US3143974A - Device for lifting railway tracks - Google Patents

Description

Aug- 11, 1964 E. ovlLLE I 3,143,974

DEVICE FOR LIFTING RAILWAY TRACKS Filed May 20, 1959` 5 Sheets-Sheet 1 Aug. 11, 1964 .Filed May 2o'I 1959 E. OvlLLE DEVICE FOR VLIFTING RAILWAY TRACKS 3 Sheets-Sheet 2 E. ovlLLE 3,143,974 DEVICE RoR LIFTING RAILWAY TRACKS Aug. 1'1, 1964 Filed MayZO, 1959 3 Sheets-Sheet 5 United States Patent ice 3,l43,974 Patented Aug. 1l, 1964 3,143,974 DEVICE EUR LIFIING RAILWAY TRAC Eugne ville, Lausanne, Switzerland, assigner to Matriel Industriel SA., Lausanne, and Constructions Mcaniques SA. Renens, Renens, Switzerland Filed May 20, 1959, Ser. No. 814,615 Claims priority, application Switzerland May 23, 1958 5 Claims. (Cl. Ilm-12) In the course of installation or maintenancework on railway lines, it is often required to place and to maintain temporarily in an exact position in a plane which is transversal to the line, one or the other, or both the heads of the rails, and this at one or at several points of the line according to requirements.

In particular, a precise positioning in height is required for the levelling operations and transversally to the line for the aligning'operations. It is clear that the problem is similar for any direction in the transversal plane and .the case of the levelling of the line will be examined more particularly.

The correct positioning in height here olfers particular difficulties owing to the precision required either in respect of the transversal inclination of the rolling plane (or warp), or in respect of the longitudinal profile of the line of rails.

Often, however, one has had to be satisfied with simple lifting and wedging devices, such as wedges, extensible wedges, mechanical, hydraulic or electric jacks, often combined with rail clamps, which in turn were sometimes suspended from frames, portals, ete-movable along the line or not or again from maintenance machines such as tamping machines, wedging machines, etc.

In order to obtain greater precision, improved systems have also been proposed which comprise at least one jack operating as a servo-motor constantly tending to increase in length and consequently to lift the track, until a contact comes to rest against a fixed stop, thus stopping the lifting motion. If for instance the point supporting the servo-motor subsides, the latter automatically increases its length, until compensation is achieved.

All these known systems, the operation of which is in effect the same as that of an extensible wedge, either automatic or otherwise, have a common defect which resides in the fact that the thickness of the wedge can only be reduced by manual adjustment, which is left to the operators judgment. The result is that the prescribed level for the rolling plane also depends, on the one hand on the iixity of the supporting point, and on the other on the rigidity of the wedge itself, and eventually, on that of the support or supports between the rail and the point of support.

Multiple disadvantages, which are very troublesome in practice, result from this, owing to the numerous causes which can modify, either in one sense or the other, in a permanent or transient but always uncertain manner, either the level of the point of support or the height between the rail and the point of support.

i It will be sufcient to mention the placing of a second jack (owing to the rigidity of the rail, for instance), the vibration tamping which is usually effected under the sleeper to increase the firmness of the wedged point (and which generally tends to lift the track), the application of a variable load over the point of support (for instance the passage of a loaded axle), the irregular and uncertain elasticity and plasticity of the bed of ballast and of the subgrade, the accidental displacement of a rail clamp in relation to the rail, the spring suspension of the vehicle supporting the clamps, the momentary defective adjustment of the reference stop of a servomotor (for instance lifting and lowering following vibrations), etc.

It is thus necessary to touch up the initial bedding, and the touching up operations must in addition be preceded and followed by relatively protracted and'delicate measuring and checking operations, which are all the more numerous as one is never sure at any given moment of the exact level of each of the adjusted points. These disadvantages are the cause of others, the most serious of which are the necessity of employing supplementary labor, a lengthier period during which the line is out of service, higher costs, etc.

It may be mentioned here that similar dilliculties and disadvantages are encountered when the line is being aligned.

The present invention aims at eliminating these disadvantages by means of a device operating as a servomotor (reversible) which is automatically controlled in both directions in function of the prescribed position in the transversal plane, for one at least of the heads of the rails.

The object of the present invention is a device for lifting railway tracks, characterized in that it comprises at least one servo-motor which can be controlled in both directions, to place and maintain at least one line of rails in a predetermined position in a plane which is transversal to the track and in relation to a lxed point, and means controlling this servo-motor, in the abovernentioned two directions, in function of the position of the rail in relation to the said fixed point, so as to 'ensure that this position this maintained.

The accompanying drawings illustrate in a schematic manner and by way of a non-limiting example, an embodiment ofthe device according to the invention, in the case of the levelling of the track.

FIGURE l is a schematic side view of this embodiment, showing a partial cross-section along 1--1 in FIG- URE 2. Y

FIGURE 2 is a simplified frontal view of the servomotor itself, along 2-2 in FIGURE 1.

FIGURE 3 is a hydraulic scheme showing the essential elements of the control.

FIGURE 4 refers to one of the elements of the scheme shown in FIGURE 3.

FIGURE 5 shows a variant of the same element. FIGURE 6 concerns a variant.

' On the left may be seen a lirst vehicle, or measuring vehicle, the four anged wheels 4 of which carry a chassis 5 on which are fixed the general supply motor-pump 6 and an oil tank in which the control members are lodged. Two lingers, only one 8 of which is shown, emerge from this tank plumb over each line of rails and in a plane x situated at equal distances from the front and rear wheels 4 of the car, whilst a single start-stop push-button 9 is provided.

'Ihe lifting device itself is harnessed tothis measuring vehicle and is arranged symmetrically in relation to the Two hydraulic jacks in FIGURE 1 to the extremities of a transversal beamseen in cross-section-made up of two profiles of U- shaped cross-section 12 and 13, between which are articulated in 14 and 14a, two levers 15 and 15a provided with hooks 16 and 16a and connected to the articulations 17 and 18 of a hydraulic jack 19 called the clamping jack. The two wheels 20 of this lifting vehicle are mounted on two levers 21 pivoted in 22 to the base f the abovernentioned prole 13 and against the upper part of which they abut by means of their respective adjusting screws 23. In a similar manner, the central drawbar 24, which is articulated at both extremities 25 and 26, abuts against the other profile 12 mentioned above, by means of its adjusting screw 27.

In order that the drawing may be clearer, the ducts and auxiliary members have not been shown.

Two adjusting stops, one of which only 28 is visible in the drawing, are arranged in the measuring plane x above each of the lingers 8 mentioned above and are secured to an auxiliary device of any suitable kindpartially shown by dotted lines-which rests on the ground, the ballast or the rails at a suiciently great distance from the described device to remain uninlluenced by it.

FIGURE 2 illustrates with the same references, a part of the components of the lifting apparatus.

The operation is then as follows:

In the position shown, the lifting apparatus is suspended from three points, i.e., 25 and the two wheels 20, by the action of the drawbar and of the two levers 21 abutting against the profiles. In reality the bases 11 and the hooks 16 have sufficient clearance in height to avoid any obstacle on the track and to allow the free motion of the device.

When the later has been immobilized at the desired point, the push-button 9 is actuated thus starting off the operation of the lifting control. Owing to the action of the clamping jack, the hooks 16 engage the underside of the heads of the rails, whilst the vertical jacks cause the bases 11 to be pushed down against the ballast. As the pressure in these jacks increases, the transversal beam 12-13 is lifted and draws up the clamping levers 15 with it, and thus lifts the two rails and their sleepers.

This lifting motion of the track continues until each of the rails having reached its prescribed level, the corresponding finger 8 comes lightly in contact with its stop 28 which is adjusted in consequence.

If for any reason, for instance if the points of support 11, 11a are lowered because the ballast subsides, or if the clamp slips slightly on the rails, or the level of one of the rails subsides, Athe corresponding finger 8 is released and causes the lifting motion to be renewed. If, on the contrary, the point of support 11 or 11a is raised, or if the level of the rail exceeds the required height, or again if the stop 28 is lowered, etc., the finger 8- is pushed in and causes the required lowering of the rail, as will be seen further on. It is easy to see that the level of each of the rails can thus be maintained exactly at the prescribed value.

When the stop push-button is released, the three jacks bring the components back to their initial positions.

The screws 23 and 27 allow the adjustment, according to the wear of the rail, for instance of the height between the hooks and the heads of the rails, so as to limit at will the lost lifting motion of the transversal beam.

It may be noted that when the latter is lifted, the screws 23 and 27 leave their rests against the U-shaped profile irons so that the beam has a certain angular freedom which avoids the loading of the measuring car at 25. On the other hand, the flanged wheels 20 continue to guide this beam transversally to the track. v

Finally, it may be remarked that a certain difference in the level of the rail may occur between the measuring plane x and the lifting plane y, a difference which de- '4 pends on the undulation which is thus created along the line of rails owing to the effect of the lifting motion.

It is clear that the distance between x and y can be adapted according to the requirements. In particular, it is possible to annul it without any difficulty, by cornbining in a single four-wheeled truck the two parts, measuring and lifting, of the described device.

In the hydraulic scheme of FIGURE 3, part of the components which have already been described have been shown again-with the same references-in particular the transversal beam 12-13 with its two servo- motors 10 and 10a and the clamping jack 19 on the one hand, and on the other-mounted on the tank 7-the start-stop pushbutton 9, and the two lingers 8 and 8a surmounted by the corresponding exterior stops 28 and 28a.

Pistons 29, respectively 29a and 30 can slide in the jacks 10, 10a and 19 forming the chambers 31 and 32 for the first, 31a and 32a for the second and 33, 34 for the last. The three chambers 32, 32a and 34 are directly connected together by the conduit 35 which on the other hand leads to the start-stop distributor 36, which in its turn is fed on the one hand-through the conduit 37, the check valve 38 and the conduit 39-by a large delivery pump 4tlcalled the rapid advance and withdrawa pump-and on the other hand by a high-pressure pump 41-the regulating pump-through a conduit 41 which opens into the chamber 33 mentioned above. This conduit also leads to two distributing relays 43 and 43a to which the chambers 31, respectively 31a of the vertical servo-motors mentioned above are connected by the conduits 44, respectively 44a.

The chambers 45 and 45a of these relays 43, respectively 43a, communicate, on the one hand with 39 by means of the two conduits 46, respectively 46a, each of which passes through a diaphragm 47, respectively 47a, and on the other hand with two distributors 48, respectively 48a-called regulating distributorsby means of two conduits 49, respectively 49a.

The ve distributors 36, 43, 43a, 48 and 48a mentioned above have their slide-valves 50, respectively 51, 51a, 52 and 52a, constantly biased by springs 53, respectively 54, 54a, 55 and 55a, tending to return them in the upward direction or towards the centre of the ligure. The bodies of these distributors are iixed inside the tank into which they can thus allow their oil to escape through the respective openings 56 and 57, 58 and 58a, 59 and 59a.

Two levers 60 and 60th-shown in dots and dashesare articulated in 61, respectively 61a, on the tank and are engaged by one of their extremities in a groove 62 provided on 9, and can rest by the other on the collar 63, respectively 63a provided on each finger S and Sa mentioned above.

The conduit 42 of the regulating pump is connected in addition to a discharge valve 64 the regulating spring 65 of which isactuated-between certain limits determined by the adjustable stops 66 and 67-by the piston 68 of the cylinder 69 which is provided with a chamber 7@ having a calibrated outlet opening 71 (diaphragmed) and is connected by the conduit 72, diaphragmed in 73, to two check valves 74 and 74a fed through two conduits 75, respectively 75a, which in turn lead to the conduits 44, respectively 44a already mentioned.

The sectionsshown by dottedv lines*of the conduits 35, 42, 44 and 44a, are flexible, articulated or sliding tubes to allow relative motion between the components that they connect together.

' The operation is then as follows:

In the position shown, the push-button 9 is in its upper position, or stop position, so that the slide-valve 50 connects 42 with the discharge through 56, which releases the pressure in the pump 41 and the chamber 33. On the other hand, 34, 32 and 32a are subjected to the pressure of the pump 40 through 39, 37 and 35, since the check valve 38, of well-known design, only opposes a negligible resistance in this direction. A certain amount of fluid flowsat a very low rate because of 47, respectively 47a-through 46, respectively 46a, to the chamber 45, respectively 45a, connected to discharge through 49 and 59, respectively 49a'and 59a, so that the slide- valves 51 and 51a, respectively biassed by 54, respectively 54a, connect 44, respectively 44a, with the discharge 58, respectively 58a, and thus annul all pressure in 31 and 31a, as well as in 75 and 75a. The pressure in 72 and 70 is also zero-because of 71-and 6s compresses 65 to a minimum determined by the adjustment of 67.

The three jacks are thus maintained in the withdrawn position by 40, whilst 41 delivers at no appreciable pressure, and therefore with a greatly reduced power consumption.

When the push-button 9 is pressed down to the start position, the slide-valve 50 connects 35 to 57 so that the pressure drops in 32, 32a and 34, whilst 37 communicates with 42 cut oic from 56. The pressure due to 40 and 41 rises progressively in 42, and therefore in 33, so that the clamping jack 19 is immediately actuated.

Simultaneously, 62 causes 60 and 60a to swing so that they move away from 63, respectively 63a, thus releasing the slide- valves 52 and 52a, which rise under the action of their spring 55, respectively 55a, and close 49 and 49a, which causes the pressure to increase in the chambers 45, respectively 45a, which continue to be fed through 46, respectively 46a, and 39, 40. The slidevalves 51 and 51a compress their respective spring 54 and 54a, and connect 42 and 44, respectively 44a-which are cut off from 58, respectively SSa-so that 31 and 31a are subjected to the increasing pressure due to 40 and 41, which causes 29 and 29a .to move in the downward direction.

Thus the two pumps 40 and 41 simultaneously feed the three jacks 19, 10 and 10a, the motion of which is therefore very rapid during this period of approach-owing to the fact that there are only small opposing resistanceswhich lasts untilcontact occurs between 16 and 1, respectively 16a and la, 11 and 11a and the ballast 3.

At this moment, the pressure still being on the increase, the beam is lifted, pulling the hooks 16 and 16a up with it which engage under the heads 1, respectively 1a, of the rails. This period, which is very short, can be considered as forming part of the period of approach.

According to the type of tamping machine used, the track may have a tendency to lift by the action of the spades at the end of the tamping operation. It is then advantageous to provide a device which loads the rail, for instance at the point of measurement. A simple solution consists in resting a heavy mass on the rail above the sleeper which has to be tamped, and which will then be lifted by the servo-motor at the same time as the rail. The mass M can be seen in FIG. 1.

At the same time, the pressure being on the increase in 75 and 75a, fluid flows at a progressively increasing rate through 74 and 74a into 70, from where it escapes through 71, the rate remaining however very small owing to 73 and 71. The pressure drop across 71 induces a certain pressure in 70, which does not however move 68, retained by the spring 65-supposing that the latter is suliiciently compressed in its minimum position of adjustment, imposed by 67-controlling the discharge valve 64, the principle of which is well known and which then prevents any iluid escaping through it from 42.

When the pressure in 42 becomes equal to the maximum pressure which can be furnished by the pump 40- Which may be supposed to be, for instance, of the centrifugal type-the check valve 3S closes and the pressure in 42 continuesto increase owing to the elect of the high pressure pump 41 and it may be seen that 68 is finally caused to move, thus compressing 65 more and more, which keeps 64 in the closed position.

When there is suicient pressure in the circuit 42, the rails and tracks are lifted thus causing the measuring truck to move in the upward direction, as previously indicated, and the general movement continues until one of the lingers, for instance 8, comes lightly to rest against the exterior point of reference 28, which, to simplify the explanation, is taken to be fixed. The slide-valve 52 is progressively pushed into the body of its distributor 48, which eventually causes 49 to communicate slightly with the discharge 59 which decreases the pressure in 45. The slide-valve 51 tends to cut olf 44 from the feed line 42 to put it practically simultaneously in communication with the discharge 58 according to the well-known double edge control method. The lifting motion of the servomotor 10 is thus arrested, independently of that of 10a Which is only arrested at the moment of contact-between 8a and 28a, according to a process similar to the previous one.

It is easy to understand that, Vas has already been said, the exact level of each rail, measured in the plane x of FIGURE 1 by the mean position of the truck on its wheels, can be maintained as long as desired and independently as long as desired and independently of any modification other than the adjustment in height of one or of the other of the reference stops 28 or 28a, which operation only requires a very small effort. In short, it may be said that the level of the rails will faithfully folloWthe level of the fingers 8 and 8a in both directions by the action of the servo-motors thus controlled, not in effort, but in position, and in a reversible manner, i.e., in both directions of adjustment of these servo-motors.

It may also be understood that, if the stop 28 or the rail itself, or both, are subjected tof vibrations, due for instance to tamping operations, it is still possible to control with precision the level of the track-according to the mean position-extreme or intermediate-of the Vibrating elements-by appropriate means, such as means to damp the motion of the slide-valve 51 for instance, which are within the scope of the man of the art.

It can be Vseen easily that the three jacks are brought back to their initial position by releasing the stop pushbutton 9. Y

Without entering into further detail concerning the operation, it is deemed suicient to mention that the two check valves 74 and 74a visibly prevent any mutual inuence between the two individual controls 10 and 10a, and at each instant allow the greater of the two pressures obtainingrin 31 and 31a to be applied to 75, this pressure then determining in 42-by a judicious choice of the dimensions of the components of the assembly 64/ 69--a pressure which is constantly slightly higher. The' power required to drive the pump 41 is thus reduced to a minimum at any instant.

FIGURE 4 reproduces-with the same references-a part of the hydraulic scheme of FIGURE 3 and shows in addition the distributor-relay 43a with its controlling distributor 48a, but with their slide-valves 51a, respectively 52a, in a middle position corresponding to the adjustment for Amaintaining a static lifting load. may be seen that the governing edges of the slide-valves and of the bodies are adjacent to one another in '76, 77 and 78 so as to create the desired presure in 45a and 44a according to a technique Well-known to the man of the art.

It is sucient to underline the fact that in this control. system, a dierence in height-measured from the mean position-between the side-valve 52a and the body 48a is transformed into a pressure variation-measured from the mean maintaining pressure-in the pressure chamber 31a of the servo-motor 10a. It is thus possible to amplify or to demultiply at Will-according to the chosen dimension or to the components-the eifect of the said differences on the control of the device, which, for instance enables the precision to be increased, the conditions of stability of operation to be improved, etc.

FIGURE 5 shows a variant of the construction of the control group of FIGURE 4 which is based on another mode of amplification of the variations in height mentioned above.

Here the members 43a and 48a are united in a single casing 79. The slide-valve 80 of the relay is constantly biassed-towards the right in the ligure-by the pressure-which, to simplify things, is supposed constantobtaining in 39, 46a, the chamber 81 and the boring 82 drilled in the slide-valve 80. The screw 83 allows the adjustment of the pressure obtaining in the duct 84-in permanent communication with the chamber 85-which bends inside the rectangular head 86 which terminates the rod 87 prolonging 80, and ending in an opening 88 over an inclined plane S9 formed at the bottom of the opening 90 with parallel faces-to guide 86 and 89- formed in the new finger 91 which slides in 79 and is constantly biassed in the upward direction by the spring 92.

The operation is then as follows:

The slide-valve 80 which for instance has an annular cross-section in 85 which is double the annular crosssection in 81, is balanced when the pressure in 85 is half the constant pressure in 81. If the pressure in 85 is lower the slide-valve moves-towards the right in the figure-until the opening 88 is partially closed by 89. It is obviously to be seen that the slide-valve 80 is cornpelled to reproduce faithfully-in the horizontal direction and with a certain ratio of amplification, determined by the inclination 89--the vertical movements of the linger 91 in relation to its casing 79. The operation of the distributing relay in the main circuit remains unchanged.

As has been previously indicated, the pressure of the fluid acting in a servo-motor, for instance 31 in FIG- URE 3, can actuate the measuring and control member 68, regulating, through 64, the power absorbed by the pump 41. This pressure-or any magnitude related to the motive uid-can also influence other devices, for instance entering into a more or less automatic system.

It is thus that-as is indicated schematically in FIG- URE 6-the conduit 75 (of FIGURE 3) can be permanently connected to the chamber 93 of a relay 94 the piston 9S of which is constantly biased in the downward direction (in the figure) by a spring 96 which can be adjusted by a screw 97. When the pressure reaches the value which has thus been predetermined, 95 is lifted and causes-by the action of a distributor 98-the closing of the conduit 99 feeding the hydraulic member controlling the closing of the spades of the tamping group 189, which may be of any usual type.

One may note here the important practical advantage of a servo-motor the position of which is controlled in both directions and which can then act as a dynamometer indicating the vertical thrust exercized by the ballast on the sleeper which is being tamped, and can thus be used to arrest the closing motion of the spades, etc.- whereas up to now it was deemed suicient to act in function of the horizontal thrust to which the spades were subjected in the ballast, which obviously occasioned errors in the evaluation of the degree of tamping achieved.

According to the type of tamping machine used, the track may have a tendency to lift by the action of the spades at the end of the tamping operation, for instance. It is then advantageous to provide a device which loads the rail, for instance at the point of measurement. It is easy to imagine the simple solution consisting of a heavy mass resting on the rail above the sleeper which has to be tamped, and which will then be lifted by the servo-motor at the same time as the rail.

As there are two regulating elements available, position and pressure, it is in addition possible to provide such stabilizing loads, which may be constant or variable, permanent or temporary, and influenced by one at least of these elements.

Many constructional variants can be imagined within the scope of the invention. It may be sufficient to mention the application of the new system to any given direction of the transversal plane of the track, in particular in the case of the aligning operations already mentioned, the use of a single servo-motor or on the contrary of more than one twin servo-motor, the combination for the simultaneous levelling and aligning operations, the systems controlled by periodic impulses, the devices actuated or controlled mechanically, by a pressure fluid (oil, air, etc.), electrically or by magnetic means, etc., etc. The examples given are therefore in no sense limitative.

It may be seen that the described device is distinguished in that it comprises at least one servo-motor automatically controlled in function of the position prescribed for at least one of the rail heads and in a plane transversal to the track (servo-motor influenced by the position of the rail). It may be:

Adapted for levelling operations;

Adapted for aligning operations;

Combined for levelling and aligning operations;

Controlled by periodic impulses;

Controlled in a continuous fashion;

Operated at more than one speed, operated at variable speeds (rapid approach and withdrawal, slow adjustment);

Actuated or controlled: mechanically, by pressure fluid,

electrically, by mixed means;

With the position of the measuring point distinct from that of the lifting point (along the track);

With a difference in position which is amplified or demultiplied (at will, automatically);

With a difference in position transformed into another physical magnitude (for instance pressure, stress, flow).

According to a further embodiment of the invention, the device for lifting can be secured to the support chassis of a tamping machine instead of having the ballast as a fulcrum.

What I claim is:

l. A device for the automatic shifting of a railway track to a predetermined position and for maintaining the track in said position, said device comprising: hydrauically actuated shifting means for shifting the track, means supporting said shifting means and in turn supported on said track and movable with said track as the latter is shifted, means for establishing the position to which said track is to be shifted, control means for said shifting means, said control means comprising a casing supported in fixed relation on said means supported on said track, sensing finger means supported on the latter means for sensing the position of the means which establishes the position to which the track is to be shifted, and pressure fluid distribution means within said casing and controlled by said sensing finger means for in turn controlling fluid distribution to said shifting means to stop the flow of pressure fluid to and from said shifting means to cause shifting of the track in opposite directions in response to the respective direction of actual deviation of the track with respect to said predetermined position.

2. A device for the automatic lifting of a railway track to a predetermined level and for maintaining the track at said level, said device comprising: hydraulically actuated jacks adapted for a raising and lowering function, means operatively associated with the jacks for engaging the track to raise and lower the same in accordance with raising and lowering of the jacks, means supported on said track for being moved therewith as the track is raised and lowered, stops for establishing the level to which said track is to be lifted, control means for said jacks, said control means comprising a member in fixed relation with said means supported on said track, sensing nger means for sensing the position of said stops, pressure fluid distribution means within said member and actuated by said sensing finger means for controlling the fluid distribution to said jacks, said fluid distribution means stopping the flow of pressure fluid to and from said jacks with the track at the predetermined level and permitting pressure uid to pass to and from said jacks for selectively raising and lowering the track in response to the direction of the actual deviation of the track with respect to said predetermined level.

3. A device as claimed in claim 2, comprising a vehicle, a tamping device mounted on said vehicle, said tamping device comprising tamping tools and control means for said tools, the latter control means being operatively connected to said jacks, the pressure prevailing in said jacks acting on said control means for said tools.

4. A device according to claim 2 comprising further track loading means positioned approximately in line with the finger sensing means.

10 for feeding pressure iluid to said shifting means, one of which pumps is adapted for supplying large volumes at low pressure and another of which pumps is adapted for supplying small volumes at high pressure, and means for preventing the escape of liuid under high pressure through the pump which feeds at low pressure.

References Cited in the le of this patent UNITED STATES PATENTS Kershaw Mar. 1, 1960 Keller Aug. 15, 1961 5. A device according to claim 4, comprising pumps 15 10 and l1). Pub. by Norberg Mfg. Co.

Claims (1)

1. A DEVICE FOR THE AUTOMATIC SHIFTING OF A RAILWAY TRACK TO A PREDETERMINED POSITION AND FOR MAINTAINING THE TRACK IN SAID POSITION, SAID DEVICE COMPRISING: HYDRAULICALLY ACTUATED SHIFTING MEANS FOR SHIFTING THE TRACK, MEANS SUPPORTING SAID SHIFTING MEANS AND IN TURN SUPPORTED ON SAID TRACK AND MOVABLE WITH SAID TRACK AS THE LATTER IS SHIFTED, MEANS FOR ESTABLISHING THE POSITION TO WHICH SAID TRACK IS TO BE SHIFTED, CONTROL MEANS FOR SAID SHIFTING MEANS, SAID CONTROL MEANS COMPRISING A CASING SUPPORTED IN FIXED RELATION ON SAID MEANS SUPPORTED ON SAID TRACK, SENSING FINGER MEANS SUPPORTED ON THE LATTER MEANS FOR SENSING THE POSITION OF THE MEANS WHICH ESTABLISHES THE POSITION TO WHICH THE TRACK IS TO BE SHIFTED, AND PRESSURE FLUID DISTRIBUTION MEANS WITHIN SAID CASING AND CONTROLLED BY SAID SENSING FINGER MEANS FOR IN TURN CONTROLLING FLUID DISTRIBUTION TO SAID SHIFTING MEANS TO STOP THE FLOW OF PRESSURE FLUID TO AND FROM SAID SHIFTING MEANS TO CAUSE SHIFTING OF THE TRACK IN OPPOSITE DIRECTIONS IN RESPONSE TO THE RESPECTIVE DIRECTION OF ACTUAL DEVIATION OF THE TRACK WITH RESPECT TO SAID PREDETERMINED POSITION.

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