US3411455A - Means for continually and simultaneously surveying and aligning railroad track - Google Patents

Description

Nov. 19, 1968 STEWART ET AL 3,411,455

MEANS FOR CONTINUALLY AND SIMULTANEOUSLY SURVEYING AND ALIGNING RAILROAD TRACK Filed July 12, I965 6 Sheets-Sheet 1 I [I I INVENTORS JOHN K. STEWART HELMUTH R.E.VON BECKMANN ATTORNEYS.

Nov. 19, 1968 J. K. STEWART ET AL MEANS FOR CONTINUALLY AND SIMULTANEOUSLY Filed July 12, 1965 6 Sheets-Sheet 2 C/ECMAE CWRVE' saw //v sp/mz 0W I mow/v) q wzwg f INVENTORS F2914. JOHN K. STEWART HELMUTH R. E. VON BECKMANN BY W5 ATTORNEYS.

NOV. 19, 1968 j RT ET AL 3,411,455

MEANS FOR CONTINUAIJLY AND SIMULTANEOUSLY SURVEYING AND ALIGNING RAILROAD TRACK Filed July l2, 1965 6 Sheets-Sheet 5 l I I I 1 L. i l l 1 5/ P/MSE 3 RA SENSITIVE R5 R2 AM LIFIER R 0 O 1 503mm? A3 5 INVENTORS JOHN K. STEWART HELMUTH R. E. VON BECKMANN BY W ATTORNEYS.

J. K. STEWART ET AL 3,411,455 MEANS FOR CONTINUALLY AND SIMULTANEOUSLY 'SURVEYING AND ALIGNING RAILROAD TRACK Nov. 19, 1968 6 Sheets-Sheet 4.

Filed July 12, 1965 INVENTORS JOHN K. STEWART HELMUTH R.E. VON BECKMANN ATTORNEYS.

NOV. 19, 1968 J STEWART ET AL 3,411,455

- MEANS FOR CONTINUALLY AND SIMULTANEOUSLY SURVEYING AND ALIGNING RAILROAD TRACK Filed July 12, 1965 6 Sheets-Sheet 5 INVENTORS JOHN K. STEWART HELMUTH R.E.VON BECKMANN ATTORNEYS.

Nov. 19, 1968 j STEWART ET AL MEANS FOR CONTINUALLY AND SIMULTANEOUSLY SURVEYING AND ALIGNING RAILROAD TRACK AlQd July 12 1965 6 Sheets-Sheet 6 wmw N? $56 mmqhG QQTA NVENTORS JOHN STEWART HELMUTH R.E. VON BECKMANN BYM v W ATTORNEYS.

United States Patent Office 3,411,455 Patented Nov. 19, 1968 3,411 455 MEANS FOR CONTINUA LLY AND SIMULTANE- OUSLY SURVEYING AND ALIGNING RAIL- ROAD TRACK John Kenneth Stewart, Dorval, and Helmuth Rolf Erich von Beckmann, Chateauguay, Quebec, Canada, assigngrs, by mesne assignments, to Tamper Inc, Columbia, .C.

Filed July 12, 1965, Ser. No. 471,285 Claims priority, application Canada, July 21, 1964, 907,729; Mar. 20, 1965, 926,145 20 Claims. (Cl. 1047) ABSTRACT OF THE DISCLOSURE Apparatus for aligning curves and spirals in railroad track by means of an infra-red reference line establishing system comprising a transmitter, a receiver and a shadow board therebetween and a detection system which compares the track condition to the established reference line, which detection system preferably utilizes the same transmitter as the reference line establishing system and comprises a second infra-red beam receiver and a second shadow board (the second beam receiver may physically be the same as the first receiver but operate in a separate mode thereto) and a track aligning jack which is commanded by the receiver of the detection system to throw the track to correct errors in the track as referenced to the reference line system and detected by the detection system.

The present invention relates to means for continually and simultaneously surveying and aligning railroad track. The invention is particularly concerned with surveying and aligning railroad track by means of a high frequency beam such as for an example an infra red beam.

In our co-pending Canadian application No. 860,141 there is described means for aligning a railroad track in combination with an infra red surveying device which infra red surveying device comprises a forward projector mounted on a rail-engaging buggy, a rearwardly located infra red receiver and a shadow element between the receiver and transmitter. In one specific embodiment of our prior application, there is described the use of two receivers with a single infra red' transmitter, which two receivers co-operate with a pair of shadow boards in order to indicate whether the track is out of alignment to the left or to the right of a desired position.

The device according to our prior proposals and the prior art generally, all suffer from the disadvantages that whilst they worked well on tangent track, they became impossible to operate in spiral curves without the assistance of an outside surveyor who would first survey the spiral track to be aligned so that the devices of the prior art would have a man-made reference line to which to work.

Of course many of the prior art devices required the assitance of a surveyor for working on tangent track and they could not operate continually to simultaneously survey and align the track.

It is an object of the present invention to provide a device suitable for aligning railroad track in tangent, spiral or curved conditions which does not require a surveying run through the spiral or curve prior to lining.

It is a further object of the present invention to provide a device which surveys and aligns railroad track substantially simultaneously by alternate operations.

According to the present invention apparatus for continually surveying and aligning railroad track comprises a reference line establishing system including high frequency beam transmitting means, at least one receiver element spaced therefrom, and at least one shadow element therebetween, the transmitting means and each element being mounted for movement along the track; a detection system comprising a high frequency beam receiving member and a shadow member spaced therefrom, each member being mounted for movement along the track on the reference line and adapted to co-operate to detect the track alignment condition relative to the reference line; and track aligning jack means operable in response to command signals from the receiving member to correct the track alignment.

In one embodiment of the invention the receiver element and the shadow element are continually driven in a direction transversely of the track at speeds which are a predetermined function of each other in alternating opposite directions, sensibly determined by beam reception by the receiver element; whereby to continually hunt about the reference line.

In one construction, the receiver element and the receiver member are arranged vertically one above the other on a common mount and the shadow element and the shadow member are correspondingly vertically staggered. According to the feature of the invention, the shadow member and shadow element, the receiver element and the receiver member and the transmitting means are all mounted on rail engaging carriages so that they may be selectively located on one side of the track or the other.

According to an alternative embodiment of the present invention, there is provided apparatus for continually and alternatingly surveying and aligning railroad track which comprises a reference line establishing system including high frequency beam transmitter means, a receiver element spaced therefrom, a shadow element therebetween, the transmitter means and each element being mounted on wheeled carriages for movement along the track, motor means for moving the shadow element transversely of the track, motor means for moving the receiver element transversely of the track, means for determining the transverse displacement of shadow element, means for determining the transverse'displacement of the receiver element and means for comparing the displacements whilst the apparatus is moving through spiral track and providing a command signal for the said motor means whereby to produce a pre-programmed relationship between the displacements; a detection system comprising a high frequency beam receiving member and a shadow member spaced therefrom, each member being mounted for movement along the track on the reference line established by the pre-programmed receiver and shadow element, and adapted to co-operate to detect the track alignment condition relative to the reference line; and track aligning jack means operable in response to command signals from the receiving member to correct the track alignment.

The following is a description by Way of example of certain embodiments of the present invention, reference being had to the accompanying drawings in which:

FIGURE 1 is a schematic plan view of an apparatus according to the present invention arranged on a railroad track;

FIGURE 2 is a part elevation showing the vertical location of the receivers, shadow units and transmittter;

FIGURE 3 is a diagrammatic view indicating the position of the different units of the system on a curved track;

FIGURE 4 is a graph of empirically derived curves showing the relative movement of the units of the system during operation;

FIGURE 5 is a circuit diagram used in one embodiment of the invention and schematically shows a bridge circuit for comparing the displacements of the different elements of the system and for applying a pre-programmed relationship to the displacements of the units;

FIGURE 6 is a schematic illustration of an infinitely variable gear operable together with the circuit of FIG- URE 5 to produce the pre-programmed relationship of the displacements of the elements of the reference line establishing system throughout any spiral curve; and

FIGURE 7 is a detail of an alternative embodiment of the invention;

FIGURE -8 is a diagrammatic representation of a drive for the receivers according to that alternative embodiment;

FIGURE 9 is a diagram to which reference is had in a computation made in the description, and

FIGURE 10 is a view similar to FIGURE 3 but of a further alternative embodiment of the invention in somewhat more elaborate apparatus than the other two embodiments.

Turning now to the drawings. A high frequency beam transmitter, in the form of at least one infra red light transmitter 10, is mounted on a self-propelled leading satellite car 11. An infra red beam receiver element 14 and an infra red beam receiver member 15 are mounted one above the other (for the sake of ilustration, they are shown one in front of the other in FIGURE 1 but their actual position is as shown in FIGURE 2) on a trailing satellite car 19. The car 19 is connected to and towed by a self-propelled aligning carriage 20 beneath which is mounted a double acting hydraulic jack 21. On the end of the rams 22 of the jack 21 are rail engaging clamp members 23, which engage the grade rail 24 and the other rail 25 to throw the track to the left or to the right. A shadow member 26 is floatingly mounted on and extends to one side of the car 20 and is biased from the rail 25 of the track and urged in the direction of the grade rail 24. Shadow element 28 is mounted on an intermediate carriage 30 which is con nected to and pushed by the self-propelled carriage 20.

It will of course be understood, that one receiver alone could be utilized as long as a suitable switching arrangement is provided to let the receiver function alternately as the receiver element of the reference line establishing system and as the receiver member of the detection system. If one receiver alone is used a suitable means for retracting the shadow element and the shadow member will need to be provided and synchronized with the aforementioned switching arrangement since shadow element 28 and shadow member 26 will need to be physically positioned in line with each other.

Each of the cars 11, 30 and 19 is spring biased from the rail 25 of the track and urged in the direction of the grade rail 24 for reference purposes.

The self-propelled leading car 11 normally proceeds the intermediate car 30, the carriage 20 and the car 19 by a considerable distance (of the order of 50 to 100 feet) and the intermediate car 30, the carriage 20 and the rear car 19 are suitably stationed by means connecting links 33, 34.

Shadow element 28 on the intermediate car 30 is mounted so that it can be arranged selectively on either side of the car 30 and is mounted so that it, the shadow element, can be driven backwards and forwards in the transverse direction as indicated by the arrow by a stepping motor 37. The shadow member 26 on the aligning carriage 20 is arranged to extend a predetermined distance D (the same as the spacing of the transmitter 10) outside the selected one of the rails 24 or 25. The double acting hydraulic jack 21 may, for example, operate in conjunction with externally located ballast engaging jacks and 41 which are used to lift the track by applying a lifting action through clamping member 23.

The receiver element and the receiver member are mounted on a common mount on the car 19 so that they may be driven backwards and forwards in a transverse direction as seen by arrow 35 by a stepping motor 36.

In order to be able to continually and alternatingly survey and correct tracks, applicant uses the transmitter 10, the shadow element 28 and the receiver 14 to establish a reference line and uses the receiving member 15 and the shadow member 26 as a detection system to detect the track condition relative to the reference line, command signals being transmitted from the receiving member 15 to jack 21 to correct the track alignment.

In operation on tangent track the front car 11 precedes the vehicles 30, 20 and 19 and projects an infra red cone of light adjacent the grade rail 24. The shadow element 28 moves forwards and backwards as indicated by the arrow 35 in response to the drive motor 37 which drives the shadow element in one direction and then in other, the sense of the direction of drive being determined by whether or not the receiving element 14 sees the transmitted beam. The receiving element 14 and the shadow element 28, which is driven in one direction and then the other by motor 37 at the same speed but in opposite directional phase to the receiver element 14; hunt about a central station and thereby establish a reference line with the transmitter 10. That is to say, the shadow element 28 is driven towards the top of the sheet as viewed in FIGURE 1, into the projected beam and the receiving element 14 is driven towards the bottom of the sheet as viewed in FIG- URE 1 across the centre of the projected beam from the transmitter 10 until the shadow element 28 obscures the receiving element 14 from the transmitted beam from the transmitter 10. As soon as the receiving element 14 ceases to receive the transmitted beam, it by means of any suitable photo-electric device, causes the motors 36 and 37 to be reversed to that the shadow element 28 is now driven towards the bottom of the sheet as viewed in FIGURE 1 and the receiving element is driven towards the top of the sheet as viewed in FIGURE 1 until the light path between the transmitter 10 and the receiver 14 is again open. As soon as the receiving element 14 receives the transmitted beam, it again causes the reversal of the motors 36 and 37 so that in this fashion the receiving element 14 and the shadow element 28 are caused to continually hunt about the reference line L. In practice, where alignment is conducted on a tie to tie basis one hunting operation per tie would probably suffice to establish the reference line. That is to say the receiver and shadow elements are intermittently driven in transverse direction.

While the appartus is operating on tangent track the shadow element 28 and the receiver 14 hunt about a reference line which is spaced by a distance D from the grade rail 24, however when the apparatus has to negotiate curved track, the receiver element and the shadow element 28 have to take up appropriate positions to establish a reference line as will be seen from FIGURES 3, 4 and 9.

The distance E is the distance of the receiver element 14 from its datum or zero position and the distance F is the distance of the shadow element 28 from its datum or Zero position. The ratio E/F is the ratio used to establish the reference line and it varies through a variety of values through spiral curves and is a constant in tangent and circular curved track.

In a circular curved track the constant value E/F is determined from the following equations which hold good for the nature and magnitude of curves F 01 cos Simplify:

Further simplify:

E/ F 1.28 for the values A= ft. B= ft. C= ft.

While entering into a spiral, that is from the time the transmitter 10 enters the spiral until the shadow element 28 enters the spiral, the ratio E/F is proportional to the distance A and the distance B (by similar triangles) and for the values given is constant at 20/25 =0.8=E/F.

However, from the time the shadow element enters the spiral unit the receiver 14 enters the curved track the ratio E/F varies constantly. By plotting a spiral curve from civil engineering tables and plotting the values E and F against the percentage of spiral, the graphs of E and F and thus the ratio E/ F as seen in FIGURE 4, was derived. The infinitely variable cone gear drive illustrated in FIG- URE 6 is designed together with the electrical bridge network of FIGURE 5 to satisfy the conditions existing through the spiral by pre-progralmming the related movements of the shadow element 28 and the receiver 14 to provide the correct E/F ratio. That is to say, the drive of FIGURE 6 and the electrical bridge network provide an electrical simulation of the graph of the ratio E/ F This is achieved by using the bridge circuit of FIGURE 5 to compare the ratio of the actual instantaneous displacement of the shadow element from its datum and that of the receiver 14 from its datum, with the E/F ratio required to form the reference line and to generate a command signal which is superimposed on a normal hunting cycle of the shadow element 28 and the receiver 14 whereby to cause these members to reposition themselves if the required E/F ratio does not exist, until the bridge is in balance and the required E/F exists.

Thus with E/F representing the required geometrical ratio and e/f representing the actual ratio of the instantaneous actual displacement positions of the shadow element 28 and receiver 14 from their datum positions, as applied to the bridge network in electrical analogue form by the transducers 50, connected to the shadow element 28, and 51 connected to the receiver element 14, then (referring to FIGURE 5),

RQ/RP=E/F (required) and R2/R4=e/f (actual) to prove that RQ/RP=R2/R4 for balance:

R3 +RD=RK Condition for balance:

RS/R2=RK/R4 RQ- R2 RP R4 R2 R4 R4(RQ--R2) =R2 (RP-R4) R4RQ-R4R2=R2RPR2R4 R4RQ=R2RP RQ/RP=R2/R4 E/ F =e/ f The required E/F ratio called for by the bridge is dependent upon the positions of the wipers of the potentiometers 55 .and 56 which are driven from the wheel of the rear car through an infinitely variable cone gear drive as illustrated in FIGURE 6. It will be clear from the graphs of E and F and of the ratio E/F, and whilst the nature of the curves is true for all spirals, since the graphs are plotted against the percentage of spiral, which is a length, it is necessary that the wipers of the potentiometers 55 and 56 have completed their travel when the apparatus For balance on the track has passed through the spiral, in other words that of the spiral length (no matter what it measures in actual distance) corresponds to the full travel of the wipers. This control is achieved by means of the gear drive of FIGURE 6 by ensuring that a gear ratio is selected in which .an input, via rail engaging wheel 46, of 100% of spiral distance will result in an output drive from the gears sufiicient to move the wipers of the potentiometers through their full distance. Mechanically this is obtained by connecting the wheel 46 of the rear car 19 by a chain drive to the input sprocket 60 of the cone gear assembly. The sprocket 60 drives a shaft 61, and through clutches indicated .at 63 and 63A, through a selected one of a pair of gear paths, the input drive cone 65. The two gear paths are necessary, as it becomes apparent later, since as the vehicles proceed through an ingoing spiral to a circular curve, the rotation of the wheel 46 is in the same direction as when the vehicles leave the circular curve through an exit spiral curve, although for the purpose of this apparatus it is required to drive the potentiometers 55 and 56 in the opposite sense while exiting. Thus by utilizing the first gear path indicated at 67 the cone gear 65 is driven in a clockwise direction, whilst by using the other gear path 68, which includes an idler 69, the cone 65 is driven in an anti-clockwise direction. The operator of the vehicle by positioning an idler friction wheel between the drive cone 65 and the driven cone 71 to a precalibrated position to correspond to the length of the spiral and indicated by the marker 73, ensures that the output from the cone 71 on the output shaft 75 which drives the wipers of the potentiometers 55 and 56, is such that when the wheel 46 has passed through the full length of the spiral, the output on shaft 75 will have been geared to drive the wipers of the potentiometers 55 and 56 from position 1 to position 2 in an ingoing spiral and from position 2 to position 1 for an exit spiral of the same length.

In operation when the device enters a spiral transitional curve between tangent track and circular track the front car 14 will of course be into the spiral curve whilst the vehicles 30, 20 and 19 are still on tangent track and the condition E/F=0.8 will pertain. On entering the spiral the operator will have selected the necessary switches to switch the resistances RE and RD out of the balancing circuit and since RA and RB will have been selected such that the bridge calls for an E/F=0.8, this 0.8 value is then electrically superimposed on the hunting circuit in such a fashion that the motor 37 becomes retarded in a direction determined by the sign of the imbalance. This causes the covered displacement of the receiver 14 to be 0.8 of the covered displacement of the shadow element 28 so that the receiver 14 is driven from its datum position until it establishes a new reference line. Thereafter the normal hunting of shadow element 28 and receiver 14 recommences around the newly established reference line. This condition exists until shadow element 28 enters into the spiral at which point the condition E/F=O.8 ceases to apply.

Since the distance between transmitter 10 and shadow element 28 is known, a suitable drive (not shown) may be connected to the wheel 46 as soon as transmitter 10 enters into the spiral so that the wheel 46 measures the distance travelled by the cars and operates to switch in resistances RE and RD into the bridge and to operate the clutch 63A to bring the infinitely variable cone drive (FIGURE 6) into driving connection with the wheel 46 (gear path 67 being selected as it is an ingoing spiral). During the passage through the spiral from the point where the condition E/F=0.8 ceases to exist until the circular curve is reached where the condition E/F=1.28 exists, the displacement of the shadow element 28 from its datum position F to the displacement of the receiver element 14 from its datum position B will vary in accordance with the curves of the graphs as seen in FIGURE 4. As the shadow element 28 enters the spiral curve, that is the point where the ratio E/F=0.8 ceases to exist, and resistances RE and RD are switched into the bridge, the drive from the wheel 46 positions the wipers of the potentiometers 55 and 56 in accordance with the requirements to electrically simulate the graph of E/F and this unbalances the bridge and must be compensated for by alteration of both RA and RB. The required E/ F is constantly compared in the bridge with the analogue of the instantaneous actual displacement from zero position of the element 28 and receiver 14, that is the actual E/F, and depending upon the sign of the inbalance, the shadow element 28 is retarded in the required direction causing the receiver not to see the transmitted beam or to see it for too long thus causing the motor 36 to reposition the receiver 14 to provide the required E/F ratio, thereby establishing the new reference line. The receiver element 14 and the shadow element 28 continue to hunt about the changing reference line throughout the spiral. When the device enters the circular curve a suitable switching arrangement is actuated to disconnect clutch 63A and thus the drive from the wheel 46. At this point the wipers of the otentiometers will have been driven to their position 2 and the bridge will now require an E/F=1.28 to be satisfied and a new reference line has to be established. This condition persists throughout the circular track.

As the device starts to leave the circular curve and enter the exit spiral, the operator operates switching which energizes the clutch 63 to cause the wheel 46 to drive, this time through gear path '68, the cone gear in the direction opposite to that for the ingoing spiral. In order to take into account the very large upswing in the ratio E/F as the vehicles approach the end of the exit spiral and re-enter tangent track, the valve of RQ in the bridge has to be increased relative to RP, or alternatively RP has to be decreased relative to RQ to provide the necessary E/F for values from 1.28 to a value approaching infinity. Since the vehicle has entered the circular curve via an ingoing spiral the wipers of the potentiometers 55 and 56 are at their position 2. On entering the exit spiral the drive shaft 75 from the cone gear drives 56 from the position 2 to position 1 but the potentiometer 55 is switched open from the bridge and a fixed resistance (not shown) equal to the maximum value of 55 is switched into the bridge circuit to take its place. Therefore, when 56 reaches position 1 equal to zero resistance, maximum value for RQ/RP, approaching infinity, is obtained.

The detection system comprising the shadow member 26 and the receiving member 15, indicates when the track at the working station, where the shadow member 26 is located, is out of alignment with reference to the reference line L, since the shadow member 26 and the receiver member are right on the reference line L. That is to say, if the receiver member 15 does not see the projected infra red beam from the projector 10, it signals the jack 21, in conventional fashion, to, operate solenoid valves to throw the track to the right and the throwing continues until the track (and the shadow member 26 biased against it) is'moved sufficiently far to let the receiver member 15 see the transmitted bean whereupon the jack is stopped instantly. If, on the other hand the receiver member 15 sees the transmitted beam, it signals to the jack 21 to throw the track to the left until the shadow member 26 obscures the transmitted beam, whereupon the jacking to the left ceases.

In practice a reference line establishing operation is performed and this is immediately followed by an aligning operation, the operation being conducted alternately to form a series of working cycles. The time difference is, however so small, that the apparatus can be said to simultaneously survey and align the track.

Obviously the receivers 14 and 15, the shadow member 26 and the transmitter 10 are selectively moved to either side of their cars when the shadow element is moved to accommodate a right hand or left hand curve.

A second embodiment of the invention is best seen 8 from FIGURES 1, 2, 7 and 8, this embodiment is suitable for use on tracks, such as for example low speed tracks, where the accuracy of lining obtained with the foregoing more sophisticated embodiment is not required. The transmitter car 11 and its infra red light transmitter 10, the intermediate car 30 and its shadow element 28, the jacking and aligning car 20 with its shadow member 26, and the rear satellite car with the receivers 14 and 15, are all basically the same as before, however the receivers 14 and 15 and thin mount 16 are now arranged on a platform 18 (indicated in dotted lines in FIGURE 1) on the rear satellite car 19.

The platform 18 (best seen in FIGURE 7) may be mounted on either side of the rear satellite car 19. The mount 16 on which the receivers 14 and 15 are located is arranged centrally on a transversely extending screw jack device 42 (FIGURE 7). The mount 16 and jack 42 are in turn mounted in a quadrant 43. The mount 16 and the receivers 14 and 15 are driven transversely on the screw jack 42 by means of a stepping motor 36 similar to the motor 36 of the previous embodiment but, which drives at a speed 1.28 times the speed of the motor 37. The screw jack 42 is arranged for pivotal movement on the quadrant 43 around its pivot point 45 by means of a drive best seen in FIGURE 8. As will be seen in FIGURE 8, one of the wheels 46 and the rear buggy 19 is connected with a gear box through a chain reduction 151. The gear box, through a worm drive 152, drives an elliptical wheel 154 on an ellipse drive 154, 155, 156. The ellipse drive 154, 155, 156 comprises a pair of identical elliptical wheels 154, mounted to rotate on different axes and connected by an elastic connection 156. The elliptical wheel 55 drives the screw jack 42 through a gear drive 158. The drive 158 drives a drum 159, and through a steel cable wound thereon, and connected at both ends to anchoring points on the quadrant 43, pivots the quadrant 43 about the pivot point 45 and therefore swings the screw jack 42 along the curved path as indi cated by the arrow 63 in FIGURE 7 whilst the receivers 14 and 15 on their mount 16 are driven along the screw jack 42. The receiver 15 then traces out a path as indicated by the ghost representations in FIGURE 7 and is maintained facing the front by means of a pantograph 62 which pivots the receivers 14 and 15 in their mount 16.

As with the previous embodiment in order to be able to continually survey and correct tracks, applicant uses the transmitter 10, the shadow element 28 and the receiver 14 to establish a reference line and uses the receiving member 15 and the shadow member 26 as a detection system to detect the track condition relative to the reference line, command signals being transmitted from the receiving member to jack 21 to correct the track alignment. The drive illustrated in FIGURES 7 and 8 is made to satisfy the conditions, explained mathematically above, existing through the spiral.

As before the front buggy 11 proceeds the train of bug ies 30, 20 and 19 and projects an infra red cone of light adjacent the grade rail. The shadow element 28 moves forward and backward as indicated by the arrow 35 in response to the drive motor 37 which drives the shadow element 28 at constant speed first in one direction and then in the other, the sense of the direction of drive being determined by whether or not the receiving element 14 sees the transmitted beam. The receiving element 14 and the shadow element 28 hunt about a central station and thereby establish a reference line with the transmitter 10. That is to say, the shadow element 28 is driven upwardly (as viewed in FIGURE 1) into the projected beam and the receiving element 14 is driven downwardly (as viewed in FIGURE 1) across the centre of the projected beam from the transmitter 10 until the shadow element 28 obscures the receiving element 14 from the transmitted beam from the transmitter 10. As soon as the receiving element ceases to receive the transmitted beam, it, by means of any suitable photo-electric device, causes the motor 36 and 37 to be reversed so that the shadow element 28 is now driven downwardly (as viewed in FIGURE 1) and the receiving element is driven upwardly (as viewed in FIGURE 1) until the light path between the transmitter 10 and the receiver 14 is again open. As soon as the receiving element 14 receives the transmitted beam, it again reverses the motors 36 and 37 so that in this fashion the receiving element 14 and the shadow element 28 are caused to continually hunt about the reference line L. Again, where alignment is conducted on a tie to tie basis one hunting operation per tie would probably sufiice to establish the reference line. That is to say the receiver and shadow elements are intermittently driven in transverse direction. It will be seen that as the device enters a left-handed spiral curve, the front buggy 14 will of course be into the spiral curve whilst the train 30, and 19 is still on tangent track and the condition E/F=0.8 will pertain. While this condition exists the receiver will be in the starting position as seen in FIGURE 7 and will be driven inwardly and hunt along the screw jack 42. Although the motor 36A drives at a speed 1.28 times the speed of the motor 37, because of the inclination of the screw jack 42 the resulting speed normal to the track is reduced and is in fact 0.8 times the speed of the shadow element 28. Continuing the progress, intermediate buggy is next into the spiral curve (which ceases the conditions E/F=0.8) then the jacking car 20, and finally the rear buggy 19. During the passage through the spiral from the point where the condition E/F=0.8 ceases to exist until the circular curve is reached where the condition E/F=1.28 exists, the distance of the shadow element 28 from its datum position F to the distance of the receiving element 14 from its datum position B will vary in accordance with the curves of the graphs seen in FIGURE 4. Now since the shadow element 28 is driven at a constant speed by the motor 37 and since the motor 37 drives in step with the motors 36A which drives the receiver 14 backwards and forwards along the screw jacks 42, variations of E to F must be compensated for by an increase or decrease of the relative speed of movement of the receiving element 14 to the shadow element 28 and this, as has been indicated hereinbefore is accomplished by means of the drive in FIGURE 8. The operator is aware of the length of the spiral before the circular curve section is reached and by the expedient of selecting the appropriate gear in the gear box 50 to correspond to length of the spiral curve, the wheel 46, through the arrangement indicated in FIGURE 8, drives the quadrant 43 rearwardly to pivot the screw jack 42 and the receiver 14 thereon about its pivot point 45 to provide the correct speed ratios to correspond to the values of E and F taken from the graphs of FIGURE 4.

With the receiver element 14 and the shadow element 28 hunting at the appropriate speed ratios about the reference line L, the reference line is maintained throughout the spiral.

The quadrant 43 continues to swing until the wheel 46 has made the necessary number of revolutions to drive it, through the selected gearing 50 against the back stop 44. A switch (not shown) disconnects the drive from the wheel 46 and now since the apparatus is in curved track the speed of the motor 36 is the appropriate 1.28 times the speed of the motor 37.

By reversal of the proceedings when coming out of the curve a rough approximation to the variations when leaving the curve is achieved.

Again, the detection system comprising the shadow member 26 and the receiving member 15, indicates When the track at the working station, where the shadow member 26 is located, is out of alignment with reference to the reference line L, since the shadow member 26 and the receiver member 15 are right on the reference line L. That is to say, if the receiver member 15 does not see the projected infra red beam from the projector 10, it signals the jack 21, in conventional fashion, to throw the track to the right and the throwing continues until the track (and the shadow member 26 biased against it) is moved sufiicient- 1y far to let the receiver member 15 see the transmitted beam whereupon the jack is stopped instantly. If, on the other hand the receiver member sees the transmitted beam, it throws the track to the left until the shadow member 26 obscures the transmitted beam, whereupon the jacking to the left ceases.

FIGURE 10 shows a somewhat more elaborate reference line establishing system of a third embodiment of the invention, in which two shadow elements 28A and 28B are used together with two receiving elements 14A and 14B and at least one projector 10. The appropriate transverse speeds for the ratio E /F and E /F are derived as before, by plotting from civil engineering tables and during hunting are used to locate a receiving member 15. Again the receiving elements 14A and 14B may be mounted vertically above one another together with the receiving member 15.

Now if 28A is of equal length to 28B and is located geometrically at an equal distance from 10 as 28B is from 26, 28A will furnish one of three pieces of information while 28B and 14B are hunting:

(1) When interception of reference line L coincides with length of 28B, the curve being lined is circular, length of 28A or 28B being indicative of degree of curvature.

(2) When 28A overshoots reference line L, the curve is a spiral with increasing degree of curvature, the amount of overshoot being proportional to a required correction for this particular spiral at receivers 14A and 14B.

(3) When 28A is missing the reference line L, the reverse of the condition in sub-paragraph 2 above applies. This provides immediate information that the curve is a spiral with decreasing degree of curvature and the amount of undershoot is indicative of rate of change of curva ture.

This instantaneous information permits automatic identification of the nature of the curve.

It will be seen also that instead of making the shadow member 26 fixed and locating the receiving member 15 the roles could be reversed and the receiving member 15 fixed with the shadow board being located on the reference line L.

What we claim as our invention is:

1. Apparatus for aligning railroad track comprising a reference line establishing system including a high frequency beam transmitting element, at least one beam receiver element spaced from the transmitter element by a predetermined distance, and at least one shadow element located at a predetermined position therebetween, means to impart a predetermined relationship to the positional displacements of the elements transversely of the track whereby to establish a reference line therewith, the elements being mounted for movement, in station, along the track; a track condition detection system comprising a beam receiving member mounted for movement along the track and being operatively located in predetermined relationship to said receiver element; a shadow member located at a predetermined poistion between the transmitter and the beam receiving member and adapted to co-operate with the beam receiving member to sense the track alignment condition relative to the reference line; and track aligning jack means operable in response to command signals from the receiving member to correct the track alignment.

2. Apparatus as claimed in claim 1 in which the means to impart the predetermined relationship to the positional displacements of the elements comprises means to drive the receiver element and the shadow element in alternatin g opposite directions.

3. Apparatus as claimed in claim 2 wherein the predetermined relationship is established by driving the receiver and shadow elements at predetermined speed ratios.

4. Apparatus as claimed in claim 1, in which the receiver element and the receiving member are arranged vertically one above the other on a common mount and in which the shadow element and the shadow member are correspondingly vertically staggered.

5. Apparatus as claimed in claim 1 in which the shadow member, the shadow element, the receiver element and the receiving member and the transmitting element are all mounted on rail engaging carriages selectively on one side of the track or the other.

6. Apparatus as claimed in claim 1 in which the transmitting element is mounted on a self-propelled lead bugg the receiver element on a rear buggy, and the shadow element on an intermediate buggy; and in which the receiving member is mounted for movement with the receiver element and the shadow member is located at a work station on a jacking car.

7. Apparatus as claimed in claim 1 wherein a plurality of receiver elements and a plurality of shadow elements are provided for the reference line establishing system.

8. Apparatus as claimed in claim 7 in which the receiver elements and shadow elements are associated in pairs and are continually driven, in order to impart the predetermined relationship to the said positional displacements, in a direction transversely of the track, the speeds of each pair of elements being a predetermined function of each other in alternating opposite directions sensibly determined by beam reception by the receiver element of the pair.

9. Apparatus as claimed in claim 7 in which the receiver elements are arranged vertically one above the other on a common mount and, to impart the predetermined relationship to the said positional displacements, are continually or intermittently driven in a direction transversely of the track, and in which the plurality of shadow elements are continually or intermittently driven in a direction transversely of the track to impart said predetermined relationship, the elements being driven in alternating opposite directions, the speed of the receiver elements and their mounts being a predetermined function of the transverse speed of the shadow elements, the sense of movement being determined by beam reception by the receiver element.

10. Apparatus as claimed in claim 2 further comprising means for determining the transverse displacement of a shadow element from a datum, means for determining the transverse displacement of the receiver element from a datum and means for examining the displacements whilst the apparatus is moving through curved track and providing a command signal for the driving means whereby to pre-programme the displacement relationship.

11. Apparatus as claimed in claim 10 in which the means for determining the transverse displacement of the shadow element from a datum includes a transducer means for providing an electrical analogue signal of the instantaneous displacement of the shadow element from its datum; in which the means for determining the transverse displacement of the receiver element from the datum includes transducer means for providing an electrical analogue signal of the instantaneous displacement of the receiver element from its datum; and in which the means for examining the displacements while the apparatus is moving through curved track includes means for generating a signal of a required relationship between the displacement of the shadow element and receiver element against which signal the said displacement analogue signals are compared whereby to produce the command signal to operate the drive means for the receiver and shadow elements to produce the required displacement relationship.

12. Apparatus as claimed in claim 10 in which the means for determining the transverse displacement of the receiver element and the means for determining the transverse displacement of the shadow element comprise transducer means adapted to apply an electrical analogue of the instantaneous displacement of the elements to the means for examining the said displacements.

13. Apparatus as claimed in claim 12 in which the means for examining the displacements comprises an electrical bridge network.

14. Apparatus as claimed in claim 11 in which the means for generating the command signal of the required relationship between the displacements of shadow ele ment and receiver element and for comparing the said analogues therewith comprises an electrical bridge network including potentiometer means controlled in accordance with the distance travelled by the apparatus through the transitional spiral section of the curve.

15. Apparatus as claimed in claim 14 in which the wipers of the said potentiometers are connected through an infinitely variable gear with a rail engaging wheel.

16. Apparatus as claimed in claim 15 in which the infinitely variable gear is provided with means to select a gear ratio corresponding to the length of the transitional spiral section of the curve whereby to drive the potentiometer wipers through their full range of travel for one hundred percent traversal of the transitional spiral section by the apparatus.

17. Apparatus as claimed in claim 16 in which the infinitely variable gear includes two gear paths one for an ingoing spiral transitional curve and a second for an exit spiral transitional curve.

18. Apparatus as claimed in claim 16 in which the infinitely variable gear comprises a pair of parallel axes, oppositely directed, cones with a friction idler therebetween to transmit rotation from a driven one of the cones to drive the other, and means to position the idler axially with respect to the cones, which last mentioned means constitute the means to select the said gear ratio.

19. Apparatus as claimed in claim 10 in which the receiver element and the beam receiving member are physically the same receiver and switching means is provided to cause its appropriate function and to snychronize the selected retraction of either of the shadow element or shadow member out of the beam to permit the performance of both functions alternately.

20. Apparatus as claimed in claim 10 in which the high frequency beam transmitter means transmits in the infra red area of the spectrum.

References Cited UNITED STATES PATENTS 3,144,834 10/1964 Stewart 1047 ARTHUR L. LA POINT, Primary Examiner.

R. A. BERTSCH, Assistant Examiner.

Images