US3926123A

US3926123A - Track surfacing apparatus

Info

Publication number: US3926123A
Application number: US404427A
Authority: US
Inventors: Franz Plasser; Erna Plasser; Josef Theurer; Egon Schubert; Klaus Riessberger
Original assignee: Individual
Current assignee: Franz Plasser Bahnbaumaschinen Industrie GmbH
Priority date: 1972-10-13
Filing date: 1973-10-09
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: JPS582281B2; AT336663B; JPS4972812A; FR2202980A1; GB1454172A; DE2330102A1; SU893140A3; ATA881672A; SU645605A3; DE2330102C2; AU6044873A; ZA737512B; US3919943A; CA1004083A; CH565898A5; FR2202980B1

Abstract

Ballast is compacted and the track is leveled simultaneously by imparting a substantially horizontal vibration to the track while pressing the track substantially vertically down to the desired level.

Description

United States Patent Plasser, deceased et al.

[ Dec. 16, 1975 TRACK SURFACING APPARATUS Inventors: Franz Plasser, deceased, late of Vienna. Austria: by Erna Plasser. heir; Josef Theurer, both of Johannesgasse 3, Vienna, Austria, A-lOlO; Egon Schubert, Lainzerstr. 24b/8; Klaus Riessberger, Paniglgasse 24, both of Vienna,

Austria Filed: Oct. 9, 1973 Appl. No.: 404,427

Foreign Application Priority Data Oct, 13, 1972 Austria 8816/72 US. Cl 104/7 R; 104/8; 104/12 Int. Cl. E01B 37/00 [58] Field of Search 104/7, 8, 7 B, 12

[56] References Cited UNITED STATES PATENTS 3,486,461 12/1969 Plasser et a1 .1 104/8 3,731,409 5/1973 Schcnkir et a1 104/12 3,766,859 10/1973 Byrne 104/12 Primary Examiner-Lloyd L. King Assistant Examiner-Richard A. Bertsch Attorney, Agent, 01' Firm-Kurt Kelman [57] ABSTRACT Ballast is compacted and the track is leveled simultaneously by imparting a substantially horizontal vibration to the track while pressing the track substantially vertically down to the desired level.

29 Claims, 21 Drawing Figures US. Patent 15ec.16,1975 sheetlof 3,926,123

U.S. Patent Dec. 16, 1975 Sheet20f9 3,926,123

US. Patent Dc.16,1975 Sheet30f9 3,926,123

U.S. Patent Dec. 16, 1975 Sheet4 0f9 3,926,123

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US. Patent l )ec.16,1975 Sheet5of9 3,926,123

U.S. Patent Dec. 16, 1975 Sheet6of9 3,926,123

U.S. Patent Dec. 16, 1975 Sheet 7 of 9 3,926,123

:IDOICS US. Patent Dec. 16, 1975 Sheet8of9 3,926,123

US. Patent De ;.16,1975 Sheet90f9 3,926,123

TRACK SURFACING APPARATUS The present invention relates to improvements in apparatus for surfacing a track consisting of rails fastened to ties resting on ballast.

In track surfacing, it has been proposed to impart at least substantially horizontal vibration to a track in a section wherein the ballast is compacted, particularly under the track ties and while the track is positioned at a desired level. In the leveled track, the ballast serves to absorb the forces to which passing trains subject the track. In view of the resiliency and wear of the ballast,

the track level changes in the course of time. Therefore, the track must be leveled from time to time to achieve the desired grade, at which the track is fixed by tamping the supporting ballast under the ties.

Tie tamping forms an essential part of many known track leveling methods. In this operation, the ballast is compacted underneath the ties by pressure and vibration to the highest attainable degree to form as rigid a track support as possible. However, none of the known tamping methods has succeeded in fixing the track at a desired level sufficiently to resist depression by passing trains for long. Immediately after tamping, the track settles rather rapidly and this downward movement slows down with time. This phenomenon results from the fact that the tamping relocates the ballast pieces in new positions in which they are subjected to the vertical, static and dynamic loads of passing trains, leading to their wear and settling. Since the ballast does not settle uniformaly along the track, many deviations from a straight level soon appear.

An attempt has been made to improve the ballast compaction by subjecting the ballast to vertical vibrations transmitted to the ballast by the track rails and/or ties, or directly by vibratory surface compactors. However, it has not been possible in commercial operations to obtain a permanently fixed ballast bed in this manner. Similar lack of success has been encountered with vibrating the track solely in a horizontal direction.

In another known track correction method, the track section to be corrected is subjected to vibrations and is raised to the desired level. Subsequently, the ballast is tamped under the ties to fix the track at the raised level. This method has not been commercially used.

It is a primary object of this invention to provide track surfacing which results in a durable and more uniformly compact ballast support for the track ties. The track surfacing of the invention discounts the usual settling of the newly tamped ballast under the loads of trains passing thereover.

The above and other objects are accomplished according to the invention by imparting a substantially horizontal vibration to the track while pressing the track substantially vertically down to the desired level to compact the ballast under the track ties and simultaneously position the track at a desired level. Any deviation of the track position from a desired level may be determined and the track pressed to the desired lower level.

Unexpectedly, the combination of the horizontal vibration and the downward pressure provides a ballast compaction which far surpasses the quality achieved with known track surfacing methods and equipment. During the ballast compaction according to the present invention, the ties are pressed into the ballast and this vertical downward movement of the track into the compacted ballast is taken into account in determining the desired track level. In this way, the track surfacing actually simulates and discounts the subsequent train traffic so that the desired level will be maintained despite of it.

Since long used track usually has been pressed by the passing train traffic below the desired grade, it will be useful in such cases to raise the track above this level and to tamp the ballast under the ties of the raised track before track surfacing is effected in accordance with the invention. When a newly laid track section is installed, this will not be necessary since such track is laid at a higher than desired grade and may then be directly leveled to the desired grade by means of the track surfacing of the present invention.

Throughout the specification and claims, the term substantially horizontal vibration means a vibration with a marked horizontal component extending transversely of the track elongation. Thus, the vibration may be produced in planes oblique to the horizontal plane as long as the resultant vibration has a marked horizontal component.

Preferably, the vibration has the same or nearly the same frequency as the natural or characteristic frequency of vibrations of the track, measured in a transverse direction, the frequency being, for instance, in the range of 8 to 13 cycles per second. This has the advantage that the vibrating force may be relatively small since the vibrated track section will be in resonance.

The track surfacing of this invention is very flexible and sensitive because it opens the way to a variety of controls. Thus, it is of particular advantage to determine the downward stroke required to press the track down to the desired level, i.e. the deviation of the track therefrom, to produce an error signal proportional to the deviation, and to control the frequency and/or the amplitude and/or the duration of the vibration and/or the force and/or the duration of the downward pressure in response to the error signal.

Controlling the force of the downward pressure on the track in response to the error signal has the best results, i.e. the track responds best to changes in the force of the pressure as far as track leveling is concerned. However, changing the vibration frequency and/or amplitude also has advantages. Combining and- /or selecting the indicated controls enables the operator to adapt the operation to ballast beds of all types.

It is particularly useful to select the downward pres sure force so that it corresponds to the order of magnitude of the train loads expected in traffic over the surfaced track section. However, since this would require very heavy surfacing equipment, it is advantageous to press the track down by a pulsating stress force. Such a stress may be a dynamic force and is, therefore, independent of the weight of the machine. In a preferred embodiment, the pressure force has a static and dynamic component, the dynamic component being an oscillating force whose amplitude does not exceed twice the static component of the pressure force. In this way, the pulsating stress will press on the track without lifting the apparatus off the track.

It is possible to effectuate track surfacing according to the invention stepwise or continuously as the apparatus advances along the track. In the latter case, it is useful to determine any deviation of the track position from the desired level continuously while imparting the horizontal vibration and downward pressure to the track. This may be done, for instance, with the track 3 correction apparatus described and claimed in US. Pat. Nos. 3,21 1,109 or 3,042,982. Since the abovedescribed controls make it possible to position the track at the desired level relatively rapidly in accor-v dance with the invention, the continuous method produces a very high efficiency.

The determinative opertional parameters, such as pressure force, frequency and amplitude of vibration, and duration, may be controlled not only in response to an original error signal but also by a continuous error signal during the movement of the track to the desired level. Thus, it may be useful to increase the pressure force as the track approaches the desired grade since the compaction of the ballast increases correspondingly so that the ballast yields less and less to the downward pressure. In this way, the duration of the downward pressure may be decreased and the efficiency of the operation proportionally increased.

Also, the amplitude of vibration may be considerably reduced or the vibration may be totally stopped shortly before the track reaches the desired level so that the ballast pieces will not be unduly dislocated by vibrations at this level.

Since the downward pressure lodges the track ties within the ballast, the track surfacing according to the present invention also tends to fix the track strongly in its lateral position. Therefore, it will be most useful to line the track ahead of the track surfacing or in the range thereof.

In the apparatus according to this invention, the arrangement and type of means for imparting a substantially vertical downward pressure on both rails of the track are of particular importance. The preferred pressure means are hydraulic rams and, to make a continuous operation possible, the rams are supported on a mobile apparatus and preferably are mounted in vertical alignment with rail engaging wheels to exert the pressure on the track by means of the wheels. Thus, with the proper pressure control for the rams, the pressure force may reach the magnitude of the weight of the apparatus.

To obtain different pressures along the track section in the surfacing zone, a plurality of hydraulic rams may be spaced in the direction of track elongation and may be subjected to different pressures. In this manner, no special controls are needed to obtain a stepped change in the pressure force exerted upon the same track point as the apparatus advances continuously along the track. It is also useful to arrange a plurality of pressure means in a direction transverse to the track since different pressures applied to such means can take into account any superelevation of the track or different track level errors at the two rails at the same track point.

Similarly, a plurality of vibration imparting means may be spaced in the direction of track elongation so that the vibration amplitude may be changed simply by switching on or off additional vibrators.

The above and other objects, advantages and features of the present invention will become more apparent from the following detailed description of certain now preferred embodiments thereof, taken in conjunction with the accompanying drawing wherein FIG. 1 is a schematic side elevational view of an apparatus incorporating structures arranged and designed to carry out the method of this invention;

FIG. 2 is a like view of such an apparatus incorporating modified structures of the indicated type;

FIGS. 3 and 4 are schematic transverse sections of the apparatus of FIG. 2 along lines IlIIII and IVIV, respectively;

, FIGS. 5 and 6 are side elevational and top plan views, respectively, of an embodiment of an auxiliary car carrying the pressure-applying and vibrator structures used in the invention;

FIGS. 7 and 8 are transverse sections of the auxiliary car along lines VIIVII and VIIIVIII, respectively, of FIG. 6;

FIGS. 9 to 13schematically illustrate various embodiments of structures for transmitting horizontal vibrations from the vibrations to the track;

FIG. 14 schematically illustrates an embodiment of a structure for transmitting horizontal vibrations directly to the track ties;

FIG. 15 is a circuit diagram of a control circuit for controlling the downwardly applied pressure in dependence on, or a function of, the position of the track;

FIGS. 16 and 17 are circuit diagrams of control circuits for controlling the frequency of the vibrations in dependence on, or a function of, the position of the track;

FIGS. 18 and 19 are circuit diagrams of control circuits for controlling the amplitude of the vibrations in dependence on, or a function of, the position of the track;

FIG. 20 is a circuit diagram of a control circuit for simultaneously controlling the downwardly applied pressure and the amplitude of the vibrations in dependence on, or a function of, the position of the track; and

FIG. 21 schematically shows an embodiment of the invention in combination with a track leveling and tamping machine, in side elevation.

Referring now to the drawing, wherein like reference numerals designate like parts operating in a like manner in all figures, FIG. 1 shows a mobile apparatus with a machine frame 1 mounted on wheels 2 running on rails 6 which, together with ties to which the rails are affixed, form the track.

Track sensing elements

3 and 4 are vertically movably mounted in frame 1 at its front and rear ends, respectively, the lower ends of the track sensing elements engaging the track while their upper ends carry a reference line, for instance a tensioned wire 5. In the illustrated embodiment, the track sensing elements are bogies whose wheels run on the track rails and which carry poles on whose tops rollers are mounted over which the tensioned wires 5 are trained. As is well known, reference wires 5 serve as a reference for determining the desired track level.

A measuring device 7 is mounted on frame 1 to mea sure the vertical distance between each rail 6 and its associated reference wire 5. For this purpose, the upper end of measuring device 7 carries a sensor for sensing the level of reference wire 5. This sensor may be, for instance, a wire engaging element, such as a fork or a roller, connected with a potentiometer. The potentiometer is adjusted mechanically by the reference wire or by servomechanical means whenever there is a change in the distance between a rail and its associated reference wire. The amount of adjustment of the potentiometer is a measure of the change of distance, as is more fully described in us. Pat. No. 3,547,039, dated Dec. 15,1970.

Thelower end of measuring device 7 is affixed to pressure'roll 8 which is pressed against the associated raily6, for instance by hydraulic ram 9 which exerts a vertically downward pressure on the roll. In this manner, the pressure roll follows the rail and transmits any changes in the distance between the railand the associated reference wire, due to a faulty track level, to the measuring device to actuate the potentiometer in the indicated manner.

Double-beveled or flanged wheels 11 are mounted on the machine frame to grip associated rail 6 (see FIGS. 9 to 13) and to hold each rail for substantially horizontal movement therewith, wheels 11 being arranged in pairs, with one wheel in front and the other wheel in back of pressure roll 8, preferably equidistant therefrom. A hydraulic motor 10 is associated with each wheel 11 to apply a downward pressure thereagainst to maintain the engagement between the wheels and their associated rails. A vibrator means (not shown) is associated with wheels 1 1 and arranged to impart vibrations or oscillations in a substantially horizontal direction transverse of the track to the wheels. Since hydraulic motors l0 assure gripping engagement of wheels 11 with rails 6, the substantially horizontal vibrations or oscillations are imparted to the track, i.e. the two rails affixed to the ties. Preferably, the vibrations imparted to the track will have the same or about the same frequency as the natural or characteristic frequency of vibrations of the track, for instance 8 to 13 cycles per second.

Mounted immediately behind the rear vibratory wheels 11 is a track lining unit 12 of generally conventional type and, therefore, illustrated only schematically. Such a unit includes track gripping rollers connected to a hydraulic motor for shifting the rollers laterally for lining the track.

The use of double-beveled wheels defining a substantially V-shaped peripheral groove engaging the rails enables the wheels to be used with rail heads of different widths and this assures constant gripping of the track rails during the continuous advance of the apparatus over a long stretch of track. Since the tail-gripping wheels are pressed down against the rails, the horizontal vibrations cannot cause disengagement of the wheels from the rails.

In essence, the apparatus of FIG. 2 has the same structure as that of FIG. 1 described hereinabove. Swivel trucks 2', 2 mounted machine frame 1 for mobility on the track rails, a pair of front and

rear sensing elements

3 and 4 carrying the reference wire 5 for determining the level of the track.

In this embodiment, a vertically adjustable auxiliary car 13 is arranged underneath machine frame 1 and is attached thereto by coupling rod 30. The auxiliary car runs on

wheels

14, 14 on the track rails. A pair of

hydraulic rams

15, 15 are mounted between frame 1 and frame 16 of the auxiliary car vertically aligned with a respective pair of

wheels

14, 14 so that the wheels are pressed vertically downwardly against the track rails. In this manner, the

car wheels

14, 14 operate in the same way as pressure rolls 8 to exert a downward pressure on the track. A pair of double-beveled or flanged wheels 17 are joumaled on axle 18 intermediate the

pressure wheels

14, 14, preferably equidistant therefrom, the axle being mounted on car frame 16 (see FIG. 4). Vibrator means 19, such as rotating unbalanced weights, are mounted on axle 18, the main component of the vibrations caused by this means extending in a substantially horizontal plane. These vibrations are transmitted from the axle by wheels 17 to the track.

As shown in FIGS. 2 and 3, auxiliary car 13 carries a measuring device 7 associated with each wheel 14 for measuring the distance between the track and the reference line 5 at each wheel. In this manner and as will be explained hereinbelow, the downward pressure exerted upon the track by hydraulic motors 15 through wheels 14 may be controlled at different track points in dependence on the position of the track at these points.

In this embodiment, too, a track lining unit 12 is mounted on frame 1 behind the arrangement for exert ing a downward pressure and a horizontal vibration upon the track.

FIGS. 5 to 8 show a specific embodiment of an auxiliary car, such as used in the embodiment of FIG. 2. The car comprises essentially a frame 16 of rectangular or quadratic shape which carries a pair of axles 20 on whose ends wheels or pressure rolls 14 are joumaled. Pivots 21 are mounted on car frame 16 vertically above

axles

20, 20, the outer ends of the piston rods of

hydraulic rams

15, 15 being affixed to the pivots while the opposite ends of the hydraulic ram cylinders are affixed to pivots 22 which are mounted on machine frame 1, each axle 20 and pivots 21, 22 lying in a vertical plane extending transversely of the track. Hydraulic rams 15 not only exert a downward pressure on wheels 14 of the auxiliary car but also serve for the vertical adjustment of the car.

A pair of symmetrically arranged

transverse braces

23, 23 reinforce and sub-divide car frame 16. A boxshaped carrier 24 is mounted on the frame between the transverse braces by means of

parallel links

25, 25 which enable the carrier to be vertically reciprocated in relation to frame 16. A pair of unbalanced

rotating weights

26, 26 is mounted on the carrier symmetrically in respect of the longitudinal axis of the track on each side thereof, the weights of each pair rotating in opposite directions, as indicated by the arrows in FIG. 8.

Bearing boxes 27 are mounted on each end of the carrier 24 and double-beveled wheels 28 are joumaled in the bearing boxes. Fluid pressure motors 29 are linked between the carrier and machine frame 1 to exert downward pressure on wheels 28 as well as to enable the carrier to be vertically reciprocated by swinging

links

25, 25 up and down. The links 25 are sufficiently resilient in a transverse direction to permit carrier 24 to be swung slightly in a direction transverse to the track so that its horizontal vibratory forces are kept from auxiliary car frame 16.

Coupling rods 30 connect the auxiliary car to machine frame 1 to prevent the car from moving in forwardly or backwardly in the direction of track elongation when the hydraulic rams 15 exert a downward pressure on the track.

Each measuring device 7 includes a vertical pole 31 pivoted to the car frame 16 and moving vertically with it in response to the track position at the track point engaged by a respective wheel 14.

Since it is the purpose of the present invention to fix the track at a desired level by subjecting it to horizontal vibrations and pressing it downwardly to the desired level, the arrangement of the means for transmitting the downward pressure and the vibrations to the track and thus to the ballast therebeneath is of special importance. In this respect, the mounting of these means on an auxiliary car, as shown in FIGS. 2 to 8, is particularly useful because this enables the vibrations to be kept away from the main frame of the mobile apparatus and any sensitive measuring instruments mounted thereon.

In addition,'the auxiliary car, being relatively small and light, can better follow the track and thus increases the accuracy of the measurements of the distance between the track and the reference line, which determine the accuracy of the leveling operation.

It is particularly useful to superimpose a dynamic component upon a static component of the downward pressure force so that the track is subjected to a pulsating stress in a vertical direction. This is accomplished most advantageously in the manner illustrated in FIG. 7 wherein a vibrator 33 constituted by a rotating unbalanced weight is mounted in the line of the downward pressure force exerted by hydraulic ram 15. In this manner, the dynamic force of vibrator 33 is arithmetically added to the pressure force of motor without uncontrollable lateral movements or vibrations.

As shown in FIG. 7, the lower end of hydraulic ram 15 is supported by a spring means 32, for instance a cup spring, on vibrator 33 which is mounted directly on frame 16 of the auxiliary car. The interposition of the spring means has the advantage of keeping vibrations away from machine frame 1.

If desired, more than one vibrator may be arranged between the pressure means 15 and the car frame 16 so that only vibrations in a horizontal direction are transmitted to the frame. If the maximum vibratory force is chosen to equal the pressure force of ram 15, the track will be subjected to a pulsating stress between zero and twice the pressure of ram 15. In this manner, considerable pressure may be exerted upon the track without unduly increasing the weight of the machine.

As shown in FIG. 7, the upper end of pole 31 of measuring device 7 is glidably guided in a bushing in frame 1 and carries potentiometer 72 which is adjusted by a fork 71 holding the reference wire 5, the potentiometer producing a control signal corresponding to the track position in a manner well known in track leveling operations.

FIG. 8 illustrates a hydraulic motor 29 associated with each bearing box 27 so that each wheel 28 is pressed against the rail head it grips. Each bearing box carries a transverse block 34, the inner ends of blocks 34 being interconnected by connecting block 35 which is pivoted to the transverse block ends at 36. This arrangement makes it possible for the wheels 28 to adapt to changes in the track gage (see also FIG. 13).

FIGS. 9 to 14 show modifications of means for transmitting horizontal vibrations or oscillatory forces to the track, such means being adaptable to varying track gages and changing widths of the rail heads.

While it would be possible to use only a single double-beveled wheel for the transmission of the horizontal vibrations to the track, it is preferred to use at least one such wheel for each rail so that both rails may be vibrated simultaneously and thus to relieve undue pressure on the fastening means'which attach the rails to the ties.

The simplest vibration transmitting means is illustrated in FIG. 9 wherein two double-beveled wheels 41 are journaled on transverse axle 40 at a fixed distance from each other. The V-shaped peripheral grooves of the wheels have a relatively small apex angle and the rail heads are received in these grooves with some play. Vibrating means 42 is arranged to impart a horizontal oscillation to axle 40, this oscillation being transmitted by wheels 41 to rails 6. As indicated by the arrows, the vibrating means comprises a pair of unbalances rotating in opposite directions so that the vertical vibrations are substantially eliminated and only the horizontal vibratory components remain. Since the rail heads are received in the wheel grooves with play, this arrangement will adapt to varying widths of the rails heads as well as small changes in the track gage.

In the embodiment of FIG. 10, two parallel transverse axles 40 are spaced from each other. The opposite ends of the adjacent axles carry double-beveled wheels 41 gripping a respective one of heads of rails 6 while the other end of each axle carries a smooth roller 43 running on top of the rail heads. The Wheels and rollers are mounted on the axles at a fixed spacing but since the axles are laterally movable independently of each other, this arrangement permits a much wider adaptation to varying track gages than the embodiment of FIG. 9. The axles may, if desired, be journaled in a frame which is laterally movable. Such gage changes will not influence the transmission of vibrations from the axles to the track due to changes in the track gage.

In the illustrated embodiment, vibrating means 42 are mounted on each axle 40 to impart horizontal vibrations thereto in a manner described in connection with FIG. 9 but care must be taken for the two vibrating means to rotate synchronously and in the same phase so that the same vibratory force is exerted upon both rails of the track. It would be possible, of course, to replace the two separate vibrating means by a single vibrator arranged to impart horizontal oscillations to both axles simultaneously.

FIG. 11 shows another modification of vibration transmitting means useful for the adjustment to variations in the track gage. A single transverse axle 40' carries two double-beveled wheels 41, 41', wheel 41 being mounted on the axle against transverse movement in relation thereto when a hydraulic motor enables the wheel 41 to be transversely moved along the axle for changing the distance between the wheels and thus to adapt them to different track gages.

The hydraulic motor comprises a cylinder 44 whose end walls define aligned bores through which axle 40 passes in a fluid-tight manner, wheel 41 being carried by the cylinder. The cylinder is glidably mounted on collar 45 of axle 40'. The collar functions as a piston when pressure fluid is delivered to, or removed from, the cylinder chambers through

conduits

46 and 47, the flow of the pressure fluid moving the cylinder laterally on the axle. To avoid interference with the transmission of the vibrations produced by vibrating means 42 from axle 40' to the wheels and the track rails gripped thereby, a stop device 48 is provided to hold the wheel 41' in an adjusted position. This device consists essentially of a two-way solenoid valve which can be moved into a stop position which prevents delivery or removal of pressure fluid from the cylinder chambers so that there can be no relative movement between piston 45 and cylinder 44.

In the embodiment of FIG. 12, the double-beveled wheels 41 are journaled in the lower ends of carrier arms 50 which are pivotal intermediate their ends about fulcrum axes 51 extending substantially in the direction of the track to enable the carrier arms to be pivoted in a vertical plane transverse to the track. The upper ends of the carrier arms are linked to doubleacting, pressure fluid operated adjustment device 52. By delivering and/or removing pressure fluid through

conduits

53 and 54, the adjustment device will pivot tions in the track gage.

While the fulcrums 51 may be mounted on boxshaped carrier 24 of the auxiliary car 13 (see FIGS. to 8), if desired, it is preferred, as shown in FIG. 12, to couple the fulcrums by a rigid carrier 55 for vibrating means 42 while the upper ends of the carrier arms 50 are guided in slotted guides in the main machine frame. In this manner, the vibratory forces are transmitted to the double-beveled wheels along the main axis so that the carrier arms may oscillate together with the laterally adjustable carrier 55 without the adjustment device 52 being unduly subjected to vibrations.

It would also be possible to connect the vibrator means directly with the carrier arms for the wheels or I to mount them directly thereon and to operate them synchronously and in the same phase.

Somewhat similarly to FIG. 8, the embodiment of FIG. 13 has two double-beveled wheels 41 mounted on the short arms of two-

armed levers

56, 56 which are pivoted intermediate their ends to frame 16 of an auxiliary car, for pivoting in a vertical plane transverse to the track about fulcrums 57. The ends of the other lever arms are linked together by connecting link 58 whose ends are pivoted to the other lever arm ends at 59, 59. This arrangement makes it possible to adapt the wheels to varying track gages, wheels 41 assuming the position indicated in broken lines at the left of the figure when the track gage decreases while the wheels swing the other way when the track gage becomes larger. Vibrating means 42 are mounted on. the car frame to impart horizontal oscillations to the wheels.

In the embodiment of FIG. 14, horizontal vibrations are transmitted to the track in a manner similar to that of FIG. 12, but, instead of being transmitted to the track rails, as in the embodiments of FIGS. 9 to 13, they are transmitted to the ends of the track ties. This embodiment is particularly useful when concrete ties are used.

As will be seen in FIG. 14, carrier an 60, 60 are spaced apart a distance corresponding roughly to the length of the ties and are pivotal in a vertical plane transverse to the track about

fulcrums

61, 61. Pressure fluid operated

adjustment devices

62, 62 are linked to the upper ends of the carrier arms while the lower carrier arm ends have

pressure plates

63, 63 which may be pressed against the tie ends by operation of the adjacent devices. Fulcrums 61 are connected by rigid carrier 64 to which horizontal vibrations are imparted by vibrator 65 which, in the illustrated embodiment, has the form of a eccentric shaft. The entire vibrating arrangement may be vertically adjusted by means of hydraulic motors 66.

It is one of the essential features of the present invention to couple the reference system, i.e. the means for surveying and indicating the level of the track, with the means for downwardly pressing and horizontally vibrating the track so that the operating parameters may be controlled so as to reposition the track at the desired level. Therfore, the apparatus comprises a reference system which includes a measuring device for ascertaining the difference between the actual and the desired track level, which is well known per se in the track leveling art, and operatively coupled thereto a control circuit responsive to the track level measurements for actuating the downward pressure and horizontal vibrating means in dependence on, or a function of, error signals produced by the measuring device at successive track points.

FIGS. 15 to 20 illustrate different embodiments of such controls enabling selected operating parameters for the track leveling operation, such as the downward pressure force, the frequency and/or amplitude of the horizontal vibrations, and the duration of the pressure and/or vibrations, to be controlled in dependence on an initial error signal, i.e. an initial measurement of the distance between the track and the reference line which indicates a deviation from the desired track level, or on continuous and successive error signals corresponding to successive track points traversed by the continuously advancing machine.

The circuit diagram of FIG. 15 shows a control enabling the downward pressure force exerted upon the track to be controlled in response to a continuous measurement of the difference between the actual and the desired track level. This control circuit comprises a bridge circuit which includes potentiometer 72 (see FIG. 7) whose output signal is adjusted by fork 71 which holds reference wire 5 and, therefore, is moved in dependence on the wire position, i.e. its distance from the actual track level. Thus, the output voltage of the potentiometer is proportional to the actual track level as compared to the desired level which is set by the reference wire. The resultant output signal of bridge circuit 70 and a signal corresponding to the desired track level are compared in amplifier 73. The resultant reference signal is amplified in the amplifier and forms the output signal of the amplifier, which is proportional to the difference between the actual and the desired track levels. The amplified output signal is transmitted to solenoid valve 74 which is continuously adjustable to control and adjustment of the valve in response to the measured track level error. Valve 74 is arranged in the hydraulic fluid flow circuit delivering hyraulic fluid to the downward pressure applying motors, for instance hydraulic motors 9 or 15 (FIGS. 1 and 2), to control the hydraulic fluid delivery, i.e. the pres sure, in proportion to the amplified control signal coming from bridge circuit 70 and amplifier 73.

The hydraulic fluid flow circuit comprises a hydraulic fluid sump whose fluid delivery line is connected to the input of constant speed pump 75. The output of the pump leads to slide valve 76 which controls the fluid flow to

rams

9 or 15 so that it stops fluid delivery entirely when the control signal is zero, i.e. the track has reached the desired level, while the fluid flow is varied by valve 74 in response to variations in the control signal. A signal indicator 77, such as an amperemeter, is arranged in the electrical circuit between amplifier 73 and valve 74 so that the size of the control signal may be read by an operator who is thus enabled to see the extent of the required track repositioning.

While the control signal, which is proportional to the track level error signal, has been used to control the downward pressure on the track in the embodiment of FIG. 15, FIGS. 16 and 17 illustrate control circuits which control the frequency of the horizontal vibrations imparted to the track in response to such control signals. In these embodiments, the structure and operation of circuit elements 70 to 73 are identical to those of FIG. 15, the embodiment of FIG. 16 also providing amperemeter 77.

In the control circuit of FIG. 16, the control signal is transmitted to valve 80 to control the amount of hydraulic fluid flowing through hydraulic fluid circuit 81. The circuit 81 includes the constant speed pump which receives hydraulic fluid from hydraulic fluid sump 83 wherein the hydraulic fluid is held at atmospheric pressure, and also hydraulic motor or motors 82 which drives or drive the vibrating means for imparting horizontal oscillations to the track. The output of motor or motors 82 is proportional to the hydraulic fluid throughput in circuit 81 controlled by valve80, i.e. proportional to the control signal, the changing motor output correspondingly varying the horizontal oscillations or vibrations. For instance, if the frequency of the vibrations was near the resonance point of the track at the beginning of the operations at a given difference between the actual and the desired track levels, it will be changed away from resonance as the track level approached the desired level.

In the control circuit of FIG. 17, the frequency of the vibrations is controlled only by electrical means. Here again, the structure and function of circuit elements 70 to 73 are identical with those of FIG. and, therefore, require no further description. However, the hydraulic fluid circuit 81 of FIG. 16 is replaced by electrical circuit 90. Direct current drive motor 91 for the vibrating means is arranged in shunt in circuit 90. The control signal is transmitted from amplifier 73 to drive motor 94 which moves sliding contact 93 of variable resistance 93 in circuit 90 so that the power supplied to field coil 92 of direct current motor 91 is changed in proportion to the control signal. This changes the rotational speed of drive motor 91 and correspondingly the frequency of the vibrations produced by the vibrating means driven by motor 91. If the control signal were sufficiently amplified in amplifier 73, it could be used directly for the adjustment of variable resistance 93 without interposition of motor 94.

FIGS. 18, 19 and 20 show controls for changing the amplitude of the horizontal vibrations in response to the error signal by switching a selected number of vibrators on or off.

Referring to the circuit diagram of FIG. 18, two separate control circuits I and II are provided for operating

drive motors

100 and 101, respectively, for the vibrating means. The two control circuits are closed, i.e. power is fed to the drive motors, by closing

switches

102 and 103, respectively. Opening and closing of the switches is controlled by

switch tripping relays

104 and 105, respectively which are operated mechanically directly by camming surface 106 affixed to the pole of measuring device 7. The distance between the camming surface 106 and reference wire 5 is constant.

Switch tripping relays

104, 105 are mounted on rolls 8 or 14 (see FIGS. 1 and 2) so that the position of the camming surface 106 in relation to

relays

104, 105 will depend on the level of the track.

If the actual track level is above the desired track level within a predetermined normal range of magnitude, camming surface 106 will actuate only relay 105 (as shown in FIG. 18) so that only control circuit I is closed to operate the vibrating means drive motor 100. However, if the actual track level is particularly high so that increased force is desirable for pressing the track 106 is mounted on the pole of measuring device 7 and remains at a constant distance from the rail on which the pole for measuring device 7 rides. Relays 104, are mounted on the frame of the apparatus or on pressure rolls 8 or 14 and will be sequentially tripped as the pole rises. Sequential operation of the relays will sequentially operate

solenoid slide valves

112 and 113 placed in the respective hydraulic fluid circuits delivering oil from sump 111 to constant speed pumps 109 and 110, respectively, supply of hydraulic fluid operating

hydraulic drive motors

107 and 108, respectively, for the vibrating means. Thus, the extent of the required correction stroke for pressing the track down to the desired level controls the operation of the vibrating means in the manner described in connection with FIG. 18.

FIG. 20 shows a control circuit diagram for controllingthe stepwise actuation of additional vibrators for increasing the vibration amplitude as well as additional hydraulic rams for increasing the downward pressure on the track in proportion to the length of the correction stroke required to reposition the track at the desired level.

The control circuit elements 70 to 73 are again the same as those described in connection with FIGS. 15 to 17, providing a control signal at the output of amplifier 73 which is proportional to the track level error. This error signal is transmitted to computer which classifies the signal into individual signal steps, the illustrated embodiment providing three signal steps, the three resultant output signals of computer 120 operating

solenoid slide valves

121, 122 and 123 which control

hydraulic drive motors

124, 125 and 126 sequentially, the valves and associated drive motors being arranged in three separate hydraulic fluid circuits. The drive motors operate the vibrating means. Furthermore,

hydraulic rams

130, 131 and 132 for experting downward pressure on the track are also mounted in the respective hydraulic fluid circuits, the pressure in the latter motors being controlled by pressure reducing

slide valves

127, 128 and 129, respectively. These valves are also controlled by the output signals from computer 120.

If the output signal of amplifier 73 indicates a relatively small track level error, it will be classified only in one step of computer 120. Thus, only a single vibrating means drive motor and a signle downward pressure ram will be actuated. As the level error increases, producing an error signal at the output of amplifier 73 proportional thereto, the computer will sequentially actuate the additional vibrating means drive motors and downward pressure rams. A further differentiation in the force applied to the track may be achieved by using vibrators with different amplitudes and rams with different pressures. It would also be possible, of course, to operate the vibrating means and the downward pressure rams independently by computer 120.

As will be obvious from the above description of certain now preferred embodiments of the present invention, apparatus according to this invention makes it possible to do track maintenance work attuned most sensitively to various requirements and conditions encountered in compacting ballast underneath a track and positioning the track at a desired level. Thus, it is possible to control not only the speed in which the desired track level is reached but also the nature of the ballast tamping. Since these factors depend at least one three parameters, i.e. the downward pressure force, the frequency and the amplitude of the horizontal vibrations to which the track is subjected, variations in these parameters may be variously controlled and coordinated to meet all requirements in a most sensitive manner. Furthermore, in a continuous track work operation, it is possible to operate the parameters sequentially at any given track point. It is also possible to anticipate an observed track depression of excessive magnitude before this point is reached by lifting the track at this point particularly high.

The invention may be advantageously combined with a mobile track leveling and lining machine of otherwise conventional structure, the track tamping, leveling and lining means being mounted on the machine frame ahead of the means for vibrating the track horizontally and pressing it downwardly, in the working direction of the machine.

An apparatus of this type is shown in F [G 21 wherein an elongated machine frame runs on the track on

wheels

2, 2, tamping assembly 140 being mounted on an overhanging frame portion whose front holds track jack 141 for leveling and/or lining the track, the leveling being effected in relation to reference line A mobile track working machine of this general type is shown, for instance, in US. Pat. No. 3,21 1,109, dated Oct, 12, 1965, but any other track leveling and/or lining machine may be used. Analogous to the embodiment of FIG. 2, auxiliary car 13 with its gear according the the invention, is mounted intermediate the machine wheels.

With a machine of this type, the track may be raised by jack 141, at which time it may also be lined by the jack, the ballast may be tamped underneath the ties by assembly 140, and the track is then pressed down to the desired track level while being horizontally vibrated at any selected track point according to the invention, the repositioning of the track simultaneously causing com paction of the ballast thereunder.

It will be clearly understood that the present invention is not limited to the specifically described embodiments thereof. For instance, while one type of measuring device has been described and illustrated, many devices are known and useful for the practice of this invention for indicating a track level error and producing a proportional error signal for controlling track leveling mechanisms. Such devices may work with reference beams of electromagnetic radiation, such as light or laser beams, instead of reference wires, as illustrated herein.

Furthermore, any suitable vibrating means may be used for imparting substantially horizontal vibrations or oscillations to the track, including rotating unbalanced weights, vibrating rams or eccenter shafts. The only essential characteristic of the vibrating means is that it has a marked horizontal component for imparting a substantially horizontal vibration to the track. It is also essential that the means for transmitting the vibrations to the track is so arranged that the track will vibrate with substantially the same frequency and amplitude as the controlled vibration of the vibrating means.

While hydraulic rams have been illustrated for exerting a static downward pressure on the track, spindledriven or like rams could equally used for this purpose, the type, arrangement and number of rams varying greatly according to requirements and conditions. Any desired dynamic pressure component may be produced not only by the illustrated vibrators but also by other suitable pulsors. Selected combinations of means for producing static and dynamic pressure components will 14 result in pressure forces of a type and magnitude encountered when trains pass over the track. When the force of the downward pressure is controlled by switching on additional rams, the sensitivity of the control will depend on the number of the rams provided.

While a number of controls have been illustrated, this does not exhaust the possibilities. For instance, the controls for the pressure, the frequency and the amplitude of the vibrations may be combined in any desired manner. Thus, the illustrated control diagrams will be understood to show only the principles of useful controls.

We have found that track surfacing according to the present invention holds the track at the desired level for a very long period of time since it compacts the ballast to an extent equivalent to that usually accom plished only by long and extensive train traffic and the resultant pressures and vibrations to which the passing trains subject the ballast. Furthermore, such track surfacing also results in a considerable compaction of the ballast at the ends of the ties, which has a most advantageous effect on the lining of the track.

The metes and bounds of the invention are defined by the appended claims.

What we claim is:

1. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and means for transmitting the vibration produced by said means to the track, and means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

2. The track surfacing apparatus of claim 1, further comprising an apparatus frame and an auxiliary car vertically adjustably mounted on the apparatus frame, the auxiliary car carrying the vibration and pressure imparting means.

3. The track surfacing apparatus of claim 1, wherein the means for imparting the downward pressure on the rails comprises hydraulic rams supported on the apparatus.

4. The track surfacing apparatus of claim 1, further comprising ballast tamping and track lifting means mounted ahead of the vibration and pressure imparting means in the Working direction of the apparatus.

5. The track surfacing apparatus of claim 2, wherein the means for transmitting the vibration comprises double-flanged wheels engaging the track rails and imparting the vibration to the track rails.

6. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and a pair of pressure plates vertically adjustably arranged for pressure engagement with the end of respective ones of the ties for transmitting the vibration produced by the vibration-producing means to the track, means for varying the distance between the pressure plates in the direction of elonga' tion of the ties to effectuate said'pressure engagement, and means arranged in association with the Vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

7. The track surfacing apparatus of claim 6, wherein the distance varying means includes a pair of guide levers carrying the pressure plates, the guide levers being operatively coupled to the vibration-producing means.

8. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and a pair of double-beveled rotatable wheels each defining a substantially V- shaped peripheral groove receiving the rail heads of the respective rails for transmitting the vibration produced by the vibration-producing means to the track rails, and means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

9. The track surfacing apparatus of claim 8, wherein the groove has an outer portion wider than the width of the rail head received therein.

10. The track surfacing appartus of claim 8, further comprising two parallel transverse axles spaced from each other and laterally movable in respect of the track, the rotatable wheels being fixedly mounted on opposite ends of the adjacent axles for gripping a respective one of the rail heads in their peripheral grooves,.and smooth rollers running on top of the rail heads carried by the other axle ends.

11. The track surfacing apparatus of claim 8, further comprising a transverse axle for mounting the rotatable wheels at respective ends thereof, one of the wheels being mounted against transverse movement in relation to the axle, the other wheel being mounted for transverse movement in relation to the axle, and means for moving the other wheel to vary the distance between the wheels for adaptation to varying track gages.

12. The track surfacing apparatus of claim 11, further comprising means for stopping the other wheel in a selected lateral position.

13. The track surfacing apparatus of claim 8, further comprising a pair of guide levers carrying the rotatable wheels, and means for pivoting the guide levers in a plane transverse to the track about fulcrum axes extending substantially parallel to the track to vary the distance between the rotatable wheels.

14. The track surfacing apparatus of claim 13, further comprising a rigid carrier interconnecting the fulcrums of the guide levers intermediate their ends, the

vibration-producing means being carried by the carrier,

hydraulic rams supported on the apparatus in associa' tion with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level, and a vibration-producing means associated with respective ones of the hydraulic rams, the latter means being arranged to produce vibrations substantially parallel to the ram pressure.

16. The track surfacing apparatus of claim 15, further comprising a spring means mounted between the vibration-producing means and the apparatus whereon the ram is supported.

17. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and means for transmitting the vibration produced by said means to the track, rail engaging wheels and hydraulic rams mounted in vertical alignment with the wheels on the apparatus in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

18. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and means for transmitting the vibration produced by said means to the track, and a plurality of hydraulic rams supported on the apparatus and spaced from each other in the direction of track elongation in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

19. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track, an apparatus frame, and an auxiliary car vertically adjustably mounted on the apparatus frame, means carried by the auxiliary car and arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby ballast under the track ties may be compacted simultaneously with positioning the track at the desired level, said pressure imparting means including rail engaging wheels mounting the auxiliary car for movement along the track and hydraulic rams in vertical alignment with the wheels to exert the pressure on the track by means of the wheels, one end of the rams being supported on the apparatus frame while the other ends thereof are supported on the auxiliary car.

20. The track surfacing apparatus of claim 19, further comprising elongated rods coupling the auxiliary car to the apparatus frame, the respective arm ends being pivotally supported on the apparatus frame and the auxiliary car.

21. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level including means for producing an error signal proportional to the determined deviation, means for imparting a substantially horizontal vibration to the track, means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under th track ties may be compacted simultaneously with positioning the track at the desired level, and

further comprising electrical control circuit means responsive to the error signal for actuating the vibration and downward pressure imparting means.

22. The track surfacing apparatus of claim 21, wherein the means for determining the track position deviations is mounted adjacent the pressure imparting means.

23. The track surfacing apparatus of claim 21, wherein the electrical control circuit means is arranged to control pressure imparting means associated with each rail separately.

24. The track surfacing apparatus of claim 21, wherein the means for determining the track position deviations includes a potentiometer adjustable in response to the deviations to produce the proportional error signals, and the electrical control circuit means includes a bridge circuit comprising the potemtiometer and having an output, and a circuit element receiving the error signals from the bridge circuit output, comparing the error signal with a reference signal proportional to the desired track level, and producing an amplified control signal resulting from the comparison for actuating the vibration and downward pressure imparting means.

25. The track surfacing apparatus of 24, wherein the pressure imparting means comprises hydraulic ram means, a hydraulic fluid circuit delivering hydraulic 18 fluid to the ram means, and a solenoid pressure control valve in the fluid circuit, the valve being arranged in the control circuit means for actuation by the control signal.

26. The track surfacing apparatus of claim 24, wherein the vibration imparting means comprises vibration-producing means and hydraulic drive motor means for actuating the vibration-producing means, and further comprising a hydraulic fluid circuit delivering hydraulic fluid to the drive motor means, and a solenoid valve controlling the fluid throughput of the hydraulic circuit, the valve being arranged in the control circuit means for actuation by the control signal.

27. The track surfacing apparatus of claim 24, wherein the vibration imparting means comprises a vibration-producing means and an electric drive motor means for actuating the vibration-producing means, and further comprising an electric circuit operating the drive motor means, the electric circuit being energized by the control signal.

28. The track surfacing apparatus of claim 27, wherein the vibration and downward pressure imparting means includes a plurality of vibration-producing means and a plurality of pressure means, the electrical control circuit means being arranged to transmit the control signal in stages to selected ones of said vibration-producing and pressure means.

29. The track surfacing apparatus of claim 21, wherein the means for determining the track position deviations includes an element vertically moving with the track according to its level, a camming surface fixedly mounted on the element, and switch means in the electrical control circuit means arranged for se quential actuation by the camming surface in response to vertical track movement for transmitting the error signal to the selected vibration-producing and pressure means.

Claims

6. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and a pair of pressure plates vertically adjustably arranged for pressure engagement with the end of respective ones of the ties for transmitting the vibration produced by the vibration-producing means to the track, means for varying the distance between the pressure plates in the direction of elongation of the ties to effectuate said pressure engagement, and means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

8. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and a pair of double-beveled rotatable wheels each defining a substantially V-shaped peripheral groove receiving the rail heads of the respective rails for transmitting the vibration produced by the vibration-producing means to the track rails, and means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level.

10. The track surfacing appartus of claim 8, further comprising two parallel transverse axles spaced from each other and laterally movable in respect of the track, the rotatable wheels being fixedly mounted on opposite ends of the adjacent axles for gripping a respective one of the rail heads in their peripheral grooves, and smooth rollers running on top of the rail heaDs carried by the other axle ends.

14. The track surfacing apparatus of claim 13, further comprising a rigid carrier interconnecting the fulcrums of the guide levers intermediate their ends, the vibration-producing means being carried by the carrier, the rotatable wheels being mounted at one end of the guide levers, and the pivoting means being linked to the other ends of the guide levers.

15. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level, means for imparting a substantially horizontal vibration to the track including a vibration-producing means and means for transmitting the vibration produced by said means to the track, hydraulic rams supported on the apparatus in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under the track ties may be compacted simultaneously with positioning the track at the desired level, and a vibration-producing means associated with respective ones of the hydraulic rams, the latter means being arranged to produce vibrations substantially parallel to the ram pressure.

21. An apparatus for surfacing a track consisting of rails fastened to ties resting on ballast, comprising means for determining any deviation of the track position from a desired level including means for producing an error signal proportional to the determined deviation, means for imparting a substantially horizontal vibration to the track, means arranged in association with the vibration imparting means for imparting a substantially vertical downward ballast compacting pressure on both rails of the track whereby the ballast under th track ties may be compacted simultaneously with positioning the track at the desired level, and further comprising electrical control circuit means responsive to the error signal for actuating the vibration and downward pressure imparting means.

25. The track surfacing apparatus of 24, wherein the pressure imparting means comprises hydraulic ram means, a hydraulic fluid circuit delivering hydraulic fluid to the ram means, and a solenoid pressure control valve in the fluid circuit, the valve being arranged in the control circuit means for actuation by the control signal.

29. The track surfacing apparatus of claim 21, wherein the means for determining the track position deviations includes an element vertically moving with the track according to its level, a camming surface fixedly mounted on the element, and switch means in the electrical control circuit means arranged for sequential actuation by the camming surface in response to vertical track movement for transmitting the error signal to the selected vibration-producing and pressure means.