EP4045714A1

EP4045714A1 - Link for a removal chain, and associated removal chain

Info

Publication number: EP4045714A1
Application number: EP20788828.0A
Authority: EP
Inventors: Vladimir Svitok; Franck MARTINET
Original assignee: Matisa Materiel Industriel SA
Current assignee: Matisa Materiel Industriel SA
Priority date: 2019-10-14
Filing date: 2020-10-14
Publication date: 2022-08-24
Anticipated expiration: 2040-10-14
Also published as: WO2021074242A1; CN114599836A; ES2962628T3; PL4045714T3; EP4045714C0; BR112022006995A2; EP4045714B1; FR3101891B1; FR3101891A1; CA3153816A1; AU2020367381A1; US20230243108A1

Abstract

Disclosed is a link (100) for a removal chain (8) for a ballast removal device (4) below a railway track (2), the link (100) comprising a member (101) that extends longitudinally between a front end (110) and a rear end (120) and is penetrated by at least one front through-hole (111) and a rear through-hole (121), said through-holes being designed to receive means hinging the link (100) to an adjacent link of the chain (8), the front through-hole (111) and the rear through-hole (121) extending along mutually parallel axes that are located in a reference plane (P) of the member (101), the link (100) further comprising an inner side (100B) of the member (101) with respect to the reference plane (P), the inner side (100B) lying opposite the outer side (100A), a concave guide surface (150) extending along an envelope (155) having an axis generatrix (G) running parallel to the axes of the hinge points (A1, A2) of the link, the guide surface (150) being designed to at least locally match a curvature (C) of a return member (40) of the removal device (4).

Description

DESCRIPTION

TITLE: LINK FOR AN EXCAVATION CHAIN 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 a link for an excavation chain intended to travel on a traffic path having a rectilinear excavation portion for a ballast clearing device below a railway track, and to an excavation chain comprising such links.

STATE OF THE PRIOR ART

[0003] In the prior art, work trains are known which are equipped with machines responsible for removing the ballast located under the sleepers of a railway track, and for 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 remove the worn part of the ballast in wagons provided for this purpose. In this way, the stripper-screening machine makes it possible to remove, 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 railroad ties, the chain working on this excavation portion transversely with respect to the orientation of the rails of the railway, dragging and transporting 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] These excavators are designed to respond to many problems. In particular, they must be strong enough to ensure a certain number of predetermined cycles to ensure excavation and transport of ballast with 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.

[0006] Despite these objectives, and given the considerable stresses undergone by excavators, improving their strength in order to minimize their maintenance is a constant problem in continuous search for improvement.

To further improve their lifespan, it is also known to provide these shovels with reinforced fingers forming claws and placed in the extension of the shovel. Such fingers are designed in a very resistant manner, the maintenance of which is easier than the link of the chain itself and which makes it possible to adapt more precisely to localized wear as a function of the forces undergone. This thus enables a reduction in the cost of maintenance and a shorter maintenance time, and therefore shorter machine downtime.

[0008] However, the wear of the links is also localized at the level of the return members. Indeed, the shocks undergone in these bent zones, taking into account the forces involved, often lead to premature wear at the level of the brackets, and more generally at the level of the return members arranged along the path traveled by the chain. The wear is also localized on the inner side of the links, opposite to the outer side from which the shovel protrudes.

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 excavation chain allowing a reduction in the wear of its links, and also allowing a reduction in wear. suffered by the referral bodies.

To do this is proposed, according to a first aspect of the invention, a link for an excavation chain intended to travel on a traffic path having an excavation portion for a ballast clearing device below of a railway track, the link comprising a body extending longitudinally between a front end and a rear end and is traversed by at least one front through hole and one rear through hole configured to receive articulation means with an adjacent link of the chain, the front and rear through-holes extending along axes parallel to each other and contained in a reference plane of the body, the link being characterized in that the body has an inner side of the body relative to the plane reference, opposite to the outer side, a concave guide surface extending over an envelope having an axis generatrix parallel to the axes of the link, the guide surface being config urea to match at least locally a curvature of a return member of the clearing device. [0011] Thanks to such a combination of characteristics, the link can circulate on a return member such as brackets on either side of a rectilinear excavation portion while locally following its curvature. In this way, wear on the inner side of the link, such as wear on the return member, is reduced. Furthermore, during such a movement, the link is stabilized by a surface contact between the guide surface of the body of the link on the one hand, and the driving surface of the return member on the other hand which locally has a substantially complementary shape. Such a surface contact in fact makes it possible to avoid a gyration movement of the link around itself during the passage of the drive member as occurs when a vertical linear linear contact takes place between the link and the link. referral body. Such stabilization aims to improve the efficiency of ballast transport by the excavator. Such a configuration also makes it possible to reduce the noise produced by the clearing device.

Contrary to popular belief, such a characteristic involves a relief on the inside of the body of the link so that a person skilled in the art might think that it would be likely to slow down the movement of the chain which carries it with a on the one hand, and cause premature wear on the other. This is not the case and experience has shown that the use of such a link offers better passage on the return members on either side of the rectilinear excavation portion. [0014] According to a particular technical characteristic, the guide surface extends along a directing curve having at least locally the shape of an arc of an ellipse, and preferably of an arc of a circle. Such a configuration provides a progressive continuous curvature for the passage of the return member.

[0015] According to one embodiment, the distance separating two front and rear longitudinal ends of the guide surface is greater than the distance separating the front and rear through holes, or even greater than the center distance between the front and rear through holes.

In a particularly advantageous configuration, the guide surface extends between its two front and rear longitudinal ends, the front ends and rear being each located substantially to the right of the front and rear through-hole, respectively. Preferably, this end is positioned in line with an intermediate zone delimited between, on the one hand, a longitudinal end portion of the through-hole situated towards the interior of the body and, on the other hand, its central axis.

According to one embodiment, the body of the link comprises, on its inner side, preferably to the right of each of the front and rear through holes, a convex surface extending between the concave guide surface and the associated end front or rear of the link body. This allows better passage of the return bodies when arriving on them. The combination of these convex surfaces bordering the concave surface being particularly reliable in limiting the wear of the link bodies and return members while limiting the noise caused by the movement of the chain. To ensure continuity between the convex surfaces and the concave guide surface, these convex surfaces each extend over an envelope having an axis generatrix parallel to that of the concave guide surface.

In an advantageous configuration, the front and rear ends of the body each have a curved convex portion, preferably in an arc of a circle so as to be free of stops. This configuration ensures effective and durable protection of the chain link joints against abrasion wear by ballast stones with sharp or sharp edges and against the action of dust, thus giving the links a longer service life. chain. This curved portion preferably extends over an envelope having a generatrix parallel to the axis of the associated through hole.

[0019] In a particular technical configuration, the link comprises a projecting part extending from an outer side of the body relative to the reference plane. The protruding part comprises for example a shovel for transporting ballast.

[0020] According to one embodiment, the shovel has a stop surface configured to receive a counter-stop of an adjacent rear link of the chain so as to limit relative rotation between the chain link and the adjacent rear link around of the axis of the rear through-hole. Such a counter-stop is particularly effective on the rectilinear excavation portion along which the shovels work and undergo a force exerted by the ballast generating a moment on the shovel tending to cause the shovel to pivot rearwardly, and therefore the body of the link. The counter-stop makes it possible to limit the effect of this moment of forces applied to the shovel so that the associated link continues its path in a rectilinear fashion.

In a particular technical configuration, at least one of the through holes configured to receive articulation means with an adjacent link of the chain has a flat so as to block in rotation an axis of the articulation means. [0022] According to an advantageous characteristic, the link comprises fingers carried by the shovel and projecting outwardly from the outer side of the reference plane in the extension of the shovel. These fingers are preferably each oriented along an axis inclined relative to the reference plane, with an inclination preferably between 65 and 80 °, preferably between 70 and 75 °. This allows for the use of shorter fingers to make the excavator lighter without losing performance or losing rigidity.

[0023] According to one embodiment, the fingers are all located above a plane perpendicular to the parallel axes of the front and rear through holes and tangent to a lower end of said shovel. This increases the life of the fingers.

[0024] According to one embodiment, the projecting part comprises a counter-stop configured to come into abutment against a stop surface of a shovel of an adjacent front link so as to limit a relative rotation between the link and the link. adjacent front around the axis of the front through-hole. According to one embodiment, the body is in one piece, that is to say in one piece, preferably obtained by casting, with or without machining of the front and rear through holes and / or of the surface of guidance.

The invention also relates to a finger for a shovel of a link of an excavation chain intended to travel on a traffic path having a excavation portion for a ballast clearing device below a railway track, the finger comprising a plurality of grooves configured to receive a locking member for ensuring adjustment of the finger in translation relative to the shovel. The position of the locking member in one of the grooves thus determines the axial position of the finger with respect to the shovel.

Such fingers can be fitted to shovels as described above but also any other shovel of the prior art whose fingers are fixed by such locking members, this regardless of the characteristics of the body of the link.

According to another aspect of the invention, it relates to an excavation chain having an excavation portion for a ballast clearing device below a railway track, the excavation chain being characterized in that it comprises a succession of chain links comprising all or part of the aforementioned characteristics to form an endless chain.

According to one embodiment, the chain links comprise links of the type comprising a projecting part, preferably links of the type comprising a shovel and links of the type comprising a counter-stop, and links of the type without part protruding. Preferably, the excavation chain comprises a succession of a plurality of chain links forming the same pattern which is repeated successively placed end to end successively along the chain, such a pattern comprising from front to back in the direction of movement of the chain: a link of the type comprising a shovel, a link of the type comprising a counter-stop, a link of the type without protruding part, then a link of the type comprising a counter-stop.

According to another aspect, the invention also relates to a ballast clearing device comprising such an excavation chain, the excavation chain preferably being moved in an endless manner by a drive mechanism and being guided on its circulation path at least by angle transmission members, the body having on an inside side of the body with respect to the reference plane, opposite the outside side, a concave guide surface extending over an envelope having an axis generator parallel to the axes of the joints of the link, the guide surface following at least locally a curvature of at least one of the return members of the excavating device, preferably at least two return members arranged on either side of the excavation portion .

According to one embodiment, a radius of curvature of the guide surface is equal, at least locally, to a radius of curvature of at least one of the return members, preferably at least of the two return members arranged on either side of the excavation portion.

BRIEF DESCRIPTION OF THE FIGURES

[0032] 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 according to one embodiment;

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

[Fig. 3]: a front view of a portion of an excavation chain according to one embodiment, at a return member at one end of a rectilinear excavation portion;

[Fig. 4]: a top view of the excavation chain portion according to the embodiment of Figure 3, at a return member at one end of a rectilinear excavation portion;

[Fig. 5]: a detailed profile view of a chain link fitted with a shovel according to this same embodiment;

[Fig. 6]: a front perspective view of a chain link provided with a shovel according to this same embodiment;

[Fig. 7]: a rear perspective view of a chain link provided with a shovel according to this same embodiment; [Fig. 8]: a perspective view of a reinforcing finger of a shovel according to one embodiment;

[Fig. 9]: a rear perspective view of a chain link provided with a shovel according to this embodiment, and equipped with reinforcing fingers according to Figure 8;

[Fig. 10]: a top view of a portion of an excavation chain according to another embodiment;

[Fig. 11]: a perspective view of the excavation chain portion according to the embodiment of Figure 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 placed 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 ducts including a transverse duct 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 bevel gearboxes.

The drive device 9 is arranged in height relative to the railway vehicle 1, above the railway track 2, on one side longitudinally opposite to the transverse duct 5, and between the ascent duct 6 and the descent duct 7. The driving device 9 is placed on the path of the excavation chain 8 and comprises a driving wheel 9 ′ driving locally 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 device 4 with respect to a direction of 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 lowered position under the railway track 2 and can be connected for example in a removable manner to the transverse duct 5 by a connector (not visible in the figures).

[0039] Figures 3 and 4 illustrate front and top views, respectively, of part of the excavation chain 8 according to one embodiment. This part of the excavation chain 8 is located at the level of a return member 40 connecting one end of a rectilinear excavation portion 8A of the chain 8 guided by the transverse duct 5 and the entrance to the longitudinal portion. outlet 8B guided by the rise duct 6. This return member 40 is formed by a fixed surface bent at an angle substantially equal to 90 degrees so that it forms a square.

The excavation chain 8 is formed of 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 chain type without end. Each of the links 100 comprises a body 101 which extends longitudinally between a front end 110 and a rear end 120 provided respectively with at least one front hole 111 and a rear hole 121 passing right through the link 100 and configured to receive means of articulation with an adjacent link of the chain 8. The longitudinal direction is understood here as the direction of movement of the link 100. The front 111 and rear 121 through-holes extend along axes parallel to each other. and contained in a reference plane P of the body 101, each link 100 comprising a projecting portion 130, 140 extending from an outer side 100A of the body 101 of the link 100 with respect to the reference plane P.

The protruding parts of the links 100 may include a shovel 130 for transporting ballast, or a counter-stop 140 configured to abut against a stop surface 131 of a shovel 130 of an adjacent link 100 before so as to limit a relative rotation between the chain link 100 8 and the adjacent front link around the axis of the front through-hole 111. As illustrated in particular in FIG. 4, the excavation chain 8 is composed of an even number of links 100, the links 100 of the type comprising a shovel 130 and the links 100 of the type comprising a counter-stop 140 being arranged successively alternately along the chain 8. In this way, each link 100 comprising a shovel 130 has a stop surface 131 located at the back of the shovel 130 and configured to receive a counter stop 140 of an adjacent rear link of the chain 8 so as to limit a relative rotation between the link 100 of the chain 8 and the link adj rear acent around the axis of the rear through-hole 121. Such a stop position of the shovel 130 against the counter-stop 140 of the associated rear link 100 is visible in FIG. 4, at the level of the link 100 located on the rectilinear portion excavation 8A. In fact, along this portion 8A, the shovels 130 undergo a force by driving the ballast which generates a moment on the shovel 130 which tends to cause the link 100 to tilt back, this tilting being a pivoting of the shovel 130 around the axis A2 of the rear through hole 121 configured to receive articulation means 160. To further limit this pivoting about the axis A2 of the rear through hole 121, at least one of the through holes 111, 121 has a flat 105 so in blocking in rotation the axis A1, A2 of the associated articulation means 160. The flat 105 of each axis is oriented so as to be contained in a plane perpendicular to the reference plane P and parallel to an axis A1, A2 of the associated through hole 111,121. Such an orientation of the plate 105 of the axes makes it possible to improve the locking in rotation of the axis in question, the force being on the flat of the axis.

The articulation means 160 are formed in this embodiment by axes passing through a rear through hole 121 of a link 100 and front through hole 111 of another link 100, the axis being blocked in translation by a circlip positioned in an interior groove of the through-hole. The circlip groove is machined in the shovel 130 to allow it to be held in place in its housing. In this embodiment, the links 100 comprising shovels 130 are outer links of the chain 8 or female links in that they have a body 101 comprising a front end 110 and a rear end 120 each provided with two side plates d 'predetermined thickness between which is inserted a plate centered at a front 110 or rear 120 end of a body 101 of a link 100 comprising a counter-stop 140 thus forming an inner link 100 or male link. The axis of the articulation means 160 is configured to fit into the corresponding through-hole formed by the alignment of through-hole portions of each of these three plates.

Along this 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 axes A1, A2 of the through holes 111, 121 are substantially vertical with respect to the ground, the reference plane P then being vertical, and the shovel 130 or the counter-stop 140 extending substantially radially towards the ground. 'outside 100A of body 101 of link 100.

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. As can be seen more particularly in Figure 5, each link 100 comprises, on an inner side100B of the body8 of the link100 with respect to the reference plane P, opposite to the outer side 100A, a concave guide surface 150 s' extending over an envelope 155 having an axisG generator (see FIG. 7) parallel to the axes of the articulations A1, A2 of the link 100. This guide surface 150 is configured to match at least locally a curvature C of a return member40 of the clearing device4 (see figure 4).

[0048] The angle transmission of the return member 40 has a convex roundness connecting two surfaces arranged at 90 degrees to each other. The guide surface 150 extends along a directing curve Cd having the shape of an arc of a circle. In the plane of figure 5, the directing curve Cd follows the envelope 155.

The guide surface 150 extends between two longitudinal ends front151 and rear 152 of said guide surface 150, the distance which separates them being greater than the distance DI separating the front 111 and rear 121 through holes. This distance d can also be greater than the center distance D2 between the through holes (not shown).

According to the embodiment illustrated in detail in Figures 3 to 9, the front 151 and rear 152 longitudinal ends of the guide surface 150 are each located substantially to the right of an intermediate zone Zi (see Figure 5) delimited between the central axis A1, A2 of the associated through hole 111,121 and the inner edge of the corresponding through hole 111,121, this intermediate zone Zi extending longitudinally over a distance corresponding to a radius of the associated through hole 111,121. By the inner edge of the through hole 111, 121 is meant a longitudinal end portion of the through hole 111, 121 located towards the interior of the body 101 of the link 100.

The link 100 also comprises, on the inner side 100B of its body 101, to the right of each of the axes A1, A2 of the front111 and rear121 through holes, a convex surface 153,154 extending between the concave guide surface 150 and the associated front 110 or rear 120 end of the body 101 of the link 100. This allows better passage of the return members 40 when they arrive on them. The combination of these convex surfaces 153, 154 bordering longitudinally on either side of the concave surface 150 is particularly reliable for limiting the wear of the bodies 101 of the links 100 and of the return members 40 while limiting the noise caused by the displacement of chain 8.

To ensure continuity between the convex surfaces 153, 154 and the concave guide surface 150, these convex surfaces 153, 154 each extend over an envelope having a generatrix of axis parallel to that of the concave guide surface 150.

Apart from the return members 40, the links 100 are therefore guided by the corresponding ducts, resting on the path by two support zones of the link 100 which are located on these convex surfaces 153, 154, namely to the exterior of the concave part delimited by the guide surface 150 and in longitudinal overlap of the front 111 and rear 121 through-holes. Such a location of these bearing surfaces formed by these convex surfaces 153, 154 also makes it possible to avoid a rearward tilting of the excavator 130 in the angle transmissions due to the changes of direction.

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 110 and rear 120 ends of the link 100 each have a curved convex portion 112, 122, for example in an arc of a circle, so as to be free of stops. Each curved portion 112, 122 preferably extends over an envelope having a generatrix parallel to the axis of the associated through hole. For these same advantages, the guide surface 150 is preferably chamfered on its side edges 156.

Each link 100 provided with a shovel 130 allowing the excavation and transport of ballast comprises fingers 132 carried by the shovel 130 and projecting outwardly from the outer side 100A of the reference plane P, in the extension of the shovel 130. In this embodiment, these fingers 132 are three in number: a central finger, a lower finger and an upper finger. 132 fingers are made for example in high strength steel and one end 132a is disposed projecting in the extension of the shovel 130.

Each finger 132 has a cylindrical body 132b configured to cooperate in a tubular receptacle 134 provided for this purpose and at least one radial groove 132c on its cylindrical body 132b. The groove 132c is dimensioned so as to receive a locking member 135 such as a screw penetrating substantially orthogonally with respect to the finger 132 in the tubular receptacle 134 and penetrating at least in part into the groove 132c. In this way, the locking member 135 is configured to block in translation the cylindrical body 132b relative to the tubular receptacle 134 of the shovel 130, the locking member 135 extending tangentially with respect to a bottom of the groove 132c. These fingers 132 make it possible to protect the shovel 130 from wear, in particular at its end and in the lower part of the shovel 130 where the wear is generally greater. As illustrated in FIG. 8, the fingers 132 may include a plurality of grooves 132c to allow adjustment of the finger 132 in translation and thus cause it to translate in its tubular receptacle 134 to take predetermined positions as a function of its wear.

The fingers 132 are removably fixed relative to the shovel 130, the removal of the locking means 135, for example by unscrewing it, allows the finger 132 concerned to be released and to be removed from its tubular receptacle 134 by the translating. The locking means 135 can also be secured by any suitable means such as a pin (not visible in the figures).

The fingers 132 are each oriented along an axis inclined relative to the reference plane P, with an inclination a of between 65 and 80 °, preferably between 70 and 75 °.

The fingers 132 are also oriented in a plane P132 inclined relative to a mean plane P130 of the shovel 130 extending substantially vertically (see Figure 4), the inclination a preferably being between 20 and 35 ° , and here equal to about 30 ° in this embodiment. Such a characteristic allows, in comparison with an equivalent useful working surface of a shovel 130 with a inclination which would be greater, to lighten the shovel 130 without losing efficiency or losing rigidity. The useful working surface of the shovel 130 is understood here as the surface swept by the shovel 130 during its movement.

The fingers 132 are all located above a Pinf plane perpendicular to the parallel axes of the front 111 and rear 121 through holes and tangent to a lower end of said shovel 130, in particular in this embodiment, also in below a Psup plane tangent to an upper end of the excavator 130 (see Figure 9). Given the orientation of the chain 8 and therefore of the shovel 130 on the rectilinear excavation portion 8A, the Pinf and Psup planes are generally horizontal. This lower end is sensitive in that it is extremely stressed in terms of abrasion wear against the ballast so that if the wear becomes too great, it can interfere with the proper attachment of the fingers 132 on the back of the machine. the shovel 130. With a lower finger 132 located entirely above the plane Pinf, a longer service life is ensured for the link 100. Preferably, the hardness of the lower surface of the shovel 130 is increased, for example by an addition by welding chromium / manganese and vanadium or by adding tungsten carbide plates.

[0061] Figures 10 and 11 illustrate an excavation line according to another embodiment. In the same way as described above, 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 endless chain type.

This embodiment differs essentially from the other embodiments illustrated in that the chain 8 comprises links without protruding part. The bodies 101 of each of the links are similar, in particular, each link 100 comprises, on an inner side 100B of the body 8 of the link 100 with respect to the reference plane P, opposite to an outer side 100A, a guide surface 150 is configured to match at least locally a curvature C of a return member 40 of the clearing device 4. As illustrated in Figures 9 and 10, the excavation chain 8 is composed of a succession of links 100 among which the links are of three different types: the 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 of 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 man of the trade might think so because of the substantially doubled spacing between two shovels 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 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 chain 8.

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. Furthermore, to reduce the number of forms of links 100, the links fixing interfaces between their bodies 101, at their front ends 110 and rear 120, are identical for a link 100 of the same type: the links comprising a shovel 130 and the so-called "intermediate" links without protruding part are so-called "female" links for their connection in the chain 8 and the links 100 comprising a counter-stop 140 are so-called “male” links for their connection in the chain 8.

As described above, the female links have a body 101, the front 110 and rear 120 ends of which are each provided with two side plates or flanges of predetermined thickness between which is interposed a centered plate of a front end 110 or rear 120 of a body 101 of another adjacent link 100. The axis of the articulation means 160 is configured to be housed in the associated through-hole formed by the alignment of through-hole portions of each of these three plates of the two links nested one in the other so as to form a hinge. To improve the strength of the intermediate link 100, namely without a protruding part, this link 100 has on an outer side 100A of the body 101 with respect to the reference plane P, opposite to the inner side 100B, a convex surface. Such a surface aims to increase the distance separating the surfaces of the inner 100B and outer 100A sides of the body 101, that is to say to increase the thickness of the body 101 of the links to make them more resistant. The guide surface 150 is itself always configured to match at least locally a curvature C of a return member4 of the excavation device4.

[0069] Of course, the invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without however departing from the scope of the invention.

Claims

1. Link (100) for an excavation chain (8) intended to travel on a traffic path having an excavation portion (5) for a ballast excavating device (4) below a railway track ( 2), the link (100) comprising a body (101) extending longitudinally between a front end (110) and a rear end (120) and is traversed by at least one front through hole (111) and one rear through hole (121) configured to receive articulation means with an adjacent link of the chain (8), the front (111) and rear (121) through holes extending along axes (A1, A2) parallel to each other and contained in a reference plane (P) of the body (101), the link (100) being characterized in that the body (101) has an interior side (100B) of the body (101) with respect to the reference plane ( P), opposite the outer side (100A), a concave guide surface (150) extending over a casing (155) having an axis generator (G) parallel to the axes (A1, A2) of the link, the guide surface (150) being configured to at least locally match a curvature (C) of a return member (40) of the excavation device (4).

2. Chain link (100) according to claim 1, characterized in that the guide surface (150) extends along a directing curve (Cd) having at least locally the shape of an elliptical arc. , and preferably of an arc of a circle.

3. Chain link (100) (8) according to claim 1 or 2, characterized in that the distance (d) separating two front longitudinal ends (151) and rear (152) of the guide surface (150) is greater at the distance (Dl) separating the front (111) and rear (121) through holes, and preferably greater than the center distance (D2) between the front (111) and rear (121) through holes.

4. Chain link (100) (8) according to any one of the preceding claims, characterized in that the front (110) and rear (120) ends of the body (101) each have a curved convex portion (112, 122 ), preferably in an arc, so as to be devoid of orders.

5. Chain link (100) (8) according to any one of the preceding claims, characterized in that the link (100) comprises a projecting part (130, 140) extending from an outer side (100A) of the body (101) relative to the reference plane (P). 6. Chain link (100) (8) according to the preceding claim, characterized in that the projecting part (130, 140) comprises a shovel (130) for transporting ballast.

7. Chain link (100) (8) according to claim 6, characterized in that the shovel (130) has a stop surface (131) configured to receive a counter stop (140) of an adjacent rear link of the chain (8) so as to limit a relative rotation between the link (100) of the chain (8) and the rear adjacent link around the axis of the rear through-hole (121).

8. Chain link (100) (8) according to any one of the preceding claims, characterized in that at least one of the through holes (111, 121) configured to receive articulation means with an adjacent link

(140) of the chain (8) has a flat (105) so as to block in rotation an axis of the articulation means.

9. Chain link (100) (8) according to any one of claims 5 to 7, characterized in that the link (100) comprises fingers (132) carried by the shovel (130) and projecting towards the exterior of the exterior side (100A) of the reference plane (P) in the extension of the shovel (130), the fingers (132) each being preferably oriented along an axis inclined with respect to the reference plane (P), with a inclination (a) preferably between 65 and 80 °, preferably between 70 and 75 °. 10. Chain link (100) (8) according to claim 8, characterized in that the fingers (132) are all located above a plane (Pinf) perpendicular to the parallel axes of the front through holes (111) and rear (121) and tangent to a lower end of said shovel (130).

11. Chain link (100) (8) according to any one of the preceding claims, characterized in that the projecting part comprises a counter-stop (140) configured to come into abutment against a stop surface (131) of a shovel (130) of a front adjacent link so as to limit relative rotation between the chain link (100) (8) and the front adjacent link around the axis of the front through hole (111).

12. Chain link (100) (8) according to any one of the preceding claims, characterized in that the body (101) is in one piece, preferably obtained by foundry, with or without machining of the front and rear through holes (111 , 121) and / or the guide surface (150).

13. Excavation chain (8) presenting an excavation portion for a device

(4) excavation of ballast below a railway track (2), the excavation chain (8) being characterized in that it comprises a succession of links (100) of chain (8) according to l any one of the preceding claims to form an endless chain (8).

14. Excavation chain (8) according to claim 13, characterized in that the links (100) of chain (8) comprise links of the type comprising a projecting part, preferably links of the type comprising a shovel (130). and links of the type comprising a counter-stop (130), and links of the type without protruding part.

15. Device (4) for excavating or clearing ballast characterized in that it comprises an excavation chain (8) according to claim 13 or 14, the excavation chain (8) being guided on its path. circulation at least by angle return members (40), the body (101) having an inner side (100B) of the body (101) with respect to the reference plane (P), opposite the outer side (100A) ), a concave guide surface (150) extending over an envelope (155) having an axis generator (G) parallel to the axes (A1, A2) of the link, the guide surface (150) at least locally matching a curvature (C) of at least one of the return members (40) of the excavating device (4).