IMPROVED TAMPING MACHINE, PARTICULARLY FOR RAILROAD BALLASTS

Abstract: The machine comprises at least two pairs of vibrating tamping hammers (40-41), each rigidly associated with a support (38-39) oscillably pivoted to the frame (30) of the machine and subject to the action of a fluidodynamic actuation jack (42-43) comprising a first extendable section, adapted to move the hammer from a substantially vertical working position to a substantially horizontal lowered idle position, and a second section, fed by distribution means with alternating cyclic operation, adapted to subject said first jack section and the related tamping hammer to a corresponding cyclic and alternating vibration.

Description: The present invention relates to an improved tamping machine, particularly for regenerating railroad ballasts. Trailer or self-propelled railcars, bearing groups of tamping machines arranged inside and outside each rail according to patterns known to the technician in the field and termed single- or twin-head, are usually employed to regenerate railroad ballasts. Each tamping machine generally has two pairs of vibrating hammers which are sunk into the ballast on one side and on the other of each tie to move the rubble constituting the ballast and tamp said tie with it. In order to vibrate the hammers and sink them into the rubble, currently known tamping machines use mechanical systems essentially of the eccentric-mass or crank type. Such mechanical systems have many disadvantages, and chiefly: a considerable structural complexity arising from the high stresses transmitted to the various elements of the machine and the need to keep the vibration frequency of the hammers within relatively modest limits, both to contain the above mentioned stresses within acceptable limits and to limit power consumption. In known machines, the vibration is furthermore simultaneously transmitted to all the pairs of hammers of each "head", where the term "head" indicates the set of elements acting on each tie. This circumstance constitutes a considerable disadvantage, as it forces the outfitting of two different types of railcar, respectively for line work and for switch work. The first is of the twin-head type and can operate simultaneously on two ties, while the second necessarily has a single head and therefore its use for line work has an unacceptable performance, thus requiring the outfitting of differentiated railcars respectively for lines and switches. CH-A-658482 shows a tamping machine with tamping tools rotatably connected to a frame. The tools are rotatably positioned by means of hydraulic jacks and the frame is vibrated by means of an eccentric shaft forced-oscillation generator. FR-A-2270377 shows a tamping machine with tamping tools which are positioned in place by means of hydraulic cylinders and which are subjected to a vibration movement produced by a hydraulic motor. The aim of the present invention is essentially to eliminate these disadvantages. In particular, an important aim of the present invention is to provide a tamping machine with a significantly simplified structure, adapted to operate with frequencies variable within a wide range of values selectable according to the state of the ballast to be regenerated and in any case adapted to operate at markedly higher frequencies with respect to those of known mechanical systems, without generating intolerable structural stresses to the advantage of a considerable increase in performance. Another important object of the present invention is to provide a tamping machine having limited dimensions and weight and therefore adapted to outfit railcars with reduced weights and dimensions. A further important object of the present invention is to provide an improved tamping machine adapted to outfit a single type of railcar for working both on line and on switches, with evident advantages in management economy and maintenance and with a considerable reduction in the operative execution times since the replacement of line cars with switch cars and vice versa is avoided during work. This aim and these objects as well as others which will become apparent from the following detailed description, are achieved by a tamping machine as defined in the appended claims. Further characteristics and advantages of the invention will become apparent from the following detailed description and with reference to the accompanying drawings, given by way of non-limitative example, wherein: figure 1 is an elevation view of a railcar equipped with tamping machines according to the present invention; figures 2 and 3 are partial and enlarged-scale elevation views, similar to figure 1, illustrating the arrangement of the tamping machines in operating conditions for line work and for switch work respectively; figure 4 is a schematic perspective view of the tamping machine according to the present invention with the pairs of hammers in working position; figure 5 is an isometric view, similar to figure 1, illustrating the manner of folding of the hammers in their idle position; figure 5a is an enlarged-scale view of a detail of figure 4; figure 6 is a diagram of a hydraulic feed circuit for the first and second sections of the hammer actuation jacks; figure 7 is a diagram, similar to figure 6, of a variated embodiment of the circuit; figure 8 is a diagram, similar to figure 6, of another variated embodiment of the circuit; figure 9 is an enlarged-scale detail view of the diagrams of figures 6 to 8, illustrating another constructive variated embodiment of said circuit. In the drawings, the reference numeral 10 indicates a railcar having a frame 11 mounted on gears 12 which rest on the track 13 to be regenerated. A group of tamping machines 20 and a generator unit (not illustrated) composed of a Diesel motor and of one or more hydraulic pumps with related fuel and hydraulic-fluid tanks are mounted on the railcar; the generator unit is accommodated in a housing 14 adjacent to a driver's cab 15. The group of tamping machines 20 is formed by four units 20a-20b, accommodated at the center of the railcar and aligned in pairs at two adjacent and consecutive ties T1-T2 of the ballast. The frame 10 has an arched raised portion 11a at the group of machines 20; pairs of fluidodynamic jacks 25a-25b, 26a-26b arranged transversely side by side extend downwards from said portion. The frame 30 of a corresponding tamping machine is suspended from each jack stem; the jacks allow to simultaneously lift all the machines, for example to transfer the railcar, as illustrated in figure 1; to lower all the machines to their working position, as shown in figure 2, which allows to use the railcar for line work; to selectively lower one or more machines, as indicated by A in figure 3, to use the railcar on switches or for other applications arising from particular requirements of the work on the ballast. Besides the above described purposes, the jacks 25-26 are preset to impart to the machines the thrust required to drive the tamping elements into the ballast, as described hereinafter. As shown in figures 4 and 5, each tamping machine which composes the group indicated by 20 is substantially constituted by a sturdy frame 30 in the shape of a double T, preferably in steel tube, comprising a longitudinal member 31 and two cross-members 32. The longitudinal member 31 has a central sleeve 33 for coupling with the stem of the corresponding suspension jack 25; the cross-members 32 have, at their ends, pairs of rigid arms 34a-34b, 35a-35b which extend upwards. Each cross-member furthermore has end pivots 36, 37 to which opposite pairs of oscillable supports 38a-38b, 39a-39b are articulated with bearings (not illustrated) interposed, to said end pivots; each oscillable support bears a corresponding tamping hammer 40a-40b, 41a-41b. The end of each oscillable support 38-39 which is opposite to the end bearing the hammer is articulated to the stem 42a-42b, 43a-43b of a corresponding fluidodynamic actuation jack 44a-44b, 45a-45b; the cylinders of said jacks are articulated to the corresponding rigid arm of the opposite cross-member; the jack 44a is therefore inserted, with its axis substantially horizontal, between the oscillable support 38a and the arm 35a, the jack 44b is inserted between the support 39a and the arm 34a, and so on. As clearly illustrated in figure 5a, each jack 44-45 is formed by a first section 46 and by a second section 47. The first section is extendable and is preset to move the corresponding tamping hammer 40-41 from a substantially vertical working position, indicated by PL in figure 5, to a substantially horizontal raised idle position indicated by PE in said figure. The second section can vibrate and is adapted to subject the first section, and the respective hammer connected thereto, to a cyclic and alternating working vibration which can be varied in frequency as will be specified hereinafter. The second vibrating section is arranged mechanically in series to the first section, the stem of the second section being rigidly connected to the cylinder of the first section. The sections of each jack are separately fed by corresponding hydraulic circuits connected to said generator unit; the first extendable section is fed by means of a corresponding feed-discharge distribution valve actuatable by the operator to exclude one or more hammers of each machine when required by the layout of the track; the second one is fed by means of feed-discharge distribution valves controlled in cyclic sequence by one or more distribution means. The diagram of figure 6 illustrates a hydraulic circuit adapted for that purpose. According to said diagram, the first section 46 of each jack 44-45 is fed by the motor-pump generator unit by means of corresponding electric distribution valves 50a-50b, 51a-51b with intermediate locking positions, the solenoids whereof are subject to corresponding selective energization actuations, for example by means of a lever, arranged in the driver's cab 15. This allows the operator to extend or retract the extendable section of each jack and consequently lower into working position or exclude each hammer of the tamping machine, arranged in operative position as illustrated in figure 3. The railcar 10, which is usable for line or switch work depending on the position of the tamping machines, furthermore allows, in the switch configuration, to selectively operate with one or two pairs of hammers for each machine, and even, if required, with a single hammer; this gives said railcar unprecedented flexibility in use and rapidity in operation. In the intermediate locking position, illustrated in the figure, the electric valves 50-51 cut off all the feed and discharge ducts of the corresponding jack section, mutually rigidly associating the stem and the cylinder of said jack. The second section 47 of each jack is fed by means of corresponding electric distribution valves 52a-52b, 53a-53b of the two-way type with no locking position, and the solenoids of said electric valves are cyclically energized by an oscillator OE with variable frequency preferably of the electronic type. As clearly illustrated in figure 6, contacts r1-r2-r3-r4 of corresponding exclusion relays correlated to the electric distribution valves 50-51 are inserted between the solenoids of the valves and the feed oscillator OE; said contacts are opened to cut off the hydraulic feed to said second section of each jack when the corresponding first section is extended to raise the respective tamping hammer to its idle position. The circuit illustrated in figure 7 differs from the one of figure 6 in that the electric distribution valves 52-53 are replaced by a rotating mechanical distributor 60 actuated by an adjustable-speed electric motor 61. In this case bypass electric valves 62, also correlated to the electric valves 50-51, are provided for the above described exclusion function. In the variated embodiment of figure 8, the second vibrating section 47 of each jack is fed by its own rotary distribution valve 63a-63b, 64a-64b actuated by a corresponding motor 65a-65b, 66a-66b according to an arrangement which avoids the insertion of the bypass valves 62 and allows to independently vary the working frequency of each hammer. The variated embodiment of figure 9 differs from what has been described above in that the electric distribution valves 50-51 are replaced with manually actuated distribution valves 70. The details of execution and the embodiments may be extensively varied with respect to what is described and illustrated only by way of non-limitative example without thereby abandoning the scope of the invention and without altering the concept of the invention. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: 1. Tamping machine, particularly for regenerating railroad ballasts, comprising at least two pairs of vibrating tamping hammers (40, 41), each rigidly associated with a support (38, 39) oscillably pivoted to the frame (30) of the machine and subject to the action of a fluidodynamic actuation jack (42, 43) comprising a first extendable section (46), adapted to move the hammer from a substantially vertical working position to a substantially horizontal raised idle position, said tamping machine characterized in that said actuation jack (42, 43) further comprises a second section (47) mechanically connected in series with said first section (46), both the first (46) and the second (47) sections of each jack (42, 43) being mutually independent hydraulic actuation jacks, said second section being fed by distribution means (52, 53) with alternating cyclic operation, to thereby subject said first jack section (46) and the related tamping hammer to a corresponding cyclic and alternated vibration. 2. Tamping machine according to claim 1, characterized in that it comprises first fluidodynamic actuation means (50, 51) for selectively and controllably moving each tamping hammer from its working position to its idle position and vice versa by means of the first section (46) of its respective actuation jack, and second fluidodynamic means (52, 53) correlated with the first means to cut off the feed of the second section (47) of the actuation jack when the hammer is in idle position. 3. Tamping machine according to claims 1 and 2, characterized in that said frame (30) has coupling means (33) for the stem of a corresponding suspension jack (25) adapted to move the machine from a raised idle position to a lowered working position and vice versa. 4. Tamping machine according to the preceding claims, characterized in that said frame (30) is in the shape of a double T with a longitudinal member (31) and a pair of cross-members (32), each cross-member having rigid arms (34a, 34b, 35a, 35b) and end pivots (36, 37) for the oscillable connection of the supports of the hammers, and in that the actuation jacks of the hammers are substantially directed horizontally and are inserted between the oscillable support (38, 39) of the corresponding hammer and the rigid arm of the opposite cross-member. 5. Tamping machine according to the preceding claims, characterized in that the first section (46) of each actuation jack (44, 45) is fed by a motor-pump unit by means of corresponding electric distribution valves (50, 51) with an intermediate locking position and in that the solenoids of said valves are subject to corresponding energization actuations activatable by the operator. 6. Tamping machine according to claims 1 to 4, characterized in that the second section (47) of each actuation jack is fed by means of corresponding electric distribution valves (52, 53) of the two-way type and in that the solenoids of said electric valves are cyclically energized by a variable-frequency oscillator preferably of the electronic type. 7. Tamping machine according to claims 2 and 6, characterized in that contacts (r1, r2, r3, r4) of corresponding exclusion relays correlated to the solenoids of the electric valves (50, 51) which control the feeding of the first jack section are inserted between the solenoids of the valves and the feed oscillator (OE), said contacts being open to cut off the feed to the second section when the first jack section is extended to raise the related tamping hammer. 8. Tamping machine according to claims 1 to 4, characterized in that the second sections of each jack are fed by means of a rotating mechanical distributor (60) actuated by a adjustable-speed electric motor (61), the feed ducts of each section having bypass valves (62) adapted to exclude said section when the hammer is raised to its idle position. 9. Tamping machine hammer according to claims 1 to 4 and 8, wherein each second section (47) of the jacks is fed by a rotating mechanical distributor actuated by a corresponding adjustable-speed electric motor (65, 66). 10. Tamping machine according to claims 1 to 4, wherein the first section of each actuation jack is fed by means of a corresponding distribution valve (70) of the manual-actuation type. 11. Railcar equipped with tamping machines according to claims 1 to 10, characterized in that it comprises at least one group (20) of four machines (20a, 20b) arranged in side-by-side pairs in corresponding alignment with adjacent track tie pairs (T1, T2), and in that each machine is rigidly associated with the stem of a corresponding suspension jack (25, 26) which allows the respective selective movement of the machine from an idle raised position to a lowered working position and vice versa.

Inventors: ROSSANIGO, CESARE
Applicants: SO.RE.MA. OPERATRICI FERROVIARIE S.N.C. DI CESARE ROSSANIGO & C.
Application year: 1989
Main classification: E01B27
IPC codes: E01B27