GB2094379A

GB2094379A - A track tamping, levelling and lining machine incorporating a stabilisation unit

Info

Publication number: GB2094379A
Application number: GB8129634A
Authority: GB
Original assignee: Franz Plasser Bahnbaumaschinen Industrie GmbH
Current assignee: Franz Plasser Bahnbaumaschinen Industrie GmbH
Priority date: 1981-01-28
Filing date: 1981-10-01
Publication date: 1982-09-15
Also published as: IT1140070B; FR2498653A1; AT371171B; IN154967B; CA1192444A; ES8302151A1; IT8124960A0; DK152386C; GB2094379B; DK38882A; ES509101A0; DE3132870A1; JPS57130603A; DK152386B; YU257481A; DE3132870C2; SE449629B; FR2498653B1; ATA37081A; YU42119B

Abstract

Railway track ballast is consolidated by an on-track machine with a ballast-penetrating tamping unit 15 and a dynamic stabilisation unit 17 which vibrates the track horizontally while applying a vertical load. The track stabilisation unit is forward of or level with the tamping unit. A track lifting and lining unit 10 may also be provided forward of the tamping unit 15. <IMAGE>

Description

SPECIFICATION A track tamping, levelling and lining machine incorporating a stabilisation unit This invention relates to a travelling on-track machine for consolidating the ballast bed of a railway track, more particularly a track tamping, levelling and lining machine, comprising undercarriages and at least one tamping unit which is arranged for vertical displacement on the chassis of the machine and which is provided with vibratable tamping tools designed to penetrate into the ballast bed and to be moved towards and away from one another and, preceding this tamping unit, a track lifting and lining unit, at least one track stabilisation unit which is designed to be brought into form-locking engagement with both rails of the track through its own on-track wheei sets, particularly guide rollers, and of which the tool frame is designed to be vibrated substantially horizontally by vibrators and to be subjected to substantially vertical loads by cylinder-and-piston drives connected to the chassis of the machine, and further comprising a tool control system and at least one levelling and, optionally, lining reference system.

It is already known (cf. G. B. Patent No.

1545574) that travelling on-track machines may be equipped with track stabilisation units between their undercarriages. Machines of this type are coupled to track tamping, levelling and lining machines or are used immediately after the track has been treated by a machine of this type in order to bring the track into a deeper position and to consolidate it to an even greater extent. This eliminates the initial settlement of the track which occurs after tamping under the weight of the rail traffic and, in particular, increases the resistance of the sleepers to transverse shifting relative to the ballast bed.Track stabilisation units of this type comprise a tool frame which is equipped with double-cone wheels designed to be brought into form-locking engagement with the railheads of both rails and which is adapted to be vibrated by vibrators transversely of the longitudinal axis of the rails. The track stabilisation unit is also designed tp receive a vertically directed load from hydraulic cylinders pivotally connected to the tool frame and chassis of the machine. In this way, the track vibrated through the double-cone wheels and subjected to the vertical load is as it were laterally embedded in the ballast, as a result of which the ballast is so to speak fluidised, the stones making up the ballast being rearranged into a more tightly packed formation.This intensifies the consolidation of the ballast below and at the ends of the sleepers below which the ballast was previously tamped by means of vibratable tamping tools and brings the track into the deeper position corresponding to the reduction in volume of the ballast. These travelling machines equipped with track stabilisation units have already proved to be successful in practice, particularly because they increase the permanence of the track in regard to its position and stabilise the track.

In addition, G. B. Patent No. 14541 72 describes a track tamping and levelling machine of which the tamping units are arranged at the front end of the machine chassis which projects beyond the undercarriage and which, behind the tamping units in the region between the two undercarriages, comprises a track stabilisation unit for stabilising the position of the track. The advantages already described may also be achieved with this known combined arrangement which stabilises the track after it has been tamped and fixed in any required lateral or vertical position. Track stabilisation units of this type which are arranged on their own travelling machines or on their own frame sections naturally involve fairly considerable outlay.

The object of the present invention is to provide a travelling on-track machine of the type described at the beginning for consolidating the ballast bed of a railway track to be corrected which, despite its simplified construction, makes it possible to establish an almost ideal, stable condition of the track and ballast bed which, hitherto, could only be achieved under particularly favourable conditions by separately using a high-performance track tamping machine equipped with all the modern accessories and a similar track stabilisation vehicle.According to the invention, this object is achieved in that the track stabilisation unit is arranged on the chassis of the machine in that part of the overall length of the machine which extends forwards in the working direction from the position of the tamping unit and in that the control system is designed for alternately activating and inactivating, above all automatically, the track stabilisation unit, the tamping unit and the track lifting unit according to a predetermined cycle.By virtue of this extremely simple arrangement, it is possible to co-ordinate the use of all the working units involved in the treatment of the track and ballast bed with one another as a function of time and place in such a way that the required maximal consolidation of the ballast bed and track is guaranteed in the course of a single working run by the machine whilst at the same time keeping to a work cycle that is adapted to the particular circumstances and requirements. In this connection, it is possible considerably to increase the effectiveness of the treatment by comparison with the use of separate machines by intentional overlapping of the effective ranges and/or operational stages of the units involved.For example, by superimposing the vibratory movement directly imparted to the ballast by the tamping tools upon the horizontal vibrations transmitted by the track stabilisation unit via the track to the ballast, it is possible to obtain a greater flow of ballast over a longer section of the track which results in more rapid and intensive consolidation of the ballast through the rearrangement of its constituent particles into a tightly packed formation. In particular, the invention affords the advantage that it is now also possible to apply the effect of the track stabilisation unit in the tamping zone to eliminate any initial settlement.

Another advantage of the arrangement according to the invention lies in the fact that the basic construction of conventional track tamping and levelling machines may be kept large intact and that components and working units which for the most part have already frequently proved to be very successful may be used for equipping the machine.

One advantageous embodiment of the invention is characterised in that the track stabilisation unit and the tamping unit are arranged in substantially the same cross-sectionai area of the chassis, the tool frame of the track stabilisation unit comprising -- for each rail - a longitudinal girder which is intended to be arranged between the tamping tools entering into the ballast bed on both sides of the rail, which is ridigly connected to the vibrators and on which the guide and gripping rollers designed to be brought into engagement with the rail are mounted.This machine construction is distinguished by an extremely compact arrangement -- particularly in the longitudinal direction of the machine - of the track stabilisation unit and the tamping unit which enables a track tamping and levelling machine to be subsequently fitted out in accordance with the invention without any need for significant modifications to the conventional chassis construction. In addition, significant operational advantages are afforded by the direct overlapping of the effective ranges of the tamping and stabilising tools.Thus, it is possible on the one hand for the entire effective range to be readily observed by the machine operator and, on the other hand, for the horizontal vibration generated by the track stabilisation unit and transmitted through the track to the ballast bed to be directly superimposed upon the vibratory movements of the tamping tools in the actual tamping zone. In this way, consolidation of the ballast bed during the tamping operation occurs not only beneath the sleepers, but also in the sleeper cribs and at the sleeper ends along the outsides of the ballast bed.

In one advantageous further development of this construction, each longitudinal girder is connected to the chassis of the machine by two cylinder-and-piston drives each pivotally connected to one of its ends and extending upwards immediately in front of and behind the tamping unit substantially in the virtical longitudinal plane of the rails. By virtue of this arrangement, not only is it possible to apply relatively heavy vertically directed loads to the longitudinal girder, it is also possible to apply loads of different weight to the front and rear ends of the longitudinal girder by admitting different levels of pressure to the two cylinder-and-piston drives.In this way, the lowering operation may be carried out with particular precision, for example by heavily loading the track in the region of the front cylinder-and-piston drive and lowering it to a corresponding depth and bringing it to exactly the prescribed level under only a moderate load in the region of the rear cylinder-and-piston drive.

In the two above-mentioned embodiments of the invention, it is particularly advisable if the gripping rollers, which are mounted in a housing designed to pivot under the power of a drive about a shaft extending longitudinally of the machine, are arranged together with said housing between two tamping tools following one another in the longitudinal direction of the machine and designed to be moved towards and away from one another in pairs on the outside of the longitudinal girder. In this way, the readily accessible space between the tamping tools which is empty towards the outside of the track is utilised for accommodating the gripping rollers, which may thus be laterally pivoted without interference.This arrangement also affords the additional advantage that, in the tamping zone, the gripping rollers are always situated above a sleeper below which the ballast is to be tamped so that the horizontal vibration generated by the vibrators may be directly transmitted to the sleepers through the rail fastenings.

Another embodiment of the invention is characterised in that the longitudinal girders associated with the two rails are joined to one another by a cross member which carries the vibration drives and to each outer end of which projecting beyond the longitudinal girders is pivotally connected a cylinder-and-piston drive extending upwards to the chassis beyond the lateral boundary profile of the tamping unit and on which are arranged at least two (per rail) cylindrical gripping rollers designed to be applied to opposite sides of the rail head, the inner gripping rollers being mounted on fixed, vertical shafts and the outer gripping rollers being mounted on shafts designed to pivot transversely of the longitudinal axis of the machine.This arrangement is distinguished by the fact that both the vertical loads and also the vibrations are directly, i.e. fully, transmitted to the associated rail through the cross member and the gripping rollers in the region of the longitudinal centre of the track stabilisation unit. This embodiment is particularly suitable for machines equipped with singlesleeper tamping units, in which case the cross member is best arranged centrally between the tamping tools designed to move towards and away from one another in pairs, which provides for a very compact arrangement in which the working parts of the tamping and stabilisation unit remain readily accessible.

Another embodiment of the invention is distinguished by the fact that the track stabilisation unit is connected to a track lifting and lining unit preceding the tamping unit in the working direction to form a mechanical assembly which is designed to be vibrated by the vibrators and to be subjected as required to a vertical load or to a lifting force by the cylinder-and-piston drives, the gripping rollers simultaneously forming the lifting elements and the guide rollers the lining elements of said assembly. This combination of two hitherto separately arranged units provides for considerable structural simplification, in addition to which it is possible in this case to retain the standard arrangement of the lifting and lining unit and the tamping units without any need to modify either the construction or the dimensions of the chassis.In particular, an already existing track tamping and levelling machine may be fitted out in accordance with the invention at low cost simply be replacing or re-building the lifting and lining unit. In this embodiment of the invention, the vibration of the above-mentioned assembly and of course its vertical loading is best only commenced on completion of the lifting and lining operation.

Finally, it is possible according to another aspect of the invention for the track stabilisation unit to be arranged between the tamping unit and a track lifting and lining unit preceding the tamping unit in the working direction of the machine. In this way, it is possible to obtain a predetermined length of track which extends from the lifting and lining unit still held in the correct lateral position by the lateral lining drives to the rear undercarriage of the machine and in which the track is able freely to vibrate horizontally under the effect of the track stabilisation unit arranged in between without in any way affecting the already corrected lateral position of the track.

The invention also reiates to a process for consolidating the ballast bed of a railway track to be corrected using a travelling on-track machine according to the invention, characterised in that the track - to which substantially horizontal vibrations may already have been imparted transversely of its axis - is raised beyond the definitive prescribed level and the ballast below it is tamped by tamping tools designed to penetrate into the ballast bed and to be moved towards and away from the particular sleeper below which the ballast is to be tamped, after which the track which continues to vibrate horizontally or to which horizontal vibrations are now imparted is subjected to a downwardly directed vertical load and is lowered to the prescribed level.The final outcome of this process is a track which is positioned exactly at the required level and which is firmly anchored in the heavily consolidated ballast bed, undergoing only minimal and - by virtue of the homogeneous condition of the ballast bed -- uniform settlement under the weight of subsequent rail traffic. The process works quickly and reliably, the individual process steps involved readily lending themselves to automation.

In one preferred embodiment of the invention, the track is only vibrated horizontally over a period of time sufficient for the tamping and lowering operation to be completed. In this way, the lifting and lining operation cannot be affected by the stabilising operation, in addition to which an intensive flow of ballast considerably increasing the degree of consolidation of the ballast over the entire area being treated is obtained through the overlapping of the vibrations imparted to the ballast by the tamping tools and the stabilisation unit.

In another embodiment of the process according to the invention, the track is raised to a preselectable level during the tamping operation, the ballast beneath the track continues to be tamped while the track is kept at that level against a holding force after which the track is lowered to the prescribed level by horizontal vibration in conjunction with a downwardly directed vertical load. This embodiment of the process reliably avoids overlifting of the track, above all by the uplift effect of the tamping tools. the lifting of the track being limited to a level which may be neutralised by the subsequent stabilising operation and the accompanying lowering of the track.In addition, this procedure affords the advantage that consolidation of the ballast beneath the sleepers may be further intensified by admitting more pressure to the feed-adjustment drives of the tamping tools.

Finally, in another embodiment of the process, the track is subjected after lowering to a vertical static load progressing with the advance of the machine, in particular by the following undercarriage of the machine. In this way, the amplitude of the horizontal vibrations imparted to the track is gradually reduced up to the point at which the following static load is applied, thus ensuring a gradual transition to the rest position of the treated track which is made even firmer by the vertically applied load.

Embodiments of the invention are described by way of example in the following with reference to the accompanying drawings, wherein: Figure 1 is a side elevation of a track tamping, levelling and lining machine according to the invention equipped with a track stabilisation unit.

Figure 2 is a side elevation on a larger scale of the combined tamping and track stabilisation unit of the machine shown in Figure 1.

Figure 3 is a partial front elevation of this combined unit in the direction of arrow Ill in Figure 2.

Figure 4 is a partial front elevation of another embodiment of a combined track tamping and stabilisation unit according to the invention.

Figure 5 is a diagrammatic side elevation of another embodiment of a machine according to the invention.

Figure 6 is diagrammatic side elevation of a further embodiment of a machine according to the invention.

The track tamping, levelling and lining machine 1 shown in Figure 1 comprises a chassis 7 which is supported by on-track undercarriages 2, 3 and which is designed to travel along the track consisting of rails 4 and sleepers 5 under its own power (propulsion drive 6). The drive and power supply systems 9 of the machine 1 are accommodated at the front end of the chassis 7 in the working direction as indicated by the arrow 8.

Arranged beneath them is a track lifting and lining unit 10 which is connected to the chassis 7 on the one hand by a tension member 11 connected by a universal joint to the underneath of the chassis and, on the other hand, by vertical cylinder-andpiston drives 1 2 which serve as lifting drives and which are pivotally connected at both ends. The track lifting and lining unit is guided firmly along both rails 4 of the track by flanged lining rollers 13 and is equipped with lifting rollers 14 which are pivotally mounted on the outside of the track and which are designed to engage below the railhead on the outside of the track.

A two-sleeper tamping unit 1 5 is arranged (for each rail 4) between the track lifting and lining unit 10 and the rear on-track undercarriage 3, being connected to the chassis 7 for vertical displacement by a cylinder-and-piston drive 1 6.

Situated in the same part of the overall length of the machine is a track stabilisation unit 17 which will be described in more detail hereinafter and which is connected to the chassis 7 on the one hand through a tension and compression element 18 and on the other hand by two vertical cylinderand-piston drives 1 9, 20 (for each rail 4) which serve as load-generating drives and which are pivotally connected at both ends.

At the rear end of the chassis 7 is an operations compartment 21 which accommodates the usual systems for monitoring and operating the various working drives and also control system 22 to which the cylinder-and-piston drives 12, 1 6, 19, 20 of the units 10, 1 5, 1 7 are connected. The machine 1 is further equipped with a levelling reference system 23 which, in the embodiment illustrated, is formed by wires 24 respectively associated with each rail 4 of which the front end is vertically guided by a sensor 25 on the uncorrected track and of which the rear end is vertically guided by the rear on-track undercarriage 3 of the machine 1 which is situated in the already corrected section of track.

Between the track lifting and lining unit 10 and the assembly consisting of the tamping unit 1 5 and the track stabilisation unit 17, thereis another sensor 26 which is guided on the rails 4 of the track and to which is connected a detecting element 27 which cooperates with the levelling reference system 23 and which may be formed in known manner by a rotary potentiometer with a bifurcate positioning element adjustable by the wire 24 passing through in between. Another such detecting element 28 is connected to the track stabilisation unit 1 7. The detecting elements 27 and 28 are in turn connected by leads 29 and 30 to the control system 22 of the machine 1.

In the drawing, the vertical loads to be applied to the track by the track lifting and lining unit 10 and/or by the track stabilisation unit 17 - either by choice or in dependence upon the particular method being used - are represented by paired arrows 31, 32 and 33 which symbolise the direction in which the particular force is applied and also the fact that the corresponding cylinderand-piston drives 12, 1 9, 20 can be switched on and off. The solid-line arrow represents the on state and the chain-line arrow the off state of the particular drive.Accordingly, the pair of arrows 31 denotes the lifting force to be applied to the track as required by the track lifting and lining unit 10 whilst the pairs of arrows 32 and 33 respectively represent the vertical loads to be applied to the track either as required or periodically by the cylinder-and-piston drives 1 9 and 20 of the track stabilisation unit 1 7.

As can be seen from Figures 2 and 3, the tamping unit 1 5 consists of a tamping tool support 35 which is mounted for vertical displacement along vertical guide posts 34 under the power of the drive 1 6 and on which four (for each side of the rail) tamping tools 36 and 37 in the form of pivotal levers are mounted to pivot about horizontal shafts 38 extending transversely of the longitudinal axis of the machine. The upper ends of the tamping tools 36 and 37 are each connected through a hydraulic feed-adjustment drive 39 to a vibration drive 41 formed in known manner by an eccentric shaft arrangement 40 driven by a hydraulic motor. Each tamping tool 36, 37 is equipped with two detachable tamping tines 42 arranged adjacent one another.The tamping unit 15 is mounted in a supporting frame 43 to which the lower ends of the vertical guide posts 34 are connected.

The track stabilisation unit 1 7 consists essentially of two frame-like longitudinal girders 44 which are each arranged above a rail 4 between the tamping tools 36 and 37 associated with the opposite sides of the rail and which are joined together by a cross member 45 extending transversely of the longitudinal axis of the machine which is equipped with or rigidly connected to vibrators 46. These vibrators 46, in the form of unbalanced shakers, are designed to impart horizontal vibrations both to the cross member 45 and to the longitudinal girders 44 rigidly connected thereto transversely of the longitudinal axis of the machine in the direction indicated by the double arrow 47.

Each of the two longitudinal girders 44 is vertically and laterally guided along the associated rail 4 (in known manner without any play) by means of two guide rollers 48 in the form of flanged rollers. Each longitudinal girder 44 comprises two gripping rollers 49 each mounted for rotation in a housing 50 which is arranged on the outside of the longitudinal girder 44 between two tamping tools 36 and 37 following one another in the longitudinal direction of the machine and designed to be moved towards and away from one another in pairs and which is connected to the londitudinal girder 44 to pivot about a shaft 51 extending longitudinally of the rails. As can be seen from Figure 3, a pivoting drive formed by a cylinder-and-piston drive 52 is associated with each gripping roller 49, being pivotally connected at one end to the housing 50 of the gripping roller 49 and at its other end to the cross member 45. The gripping roller 49 is designed to be brought into form-locking engagement by the drive 52 with the underneath of the railhead on the outside of the associated rail 4. By virtue of the pincer-like engagement of the guide rollers 48 and the gripping rollers 49 with the opposite sides of the railhead, the horizontal vibrations generated by the vibrators 46 are directly transmitted in the direction of the double arrow 47 to the rail 4 and via the sleepers 5 to the adjacent regions of the ballast bed.The load applied by the cylinder-and-piston drives 1 9 and 20 is centrally introduced into the track within the vertical longitudinal plane of the rails.

Figure 4 shows another embodiment of the invention in which a single-sleeper tamping unit 53 is combined with a track stabilisation unit 54 which differs from the embodiment described in the foregoing in the following respect: The cross member 56 rigidly connected to the vibrators 55 has an end 58 which projects beyond the longitudinal girder 57 towards the outside of the track and to which only one cylinder-andpiston drive 59 projecting upwards beyond the lateral boundary profile of the tamping unit 53 is pivitally connected, its upper end being pivotally connected to a laterally projecting bracket 60 of the chassis 61 of the machine. In the region of the rail 4, two cylindrical gripping rollers 62, 63 designed to be applied to opposite sides of the railhead are arranged on the cross member 56.

The inner gripping roller 62 is mounted on a fixed, vertical shaft 64 whilst the outer gripping roller 63 is mounted on a shaft 65 designed to pivot sideways transversely of the longitudinal axis of the machine. A cylinder-and-piston drive 66 acting as a pivoting drive is pivotally connected to the shaft 65, its outer end being pivotally connected to the end 58 of the cross member. In this case, too, the longitudinal girder 57 is vertically guided by means of flanged guide rollers 67 of which two, four or even more may be provided for each longitudinal girder.

The tamping unit 53 shown in Figure 4 is equipped with bifurcate tamping tools 69 which are arranged astride the rail 68 and of which the side arms 70 (shown in part only on the left-hand side of Figure 4 in the interests of clarity) each carry a tamping tine 71 designed to penetrate into the ballast bed to the left and right of the associated rail 68. In the longitudinal direction of the machine, the cross member 56 is arranged centrally between the two bifurcate tamping tools 69 and above the particular sleeper 72 below which the ballast is to be tamped. The pair of arrows 73 denotes the direction of action and also the application and removal of the vertical load capable of being applied to the track by the cylinder-and-piston drive 59, whilst the double arrow 74 indicates the direction of the vibrations generated by the vibrators 55.

Figure 5 shows in highly diagrammatic form a tracktamping, levelling and lining machine 75 constructed in accordance with the invention which comprises a chassis 79 designed to travel along the rails 78 of the track by means of ontrack undercarriages 76, 77. The arrow 80 denotes the normal working direction of the machine.For each rail 78, the machine is equipped with a single-sleeper tamping unit 82 which is connected to the chassis 79 for vertical displacement by means of a cylinder-and-piston drive 81 and -- preceding this single-sleeper tamping unit 82 in the working direction as indicated by the arrow 80 - an assembly 85 which is designed to travel along the track by means of guide rollers 83 and which is equipped with gripping rollers 84, combining the constructional features and mode of operation of a track lifting and lining unit and track stabilisation unit.To this end, the assembly 85 comprises vibrators 86 for generating horizontal vibrations directed transversely of the axis of the track which are capable of being transmitted through the tool frame 87 and the guide and gripping rollers 83, 84 of the assembly 85 to the two rails 78 of the track.

The tool frame 87 is pivotally connected to the chassis 79 of the machine on the one hand through a tension member 88 and on the other hand through a cylinder-and-piston drive 89 (for each rail 78). Where the assembly 85 is used as a track lifting and lining unit, the cylinder-and-piston drives 89 activated in the lifting direction supply the lifting force required to lift the track (the pair of arrows 90) which is transmitted to the rails 78 of the track by the gripping rollers 84 brought into engagement with the railhead. If the track is also to be laterally aligned, the flanges of the guide rollers 83 transmit the lateral lining forces to the rails of the track.Where the assembly 85 is used as a track stabilisation unit, the cylinder-and piston drives 89 are activated in the lowering direction to apply the necessary vertical load (pair of arrows 91) to the track through the guide rollers 83. By means of the vibrators 86, the track is at the same time horizontally vibrated transversely of its axis. The actual level of the track is monitored both during the lifting operation and also during the stabilising operation by means of a sensor 92 which is guided on the track between the tamping unit 82 and the assembly 85 and which cooperates in the manner already described with reference to Figure 1 with a levelling reference system (not shown in the drawing) which determines the prescribed level of the track.

Finally, Figure 6 shows another embodiment of a machine 93 according to the invention in which the tamping units 96 each connected to the chassis 95 of the machine for vertical displacement by the cylinder-and-piston drive 94 are preceded in the working direction (arrow 97) by a separate track stabilisation unit 98 which is in turn preceded by a track lifting and lining unit 99.

Each of these two units 98 and 99 have separate cylinder-and-piston drives 100 and 101 through which the necessary vertical load (pair of arrows 102) and the necessary lifting force (pair of arrows 103) are respectively applied to the track stabilisation unit 98 and to the track lifting and lining unit 99. For determining the actual level of the track, the machine 93 is also provided with a sensor 105 which is vertically guided on the rails 104 of the track and which cooperates with a levelling reference system, being arranged immediately in front of the track stabilisation unit 98, although alternatively it could also be arranged between the tamping unit 96 and the stabilisation unit 98.

The basic principles of the process according to the invention for consolidating the ballast bed of a railway track to be corrected using machines. of the type illustrated and described in the foregoing are described in detail in the following. Where a machine 1 of the type shown in Figures 1 to 3 is used, it is first driven up to the tamping zone where - optionally with the vibrators 46 of the track stabilisation unit 1 7 already running -- the track is lifted beyond the prescribed level in the direction of the pair of arrows 31 by the lifting rollers 14 of the track lifting and lining unit 10.

When the tamping unit 15 begins to be lowered, the vibrators 46 are switched on - unless this has already been done - and the ballast to be tamped beneath the two sleepers 5 is tamped by the tamping tools 36, 37 which have penetrated into the ballast bed, are vibrated by the vibration drive 41 and make a pincer-like closing movement towards the sleeper lying between them under the power of the drives 39, the ballast in the entire tamping zone being vibrated by the transverse vibrations (double arrow 47) imparted to the track by the vibrators 46, enabling the stones making up the ballast bed to be rearranged into a very tightly packed formation.Immediately before or on termination of the tamping operation and elevation of the tamping unit 1 5, pressure is admitted to the cylinder-and-piston drives 19, 20 of the track stabilisation unit 1 7 and the track which continues to be horizontally vibrated (in the direction of the pairs of arrows 32. 33) is subjected to a vertically directed load. Under this combined load, the sleepers 5 are embedded in the already preconsolidated ballast and the track is lowered to the prescribed level commensurate with the reduction in volume of the ballast which is undergoing increasing consolidation.The fact that the weight of the rear on-track undercarriage 3 is applied to the track prevents the transverse vibration of the track from spreading beyond the already corrected area and, as the machine continues its advance, contributes towards the definitive positional stablisation of the track. The extent to which the track is lifted and subsequently lowered is monitored by the detecting elements 27, 28 in conjunction with the levelling reference system 23 and the individual operations involved are controlled -- best automatically - by the control system 22 according to a predetermined cycle.

In one variant of the process according to the invention, which may be applied with particular advantage in cases where the track is to be lifted only slightly, if at all, the track is lifted solely by the uplift produced by the tamping tools 36, 37, the upward movement of the track being stopped by the guide rollers 48 of the track stabilisation unit 1 7 locked at a predetermined level and the tamping operation being continued against this holding force until the ballast beneath the sleepers has been consolidated to the high level required.

The sequence of operations is the same where a machine of the type shown in Figure 4 is used, whereas certain modifications have to be made to the sequence of operations involved where a machine of the type shown in Figure 5 is used. In this case, the track is first lifted in the direction of the pair of arrows 90 and, optionally, laterally aligned by the assembly 85 acting as a lifting and lining unit and then - while it is still raised - is horizontally vibrated in the transverse direction by the vibrators 86.At the same time, the ballast below the track is tamped by the tamping tools of the tamping unit 82 and only after this has been done is the cylinder-and-piston drive 89 reversed and the track subjected to the vertically directed load (corresponding to the pair of arrows 91) of the assembly 85 which is now operating as a track stabilisation unit. In this case, too, the vibrations of the track are prevented from spreading beyond the already corrected area by the weight of the rear on-track undercarriage 77.

The sequence of operations is the same where a machine 93 of the type shown in Figure 6 is used, although in this case the lifting and lining operation and the subsequent stabilising operation are carried out by separate units at points of the track situated at a distance apart from one another.

According to the invention, numerous modifications to the embodiments described and illustrated are possible, particularly in regard to the construction and arrangement of the track stabilisation unit and also in regard to the other units cooperating therewith. For example, although the track stabilisation unit may still be arranged in the vicinity of the tamping units, it may be offset relative to longitudinal centre thereof if this creates better conditions for the interengaging arrangement and independent operation of the two units without any mutual interference. There are of course also numerous possibilities of variation in regard to the choice of the levelling reference system. Thus, instead of using a physical reference system, it is possible with equal effect to use optical levelling reference systems, for example infra-red or laser-based levelling reference systems.

Claims

1. A travelling on-track machine for consolidating the ballast bed of a railway track, more particularly a track tamping, levelling and lining machine, comprising undercarriages and at least one tamping unit which is arranged for vertical displacement on the chassis of the machine and which is provided with vibratable tamping tools designed to penetrate into the ballast bed and to be moved towards and away from one another and, preceding this tamping unit, a track lifting and lining unit, at least one track stabilisation unit which is designed to be brought into form-locking engagement with both rails of the track through its own on-track wheel sets, particularly guide rollers, and of which the tool frame is designed to be vibrated substantially horizontally by vibrators and to be subjected to substantially vertical loads by cylinder-and-piston drives connected to the chassis of the machine, and further comprising a tool control system and at least one levelling and, optionally, lining reference system, characterised in that the track stabilisation unit is arranged on the chassis of the machine in that part of the overall length of the machine which extends forwards in the working direction from the position of the tamping unit and in that the control system is designed for alternately activating and inactivating, above all automatically, the track stabilisation unit the tamping unit and the track lifting unit according to a predetermined cycle.

2. A machine as claimed in Claim 1, characterised in that the track stabilisation unit and the tamping unit are arranged in substantially the same cross-sectional area of the chassis, the tool frame of the track stabilisation unit comprising -- for each rail - a longitudinal girder which is intended to be arranged between the tamping tools entering into the ballast bed on both sides of the rail, which is rigidly connected to the vibrators and on which the guide and gripping rollers designed to be brought into engagement with the rail are mounted.

3. A machine as claimed in Claim 2, characterised in that each longitudinal girder is connected to the chassis of the machine by two cylinder-and-piston drives respectively connected to one of its ends and extending upwards immediately in front of and behind the tamping unit substantially in the vertical longitudinal plane of the rails.

4. A machine as claimed in Claim 2 or 3, characterised in that the gripping rollers, which are mounted in a housing designed to pivot under the power of a drive about a shaft extending longitudinally of the machine, are arranged together with said housing between two tamping tools following one another' in the longitudinal direction of the machine and designed to be moved towards and away from one another in pairs on the outside of the logitudinal girder.

5. A machine as claimed in Claim 2, characterised in that the longitudinal girders associated with the two rails are joined to one another by a cross member which carries the vibration drives and to each outer end of which projecting beyond the logitudinal girders is pivotally connected a cylinder-and-piston drive extending upwards to the chassis beyond the lateral boundary profile of the tamping unit and on which are arranged at least two (per rail) cylindrical gripping rollers designed to be applied to opposite sides of the railhead, the inner gripping rollers being mounted on fixed, vertical shafts and the outer gripping rollers being mounted on shafts designed to pivot transversely of the longitudinal axis of the machine.

6. A machine as claimed in Claim 1, characterised in that the track stabilisation unit is connected to a track lifting and lining unit preceding the tamping unit in the working direction to form a mechanical assembly which is designed to be vibrated by the vibrators and to be subjected as required to a vertical load or to a lifting force by the cylinder-and-piston drives, the gripping rollers simultaneously forming the lifting elements and the guide rollers the lining elements of said assembly.

7. A machine as claimed in Claim 1, characterised in that the track stabilisation unit is arranged between the tamping unit and a track lifting and lining unit preceding it in the working direction.

8. A process consolidating the ballast bed of a track to be corrected using a travelling on-track machine of the claimed in any of Claims 1 to 7, characterised in that the track - to which substantially horizontal vibrations may already have been imparted transversely of its axis - is raised beyond the definitive prescribed level and the ballast below it is tamped by tamping tools designed to penetrate into the ballast bed and to be moved towards and away from the particular sleeper below which the ballast is to be tamped, after which the track which continues to vibrate horizontally or to which horizontal vibrations are now imparted is subjected to a downwardly directed vertical load and is lowered to the prescribed level.

9. A process as claimed in Claim 8, characterised in that the track is only subjected to horizontal vibration over a period long enough for the tamping and lowering operations to be completed.

10. A process as claimed in Claim 8 or 9, characterised in that, during the tamping operation, the track is raised to a level selectable in advance, the ballast beneath it continues to be tamped while the track is kept at that level against a holding force, after which the track is lowered to the required level by horizontal vibration in conjunction with a downwardly directed vertical load.

11. A process as claimed in any of Claims 8 to 10, characterised in that, after it has been lowered, the track is subjected to a vertical static load progressing with the advance of the machine, in particular by the next undercarriage of the machine.

12. A machine for consolidating railway track ballast, substantially as herein described with reference to Figure 1 to 3, Figure 4, Figure 5 or Figure 6 of the accompanying drawings.

13. A process for consolidating the ballast bed of railway track, substantially as herein described with reference to the accompanying drawings.