US3038332A - Vehicles for the testing of railway tracks - Google Patents

Description

June 12, 1962 P. GROSSMANN 3,038,332

VEHICLES FOR THE TESTING OF RAILWAY TRACKS Filed June 10, 1958 2 Sheets-Sheet 1 June 12, 1962 P. GROSSMANN VEHICLES FOR THE TESTING OF RAILWAY TRACKS Filed June 10, 1958 2 Sheets-Sheet 2 W Y3 512 E .11.

United States Patent 3,038,332 VEHICLES FOR THE TESTING OF RAHLWAY TRAQZKS Paul Grossmann, Crissier, Switzerland, assignor to Materiel Industriel S.A., Lausanne, Switzerland, and Constructions Mecaniques S.A.-Renens, Renens, Switzerland, both corporations of Switzerland Filed June 10, 1958, Ser. No. 741,144 Claims priority, application Switzerland June 17, 1957 2 Claims. (Cl. 73-446) This invention relates to the testing of railway tracks.

The supervision of the condition of railway tracks comprises, in particular, the control of the regularity of the lengthwise profile of each rail line, that is to say the regularity of the longitudinal levelling in a substantially vertical plane.

It is known that the so-called levelling faults, the importance of which as regards comfort and safety need not be stressed, arise essentially, with the exception of inevitable slight initial faults, from the fact that the track, the ballast bed and the ground which supports the same are not absolutely rigid, but on the contrary become more or less deformed upon the passage of each loaded axle. As a result, each rail gives rise, in the vertical plane, to an undulation extending on both sides of the loaded point.

Normally, on a well built track in good condition, the said deformation may be considered as elastic, because it practically disappears with a load and the rail then recovers its initial level. The area ailected by the loaded axle generally extends over several meters.

These frequently repeated movements of the track, accompanied by a whole series of other factors such as, expansion, rain, etc, result in a progressive packing of the ballast and of the ground itself, a packing which generally occurs irregularly along and across the track. It will result with the track being unloaded, that certain sleepers rest only partially or even do not rest at all on the ballast bed, and that they remain suspended from each of the rail lines.

As long as the space under the said sleepers is not too accentuated, the elasticity of the rail allows it to recover its initial level after each passage. On the other hand, if the packing is allowed to continue, the rail gives way beyond its elastic limit and there then remain a permanent deformation which increases at each fresh passage of a loaded axle.

Experience shows that these two kinds of faults, called dancing sleepers and permanent deformation, reveal themselves particularly at the rail joints, which are well known weak points of the track. In spite of the possible presence of bracings, double sleepers, corner fish-plates, etc., the discontinuity of the runway subjects the ends of the rails and their fixtures to a real hammering which accentuates still more the local packing of the ballast and, thereby, the risk of permanent deformation. At this last stage, the lengthwise profile then shows at right angles to the joint a bent back point called a low point.

The characteristic of the fault implies a reconditioning of the track according to very different methods. Whereas in the first case, a plain normal tamping sufiices to correct dancing sleepers, such is not the case to eliminate any permanent deformation of the rail, which cannot be done on the spot. Indeed, the correct straightening of a deformed rail is a very delicate operation which, if it is not carried out with all the required care, leaves 1'11 the steel extremely dangerous stresses. Consequently, one cannot content oneself with an ordinary cold straightening. Further, the other methods which could be considered such as heat straightening consolidation through welding of the rail head, etc., encounter dilficulties so that it is preferable more often than not to replace the deformed rails by new rails, resulting in additional work, and a higher cost of repairs, without taking into account the disadvantages which follow any prolonged period of non-usage of the track,

It is therefore of very great interest that devices serving to test the track permit of discerning immediately the two kinds of faults mentioned above; the present invention has the achieving of this aim as a principal object.

In a general manner, since the testing of the tracks must be periodical and extend over their whole length, the invention contemplates that the only practical approach is to cause to circulate an appropriate vehicle thereon. At the present time-with the exception of light apparatus, which practically does not deform the track, and which is of no interest to the present inventionthere are known vehicles which permit of measuring and recording the irregularitie in the lengthwise profile, but however without rendering possible a discrimination between the two mentioned types of levelling faults. This arises from the fact that all of the said vehicles make use of a system of vertical measurements based either on several axles all loaded, or on a relatively light feeling device, arranged between bearing axles, so that all the vertical guide marks are thus in the zone of the track deformed by the highly loaded axles.

The present invention provides a vehicle for the test ing of railway tracks, in the vertical plane, comprising for each rail, a measuring device effective from at least two loaded measuring points and at least one non-loaded measuring point, and further provides relative vertical movements of the said points during the movement of the vehicle on the track, the non-loaded point being situated beyond the one or more straight segments determined by the said loaded points and being in contact with the rail, and being at a distance of at least two meters from the said loaded points.

The drawing shows, by way of example, one embodiment of the vehicle according to the invention and explanatory diagrams.

In the drawing:

FIGURES l to 10 are explanatory diagrams.

FIGURE 11 is a diagrammatical view of the said embodiment.

FIGURE 12 is an explanatory diagram corresponding to FIG. 11.

The vehicle shown permits the testing of a railway track by means of only three measuring points for each of the rail lines, the vehicle being fitted to produce one load on two of the measuring points.

FIGURE 1 shows diagrammatically, in side view, an

unloaded point I, placed outside two loaded points 2 and 3 which produce on one of the rail lines 4 a vertical deformation 5-shown in a very exaggerated manner for purposes of clarity-the point 1 being, to simplify the description, completely outside the said deformed zone. It is clear that the angular divergence a or any geometrical size which is a function thereof (tangent, chord, etc.), may serve to measure the amount of the deformation relative to the nondeformed runway, the values of the loads at 2 and 3 being chosen at random such as, for example, equal to one another, and the distances D and B being also chosen arbitrarily.

Practically, it is advantageous to use a measuring device which may move along the track, while maintaining constant the loads 2 and 3 as well as the distances D and E between the guide points, thus permitting of noting easily, in a continuous manner, the variable value of the angular divergence along a line of the rails and, thus, of measuring or recording, and while distinguishing them, the irregularities of the lengthwise profile.

Indeed, it will first of all be noticed that, on a faultless horizontal traok, the elastic undulation which accompanies the loaded points 2 and 3 remains constant, so that one can accept, for the purpose of simplification, an initial adjustment cancelling a which therefore produces the diagram of FIG. 2. In reality, the variations in the levelling of the unloaded track, combined with the variations in the elasticity of the loaded track, then show an angular divergence, measured from a mean position, in one direction or the other, as will be examined briefly in the case of the two mentioned faults.

FIGURES 3, 4, and 5 show three typical successive positions of the measuring devicepassing from left to right in the drawingat right angles to a joint 6 where there exists an area of dancing sleepers, and FIGURE 6 shows diagrammatically the corresponding characteristic recording.

The unloaded point 1 advances wiwthout bending the rail to any appreciable extent until it is on the floating joint, as shown in FIG. 3. But, when the loaded point 2 nears the said joint, the rail is deformed elastically and there is observed an angular divergence which increases to a maximum a --for the position shown in FIG. 4--thus indicating the low point. Then, the movement continuing, the angle diminishes, passes through zero and increases in the other direction to an extreme a for the position shown in FIG. 5, and finally diminishes again to zero when the loaded point 3 leaves the perturbed zone. Thus, a dancing sleeper joint, but with nonpermanent deformations of the ends of the rails, will be inscribed for example on a recording by a signal formed by two successive recording points Y2 and Y3, but of different direction, such as drawn diagrammatically in FIG. 6.

If, on the other hand, the measuring device passes over a joint where there exists a permanent deformation of the ends of the rails (FIGS. 7 to the point 1, although not loaded, starts by indicating on the diagram a high point a (FIG. 7) followed as previously by low point a (FIG. 8) and high point a (FIG. 9), so that a permanent deformation is signalled, for example, by an inscription through three alternate points Y1, Y2, and Y3, such as diagrammatically drawn in FIG. 10.

It will be seen, in addition to the distinctive character of the two kinds of levelling faults by means of a signal by two or three alternate points, that, for a given device, the spacings d and e between the inscription points remain constant, since they are proportional to the respective distances D and E between the measuring points, in the fixed ratio between the unrolling of the recording band and the distance travelled on the track.

Moreover, it is obvious that the heights of the signal points may be made proportional to the intensity of the fault noted, so that the inscriptions may serve to measure effectively the said intensity.

The shape of the inscription curves may furnish additional information regarding the kind of irregularities in the lengthwise profile. Thus, very sharp inscription points show a sudden variation of the runway which indicates turned back edge at a joint, whereas a junction 4 gradient, for example, is indicated by an undulated inscription.

It is obviously possible to make use of multiple combinations of the loaded or unloaded measuring points, by resorting, for example, to lever arms, loads adjustable at will, etc., and which thus permit, according to needs, of modifying the structure of the signals, the shape of the inscription points, to regulate their relative importance, etc.

FIGURE 11 shows, diagrammatically, an embodiment of the invention. The latter comprises an unloaded measuring point 1, disposed ahead of and at least at a distance of two meters from two loaded measuring points 2 and 3 which are the two loaded points of one of the lines 4 of the rails. On the supposition that the construction as a whole is fitted symmetrically relative to the median plane of the track in order to permit simultaneous testing, but independently of the two runways, one will confine oneself, for the simplicity of the explanation, to describing one of the halves only of the construction which is seen in partial section vertically to one of the rail lines, in FIG. 11 greatly enlarged in height. A rail is accordingly loaded as shown by arrows F1 and F2 through the agency of forks 10 and 10a, a first chassis inelastically supported, which itself supports, through elastic elements 12 and 12a, 21 second suspended chassis. The vehicle pushes before itaccording to the accepted direction of displacement, by means of a system of rods 14, hinged in all directions, a chariot 15 of very light construction, with an axle 16 the wheel 17 of which substantially does not deform the rail at the unloaded measuring point 1. Since the chariot 15 is not suspended elastically on the track, its upper edge 18 is at a fixed distance from the axis of the wheel and thus constitutes a secondary measuring basis on which constantly bears a horizontal lever 19, pivoting at Zn on the non-suspended chassis ll, so as to remain in the plane of the rail line. At the other end 21 of the said lever 19 is secured a cable 22 of a sheathed transmission or Bowden cable 23 which rises vertically from a point of support 24 on the nonsuspended chassis 11 and ends against a casing 25 of a band recorder 26, of known type, having a stylus 27 which is actuated by the cable 22 held taut by a spring 28 to eliminate looseness. The band 26 is unrolled by means of a very simple transmission, not shown, dependent on the travel of the vehicle on the track. This arrangement permits of transmitting integrally to the recorder secured to the suspended chassis 13 the movements of the end 21 of the lever in relative to the support point of the non-suspended chassis 11.

The operation of the said three measuring points is easy to examine following the explanations previously given. FIG. 12 shows, by way of example, the graphic calculation of the value Y of the inscription point corresponding to a lowering X of one of the measuring points.

What is claimed is:

1. A vehicle for testing a rail for vertical deformations therein and capable of distinguishing permanent and temporary deformations, said vehicle comprising first rneans defining two spaced measuring points rigidly connected together for loading said rail, second means connected with said first means and vertically displaceable with respect thereto, said second means contacting said rail without load at a point outside the zone between said first points, said point being sufiiciently remote from the first points that the rail at said point is undeflected by the loading means, and third means to indicate the displacement of the second means with respect to the first means with said rail being traversed by said vehicle.

2. A vehicle for testing a railway track, which includes rails and sleepers, said vehicle including means for distinctively detecting permanent vertical deformations and elastic vertical deflections of the rails under load, said vehicle comprising first and second means responsive to the relative vertical position of a pair of longitudinally spaced points on the same rail, means for loading the rail in the vicinity of the said pair of points suificiently to deflect the said rail Where the sleepers supporting the rail are floating, third means responsive to the position of a third point on the said same rail relative to the position of the said pair of points, said third point being sufficiently remote from the said pair of points that the rail at said third point is substantially undefiected by the loading means.

References (Iited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS France Feb. 3, Australia May 2,

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