US3463095A

US3463095A - Track aligning machine

Info

Publication number: US3463095A
Application number: US682099A
Authority: US
Inventors: Franz Plasser; Josef Theurer
Original assignee: Individual
Current assignee: Franz Plasser Bahnbaumaschinen Industrie GmbH
Priority date: 1966-11-14
Filing date: 1967-11-13
Publication date: 1969-08-26
Anticipated expiration: 1986-08-26
Also published as: JPS5347020B1; GB1215938A; DE1605363C3; DE1605363A1; DE1605363B2; DE1780642B2; AT309499B; CH476161A; DE1780642C3; DE1780642A1

Description

Aug. 26, 1969 F, PLASSER ETAL 3,

TRACK ALIGNING MACHINE I 6 Sheets-Sheet 1 Filed Nov. 13, 1967 INVENTORS Franz Pllsser 3 564 Thea/er 1969 F. PLASSER ETAL 3,463,095

TRACK ALIGNING MACHINE Filed Nov 13, 1967 v 6 Sheets-Sheet 2 INVENTORS Fran L P/asse r BY Toad Theurer' HTTORNEYS Aug. 26, 1969 F. PLASSER ETAL 3,463,095

TRACK ALIGNING MACHINE Filed Nov. 13, 1967 6 Sheets-Sheet 5 I NVENTQR Franz Plassar 32 Theur'er HTTDRNEYS Aug. 26, 1969 F. PLASSER ETAL TRACK ALIGNING MACHINE 6 Sheets-Sheet 4 Filed Nov. 13, 1967 INVENTORSM Fwam; P! as s e r $931.1 The a r HTTOKNEYs g 1969 F. PLASSER ETAL 3,463,095

TRACK ALIGNING MACHINE Filed NO 13, 1967 6 Sheets-Sheet L l I uan] I I l l l I l INVENTORS Franz Plasser 3056.4 Theurev HTTORNEY5 F. PLASSER ETAL TRACK ALIGNING MACHINE Aug. 26, 1969 6 Sheets-Sheet (5 Filed Nov. 13. 1967 INVENTORS Fra n1 Plass Jose F The ur' r- I. I M

ET R ZW United States Patent ()fiice 3,463,095 Patented Aug. 26, 1969 3,463,095 TRACK ALIGNING MACHINE Franz Plasser and Josef Theurer, both of 3 Johannesgasse, Vienna 1, Austria Filed Nov. 13, 1967, Ser. No. 682,099 Claims priority, application Austria, Nov. 14, 1966, A 10,489/ 66 Int. 'Cl. E011) 33/00 US. Cl. 104-8 19 Claims ABSTRACT OF THE DISCLOSURE A track aligning machine for measuring, recording and/or correcting the position of rails comprising a vehicle suitable for rail travel and having rail alignment devices depending therefrom to selectively engage and displace the rails. At least one linearly extending chordal reference element is mounted on the vehicle with the ends thereof spaced from the rail. A transmission device is operatively connected between the chordal element and a transducer element which senses deviations of the rail from the desired path. An adjustment means is responsively connected to the transducer element to indicate the need for rail alignment.

The present invention relates to a system for aligning railway tracks, particularly for correcting the curves and transition curves between straight sections and curves.

Patents 3,165,838 and 3,314,373, both issued to the present inventors, are representative of known devices and methods of aligning railway tracks in which two chords of diiferent length are used. The end points of two chordal elements are held at a given distance from one rail of the track. The distances between the chords of the rail and the chordal elements are then measured, for instance at the center of the shorter chord. On the basis of these arc-height spacings it can be determined in what direction and to what extent the track must be displaced transverse to its longitudinal direction in order to obtain the greatest possible vibration-free travel of trains on the track.

Methods are also known which operate with only a single chord. The track aligning machine in accordance with the present invention can be equipped both with one and with two chordal elements.

In the known machines, the chordal elements form part of an electric circuit and are associated with fork members which are displaceable, for instance on a spindle by means of an electric motor, transverse to the direction of the track. The electric motor is connected for rotation in one direction or the other when the chordal element comes into contact with one or the other of the tines of the fork. With this arrangement it is not possible to avoid a break in the chord at the height of the fork, so that a linear course is not assured and accordingly errors in measurement can occur.

It is furthermore not possible in the known devices to establish a desired course of the track, particularly in the transition curves between a straight section and a curved section. Rather complicated calculations are generally required to accomplish this.

An object of the present invention is to provide a track aligning machine in which the relative changes in spacing of a given point of a chord, bent in the manner indicated from the associated rail, actuates an electromechanical transducer lying in an electric switch circuit. By an adjusting means, further provided in the switch circuit, it is assured that no control signal is given oil? by the switch circuit when the arc-height spacings are within a given range. The switch circuit will give an instruction to the operator to actuate the track aligning devices so as to produce a corresponding correction when the arc-height spacing deviate from the range. The rail correction can also be effected by automatic control of the track aligning devices. This function is particularly desirable when checking general transition curves of a parabolic course between straight lengths and curved portions of the track.

It is furthermore an object of the invention to arrange an adjusting device in the switch circuit in such a manner that it changes the switch circuit as a function of the advance of the machine so that the desired function is obtained.

The means for accomplishing the foregoing objects and other advantages, which will be apparent to those skilled in the art, are set forth in the following specification and claims and are illustrated in the accompanying drawings dealing with various embodiments of the present invention. Reference is made now to the drawings in which:

FIG. 1 is a side view of a track aligning machine;

FIG. 2 is a schematic plan view taken along lines IIII of FIG. 1;

FIG. 3 shows a schematic perspective view of one embodiment of the measurement point M taken along line III-III of FIG. 2;

FIG. 4 is an electrical schematic diagram of a first embodiment of a switch circuit;

FIG. 5 is an electrical schematic diagram of a second embodiment of a switch circuit;

FIG. 6 shows schematically an arrangement for transmitting the advancing movement of the rail vehicle to the potentiometer;

FIG. 7 shows schematically an embodiment in which two chords are contacted;

FIG. 8 shows a variant of the embodiment of FIG. 7 in which only a single chord is contacted;

FIG. 9 shows a wiring diagram corresponding to the embodiment shown in FIG. 7; and

FIG. 10 is a graph.

The track aligning machine, shown in FIG. 1, comprises an undercarriage frame 1 having spaced

wheel sets

2 and 3 thereon for movement along a track 4. In the center, between the

wheel sets

2 and 3 are track aligning devices 5, provided on both sides of the frame 1. The development and arrangement of the rail vehicle are not features of the present invention and are known to the man skilled in the art. Accordingly a detailed description thereof is unnecessary.

The track aligning devices 5 can be actuated in one direction or the other so that the section of track extending between the

wheel sets

2 and 3 is displaced arcuately, in one direction or the other, transverse to the longitudinal direction of the track. Since the rail vehicle can move by its own power on the track, the track aligning machine is operated to advance in steps of a given distance, for instance one quarter of the distance between the

wheel sets

2 and 3. The vehicle is halted between steps to allow operation of the track aligning devices 5, whereaftcr the vehicle again advances by the same amount. In this Way it is possible to align track sections of any desired length, i.e., to bring them into a position in which trains traveling over them at high speed are exposed to the lowest possible lateral accelerations and vibratory forces. Since the trains exert great force on the track, particularly along curves, the track is gradually forced out of the desired position so that realignment with a track aligning machine, and preferably the present invention, be-

comes necessary.

The present invention is concerned with determining the direction and the amount of displacement of the track required to properly align the rails and therefore is concerned with control of the track aligning devices.

The railway vehicle shown has a telescopically extractable bar 7 at both its front and at its rear ends.

Measurement carriages

6 and 8 are respectively fastened to front and rear bars. The

measurement carriages

6 and 8 are conventional and therefore have not been shown in detail. Each carriage can be pressed against one or the other of the rails so that errors in measurement as a result of tolerances are avoided.

The ends of a chordal element 9 which extends below the undercarriage of the rail vehicle are fastened to the

measurement carriages

6 and 8. By pressing these

small measurement carriages

6 and 8 against a rail along a curve, the carriage is generally pressed against the outer rail of the track, assurance is thus had that the ends of the chord 9 will be held fast and at a precisely defined distance from the reference rail. The telescopic rods 7 furthermore see to it that the chord 9 at all times has a straight course. Although the track aligning machine of the present invention can also operate with a single chord, there has been provided in the embodiment shown in the drawing a second chordal element 10 which is only half as long as the chord 9. The second chordal element 10 extends from the measurement carriage 6 to the center of the undercarriage frame 1 where it is fastened to the point 10a. In the example shown, the point 10a lies in the line of attack of the track aligning devices 5.

In order to make the vehicle suitable for use both for forward and for rearward travel, a second short chordal element 10 can be provided extending from the point 10a to the measurement carriage 8.

The rail vehicle has a measuring device M, by means of which the distance of the

chordal elements

9 and 10 from the reference rail of the track 4 is measured at a point which lies in the center of the shorter chord 10 and which divides the longer chord 9 in a ratio of A 2% For operation in the rearward direction, a second meas urement device M can be provided, as shown in FIG. 1. The distances of the

chordal elements

9 and 10 from the reference rail at the measurement point M are referred to hereinbelow as arc-height distances. The measurement method is in itself known and is described, for instance, the above mentioned patent 3,314,373.

FIG. 3 shows schematically an embodiment of the measurement device M. Each of the two

chordal elements

9 and 10 is connected with a

rope

13 or 13 respectively. The rope 13 extends over pulleys 11 and 12, and the rope 13' over the pulleys 11' and 12'. The

pulleys

11, 11' and 12, 12 have their shafts supported on the undercarriage frame. The shafts of

rotary potentiometers

14 and 15, the housings of which are also fastened to the undercarriage frame, are fixed to the shafts of pulleys 12 and 12', respectively. The ends of the windings of the potentiometers are connected to a power source 16 and the wipers are connected to

lines

17 and 17, respectively.

One possible switching arrangement is shown in FIG- URE 4 in which the wipers 17 and 17' of the potentiometers 14 and are connected to a measuring instrument 18.

When the

chordal elements

9 and 10 have the correct distance from the reference rail of the track *4, the wipers 17 and 17' assume a position in which they tap off the same voltages from their associated

potentiometers

14 and 15. The measuring instrument 18 accordingly does not receive any voltage difference and indicates a value of 0. When the short chordal element 10 is half as long as the long chordal element 9, the resistance of the

potentiometers

14 and 15 should be in a ratio of 1:3 (referring to the angle of rotation and assuming the same diameter for the pulleys 12 and 12'). The same effect is of course obtained when the ratio of the diameter of the pulleys is correspondingly varied. It can be shown that upon travel onto a curve, having a constant radius, the arc-height distance of the

chordal elements

9 and 10 from the rail changes in this very ratio. Therefore, when the track 4 lies properly in the curve, the instrument 18 will always indicate a value of 0. This means that the track aligning devices 5 remain out of operation. In case of a displaced track, the distance ratio of the chord-

a1 elements

9 and 10 from the reference rail changes. This means that the indicating instrument 18 will be deflected in either. a clockwise or counterclockwise direction.

By actuating the track aligning devices 5, the displacement error can be corrected until the indicating instrument 18 again indicates a value of zero. Instead of the indicating instrument 18, an automatic control can of course also be used.

A parabolic transition curve is generally interposed between a straight section of a track and a curved section. In order to be able to work parabolic transition curves, the invention further provides the track aligning machine with the parts shown in FIGURES 5 to 9.

Referring to the wiring diagram of FIG. 5,

potentiometers

19, 20 and 23g are connected parallel to the

potentiometers

14 and 15. All of these potentiometers are connected to the voltage source 16 by closing the switch 23i. They accordingly act as voltage dividers. The positions of the wipers 17 and 17' of the potentiometers 14a and 15 are dependent on the arc-height distance of the

chordal elements

9 and 10 from the reference rail, as has already been described. The

wipers

24 and 25 of the

potentiometers

19 and 20 are manually adjustable. Between the

wipers

24 and 25 there is connected a potentiometer 22 and the wiper 22' of which is adjusted as a function of the advance of the track aligning machine along the section of track to be worked. When the track aligning machine moves from a straight section onto a curve, then at the start of the transition curve the potentiometer 19 is adjusted to a measurement value which corresponds to the length of the transition curve. This can, for instance, be 500 meters. The rotary potentiometer 20 is adjusted to a given final measurement value which corresponds to the arc-height distance at the end of the transition curve, and therefore at the start of the actual track curve. The wiper 22 advances with the advance of the track aligning machine on the transition curve until, at the end of the curve, the voltage corresponding to the curve radius, which voltage had beenset on the potentiometer, is tapped off. The resistor 23a associated with the wiper 22' and the resistor 23c associated with the wiper 17 are preferably the same size so that no correction is necessary. If the chordal element 9 is at the correct distance from the reference rail, the wiper 17 of the potentiometer 14 will tap off the same voltage as the wiper 25 of the potentiometer 20. These voltages will cancel each other at the point of intersection 232. The indicating instrument 18 would accordingly not receive any voltage through the variable resistor 23d and the fixed resistor 23b. If the distance of the chordal element 10 from the reference rail corresponds to its desired value and th wiper 17 on the potentiometer 15 accordingly taps off the same voltage as the Wiper 23/1 on the potentiometer 23g, then there will also be a zero indication at the indicating instrument 18. Any deviations of the rail will thus appear on the measuring instrument 18. When the potentiometer and resistors are correspondingly adapted to each other, the instrument 18 can be so calibrated that the displaced position of the track can be read off directly in inches. However, this is not absolutely necessary since the position of track is generally immediately corrected until the indicating instrument 18 indicates a value of zero.

The control of the potentiometer 22 can be noted from FIG. 6. A flanged wheel travels on one rail of the track 4. The wheel 100 is connected to drive a shaft 102 via a worm gear 101 by means of a clutch 104, adapted to be manually actuated by lever 103, the shaft 102 can be brought into engagement with another shaft 105. The shaft 105 via a worm 106 and a worm gear 107 drives a cam 27. A cam follower 26 has one end biased against the cam so that the other end displaces the wiper 22" of the resistor 22. The cam 27 has specific curved profile sections corresponding to the points A, B, C and D which are calculated in accordance with the voltages to be tapped off.

When the aligning machine is on a straight section, the

potentiometers

19 and 20 are set to zero. When this is true or in all cases in which the

wipers

24 and 25 of the p tentiometers 19 and 20 have the same position, the rotation of the cam 27 and thus the movement of the wiper 22 of the potentiometer 22 has no effect since there is no voltage difference in the potentiometer 22.

If the machine now arrives at the transition curve located at the start of a curved portion of the track, the potentiometer 20 is adjusted to the value of the arc-height distance to be expected in the curved track. This distance becomes greater as the radius of the curve becomes smaller. The potentiometer 19 is set to the length of the transition curve. The cam 27 is turned by the operator until the start of the Section B rests against the cam follower 26. As the machine advances further into the region of the transition curve, the cam 27 makes a quarter of a revolution. When the point C is reached, the wiper 22' has moved over its full path. Since behind the point C the cam has a constant radius, no further displacement takes place.

At the end of the transition curve the operator will reset the potentiometer 19 to the value which the potentiometer 20 has. The setting of the full arc height of the actual track curve is then reached and is retained over the length of the track curve. At the end of the actual track curve, there is another transition curve adjoining the straight section. Therefore the increased arc-height distance must be again removed. The operator will reset the potentiometer 19 to zero and thereupon see to it that the point D on the cam 27 is against the cam follower 26. The output power transmitted by the potentiometer 22 to the indicating member 18 then begins to change again in a direction corresponding to a reduction of the arc height for the alignment point located within the transition arc, until the next track curve or a straight section with an arc height of zero is reached at the end of the transition curve. Thereupon the operator sets the potentiometer 20 to zero and the entire process for the setting is completed for the transition curve. This process takes place in similar manner when operating in the case of the transition curve from a curved track towards a straight section.

The main advantages of this solution reside in the fact that spindles, electric contact systems and servomotors are unnecessary and the error necessarily caused in the collaboration between a chordal element and an electric contact is avoided. Similarly it is possible to dispense with the signaling by means of which the operator is advised of the direction of the error. The chordal elements are not affected or kinked by the device and it is accordingly not necessary to take special measures to avoid such kinks. In addition to this the invention is characterized by simplicity and low cost, and by the fact that it is particularly suitable for also recording measured values.

In the embodiment shown in FIG. 7 a spindle 108 is rotatably supported on the undercarriage of the vehicle and is rotated by means of a motor 109.

Housings

28 and 29 are mounted on the spindle 108. The sections of the threaded spindle 108 associated with the

housings

28 and 29 may be of different pitch. Upon rotation of the spindle 108 in one direction of rotation or the other, the

housings

28 and 29 move in one direction or the other transverse to the direction of the track. A fork 30a is pivoted to the housing 28 with its tines surrounding the chordal element 10. By bringing the fork 30a, for instance into the position 30, a potentiometer arranged in the housing 28 and which corresponds to the potentiometer 14 is displaced. A fork 30b depends from housing 29 with the tines thereof surrounding chordal element 9. When the latter comes against one or the other tines of the fork 30b a motor 109 is driven in one direction or the other of rotation, the

housings

28 and 29 being displaced transverse to the track 4, according to the ratio of the thread pitches of the spindle 108, until the chordal element 9 is located precisely in the middle between the tines of the fork 3%.

A wheel 111 travels on one rail of the track 4 and, via a flexible shaft 112, drives a gearing arranged in a box 34. This gearing on the one hand drives a Worm 36 via a shaft 113 and a clutch 35, and on the other hand drives a recording device 118 via a flexible shaft 114. The worm 36 in its turn drives a cam 27' against which rests a cam follower 26 which displaces the resistor 22'.

The aligning of the track is effected both in the straight sections and in the track curves and transition curves in accordance with the indication of the measuring and indicating instrument 18, or the recording device 118. In this regard the track must be shifted until the

instruments

18 and 118 indicate a value of zero. The deflection of the pointer of measuring instrument 18 or the size of the curve on the recording device 118 gives a measure of the amount by which the track must be displaced to effect the correction. This arrangement can be employed, in principle, for use with only one chordal element. The potentiometer 15 associated with the chordal element 10 would then have to be provided in a stationary place on the vehicle with respect to the chordal element. The screw spindle 108 would then merely serve for the transverse displacement of the entire system-and therefore for the adjusting of the measurement point to the course of the chordal element.

Two adjustable potentiometers 31' and 32' are provided, the former being set to the length of a transition curve and the second to a given characteristic value of the course of the track and, therefore, to the curve radius which continuously changes in the transition curve. The cam 27' is of such a nature that, in the transition curve, the logarithmically proceeding increase or decrease of the measurement values transmitted to the indicating member 18 of the recording device 118 is in addition controlled to the adjusted measurement value and influenced thereby. The adjustment of the potentiometer 22 by the cam 27 is eifeced in accordance with the corresponding length of the chordal element 10, which is for instance 24 meters long, for the purpose of taking into consideration the ratios of the measurement values upon the traveling onto a transition curve or upon traveling from the transition curve, i.e., to provide for that phase during which one point of the traveling chordal element is still outside of the transition curve while the other end point is already within the transition curve.

FIG. 8 shows an embodiment in which a swingable fork follows the travel of the chordal element 9 and is, for example, swung into the position 130', shown in dashed lines. The shaft of a rotary potentiometer 15 is connected with the shaft of the fork 130. In this embodiment the spindle 108 can be dispensed with, i.e., the box 129 containing the potentiometer 15 can be rigidly connected with the undercarriage. Otherwise this embodiment corresponds to the embodiment shown in FIGURE 7. The wiring diagram of the embodiment of FIG. 7 can be noted in FIG. 9. The two

potentiometers

31 and 32 are set by means of the adjustable knobs 31' and 32' (FIGURE 7) to the length of the transition curve and to the arc radius which gradually changes within the transition curve. The linear potentiometer 22', which is adjustable over the path 1 is associated with the

potentiometers

31 and 32 and is controlled by the cam 27' via the cam follower 26 so as to exercise a balancing action upon the travel of the chordal element along the path 1 into the transition curve. The continuously varying output measured value effected in this manner by the

potentiometers

31, 32 and 22 passes via an amplifier 37 to the indicating and comparison instrument 18 which in its turn contains a comparison value from the potentiometer 14, associated with the chordal element 10. This potentiometer 14 is the actual measuredvalue transmitter. A member consisting of a feeler 38 and

corresponding contacts

39 and 40 serve, if necessary, to balance the voltages. Resistors 23 and 23 (the latter being variable) serve for adapting and balancing of the switching and measuring currents fed to the potentiometers and the indicating member 18, respectively.

From the diagram of FIG. 10 there can be noted the voltages (U) as a function of the arc-height distances (h) of the long and the short chordal elements.

It should also be mentioned in particular that two possibilities exist with respect to the development of the cam 27. In one possibility the cam 27 controls the change in the arc height over the entire range of the length of the transition curve, namely, beginning at the moment when the measurement carriage 8 and the longer chordal element 9 enter into the region of the curvature until the time when the measurement carriage 6 enters into the curve of constant radius and accordingly the arc height remains constant until the measurement carriage 8 again comes to the transition are which leads into the straight section. In the case of the second possibility there is taken into consideration only the adjustment of the arc-height distances which is necessary when the chordal element moves from a straight section into a curve or passes from a curve into a straight section. In the former case the cam surface corresponds to an entire seciton of a transition curve and therefore to a maximum of 200 meters, in the second case only the length of the chordal element, for instance 24 meters, need be taken into consideration. In the showing of FIG. 6, the periphery of the cam from the point A to the point B corresponds to an actual length of the transition curve of about 200 meters. This is the extreme length of the transition curves. The function is quadratic. In the case of shorter transition curves, only a part of the distance between the points A, B is utilized.

With regard to FIG. it should be borne in mind that, in order to facilitate the adjustment, the

resistors

23a, 23b, 23c and 23f should preferably have the same valve.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive.

We claim:

1. A machine for aligning tracks comprising a rail vehicle having an undercarriage and sets of flanged wheels depending therefrom engaging with said track;

track aligning devices mounted on the rail vehicle to displace the track transversely to either side of its longitudinal direction;

an electric switch circuit connected to supply control signals to actuate the track aligning devices;

an electro mechanical transducer connected in said switch circuit;

at least one linearly extending chordal reference element mounted on said rail vehicle with the ends of said element being fixed a given distance from one rail of the track;

a transmission means connected between the chordal element at a place between the ends thereof and said transducer to determine the variation of arc-height distance upon travel over the track; and

an adjusting means which is adjustable to any areheight distance and which upon displacement of the chordal element from the rail as compared with said arc-height distance causes said switch circuit to deliver a contral signal for a corresponding correction of the course of the track.

2. A track aligning machine according to claim 1, in which the electro mechanical transducer is a rotary potentiometer.

3. A track aligning machine according to claim 1, in which the adjusting means comprises a variable electrical resistor.

4. A track aligning machine according to claim 1, in which the adjusting device comprises a housing displace ably mounted on the undercarriage transverse to the direction of the track, said electro mechanical transducer being mounted in said housing.

5. A track aligning machine according to claim 1,in which the switch circuit contains at least one switch element which, when a given point of the track is reached, can be adjusted to a starting value and which is displaceable as a function of the advance of the rail vehicle on the track.

6. A track aligning machine according to claim 1, in which the adjusting device, upon the advance of the rail vehicle, changes its electrical value in accordance with a characteristic which, starting from an initial value upon leaving a linear section of track, follows a parabolic course of the track up to a curve section of constant radius to thereby assure that no control signal for track correction is given off by the switch circuit.

7. A track aligning machine according to claim 1, in which the switch circuit contains an indicating instrument which indicates the direction in which the track is displaced and the amount of correction required.

8. A track aligning machine according to claim 1, in which the switch circuit contains a graphic recording device on which the arc-height values are recorded as a function of the path traversed in the form of a curve on a recording support.

9. A track aligning machine according to claim 1, having a fork mounted on a shaft rotatably supported on the undercarriage, the chordal element being located between the fork tines and the shaft being operatively connected to actuate a rotary potentiometer.

10. A track aligning machine according to claim 1, further comprising a second chordal element shorter than said at least one chordal element, a second transmission means and a second electro mechanical transducer operatively connected to said chordal element, said second electro mechanical transducer being connected into said electric switch circuit and being adjusted relative to the arc-height distance of the shorter chord from the rail.

11. A track aligning machine according to claim 10, in which a transmission means and an electro mechanical transducer are operatively connected to each of the two chordal elements.

12. A track aligning machine according to claim 1, in which the transmission device consists of a flexible element fastened to the chordal element.

13. A track aligning machine according to claim 12, further comprising at least one pulley rotatably mounted on the undercarriage of the rail vehicle, said flexible element drivably engaging said pulley, a rotary potentiometer connected in the electric switch circuit and means for transmitting the rotary movement of said pulley to said potentiometer.

14. A track aligning machine according to claim 11, in which a separate flexible element is fastened to each of the two chordal elements, each of said flexible elements being guided over a pair of pulleys mounted on the undercarriage, a pulley of each pair being connected for movement with a rotary potentiometer and both rotary potentiometers being connected in the electric switch circuit.

15. A machine for aligning tracks comprising a rail vehicle having an undercarriage and pairs of wheels depending therefrom at a substantial distance from each other;

track aligning means mounted on the rail vehicle between the pairs of wheels, said aligning means being adapted to displace a section of the track extending between the pairs of wheels in arcuate form in either direction with respect to the longitudinal axis of the vehicle;

two carriages movably mounted on the track;

two rods connecting said carriages with the rail vehicle to hold them at a given distance from the ends thereof;

a first longer chordal element, one end of which is fastened to one carriage and the other end of which is fastened to the other carriage and which extends through below the undercarriage of the rail vehicle;

a second shorter chordal element one end of which is fastened to one carriage and the other end of which is fastened to the undercarriage of the rail vehicle;

two transmission means are fastened to the undercarriage of the rail vehicle and each of which engages in one of the chordal elements in order to sense their displacements transverse to the direction of the track;

a switch circuit means having at least two variable resistors, each of said resistors being connected with one of the transmission devices so that its resistance is varied proportionally to the transverse displacement of the associated chordal element.

16. A track aligning machine according to claim 15, in which the first chordal element is twice as long as the second chordal element and in which transmission means are arranged in the center between the points of attachement of the shorter chordal element, and in which the resistance ratio of the two potentiometers is 1:3.

17. A track aligning machine according to claim 16, further comprising at least one spindle rotatably mounted on the undercarriage and arranged transverse to the direction of the track, two housings displaceably mounted on the spindle, one of said potentiometers being mounted in each said housing.

18. A track aligning machine according to claim 16, in which the switch circuit contains two variable resistors each of which has a wiper, another resistor connected between the two wipers, said two wipers being adjusted as a function of the advance of the rail vehicle on the track.

19. A track aligning machine according to claim 18, further comprising a cam, a measurement wheel traveling on the rail and which rotates accordingly upon the advance of the vehicle, said cam being operatively connected to said wheel to rotate in such a manner that the transition path from a linearly extending section of the track into a curved section corresponds to less than one full revolution of the cam and a cam follower hav ing one end against the cam and the other end operatively connected to displace the linear resistor.

References Cited UNITED STATES PATENTS 3,292,557 12/1966 Warnick 1048 3,314,373 4/1967 Plasser et a1. 104-8 3,380,394 4/1968 Fornerod 104-8 ARTHUR L. LA POINT, Primary Examiner R. A. BERTSCH, Assistant Examiner