, so as to be movable or height-adjustable. The chain is driven in an endless manner by a drive mechanism. The path of the chain is configured such that it comprises a straight excavation portion located under the sleepers of the railroad, the chain working on this excavation portion transversely with respect to the orientation of the rails of the railroad, carrying along and transporting the ballast with them. On either side of said straight excavation portion, brackets are arranged, which form return members for the excavation chain. Said brackets are located at the ends of the straight excavation portion, along which portion the ballast is removed, and are generally formed by a bent fixed wall on which the links of the chain slide successively. The chain moves along a longitudinal feed path and then moves over the straight excavation portion after having passed through a first bent portion formed by one of the brackets. The chain which follows its path then emerges from said straight excavation in order to move over the longitudinal outlet portion after having passed through a second bent portion formed by the other of the brackets. The shovels arrive on said straight excavation portion having been unloaded, and re-emerge therefrom loaded with ballast, towards the longitudinal outlet portion. The longitudinal feed and outlet portions are connected, in a region located at a height with respect to the rail vehicle, by a transverse discharge portion where the ballast is discharged onto conveyor belts. The shovels, offloaded of ballast, then continue their path towards the longitudinal feed portion, then repeating these operations.

The document EP 2 848 735 A1 describes an example of shovels of the prior art.

Said shovels are designed to overcome a number of problems. In particular, they must be sufficiently resistant to ensure a certain number of predetermined cycles, in order to ensure the excavation and transport of ballast, requiring minimum maintenance. Said shovels must furthermore allow for effective transport of the ballast towards the discharge thereof, with a view to the screening operation, in order to improve the output of the ballast clearing machine by the excavation of the ballast, as well as that of the cleaner attachment, in order to make it possible to improve the reuse rate of the sound ballast.

In addition to these limitations, the excavation chain itself must be sufficiently resistant for transporting said shovels, in order to ensure the excavation and transport of ballast, requiring minimum maintenance. In particular, the assembly of links that are articulated together must not constitute a point of weakness for the chain, and must allow for sufficient pivoting in order to be able to pass the return members that are arranged on the path thereof and are not stressed.

DISCLOSURE OF THE INVENTION

The invention aims to overcome all or some of the disadvantages of the prior art, by proposing in particular an articulation between two links, which is designed to limit the wear of said links, so as to be able to reduce the maintenance operations and guarantee a longer service life of the links and of the associated chain.

In order to achieve this, according to a first aspect of the invention an articulated assembly of two links for an excavation chain for a ballast excavation device is proposed, a first of the two links comprising a single-piece body having two flanges which are in parallel with one another and with a reference plane of the articulated assembly, and through each of which a through-hole passes which is aligned with a geometric articulation axis of the articulated assembly, perpendicular to the reference plane, a second of the two links comprising a single-piece body comprising a guide flange that is inserted between the two parallel flanges of the first of the two links, a guide hole passing through the guide flange, which guide hole is aligned with the geometric articulation axis, the articulated assembly further comprising a hinge pin that is inserted into the guide hole and the through-hole in each of the two parallel flanges, the articulated assembly being notable in that:

• • the guide hole is reinforced by a bushing designed to receive the hinge pin and to guide the hinge pin so as to rotate relative to the single-piece body of the second link; and in that
  • the through-hole of one or the other of the two parallel flanges, referred to as the flange for preventing rotation of the hinge pin, comprises a flat portion cooperating with a flat region of the hinge pin so as to prevent the hinge pin from rotating relative to the single-piece body of the first link.

Such a combination of features is particularly advantageous in that it makes it possible to limit the wear of the hinge pin and the two links of the assembly. Indeed, on the one hand the assembly is prevented from rotating with respect to the first of the two links comprising the two mutually parallel flanges limiting the friction between said two parts, and on the other hand the assembly allows the rotation of the second of the two links in the region of the guide flange thereof, reinforced by a bushing with the hinge pin of the assembly, forming a hinge. Furthermore, it allows for particularly simple mounting and dismantling.

The flat portion and the flat region are preferably located in a plane in parallel with the geometric articulation axis. The very simple shapes resulting therefrom facilitate the formation of the hole comprising the flat portion, and make it possible in particular to envisage manufacture of the corresponding link by molding without reworking by machining.

According to an embodiment, one or other of the two flanges, in parallel with the first of the two links, referred to as the flange for preventing translation of the hinge pin, comprises a translation prevention interface which is designed to receive a means for preventing translation of the hinge pin in at least one direction in parallel with the geometric articulation axis. The prevention means is preferably detachable with respect to the prevention interface. In this way, the maintenance operation consisting in removing the hinge pin from the assembly between the two links is facilitated.

The translation prevention interface and the means for preventing translation of the hinge pin preferably do not prevent the rotation of the hinge pin about the geometric articulation axis.

According to an embodiment, the prevention interface is an annular groove inside the through-hole associated with one of the two flanges of the first of the two links, the prevention means preferably comprising an inner resilient ring. An annular groove of this kind is a relatively simple shape to machine, and make it possible to receive the resilient ring therein, such that the hinge pin is prevented from moving in translation with respect to the geometric articulation axis.

More precisely, the hinge pin is prevented from moving in translation with respect to the geometric articulation axis in a first direction, by being in abutment against said resilient stop ring, and being in abutment against a lateral surface of the flat portion.

According to an embodiment, the inner resilient ring has a quadrilateral, preferably rectangular, axial cross section, and more preferably a square cross section. Such a cross section of the resilient ring aims to increase its loading resistance.

According to an embodiment, the flange for preventing translation of the hinge pin is separate from the flange for preventing rotation of the hinge pin.

According to an embodiment, the first of the two links comprises a separate second geometric articulation axis, which is perpendicular to the reference plane. The flat portion of the through-hole is oriented so as to be contained in a plane. This plane is preferably perpendicular to a plane containing the two geometric articulation axes, and is preferably located between the two geometric articulation axes. Such an orientation of the flat portion makes it possible to improve the prevention of rotation of the hinge pin in question, the force being applied to the flat region of the hinge pin.

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

According to an embodiment, the hinge pin comprises, on one of the two ends thereof, an anchoring interface, for example a threaded hole that is coaxial with the geometric articulation axis, so as to allow it to be grasped by a tool in order to be manipulated. A feature of this kind further facilitates the maintenance of the assembly. The anchoring interface is preferably a detachable fixing interface for ensuring the cooperation of the tool with the hinge pin, the time of just one maintenance operation.

According to another aspect of the invention, this relates to an excavation chain having an excavation portion for a device for excavation of ballast under a railroad, the excavation chain being notable in that it comprises a succession of chain links which are connected in pairs by an assembly as described above, so as to form an endless chain.

According to an 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 links forming a second link of an assembly with its two adjacent links. Each link comprises 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 one first link forms a first of the two links for an assembly with an adjacent second link, and each of the two ends of one second link forms a second of the two links for an assembly with an adjacent first link.

Alternatively, one link has an interface like a first link at one of its front and rear ends, and forms an interface like a second link at the other of its front and rear ends.

According to another aspect, the invention also relates to a method for manufacturing a link intended to equip an excavation chain as described above, which is notable in that it comprises a step of molding, consisting in casting a metal or a liquid or pasty alloy, preferably of steel, into a mold.

According to an embodiment, the flat portion of the through-hole of one of the two flanges in parallel with the first of the two links is formed together with the body of the associated link, during the molding step, so as not to be machined.

According to an embodiment, the manufacturing method comprises a step of machining, on one or other of the two flanges of the first of the two links, preferably separately from the flange for preventing rotation of the hinge pin, a rotation prevention interface for receiving a means for preventing translation of the hinge pin, for example an annular groove inside the associated through-hole.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become clear from the following description, given with reference to the accompanying drawings, in which:

FIG. 1: is a simplified side view of a work train equipped with a ballast clearing machine/cleaner attachment;

FIG. 2: is a partial view of an excavation or clearing device, viewed from the front, without an excavation chain;

FIG. 3: is a perspective view of an excavation chain portion according to an embodiment;

FIG. 4: is a front view of an excavation chain portion according to this embodiment;

FIG. 5: is a cross section according to A-A in FIG. 4;

FIG. 6A: is an exploded view of a succession of links assembled according to this embodiment;

FIG. 6B: shows a detail of FIG. 6A, showing a perspective view of a resilient ring according to an embodiment;

FIG. 7: is a plan view of a succession of assembled links intended for equipping an excavation chain;

FIG. 8: is a partial view of the cross section B-B in FIG. 7;

FIG. 9: is a partial view of the cross section C-C in FIG. 8;

FIG. 10: is a side view of a first link according to an embodiment;

FIG. 11: is a plan view of FIG. 10;

FIG. 12: is a cross section according to D-D in FIG. 10.

For reasons of improved clarity, the identical or similar elements are indicated by identical reference signs in all the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

With reference to FIG. 1, a rail vehicle 1 such as a ballast clearing machine/cleaner attachment equipped with a device for clearing or excavation 4 for cleaning the ballast of a railroad track 2 is shown. Said clearing or excavation device 4 is arranged between two bogies 3 of the train 1.

The ballast clearing device 4 comprises an excavation chain 8 that is driven in an endless manner by means of a drive mechanism 9, and guided by pipes, including a transverse pipe 5 located under the track 2 in the work position, along which the chain circulates over a substantially straight excavation portion 8A. The clearing device 4 also comprises riser pipes and downpipes 6, 7 which are connected on either side of the transverse pipe 5 to which they are connected by bent portions forming angle returns 40, also referred to as “brackets” (see FIG. 2). It is understood that the excavation portion is generally straight, although the excavation is ensured in a part of the curve of each of the angle returns.

The drive device 9 is arranged at a height with respect to the rail vehicle 1, above the railroad 2, on a side longitudinally opposite the transverse pipe 5, and between the riser pipe 6 and the downpipe 7. The drive device 9 is positioned on the path of the excavation chain 8 and comprises a drive wheel 9′ which engrains locally with the links 100 of the excavation chain 8 so as to move it. An endless path is thus formed, for guiding the excavation chain 8. Arrows shown in FIG. 2 indicate the direction of movement of the chain 8. At the top ends of the riser pipe 6 and downpipe 7, to the side of the drive device, idler wheels 41 forming return members 40 are provided for ensuring expedient movement of the chain 8 in the region of these bent zones.

Once the ballast has been transported upwards in the riser pipe 6, it is discharged onto a conveyor belt 10 and then transported to a screening unit 11 with the aim of sorting the sound ballast from the spent ballast.

The vehicle 1 further comprises a unit for lifting 13 the railroad 2, which is connected to a chassis 14 of the vehicle 1 and which is located upstream of the clearing or excavation device 4, with respect to a work direction 12 of the vehicle 1. A height regulation device 16 is also provided, and connected to the frame 14 of the vehicle 1, which is designed to move the clearing device 4, using drive means 15, from a lifted position to a position lowered under the railroad 2, and which can be for example detachably connected to the transverse pipe 5 by a connection (not shown in the drawings).

FIGS. 3 and 4 show a portion of an excavation chain 8 according to an embodiment. The excavation chain 8 is formed of a succession of links 100 which are 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, in the region of their respective ends. More precisely, each assembly of two articulated links is formed between a first link 101 and a second link 102. Each articulation between two links is achieved by an assembly 10, the details of which are illustrated in particular in FIGS. 5 and 9.

The first 101 of the two links comprises a single-piece body 101′ comprising two flanges 110a, 110b which are in parallel with one another and with a reference plane P of the articulated assembly 10. A through-hole 111, aligned with a geometric articulation axis X of the articulated assembly 10, perpendicular to the reference plane P, passes through each of the two flanges 110a. 110b. FIGS. 10, 11 and 12 are views of a link comprising articulation means at least of its longitudinal ends, of which each end of the link is equipped with two mutually parallel flanges 110a, 110b, i.e. the link is a first link, both with respect to the assembly 10 which connects it to the adjacent front link, and also with respect to the assembly which connects it to the adjacent rear link.

The second 102 of the two links comprises a single-piece body 102′ comprising a, preferably single, guide flange 120 which is inserted between the two parallel flanges 110a, 110b of the first 101 of the two links, a guide hole 112 aligned with the geometric articulation axis X passing through the guide flange 120.

The articulated assembly 10 further comprises a hinge pin 160 that is inserted in the guide hole 112 and the through-hole 111 of each of the two parallel flanges 110a, 110b. In this manner, the hinge pin 160 allows for 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, in order to receive, between the two, the guide flange 120 of the second 102 of the two links 101, 102 forming a male interface which links and couples, by means of the hinge pin 160, with the associated female interface.

In order to limit the wear between the second link 102 and the hinge pin 160, the guide hole 112 is reinforced by a bushing 113 which is designed for receiving the hinge pin 160 and for guiding the hinge pin 160 in rotation with respect to the body 102′ of the second link 102. The bushing 113 is preferably shrunk on, for example cold shrunk on, in the guide hole 112 of the body 102′ of the second link 102 made of manganese steel. In this way, the bushing 113 is arranged so as to be coaxial to the geometric articulation axis X and designed to be in a pivot connection with the hinge pin 160, said bushing 113 being kept fixed in the body 102′ of the second link, in particular in the guide hole 112. The bushing is housed integrally in the guide hole 112 of the guide flange 120, so as not to project, which makes it possible to limit the friction between the parts of the assembly 10. In other words, the bushing 113 is preferably either flush, or slightly retracted with respect to the laterally emerging ends of the guide flange 120, in the guide hole 112, in order to avoid a projection of this kind.

In order to further limit the wear of the articulation 10, between the first flat region 101 and the hinge pin 160 the through-hole 111 and one 110b of the two parallel flanges comprises a flat portion 105 which cooperates with a flat region 161 of the hinge pin 160 in order to prevent rotation of the hinge pin 160 with respect to the single-piece body 101′ of the first link 101 (see for example FIGS. 8 and 9). Since the rotation about the geometric articulation axis X is prevented, the friction is limited. The pivot articulation between the first and second links 101, 102 of the assembly 10 is, in turn, always allowed by the degree of rotational freedom of the second link 102 with the hinge pin 160.

A link 100 of the chain 8 comprises a front end and a rear end. In this manner, the first link 101 of the assembly has a separate second geometric articulation axis, in parallel with the first and perpendicular to the reference plane P. The flat portion 105 of the through-hole 111 is oriented so as to be contained in a plane Pp that is perpendicular to a plane containing the two geometric articulation axes X and perpendicular to the reference plane P. An orientation of this kind promotes absorption of forces, depending on the advancement direction of the chain 8 and the direction of rotation of the links with respect to one another when they pass certain obstacles such as the return members 40.

In order to retain the hinge pin in the articulated assembly, and in particular to prevent its translational motion according to the geometric articulation axis X, this is locked in both directions. Indeed, the hinge pin 160 comprises a substantially cylindrical body, one end of which is provided with a flat region 161. In a configuration of this kind, an intermediate part of the hinge pin 160 is cylindrical so as to ensure the pivot connection to the second link 102 in the guide hole 112 of the guide flange 120. The cylindrical part is separated from the flat region 161, according to the axis of the hinge pin 160, by an indentation 163 that extends in a plane perpendicular to the geometric articulation axis X of the assembly 10.

In the assembled position, the indentation 163 of the hinge pin 160 comes into contact with and bears against an inner face 110b′ of the flange 110b on a lateral edge 105′ of the flat portion 105, which allows for locking of the hinge pin 160 in a first direction.

In order to ensure the prevention of the translation of the hinge pin 160 in the opposite direction, one 110a of the two flanges, in parallel with the first 101 link comprises a translation prevention interface 103 which is designed to receive a means 104 for preventing translation of the hinge pin 160. In particular, the prevention interface 103 is an annular groove which is machined, in this case bored, in the inside of the associated through-hole 111. The prevention means 104 comprises an inner resilient stop ring which comes to rest in the annular groove 103, and a portion of which is positioned on the path of the hinge pin 160 in order to form an obstacle for it and to prevent its movement in translation. In particular in order to allow for better retention of the resilient ring 104 in the bored groove 103, said resilient ring 104 has a quadrilateral, preferably rectangular, cross section. In order to ensure optimal locking of the hinge pin 160, every means for preventing the hinge pin 160 from moving in translation in a given direction is borne by two separate flanges of two parallel flanges 110a, 110b, i.e. the flange 110a of the first 101 of the two links comprising the annular groove 103 is separate from the flange 110b of the first 101 of the two links comprising the flat portion 105.

A resilient stop ring 104 is illustrated in greater detail in FIG. 6B. The resilient ring 104 comprises a body 104a extending in an annular manner over a particular angular sector, preferably larger than 240°, defining an inner space 104c. The body 104a comprises, at each of the ends thereof, ears 104b which extend radially towards the inside 104c of the body 104a and are designed to be grasped by a tool such as pliers. The resilient ring 104 is formed as a single piece, i.e. integrally. The resilient ring 104 is formed of a solid material, i.e. which does not comprise any holes, whether on its body 104a or its ears 104b. The resilient ring 104 is formed of steel for example.

The ears of the resilient ring 104 each comprise a bend 104d such that the end part faces in the direction away from the other ear. This allows for stiffening and reinforcement of the load resistance.

The resilient ring 104 is designed to be inserted into and to cooperate in a groove 103 in order to lock the hinge pin 160 in a direction of translation according to the geometric articulation axis X. The resilient ring 104 is dimensioned such that it is in contact with and bears, radially with respect to the geometric articulation axis X, against a bottom of the circular groove when it is positioned in said groove 103.

The hinge pin 160 comprises an anchoring interface 162 such as a threaded hole that is coaxial with the geometric articulation axis X, so as to allow it to be grasped by a tool in order to be manipulated. Said anchoring interface 162 is located on the side of the assembly where the resilient ring 104 is mounted in one 110a of the two parallel flanges of the first link 101, i.e. on the side the operator must access in order to perform the mounting and dismantling of the assembly 10. In the region of the hinge pin 160, the anchoring interface 162 is located at one of the ends thereof, opposite that comprising the flat region 161. In order to carry out the maintenance of each assembly 10, the operator may act from the same side of the chain 8, using pliers in order to remove the resilient ring on the one hand, and using a suitable tool, for example a slide hammer, for cooperating with the threaded hole 162 leading onto a face of the end of the hinge pin 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. In this case, the longitudinal direction extends as the direction of movement of the link 100. Each link 100, 101, 102 is connected, in a manner articulated to two other adjacent links of the chain 8, to each of the front and rear ends thereof. Each link is articulated, at the two front and rear ends thereof, with an adjacent link, such that one link is articulated by two separate assemblies 10, longitudinally on either side of its body.

Each articulation between two links is formed by an assembly 10, as described in detail above. It follows that each end of the link is designed, in this case, either as a first 101 of the two links of the assembly in question, or as a second 102 of the two links of the assembly in question. In particular, in this case:

• • a first group of links of the chain 8 comprises, for each of the links, on one side, a first end forming a first link 101 of an assembly, and, on another side, a second end, opposite the first, which also forms a first link 101 of another assembly: and
  • a second group of links of the chain 8 comprises, for each of the links, on one side, a first end forming a second link 102 of an assembly, and, on another side, a second end, opposite the first, which also forms a second link 102 of another assembly.

Preferably, each link body 101′, 102′ is symmetrical with respect to a plane of symmetry perpendicular to the longitudinal axis thereof and perpendicular to the reference plane P, but also perpendicular to a plane containing the two geometric articulation axes X. 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 an interface referred to as “female,” with its two flanges 110a, 110b, in order to receive, between the two, the guide flange 120 of the second 102 of the two links 101, 102 forming an interface referred to as “male” which links and couples, by virtue of the hinge pin 160, with the associated female interface. Thus, in the embodiment as shown, each link body comprises one similar interface, female or male, at the two ends thereof, hence the simplified term of “link” which can be used to refer to it in the chain 8, either a female chain link or a male chain link.

Of course, the arrangement of the assemblies in the chain 8 may be different. For example, one link may comprise, on one side, a first end forming a first link 101 of a first assembly, and, on another side, a second end, opposite the first, forming a second link 102 of another assembly.

As shown in particular in FIGS. 3, 4, 6A and 7, the excavation chain 8 is made up of a succession of links 100, among which the links are of three different types, although they each comprise a body designed either as a male link 102 or as a female link 101.

The excavation chain comprises the links 100 of the type comprising a shovel 130, the links 100 of the type comprising a counter stop 140, and the links 100 of the type without a projecting part, i.e. formed essentially on their body 101.

The function of such links 100 without a projecting part is primarily that of making the excavation chain 8 more lightweight. Another function is that of better adjusting the volume of excavated ballast to the maximum capacity of the screen, without losing too much of its own capacity, which is reduced by an order of magnitude of 20%, and not 50% as a person skilled in the art may think on account of the substantially doubled space between two shovels 130 in a design of this kind. This is made possible in particular by virtue of the shovel 130 which is similar to that described above, and in particular the tilting thereof.

In this embodiment, each of the links 100 of the type comprising a shovel 130 is arranged between two links 100 of the type comprising a counter stop 140. Furthermore, each link 100 without a projecting part is also arranged between two links of the type comprising a counter stop 140. One link in two is thus provided with a counter stop 140, the other links alternately being a link of the type comprising a shovel 130 and a link of the type without a projecting part.

A pattern of the chain 8 is thus formed by a link 100 of the type without a projecting 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 or rear end of said set of three links: these four links 100, together and in this order, form a pattern which is repeated successively along the chain 8.

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

A configuration of this kind has several advantages. Said link 100 comprising a shovel 130 comes directly in front of a link comprising a counter stop 140 in such a way, as already described, as to limit a relative rotation of the link bearing the shovel 130. Furthermore, a configuration of this kind makes it possible, on the one hand, to ensure a sufficiently small space between the links comprising a shovel 130 to ensure the effective excavation and transport of the ballast, and, on the other hand, to ensure a sufficiently large space to ensure the expedient movement of the chain with the necessary flexibility for passing the return members 40.

In order to ensure effective and lasting protection of the articulations of the links 100 of the chain 8 against wear due to abrasion by the ballast, and against the action of dust, thus conferring a longer service 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 comprise a convex curved portion, for example a longitudinal end that is rounded in a circular arc shape, such that it does not have sharp edges. Each curved portion preferably extends over a casing having a generatrix in parallel with the associated geometric articulation axis X. Said convex curved portions forming rounded ends are carried by each of the parallel 110a, 110b and guide 120 flanges. Furthermore, for the same assembly, the convex curved portions of each of the parallel 110a, 110b and guide 112 flanges through which the same hinge pin 160 passes have a substantially identical radius of curvature, such that, when the articulation passes a return member, the contact of the articulation on the return member is distributed over the first and second links 101, 102 that are articulated together.

In order to further reduce the risk of premature wear of the assembly, and thus of the articulation, the guide flange 120 exhibits clearance with respect to the two other parallel flanges 110a, 110b, between which it is positioned, which is sufficient for preventing friction during their relative rotation, but is sufficiently small to avoid allowing the ballast to become lodged in the articulation.

Along the straight portion of the excavation 8A, the links 100 move transversely with respect to the railroad 2, which corresponds to the longitudinal direction of the bodies 101 of the links 100 on said portion. The links 100 are oriented such that the geometric axes X of each of the articulations 10 are substantially vertical with respect to the ground, the reference plane P thus 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 corresponds to the side where the ballast is excavated and transported. An internal side of the bodies 101′, 102′ of the links is in turn designed to come into contact with and to come to bear against the return members 40 on the path traveled by the chain 8. Given the vertical orientation of the geometric axes X, it is possible to understand the interest in the hinge pins 160 being located entirely in the space delimited by the through-holes 111 and the guide holes 112, so as not to project vertically, below or above, from the bodies of the links. Indeed, a design of this kind prevents wear of the hinge pins 160 of each assembly 10.

In this embodiment, the links 100 are produced for example from manganese steel and are formed integrally. An example of the method for manufacturing said link 100, obtained by smelting, comprises at least one step of metal injection, and in particular a step of molding in a mold formed for example of a form and an associated counter-form.

The bodies 101′, 102′ of each of the links 100, 101, 102 is made of cast steel, the flat portion 105 of the through-hole 111 of one 110b of the two flanges in parallel with the first 101 of the two links being formed together with the body 101′ of the associated link, so as not to be machined. In this manner, the only machining required on the bodies of the links 100 participating in the assembly relates to the bore 103 designed for receiving the resilient ring 104.

Of course, the invention is described above by way of example. It will be understood that a person skilled in the art is able to implement different variants of the invention, without in any way departing from the scope of the invention.

Claims

1. An articulated assembly of two links for an excavation chain of a ballast excavation device comprising:

a first of the two links comprising: a single-piece body having two flanges which are in parallel with one another and with a reference plane of the articulated assembly, and through each of which a through-hole passes which is aligned with a geometric articulation axis of the articulated assembly, perpendicular to the reference plane, and the second of the two links comprising: a single-piece body comprising a guide flange that is inserted between the two parallel flanges of the first of the two links, a guide hole passing through the guide flange, which guide hole is aligned with the geometric articulation axis, the articulated assembly further comprising a hinge pin that is inserted into the guide hole and the through-hole in each of the two parallel flanges wherein the guide hole of the articulated assembly is reinforced by a bushing designed to receive the hinge pin and to guide the hinge pin so as to rotate relative to the single-piece body of the second link; and

the through-hole of one or the other of the two parallel flanges, referred to as the flange for preventing the rotation of the hinge pin, comprises a flat portion cooperating with a flat region of the hinge pin so as to prevent the hinge pin from rotating relative to the single-piece body of the first link.

2. The articulated assembly of claim 1, wherein the flat portion and the flat region are located in a plane in parallel with the geometric articulation axis.

3. The articulated assembly of claim 1, wherein the one or other of the two flanges, in parallel with the first of the two links, referred to as the flange for preventing translation of the hinge pin, comprises a translation prevention interface which is designed to receive a means for preventing translation of the hinge pin in at least one direction in parallel with the geometric articulation axis.

4. The articulated assembly of claim 3, wherein the translation prevention interface and the means for preventing translation of the hinge pin do not prevent the rotation of the hinge pin about the geometric articulation axis.

5. The articulated assembly of claim 4, wherein the translation prevention interface is an annular groove inside the hole through the flange for preventing translation of the hinge pin.

6. The articulated assembly of claim 5, wherein the means for preventing translation comprises an inner resilient ring that has quadrilateral, axial cross section.

7. The articulated assembly of claim 3, wherein the flange for preventing translation of the hinge pin is separate from the flange for preventing rotation of the hinge pin.

8. The articulated assembly of claim 1, wherein the first of the two links has a separate second geometric articulation axis, perpendicular to the reference plane, the flat portion of the through-hole being oriented so as to be contained in a plane that is located between the geometric articulation axis of the articulated assembly and the separate second geometric articulation axis, perpendicular to a plane containing the two geometric articulation axes.

9. The articulated assembly of claim 1, wherein the body of each of the two links is made of cast steel, the flat portion of the through-hole of one of the two flanges in parallel with the first of the two links being formed together with the body of the associated link, so as not to be machined.

10. The articulated assembly of claim 1, wherein the hinge pin comprises, on one of the two ends thereof, an anchoring interface, to allow it to be grasped by a tool in order to be manipulated.

11. An excavation chain having an excavation portion for a device for excavation of ballast under a railroad, the excavation chain comprising a succession of chain links which are connected in pairs by an assembly, so as to form an endless chain.

12. The excavation chain of claim 11, wherein the chain is formed by an alternating succession of links forming the first link of an assembly with each of the two adjacent links, and links forming a second link of an assembly with its two adjacent links.

13-15. (canceled)

16. The articulated assembly of claim 10, wherein the anchoring interface is a threaded hole that is coaxial with the geometric articulation axis.

17. (canceled)