Methods and machines for compacting the underside of an orbit

Abstract

A method and machine for compacting the undersides of a plurality of sleepers (4) of a track (3) supported one behind the other in a ballast bed (2) by a tamping assembly (7), the tamping assembly (7) comprising a plurality of tamping units (14) arranged one behind the other in a working direction (25) and independently adjustable in height, the tamping units (14) equipped with tamping ice axes (22) that are accessible to one another, the tamping assembly (7) lowering the tamping ice axes (22) of the front tamping unit (14) and the rear tamping unit (14) into the ballast bed (2) to different immersion depths (T1, T2, T3) during one tamping cycle, and then moving the tamping assembly (7) further in the working direction (25) by a number of sleepers (4) that is less than the number of tamping units (14) arranged one behind the other for the next tamping cycle. In this way, the tamping units (14) arranged in succession tamping the underside of the same sleeper (4) multiple times in different depth zones (Z1, Z2, Z3) of the ballast bed (2).

Description

Technical Field

[0001] The present invention relates to a method for tamping the underside of a plurality of sleepers supported one behind the other in a ballast bed of a track by means of a tamping assembly, the tamping assembly comprising a plurality of tamping units which are arranged one behind the other in the working direction and are height-adjustable independently of one another, these tamping units being provided with tamping picks which can approach one another. Furthermore, the present invention relates to a machine for carrying out the method.

Background Art

[0002] In order to restore or maintain a preset track position, a track including a ballast bed is regularly processed by a tamping machine. In this case, the tamping machine travels along the track, and a track frame formed by sleepers and rails is lifted to a target level by a lifting / aligning unit. Fixing of a new track position is carried out by tamping the underside of the sleepers using a tamping assembly. The tamping assembly comprises a tamping tool provided with a tamping pick. The tamping pick is vibration-loaded during the tamping operation and sinks into the ballast bed and is brought closer to one another. In this case, the ballast is pushed forward and compacted under each sleeper.

[0003] Particularly, a track tamping machine uses a tamping assembly to tamp the undersides of a plurality of sleepers simultaneously. The high processing speed achieved thereby enables continuous working on one track with a short maintenance interval. Furthermore, modern tamping machines are excellent in that, in addition to the tamping assembly, they have little wear effect on the ballast.

[0004] A machine described at the beginning, comprising a method and at least two tamping units arranged sequentially, is known in accordance with Austrian Patent Application Publication No. 513034. Each tamping unit is height-adjustable on a common unit support. A tamping cycle is initiated by lowering the tamping units together. In this case, such joint lowering of adjacent tamping units to tamp the underside of adjacent sleepers in the longitudinal direction of the machine is performed with a time delay. This facilitates the sinking of directly adjacent tamping pickaxes, in particular, into a common sleeper section. [Overview of the project] [Problems that the invention aims to solve]

[0005] The fundamental problem of this invention is to improve the method of the embodiment described at the beginning, in particular, to obtain qualitatively high-value tamping results when the orbital lift is large and when a new layer is present. Furthermore, another objective of this invention is to provide a correspondingly improved machine. [Means for solving the problem]

[0006] According to the present invention, this problem is solved by the features of claims 1 and 10. The dependent claims describe advantageous configurations of the present invention.

[0007] In this invention, during a single tamping cycle, the tamping picks of the forward tamping unit and the tamping picks of the rear tamping unit are lowered to different sinking depths into the ballast bed, and for the next tamping cycle, the tamping assembly is moved further in the working direction by a number of sleepers less than the number of tamping units positioned sequentially. In this way, the sequentially positioned tamping units compact the underside of the same sleeper multiple times in different depth zones of the ballast bed. As a result, homogeneous compaction of the entire ballast cushion under each sleeper is achieved.

[0008] The forward movement of each sleeper results in a more uniform compaction process. Furthermore, the ballast load is reduced because a different set of ballast is dynamically pressed during each tamping cycle. Hollow layers are prevented, especially when the track is significantly lifted. Even with greater lifts, only one tamping pass is required, saving time by eliminating backward movement and creating repeated gradients during separate tamping passes.

[0009] In the case of more than two tamping units arranged in succession, it is advantageous to pre-set a nearly uniformly stepped settling depth. Furthermore, it is advantageous to lower the tamping pickaxe of each forward tamping unit into the ballast bed to a greater settling depth than the tamping pickaxe of the tamping unit positioned behind it.

[0010] In an improved version of the method, the track sleepers and the rails attached to them are lifted by a lifting unit before the lower compaction, and the sinking depth of each is predetermined according to the lifting value. The steps of the sinking depth change with the change in the lifting value, thereby achieving optimized compaction of the ballast track bed.

[0011] Another improvement involves operating each tamping unit, positioned one behind the other, with inherent vibration parameters for the vibration load of the tamping pickaxe and / or inherent squeeze parameters for the squeeze motion between the tamping pickaxes. In particular, the inherent vibration frequency, vibration amplitude, and squeeze time can be preset for each tamping unit. Thus, the tamping pickaxes of each tamping unit, positioned one behind the other, are made to vibrate inherently and move closer to each other. This takes into account the different ballast characteristics within each track bed layer and the different pickaxe counterforces based on different sinking depths.

[0012] To fix the raised track frame in place over a large area, it is advantageous to simultaneously compact the underside of multiple sleepers positioned directly in front of and behind each other by multiple tamping units during a single tamping cycle, by sinking adjacent tamping picks of tamping units positioned directly in front of and behind each other into the same sleeper section. In this case, a compact multi-sleeper tamping assembly (series assembly) equipped with tamping units formed to be narrow in the longitudinal direction of the machine is used.

[0013] In this improved version of the modification, multiple tamping units, which are positioned directly one after the other, are descended with a time stagger during a single tamping cycle. Therefore, tamping picks sinking into the same sleeper section do not simultaneously collide with the ballast bed surface. First, one tamping pick is driven into the ballast bed, causing the surrounding ballast grains to vibrate. The tamping pick, which is descended with a time delay, then collides with the already fluidized ballast grains. This significantly reduces the impact resistance. In this way, wear between the tamping unit and the ballast grains is reduced.

[0014] Advantageously, during a single tamping cycle, the tamping pickaxe of the rear tamping unit is lowered to a first sinking depth, and the tamping pickaxe of the front tamping unit is lowered to a second sinking depth, thereby compacting the underside of at least two sequentially positioned sleepers in two different depth layers of ballast track bed.

[0015] In this case, one variation is specified to pre-set different sinking depths for all tamping units arranged sequentially. Therefore, for more than two tamping units arranged sequentially, the lower part of the ballast bed is compacted in more different depth zones than two. This variation is particularly advantageous when the ballast bed is loose and has a large lifting value.

[0016] Another variation involves tamping units arranged in succession to form a single descent group that is lowered to a single common sinking depth. Each descent group compacts the ballast bed beneath multiple sleepers simultaneously in the same depth zone of the ballast track bed. For example, two descent groups are provided, each with two tamping units arranged in succession. In this case, lower compaction is performed in two depth zones. In this case, the tamping assembly is advanced by the length of two sleepers after each tamping cycle.

[0017] To compact the underside of each sleeper multiple times in small steps of depth zone, it is advantageous to advance the tamping assembly by one sleeper pitch using a running drive after each tamping cycle. In this way, the underside of the ballast base beneath each sleeper is compacted in successive steps by the tamping units positioned one after the other.

[0018] The machine according to the present invention comprises a tamping assembly for simultaneously compacting the underside of a plurality of sequentially positioned sleepers of a track by a plurality of tamping units arranged sequentially in the longitudinal direction of the machine, each tamping unit comprising a tool support whose height is adjustable by a height adjustment drive, the tool support supporting opposing tamping tools, the tamping tools being vibrable and approaching each other via the drive. In the present invention, in order to carry out one of the methods described above, the machine is configured such that all height adjustment drives are connected to a single common control unit, which stores different drop values ​​for the height adjustment drives of the sequentially positioned tamping units. Thus, the sinking motion of the sequentially positioned tamping units is harmonized with each other by the control unit.

[0019] Advantageously, each height adjustment drive is connected to a distance measuring device, which in turn is connected to a control unit. Each distance measuring device supplies a distance measuring signal for the height position of the assigned tool support. This allows adjustment of the descent to a preset sinking depth. In a simpler variation, different descent values ​​are stored in the form of stepped operating periods for each height adjustment drive. In the case of a hydraulic height adjustment drive, the flow rate of the hydraulic fluid may be used as a measure of the sinking of the assigned tool support.

[0020] Another improved configuration specifies that each tamping unit is assigned a vibration drive, and opposing tamping tools are each connected to their assigned vibration drive via a squeeze drive. In particular, each vibration drive is independently controllable, thereby allowing each tamping unit to be operated with its own vibration frequency and amplitude.

[0021] Furthermore, in order to apply pressure to the squeezing drive device, it is advantageous if each of the tamping units arranged one behind the other is assigned a specific pressure stage of the hydraulic system. In this way, the squeezing operation of each tamping unit can be adapted to the depth zone to be processed in the ballast bed.

[0022] Advantageously, in the transverse direction with respect to the longitudinal direction of the machine, a plurality of tamping tools arranged side by side form a squeezing group including the assigned squeezing drive device, and each squeezing group can be uniformly controlled by a control device. This applies to the tamping units that compact the underside of the sleepers on both sides of both rails of the track arranged side by side. During operation, the squeezing groups are controlled together, thereby ensuring a uniform compaction operation along the sleepers.

[0023] In an advantageous feature of the machine, a lifting unit is arranged in front of the tamping assembly, and a preset lifting value of this lifting unit is supplied to the control device of the tamping assembly. In this way, the lowering value can be instantaneously adapted to the preset lifting value.

[0024] The present invention will be exemplarily described below with reference to the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] It is a schematic diagram of a machine equipped with a tamping assembly. [Figure 2] It is a schematic side view of a tamping assembly for simultaneously compacting the underside of three sleepers. [Figure 3] It is a schematic diagram of the tamping operation by the tamping assembly shown in FIG. 2. [Figure 4] It is a schematic front view of the tamping assembly. [Figure 5] It is a schematic diagram of the tamping operation by a tamping assembly for simultaneously compacting the underside of four sleepers. [Figure 6] Schematic diagram of a tamping operation with a tamping zone transition according to the prior art. [Figure 7] Schematic diagram of a tamping operation having tamping zones at different depths.

Mode for Carrying Out the Invention

[0026] The machine 1 shown in FIG. 1 is formed as a track tamping machine for simultaneously ramming the underside of three out of a plurality of sleepers 4 supported on the ballast bed 2 of the track 3. The machine 1 includes a machine frame 6 supported by a rail traveling device 5. A tamping assembly 7 is attached to this machine frame 6. Further, the machine 1 includes a lifting / aligning unit 8 for lifting and aligning the track frame formed by the sleepers 4 and the rails 9. The instantaneous rail position is detected by a measurement system 10.

[0027] The tamping assembly 7 is attached to the machine frame 6 by a position adjusting device 11. The tamping assembly 7 includes a unit frame 12 provided with guides 13 and a plurality of tamping units 14, as shown in FIG. 2. In a variant not shown, a respective unit frame 12 is assigned to each tamping unit 14. Each tamping unit 14 includes a tool support 15 supported height-adjustably by a height adjusting drive 16 on the assigned guide 13. Tamping tools 18 facing each other in the machine longitudinal direction 17 are rotatably supported on each tool support 15.

[0028] Furthermore, a vibration drive device 19 is positioned on each tool support 15. A tamping tool 18 is connected to this vibration drive device 19 via a squeeze drive device 20. In an alternative variant not shown, a hydraulic cylinder is positioned between the tool support 15 and each tamping tool 18. This hydraulic cylinder is configured as both a vibration drive device 19 and a squeeze drive device 20. Pulsating hydraulic pressure is supplied to the hydraulic cylinder to generate vibration. During the squeeze operation, the pulsating hydraulic pressure is superimposed on the squeeze pressure generated by the hydraulic cylinder.

[0029] Each tamping tool 18 is equipped with a swivel lever 21 having an upper lever arm and a lower lever arm. This swivel lever 21 is supported by an assigned tool support 15. The upper lever arm is coupled to an assigned squeeze drive unit 20. Two tamping pickaxes 22 are typically attached to the free lower lever arm.

[0030] The height adjustment drive unit 16 is controllable by a single common control unit 23. This control unit 23 stores different descent values ​​for each individual tamping unit 14. To detect the height position of each tool support 15, each height adjustment drive unit 16 is assigned a travel distance measuring device 24. This travel distance measuring device 24 comprises, for example, a cable with a Bowden cable sensor. Alternatively or supplementarily, the height adjustment drive unit 16 may incorporate a position detection means, for example, as a means for measuring the stroke of a piston in a hydraulic cylinder.

[0031] During the tamping cycle, the height adjustment drive unit 16 is controlled by the control device 23 based on different drop values. For example, each drop value indicates how long the control valve of the height adjustment drive unit 16, which is formed as a hydraulic cylinder, will be open. The piston stroke of the corresponding hydraulic cylinder or the distance to be achieved between the tool support 15 and the machine frame 6 may also be defined as a drop value.

[0032] Furthermore, it is advantageous to configure a closed-loop control circuit for each preset descent value. In this case, the control device 23 generates control signals for each height adjustment drive device 16. The position of the tool support 15 or tamping pickaxe 22 is continuously detected by the travel distance measuring device 24 and compensated for with the preset descent value.

[0033] In one improved configuration, the resistance of the tamping pickaxe 22 upon impact with the ballast track bed 2 is detected. For this purpose, each tamping unit 14 is equipped with a corresponding sensor system. For example, an acceleration sensor is placed on each tamping tool 18. From the detected acceleration, the descent distance traveled by each tamping pickaxe 22 after impact with the ballast track bed 2 is derived. Based on this, the corresponding sinking depths T1, T2, and T3 are directly determined starting from a common height reference R. As the height reference R, in addition to a preset upper limit of the ballast track bed 2, for example, the height position of each tamping unit 14 at the elevated position can be used.

[0034] A single tamping cycle is divided into several stages. In the first stage, the tamping assembly 7 is positioned above the sleeper 4 whose lower side is to be compacted. Specifically, the tamping pickaxe 22 is brought to a position above the sleeper section located between the sleepers 4. In the second stage, the tool support 15 and the tamping tool 18 located on this tool support 15 are lowered. In this case, the vibrating tamping pickaxe 22 sinks into the ballast track bed 2. According to the present invention, stepped descent values ​​are set in advance for the tamping units 14 which are arranged in succession, so that the corresponding ends of the tamping pickaxes reach different sinking depths T1, T2, and T3, as shown in Figure 3.

[0035] During the third stage, the tamping pickaxes 22 of the opposing tamping tools 18 are brought closer together. In this case, different depth zones Z1, Z2, and Z3 of the ballast track bed 2 are compacted according to the sinking depths T1, T2, and T3. The extent of each depth zone Z1, Z2, and Z3 depends on the dimensions of the pickaxe plate positioned at the end of the tamping pickaxe. Specifically, the pickaxe plate transfers the kinetic energy of the tamping tool 18 to the ballast grains located in each depth zone Z1, Z2, and Z3. In this case, the ballast grains vibrate and take on a fluid-like state. As a result, denser packing and downward movement of the ballast grains on each sleeper 4 are achieved.

[0036] Advantageously, when assigning sinking depths T1, T2, and T3, the height of each pickaxe plate is taken into consideration. In this case, the resulting depth zones Z1, Z2, and Z3 are defined such that the lowest depth zone Z3 reaches the lower limit of the loose ballast layer. The height of this loose ballast layer depends on the track condition (new layer, old layer), the amount of new ballast, and the raising of the track frame. The smallest sinking depth T1 is selected such that the uppermost depth zone Z1 reaches below the assigned sleeper.

[0037] In the fourth stage of the tamping cycle, the tamping pickaxe 22 is returned by the squeeze drive unit 20 and pulled out from the ballast bed 2 by the rise of the tool support 15. As the tamping pickaxe 22 rises above the upper edge of the sleeper, the tamping assembly 7 moves forward in the working direction 25 and a new tamping cycle begins.

[0038] Figure 3 shows the end of the third stage of each of three consecutive tamping cycles. During the first tamping cycle in the upper figure, the undersides of the three sleepers 4 are compacted sequentially in different depth zones Z1, Z2, and Z3, which are shown in hatched areas. The front tamping unit 14 is lowered to the deepest depth and works on the lowest depth zone Z3. The middle tamping unit 14 works on the middle depth zone Z2, and the rear tamping unit 14 works on the uppermost depth zone Z1, which is located just below the sleeper 4.

[0039] For the next tamping cycle in the middle diagram, the tamping assembly 7 has moved further in the working direction 25 by one sleeper pitch t. In this case, the intermediate tamping unit 14 is tamping the underside of sleeper 4, which has already been tamped on its underside by the forward tamping unit 14. Thus, after processing in the lowest depth zone Z3, the ballast track bed 2 below this sleeper 4 is now processed in the intermediate depth zone Z2. The corresponding underside of sleeper 4 is tamped by the rear tamping unit 14 in the third uppermost depth zone Z1. Below all sleepers 4, which have already been completely tamped on their undersides, lies a compaction region V formed from three overlapping depth zones Z1 to Z3.

[0040] Therefore, each compaction area V arises from a set of different sinking depths T1 to T3. These sinking depths T1 to T3 are consequently derived from descent values ​​for each tamping unit 14, which are stored in the control device 23.

[0041] As is evident in the exemplary configuration shown in Figure 4, each rail 9 of the track 3 is assigned two tamping units 14 that can be lowered independently of each other. Thus, the tamping assembly 7 comprises four tamping units 14 arranged in a row. In a simplified variant (not shown), each rail 9 is assigned a composite tamping unit 14 with an inner tamping tool 18 and an outer tamping tool 18. To tamp the underside of the sleepers 4, a row of tamping units 14 arranged in a row is provided. These tamping units 14 form a squeeze group. The tamping pickaxes 22 of this squeeze group are lowered to a common sinking depth T1, T2, T3 and brought together.

[0042] Figure 5 shows the tamping operation by four tamping units 14 arranged in succession. In this case, two forward tamping units 14 or rows are combined to form one forward descent group 26, and two backward tamping units 14 or rows are combined to form one backward descent group 26. Both descent groups 26 are lowered to different tamping depths T1 and T2 during a single tamping cycle. The forward descent group 26 processes the ballast track bed 2 in the lower depth zone Z2. The upper depth zone Z1, located just below the sleepers 4, is processed by the backward descent group 26.

[0043] After the first tamping cycle in the upper diagram, the tamping assembly moves forward by a distance of 2 sleeper pitches t. Therefore, even in this configuration, the number of sleepers 4 required for the tamping assembly 7 to move further in the working direction 25 is less than the number of tamping units 14 arranged in succession. For forward movement in the working direction 25, the machine 1 is equipped with a travel drive 27 controlled by a machine control device 28. Advantageously, the machine control device 28 is connected to a control device 23, which allows the vertical movement of the tamping units 14 and the forward movement of the tamping assembly 7 to automatically synchronize with each other.

[0044] The lower diagram of Figure 5 shows the end of the third stage of the subsequent tamping cycle. The rearward descent group 26 has finished compacting in the corresponding lower compaction area V of the sleeper 4. The forward descent group 26 has begun lower compaction of the two subsequent sleepers 4 in the lower depth zone T2. This method combines lower compaction of each zone with an increased processing speed based on periodic advancement of twice the sleeper pitch t.

[0045] An alternative approach may be advantageous in reducing the periodic advance to a single sleeper pitch t, ​​while introducing four more finely stepped subsidence depths. This variation is advantageous when there is a large rise in the track frame or when the ballast bed 2 is a relatively loose new layer. In this way, qualitatively high-value compaction is achieved in the compaction area V with a large vertical extension.

[0046] In an improved version of the method according to the present invention, different descent depths T1 to T3 are preset according to the lifting value. In this case, the lifting value for controlling the lifting / straightening unit 8 is also supplied to the control device 23 of the tamping assembly 7. In an alternative feature, the instantaneous actual lifting value is detected by the measurement system 10 and reported to the control device 23.

[0047] For example, for sinking depths T1-T3 when the lifting value is higher, a larger stepping is selected to increase the compaction area V in the vertical direction. In particular, the formation of descent groups 26 according to a preset lifting value is advantageous. For example, to compact the underside of four sleepers 4 simultaneously, it is determined based on the lifting value which of the two methods described above is implemented by the tamping assembly 7. In this case, two sinking depths T1, T2 or four more finely stepped sinking depths are preset for two descent groups 26.

[0048] Figure 6 shows a conventional tamping operation using a tamping assembly to simultaneously compact the underside of three sleepers 4. According to the prior art, all tamping picks 22 are lowered to a single common sinking depth T and brought close together in a single depth zone. Then, the tamping assembly 7 is advanced by a 3-slope pitch t. Thus, the underside of all sleepers 4 is compacted only once after one continuous operation.

[0049] Furthermore, a method known as multiple tamping is also known, in which the tamping pickaxe 22 is lowered into the same sleeper section two or more times, bringing them close together, and then the subsequent movement to the next sleeper 4 takes place. In this method as well, the tamping pickaxe 22 always acts on the same depth zone without affecting the size of the compaction area V.

[0050] In contrast, Figure 7 shows the method according to the present invention. In the method according to the present invention, different sinking depths T1 to T3 are provided, which are stepped almost uniformly. The underside of each sleeper 4 is compacted in three consecutive different depth zones Z1 to Z3. The underside of the sleeper 4 below the foremost tamping unit 14 is first compacted in the deepest zone Z3. Final compaction of the underside of a corresponding amount of sleeper 4 has already been performed for a distance of two sleeper pitches t in the opposite direction to the working direction 25. In this way, a stepped, gradient structure of the compaction area V spanning the three sleepers 4 is created. In this case, the height of the compaction area V is significantly greater than in the conventional method. Furthermore, based on the uniform compaction progression, a particularly homogeneous and stable ballast track bed 2 and a sustained track position are obtained as a result.

[0051] Furthermore, the compaction energy is adapted to each track bed layer. Thus, advantageously, each tamping unit 14 is operated with its own vibration and squeeze parameters. For example, deeper track bed layers are supplied with greater vibration energy because there is less risk of lateral ballast runoff. Additionally, higher squeeze pressure may be advantageous because deeper layers generate higher counterpressure. In any case, the compaction operations performed across multiple sleepers 4 in different depth zones T1-T3 are harmonized with each other. Therefore, the method according to the present invention provides a uniform compacted structure for the ballast track bed 2 in both the vertical and working directions 25.

Claims

1. A method for compacting the underside of a plurality of sleepers (4) supported in succession within a ballast bed (2) of a track (3) using a tamping assembly (7), wherein the tamping assembly (7) comprises a plurality of independently height-adjustable tamping units (14) arranged in succession in the working direction (25), and the tamping units (14) are equipped with tamping picks (22) that can approach each other, During one tamping cycle, the tamping pickaxe (22) of the front tamping unit (14) and the tamping pickaxe (22) of the rear tamping unit (14) are each moved into the ballast track bed (2) to different depths (T １ , T ２ , T ３ ) is lowered, and for the next tamping cycle, the tamping assembly (7) is moved further in the working direction (25) by a number of sleepers (4) less than the number of tamping units (14) arranged in succession, The sleepers (4) of the track (3) and the rails (9) attached to the sleepers (4) are lifted by the lifting unit (8) before the lower compaction, and the respective sinking depth (T １ , T ２ , T ３ A method characterized by pre-setting ) according to the rising price.

2. The method according to claim 1, characterized in that each of the tamping units (14) arranged in succession is operated by a specific vibration parameter for the vibration load of the tamping pick (22) and / or a specific squeeze parameter for the squeeze motion between the tamping picks (22).

3. The method according to claim 1 or 2, characterized in that, during a single tamping cycle, the tamping picks (22) of adjacent tamping units (14) positioned directly in front of and behind each other are sunk into the same sleeper section, thereby simultaneously compacting the underside of multiple sleepers (4) positioned directly in front of and behind each other by multiple tamping units (14).

4. The method according to any one of claims 1 to 3, characterized in that, during a single tamping cycle, a plurality of tamping units (14) arranged directly in front of and behind each other are lowered in a time-staggered manner.

5. During one tamping cycle, the tamping pickaxe (22) of the rear tamping unit (14) is moved to a first sinking depth (T １ ) is lowered to the second sinking depth (T ２ The method according to any one of claims 1 to 4, characterized in that the lower side of at least two sleepers (4) positioned in succession is compacted in two different depth layers of the ballast track bed (2) by lowering it to the ballast bed (2).

6. All the tamping units (14) arranged one after the other are each preset with a different sinking depth (T １ , T ２ , T ３ ), characterized in that it is the method according to any one of claims 1 to 5.

7. The tamping units (14) arranged in succession have a common sinking depth (T １ , T ２ , T ３ The method according to any one of claims 1 to 5, characterized in that it forms a single descent group (26) that can be lowered to ).

8. The method according to any one of claims 1 to 7, characterized in that after one tamping cycle, the tamping assembly (7) is advanced by a travel drive device (27) by one sleeper pitch (t).

9. A machine (1) equipped with a tamping assembly (7), the tamping assembly (7) is for simultaneously compacting the underside of a plurality of sequentially positioned sleepers (4) of a track (3) by a plurality of tamping units (14) arranged sequentially in the longitudinal direction (17) of the machine, each tamping unit (14) having a tool support (15) whose height is adjustable by a height adjustment drive device (16), the tool support (15) supporting opposing tamping tools (18), the tamping tools (18) being vibratable and approaching each other via the drive device, in the machine (1), The machine (1) is configured such that, in order to carry out the method according to any one of claims 1 to 8, all height adjustment drive devices (16) are connected to one common control device (23), and the control device (23) stores different descent values ​​for the height adjustment drive devices (16) of the tamping units (14) which are arranged in succession, A machine (1) characterized in that a lifting unit (8) is placed in front of the tamping assembly (7), and a lifting value predetermined for the lifting unit (8) is supplied to the control device (23).

10. The machine (1) according to claim 9, characterized in that each height adjustment drive device (16) is connected to a travel distance measuring device (24), and each travel distance measuring device (24) is connected to the control device (23).

11. The machine (1) according to claim 9 or 10, characterized in that each tamping unit (14) is assigned a vibration drive device (19), and opposing tamping tools (18) are each connected to the assigned vibration drive device (19) via a squeeze drive device (20).

12. The machine (1) according to claim 11, characterized in that each of the tamping units (14) arranged in succession to each other is assigned a specific pressure stage of the hydraulic system in order to apply pressure to the squeeze drive device (20).

13. The machine (1) according to claim 11 or 12, characterized in that a plurality of tamping tools (18) arranged side by side in a direction lateral to the longitudinal direction (17) of the machine, including an assigned squeeze drive device (20), form a squeeze group and can be controlled together by the control device (23).

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