Mechanisms and methods with tamper units

Abstract

The invention relates to a machine with a tamping unit for simultaneously tamping a plurality of immediately successive sleepers of a track by means of a plurality of tamping units arranged one after the other in the longitudinal direction of the machine, wherein each tamping unit comprises a height-adjustable tool carrier on which mutually opposite tamping tools are supported, which tamping tools are coupled to vibration drives arranged on the tool carrier by means of feed cylinders. Here, each vibration drive comprises an eccentric shaft with a first eccentric and a second eccentric, the symmetry axes of which run at right angles to a common rotational axis, the two eccentric planes being enclosed at a relative angle to one another, and a first feed cylinder is supported on the first eccentric, a second feed cylinder opposite thereto being supported on the second eccentric, and the cylinder axes of the two mutually opposite feed cylinders enclose a position angle which is approximately the relative angle of the eccentric planes.

Description

Technical Field

[0001] This invention relates to a machine with a tamping unit for simultaneously tamping multiple adjacent, sequentially positioned sleepers of a track using multiple tamping units arranged longitudinally along the machine. Each tamping unit includes a height-adjustable tool holder on which opposing tamping tools are supported. These tamping tools are coupled to a vibration actuator arranged on the tool holder via a feed cylinder. Furthermore, this invention also relates to a method of operating the machine. Background Technology

[0002] To restore or achieve a predetermined track position, the track with a ballast bed is periodically processed by tamping machinery. During this process, the tamping machinery travels along the track and, via lifting and straightening units, raises the track grid consisting of sleepers and rails to a rated level. The new track position is then secured by tamping the sleepers by the tamping units. The tamping units consist of tamping tools equipped with picks, which are vibratoryly inserted into the ballast bed and fed relative to each other during tamping. In this process, the ballast beneath the corresponding sleeper is compacted.

[0003] In particular, tamping machinery uses tamping units to tamp multiple sleepers simultaneously. This results in high processing speeds, enabling major track overhauls within short track closure durations. Modern tamping machinery also exhibits lower wear on both the tamping unit and the ballast.

[0004] Such a machine is known from document AT 513 034 A1, which has at least two tamping units arranged sequentially. Each tamping unit is height-adjustable and arranged in a common frame. The tamping cycle begins with the common descent of the tamping units. This common descent of adjacent tamping units used for tamping sleepers adjacent along the longitudinal direction of the machine occurs with a time delay. This makes in particular the insertion of pickaxes inserted directly into the common sleeper box easier. Summary of the Invention

[0005] The technical problem to be solved by this invention is to improve the above-mentioned type of machinery so as to achieve lower noise emissions in addition to reducing wear. Furthermore, a corresponding method for operating the improved machinery is also provided.

[0006] According to the present invention, the technical problem is solved by a machine having a tamping unit and a method for operating the aforementioned type of machine.

[0007] Here, each vibration actuator includes an eccentric shaft with a first eccentric disk and a second eccentric disk. The axes of symmetry of these two eccentric disks and their common axis of rotation support two eccentric planes, which are positioned relative to each other at an angle. A first feed cylinder is supported on the first eccentric disk, and a second feed cylinder, positioned opposite each other, is supported on the second eccentric disk. The cylinder axes of these two opposing feed cylinders form a position angle that approximates the relative angle of the eccentric planes. In this way, the angular positions of the eccentric disks and feed cylinders are matched to achieve mass balance in the vibrating unit components. In particular, the inertial forces of the synchronously oscillating tamping tools cancel each other out. Therefore, the tamping unit operates more smoothly.

[0008] The feed cylinder is not horizontally oriented, therefore the relative angle is not equal to 180°. In the inclined, hinged feed cylinder, the arrangement according to the invention induces optimal oscillations of the tamping tools moving synchronously toward each other in opposite directions. Specifically, the oscillations of the two opposing tamping tools undergo a phase shift, which causes them to reach their respective reversal points simultaneously. The accelerating and decelerating forces of the oscillating mass of the tamping tools and the oscillating partial mass of the feed cylinder cancel each other out.

[0009] The pickaxe positioned at the free lower end of the tamping tool oscillates synchronously with maximum relative motion, achieving maximum energy input to the ballast bed without subjecting the tool frame and corresponding unit suspension to disruptive reaction oscillations. This results in lower oscillation loads on the unit and machinery. This protects both the components of the tamping unit and the ballast particles in the ballast bed to be compacted. Compared to known tamping unit structures, the targeted introduction of vibration into the ballast bed and mass balance together reduce noise emissions.

[0010] Advantageously, each tamping unit includes at least one feed cylinder whose cylinder axis is oriented downwards at an angle greater than 20° relative to the horizontal. This allows for a particularly narrow structural type of each individual tamping unit along the longitudinal direction of the machine, so that the track can be processed simultaneously with all tamping units even with small sleeper spacing.

[0011] In a favorable extended design, each eccentric shaft is connected to an oscillating load. During operation, the eccentric shafts and the oscillating load are driven together at a predetermined speed. The oscillating load here plays a stabilizing role in the speed. Specifically, the reaction torque of the oscillating feed cylinder and tamping tool in the oscillating cycle is balanced by the kinetic energy temporarily stored in the oscillating load. Here, the vibration amplitude of the tamping tool is maintained unaffected by the stiffness of the ballast bed.

[0012] To further improve mass balance, the rotating unit, consisting of an eccentric shaft and a oscillating load, is designed such that its common center of mass reference axis of rotation is located opposite the axes of symmetry of the two eccentric disks. In this way, the rotating unit serves as the balancing mass for the moving mass of the feed cylinder of the opposing tamping tool.

[0013] In an advantageous embodiment of the invention, the tamping unit comprises, along the mechanical longitudinal direction, a front tamping unit and a rear tamping unit with asymmetrically arranged feed cylinders, and an intermediate tamping unit with symmetrically arranged feed cylinders. The intermediate tamping unit here has a particularly narrow structural type, so that sleepers can be tamped simultaneously even with small sleeper spacing. The halves of the front and rear tamping units facing the intermediate tamping unit also have a narrow structural type. The halves of the front and rear tamping units facing away from the intermediate tamping unit use a wider structural type to achieve a larger opening width between the opposing tamping tools.

[0014] In this design of the invention, it is preferable that the front tamping unit and the rear tamping unit each have an eccentric shaft with different eccentricities. Here, the different lever ratios and different eccentricities of the opposing tamping tools are matched to ensure that the vibration amplitude of the freely oscillating pickaxe tip is equal.

[0015] Preferably, the front tamping unit and the rear tamping unit each have opposing tamping tools, which are supported on an associated tool holder by vertically spaced pivot bearings. Preferably, the bearings of the tamping tools facing the middle tamping unit are arranged lower to achieve a narrower structural type while maintaining a constant lever ratio.

[0016] Furthermore, it is preferable that the front tamping unit and the rear tamping unit each have a half facing the middle tamping unit, which is constructed to correspond with the symmetrical half of the middle tamping unit. This simplifies the construction of the tamping unit and makes it easier to operate the individual tamping units. It also reduces the number of different spare parts.

[0017] Advantageously, the intermediate tamping unit, as well as the halves of the front and rear tamping units facing the intermediate tamping unit, are respectively connected to a first feed pressure system, and the halves of the front and rear tamping units facing away from the intermediate tamping unit are respectively connected to a second feed pressure system. Different feed pressure systems enable the same static and dynamic feed force to be achieved on all tamping tools.

[0018] Further improvements stipulate that the corresponding front and rear tamping units, in their respective halves away from the intermediate tamping unit, include feed cylinders with a large stroke to tampe the double sleepers. In this way, the tamping unit can be widely used and can handle all sleeper arrangements found on track sections.

[0019] Furthermore, it is advantageous that multiple tamping tools arranged transversely to the longitudinal direction of the machine, along with their associated feed cylinders, form a feed group that can be controlled collaboratively. This involves tamping units arranged side-by-side, which tampe a sleeper on both sides of the two rails of the track. During operation, these feed groups are controlled collaboratively to ensure a uniform compaction process along the sleeper.

[0020] In the method for operating the machinery according to the invention, the vibration actuator and feed cylinder of the corresponding tamping unit are manipulated such that the position angle of the feed drive fluctuates within a range of relative angles around the eccentric plane of the corresponding eccentric shaft. In this way, during tamping, the current position angle remains approximately the relative angle. In particular, in the intermediate pivot position of the feed drive, the position angle is equal to the relative angle. In this case, the vibrating masses of the corresponding tamping unit oscillate synchronously in opposite directions, thereby achieving mass balance. This minimizes unit load and noise generation.

[0021] An extended design of the method specifies that each eccentric shaft is driven by an associated vibration drive motor, and all vibration drive motors are operated synchronously via a common control device. This coordinates the oscillating movements of the tamping units to optimize the smooth operation of the entire tamping unit.

[0022] Furthermore, it is advantageous that the corresponding eccentric shafts are driven at variable speeds based on the height position of the corresponding tamping unit. Before the tamping process, all tamping units are in their initial position above the track. In this position, the speed of the corresponding eccentric shafts remains reduced to further minimize noise generation. The operating speed is only increased when the height position is changed during descent; the operating speed is higher during insertion than during feed.

[0023] Further improvements stipulate that the feed groups, arranged transversely to the longitudinal direction of the machine, are controlled by a common control signal. This method achieves a uniform compaction process along the sleepers.

[0024] Advantageously, during the feeding process, a first feed pressure is applied to the middle tamping unit and the half of the front and rear tamping units facing the middle tamping unit, respectively, while a second feed pressure is applied to the half of the front and rear tamping units facing away from the middle tamping unit. Different feed pressures enable the same static and dynamic feed force to be achieved on all tamping tools. Attached Figure Description

[0025] The invention will now be explained by way of example with reference to the accompanying drawings. In the drawings:

[0026] Figure 1 A schematic diagram of a machine with a tamping unit is shown.

[0027] Figure 2 A side view schematic diagram of a tamping unit used to simultaneously tamp three sleepers is shown.

[0028] Figure 3 A side view of the intermediate tamping unit is shown.

[0029] Figure 4 Showing according to Figure 3 Kinematic diagram

[0030] Figure 5 Showing according to Figure 3 Schematic diagram of the kinematics of the object in multiple working positions.

[0031] Figure 6 Side view schematic diagram showing the front and rear tamping units

[0032] Figure 7 Showing according to Figure 6 Kinematic diagram

[0033] Figure 8 Showing according to Figure 6 Schematic diagram of the kinematics of the object in multiple working positions.

[0034] Figure 9 A side view schematic diagram of the eccentric shaft is shown.

[0035] Figure 10 A top view of the eccentric shaft is shown.

[0036] Figure 11 A front view schematic diagram of the tamping unit is shown.

[0037] Figure 12 A schematic diagram of a tamping unit for simultaneously tamping four sleepers is shown. Detailed Implementation

[0038] Figure 1 The machine 1 shown is designed as a track tamping machine, used to simultaneously tamp three sleepers 4 supported in the ballast bed 2 of the track 3. The machine 1 includes a mechanical frame 6 supported on a rail traveling mechanism 5, with a tamping unit 7 fixed to the mechanical frame. Furthermore, the machine 1 includes a lifting and straightening unit 8 for lifting and straightening the track grid formed by the sleepers 4 and rails 9. The current rail position is detected by a measuring system 10.

[0039] The tamping unit 7 is fixed to the machine frame 6 by an adjusting device 11. The tamping unit includes a unit frame 12 with a guide device 13 and a plurality of tamping units 14. In a variant not shown, each tamping unit 14 is assigned its own unit frame 12. Each tamping unit 14 includes a tool holder 15, which is supported in a height-adjustable manner on the corresponding guide device 13 by a height adjustment actuator 16. Tamping tools 18, which are opposed to each other along the machine longitudinal direction 17, are pivotally supported on their respective tool holders 15.

[0040] Furthermore, a vibration actuator 19 is arranged on the corresponding tool holder 15, and the tamping tool 18 is coupled to the vibration actuator via a feed cylinder 20. Each tamping tool 18 includes a pivot lever 21 having an upper lever arm and a lower lever arm. The pivot lever 21 is supported on the corresponding tool holder 15 by a pivot bearing 22, wherein the upper lever arm is connected to the corresponding feed cylinder 20. Two pickaxes 23 are typically fixed on the free lower lever arm.

[0041] The opposing pickaxes 23 of each tamping unit 14 are in the starting position. Figure 2 The tamping units 14 are equidistant from the central vertical plane 24. The distance between the central vertical planes 24 of the sequentially arranged tamping units 14 is equal to the minimum sleeper spacing t of the sleepers 4 to be tamped. Therefore, the dimension of the tamping unit 14 along the machine longitudinal direction 17 depends on this minimum sleeper spacing t.

[0042] The intermediate tamping unit 14, positioned between the front and rear tamping units 14, has a narrow structural type along the machine longitudinal direction 17. This structure requires a downwardly oriented feed cylinder 20. For both the front and rear tamping units 14, only the half facing the intermediate tamping unit 14 is designed accordingly. The other half has a nearly horizontally oriented feed cylinder 20. This provides a larger pivot range for the corresponding tamping tool 18. The resulting increase in the opening width between the opposing pickaxes 23 can accommodate larger sleeper spacing t or double sleepers to be tamped.

[0043] With the help of Figures 3 to 5 The construction of the intermediate tamping unit 14 will be explained in more detail here. Figure 4 Show Figure 3 The kinematic model of the tamping unit 14 shown. Figure 5 The kinematic model 3 is shown in three working positions. The eccentric shaft 25 of the vibration actuator 19 is supported on the tool holder 15. During operation, the eccentric shaft 25 rotates about the rotation axis 26. The eccentric shaft 25 includes two eccentric disks 27, 28 that are offset relative to each other, and the axes of symmetry 29, 30 of the two eccentric disks have their respective eccentricities e1, e2 with respect to the rotation axis 26.

[0044] Furthermore, the axes of symmetry 29 and 30 and the axis of rotation 26 tension two eccentric planes 31 and 32, which enclose each other at an angle δ. The cylinder axis 33 of the feed cylinder 20 encloses the position angle β. In the case of the intermediate tamping unit 14, the opposite feed cylinders 20 are arranged symmetrically. The corresponding cylinder axis 33 is inclined downwards at an angle α relative to the horizontal line. The angle α is at least 20°. Ideally, the angle α is specified to be in the range of 30° to 50° to ensure optimal force transmission except for narrow structural types.

[0045] During the tamping process, the inclination angle α and position angle β change slightly due to the vibration and feed motions. For ease of illustration, in Figure 5 The figure shows different positions of the feed cylinder 20 with the eccentric shaft 25 stopped. The solid lines represent the position of the tamping tool 18 after feeding. In the positions shown, the cylinder axis 33 is located in the eccentric planes 31 and 32, so the position angle β is equal to the relative angle δ. Again, for ease of explanation, the eccentricities e1 and e2 are shown as excessively large compared to the other dimensions. The circular motion of the feed cylinder 20's articulation device during one revolution of the eccentric shaft 25 is not considered in the figure. The effect of this circular motion on the change in position of the cylinder axis 33 is negligible compared to the effect of the feed motion caused by piston movement.

[0046] Once the eccentric shaft 25 begins to rotate during operation, the eccentric planes 31 and 32 rotate together at a constant relative angle δ. The position angle β is at β min to ß max The range varies, which is related to the kinematic design and piston stroke of the tamping unit 14. During the feeding process, the feed cylinder 20 pivots slightly about the axes of symmetry 29 and 30 of the eccentric disks 27 and 28. Figure 5 In the diagram, the two extreme positions are represented by dashed lines and dotted lines, respectively. Here, the value of the position angle β remains approximately the same as the value of the relative angle δ. In the optimized kinematic design of the tamping unit 14, the value of the relative angle δ is always located at β of the position angle β during operation. min to ß max The value range.

[0047] For the front and rear tamping units 14, the corresponding kinematic relationships are as follows: Figures 6 to 8 As shown in the diagram. In contrast to the intermediate tamping unit 14, the feed cylinder 20 and tamping tool 18 are arranged asymmetrically here. The pivot levers 21 associated with the different feed cylinders 20 are adjusted accordingly. On the side facing the intermediate tamping unit 14, the cylinder axis 33 of the feed cylinder 20 is inclined downward at an angle α relative to the horizontal line.

[0048] exist Figure 8As can be seen, the intermediate positions of the two feed cylinders 20 relative to their respective pivot ranges do not occur simultaneously. In the position shown after feeding (solid line), the shorter feed cylinder 20 is in the intermediate position, while the longer feed cylinder 20 is in the terminal position of downward pivoting. The minimum position angle β occurs in this position. min During the reset motion of the tamping tool 18, the longer feed cylinder 20 passes through its intermediate position, where the position angle β is equal to the relative angle δ of the eccentric shaft 25. After reset, the position angle β has its maximum value. max Therefore, during the feed and reset motions, the value of the position angle β is within the range β. min to ß max The relative angle δ around the eccentric planes 31 and 32 fluctuates.

[0049] To ensure approximately the same lever transmission ratio on both sides, pivot bearings 22 are vertically spaced on the tool holder 15. The relatively long structure of the nearly horizontally arranged feed cylinder 20 enables a larger feed stroke. Therefore, the position angle β is within a large range. min to ß max Internal fluctuations.

[0050] exist Figure 9 and Figure 10 The eccentric shaft 25 used for the front tamping unit or the rear tamping unit 14 is shown in detail. Figure 10 The cross-section of the diagram is in Figure 9 As shown in the diagram, a first eccentric disk 27 is centrally located along an eccentric shaft 25. A shorter, downwardly oriented feed cylinder 20 is supported on this first eccentric disk 27. A second eccentric disk 28 is divided into two parts, with two sub-eccentric disks arranged on either side of the first eccentric disk 27. A longer feed cylinder 20 is supported on the second eccentric disk via a forked end. These two feed cylinders 20... Figure 9 , Figure 10 The middle part is represented by a dotted line.

[0051] In the position shown, the cylinder axis 33 of the feed cylinder 20 falls within the eccentric planes 31 and 32. The oscillating motion of both feed cylinders 20 simultaneously reaches the external reversal point. Once the eccentric shaft 25 continues to rotate, the ends of the two feed cylinders 20 supported on the eccentric disks 27 and 28 move in opposite directions. Through synchronized oscillating motion, the oscillating masses are largely balanced. This is particularly applicable to synchronously oscillating pickaxes 23.

[0052] Mass balance is reinforced by a oscillating load 34, which rotates together with the eccentric shaft 25 about the same axis of rotation 26. The eccentric shaft and the oscillating load 34 constitute a rotating unit whose center of mass 35 is approximately located on the plane of symmetry 36 of the two eccentric planes 31 and 32. Here, the center of mass 35 is spaced from the axis of rotation 26 and opposite to the axes of symmetry 29 and 30 of the two eccentric disks 27 and 28. The oscillating load 34, with its off-center center of mass 35, resists the inertial force of the oscillating feed cylinder 20. The dimensions of the oscillating load 34 are matched to the mass of the feed cylinder 20. For example, the oscillating load 34 is designed as a disk that is flattened or has grooves in one position to achieve the off-center center of mass 35.

[0053] In the eccentric shaft 25 shown for the front or rear tamping unit 14, different eccentricities e1 and e2 cause the same amplitude at the free end of the pickaxe 23. In the eccentric shaft 25 for the intermediate tamping unit 14, due to the symmetrical arrangement, the two eccentricities e1 and e2 are equal.

[0054] exist Figure 11 As can be seen, each rail 9 of track 3 is assigned two individually lowerable tamping units 14. Therefore, the tamping unit 7 comprises four tamping units 14 arranged side-by-side in a row. For each tamping unit 14, its associated eccentric shaft 25 is driven by a vibration drive motor 37. All vibration drive motors 37 are operated by a common control device 38 to ensure synchronized operation. In this way, the oscillations of the individual tamping units 14 cancel each other out, thereby minimizing the vibration transmitted from the tamping unit 7 to the mechanical frame 6.

[0055] In a simplified variant not shown, each rail 9 is equipped with a combined tamping unit 14 having tamping tools 18 on the inner side and tamping tools 18 on the outer side of the rail. In this case, the tamping unit 7 includes two combined tamping units 14 arranged side by side in a row.

[0056] To tamp the sleepers 4, the tamping units 14 arranged side by side form a feeding group. The pickaxes 23 of these feeding groups descend and feed together (two feeding groups per row). Figure 12 The diagram shows a tamping unit 7 with four rows of tamping units 14 arranged adjacent to each other. Eight feed groups are generated here, each controlled jointly. The feed groups for the middle tamping units 14, as well as the feed groups towards the front and rear tamping units 14, are supplied via a first feed pressure system 39. The foremost and rearmost feed groups are supplied via a second feed pressure system 40.

[0057] In this way, feed groups of different sizes are subjected to different feed pressures during the feeding process. Here, these feed pressures are matched to produce the same static and dynamic feed forces on all the pickaxes 23. For a uniform feeding process along the sleeper 4, the corresponding feed groups are controlled by a common control signal.

Claims

1. A machine (1) having a tamping unit (7) for simultaneously tamping multiple adjacent sleepers (4) of a track (3) positioned sequentially, said tamping unit having multiple tamping units (14) arranged sequentially along the longitudinal direction (17) of the machine, wherein, Each tamping unit (14) includes a height-adjustable tool holder (15) on which opposing tamping tools (18) are supported. These tamping tools are coupled to vibration actuators (19) arranged on the tool holder (15) via feed cylinders. The vibration actuators (19) are characterized by including an eccentric shaft (25) with a first eccentric disk (27) and a second eccentric disk (28). The axes of symmetry (29, 30) of these two eccentric disks and a common axis of rotation (26) respectively support two eccentric planes (31). The two eccentric planes (31, 32) are opposite each other and form a relative angle (δ). The first feed cylinder is supported on the first eccentric disk (27), and the opposite second feed cylinder is supported on the second eccentric disk (28). The cylinder axis (33) of the first feed cylinder and the cylinder axis (33) of the opposite second feed cylinder form a position angle (ß). The position angle (ß) is approximately the same as the relative angle (δ) of the eccentric planes (31, 32). This causes the masses of the corresponding tamping units to oscillate synchronously in opposite directions, thereby achieving mass balance.

2. The machine (1) according to claim 1, characterized in that, Each tamping unit (14) includes at least one feed cylinder whose cylinder axis (33) is tilted downwards.

3. The machine (1) according to claim 2, characterized in that, The feed cylinder has an inclination angle (α) greater than 20° relative to the horizontal line.

4. The machine (1) according to claim 1, characterized in that, Each eccentric shaft (25) is connected to the oscillating load (34).

5. The machine (1) according to claim 4, characterized in that, The eccentric shaft (25) and the oscillating load (34) constitute a rotating unit with a center of mass (35), which is located opposite the axes of symmetry (29, 30) of the two eccentric disks with reference to the axis of rotation (26).

6. The machine (1) according to any one of claims 1 to 5, characterized in that, The tamping unit (7) includes a front tamping unit and a rear tamping unit with asymmetrically arranged feed cylinders, and an intermediate tamping unit with symmetrically arranged feed cylinders.

7. The machine (1) according to claim 6, characterized in that, The front tamping unit and the rear tamping unit each have an eccentric shaft (25) with different eccentricities (e1, e2).

8. The machine (1) according to claim 6, characterized in that, The front tamping unit and the rear tamping unit each have opposite tamping tools (18), which are supported on an associated tool holder (15) by vertically spaced pivot bearings (22).

9. The machine (1) according to claim 6, characterized in that, The front tamping unit and the rear tamping unit each have a half facing the middle tamping unit, which is constructed to correspond to the symmetrical half of the middle tamping unit.

10. The machine (1) according to claim 9, characterized in that, The intermediate tamping unit and the half of the front tamping unit and the rear tamping unit facing the intermediate tamping unit are respectively connected to the first feed pressure system (39), and the half of the front tamping unit and the rear tamping unit facing away from the intermediate tamping unit are respectively connected to the second feed pressure system (40).

11. The machine (1) according to claim 9, characterized in that, The corresponding front tamping unit and the rear tamping unit, which are separated from the middle tamping unit, each include a feed cylinder with a large stroke to tampe the double sleepers.

12. The machine (1) according to claim 1, characterized in that, Multiple tamping tools (18) arranged side by side with the machine longitudinal direction (17) together with the associated feed cylinder form a feed group that can be controlled together.

13. A method for operating the machine (1) according to any one of claims 1 to 12, characterized in that, The vibration driver (19) and feed cylinder of the corresponding tamping unit (14) are manipulated so that the position angle (β) of the feed drive device fluctuates within the range of the relative angle (δ) of the eccentric planes (31, 32) around the corresponding eccentric shaft (25).

14. The method according to claim 13, characterized in that, Each eccentric shaft (25) is driven by an associated vibration drive motor (37), and all vibration drive motors (37) are operated by a common control device (38) to operate synchronously.

15. The method according to claim 13, characterized in that, The feed groups, arranged side by side with the machine longitudinal direction (17), are controlled by a common control signal.

16. The method according to claim 13, characterized in that, During the feeding process, a first feeding pressure is applied to the middle tamping unit, as well as the half of the front tamping unit and the rear tamping unit facing the middle tamping unit, and a second feeding pressure is applied to the half of the front tamping unit and the rear tamping unit facing away from the middle tamping unit.

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