US2049764A - Rail flaw detector mechanism - Google Patents

Description

Aug. 4, 1936. H DRAKE 2,049,764

RAIL FLAW DETECTOR MECHANISM Filed March 23, 1935 5 i 19 o o i o e o o o o R F II 12 2/ 20 30 31 1) r 7 Q I 4 24 I v 34$ 4, I 25 25 Zhwentor Harcourt C. Make 88 1 W I (Ittorneg Patented Aug. 4, 1936 STATES.

PATENT v 2,049,764 RAIL FLAW DETECTOR MECHANISM poration of New York Application March as, 1935, Serial Natale 11 Claims.

This invention relates to rail flaw detector mechanisms and more particularly to the type of mechanism employed on the Sperry rail flaw detector cars. These cars operate on the fundamental principle of sending current of high amperage through the rail to establish an electromagnetic field and then exploring said field for irregularities caused by the presence of flaws within the rail. The exploring or detector means comprises one or more sets of inductive means arranged intandem along the rail. It was discovered that if coils extending substantially across the railhead were employed, centrally located fissures were sometimesmissed because the diminution of flux at one point was counterbalanced by the increase in fiux at other points across the rail head and a coil extending substantially across the rail head integrated the flux so that apparently there was no diiferent total flux at a place of fiaw than at a'region without flaw.

, In order to obviate this objection a plurality of sets of coils were employed, each set coacting with only a portion of the rail head width so that one set of coils detected fissures nearer the gauge side while .thefother set detected fissures nearer the outside"of"the-rail head. The coils of each set are balanced-and in opposition, and the coils of one set were arranged to alternate with the corresponding coils of the other set whereby a multiplied output was obtained in reponse to a flaw. It has been customary to mount all of said coils within a housing which was supported on a carriage at a constant distance above the rail surface. This construction, however, was found to be subject to picking up irregularities in 'fiux due to surface defects such as burns caused by the slipping of locomotive wheels and which were not internal defects. It was found that if each coil, could be so mounted that it followed the contour of the rail surface and could at all times maintain its parallelism with said surface, such surface defects did not affect the detector means and therefore caused no confusion with real internal defects. It has therefore been proposed that each coil be mounted individually as shown in applicants Patent No. 1,960,968 granted May 29, 1934, but this necessitated a complicated construction and resulted in error because one coil of a balanced pair could move laterally with respect to the other coil with a result that induced E. M. F., thus giving an indication of flaw where none actually existed. I

It is the object of the present invention to provide a mounting for a plurality of sets of coils which will permit each coil of each set to main- (tCl. 175-183) tain its axis at all times at a fixed distance above the rail surface by following the contour of the rail surface and at the same time prevent lateral movement of one coil of a balanced pair relative to the other coil. y it Further objects and advantages of this inven-'- tion will become apparent in the following detailed description thereof.

In the accompanying drawing,

Fig. 1 is a side elevation of a portion of a Sperry 1o rail flaw detector car showing my invention applied thereto.

Fig. 2 is an enlarged side elevation of the detector mechanism and its mounting.

Fig. 3 is a plan view of the detector mechanism 15 of Fig. 2, i

Referring to Fig. 1, there is shown a portion of a Sperry rail flaw detector car adapted to' travel along the rails to be tested. Current is supplied to the portion of the rail under test from a generator G within the car which supplies current to the rail R by means of sets of brushes H and i2. Said brushes l l and B2 are carried by a current brush carriage i5, said carriage being supported from the car body by means such as 25 cables l6 and springs, not shown, which normally maintain the current brush carriage in raised or ineffective position. When it is desired to lower said carriage into engagement with the rail,

fiuid pressure such as compressed air is supplied 30 to cylinders H to depress pistons l8 operating therein, said pistons being connected to the current brush carriage so that said carriage is lowered against the action of the retractile springs. The current brush carriage may be 35 adapted to ride along the rail on means such as flanged wheels iii.

The electromagnetic field surrounding the rail is uniform as long as there are no flaws. When flaws occur there is a distortion of the electromagnetic field in the region of the flaw and such distortions are designed to be detected by induction means which maycomprise a plurality of \pairs of opposed induction coils 20,20, each of said. pairs of induction 'coils being supported in a with respective widths of the railhead, one coacting mainly with the portion of the rail head near the gauge side and the other with the portion of the rail head near the outside. The coils of each pair are balanced and oppositely wound, and the coils of one pair alternate with the corresponding coils of the other pair. It will now be seen that as the car travels along the rail each pair of inductive coils 20, 20' will normally cut a constant number of lines of force as long as the rail is free from defect, since the electromagnetic force is undistorted. When a region of flaw is encountered, one'of the coils of each pairwill cut a different number of lines of force and there will be generated a differential E. M. F. which after being amplified may be caused to operate indicating means, such as pens operating on a chart, and rail marking means, such as a paint gun. The alternating arrangement of the coils provides a larger response to a flaw than could be obtained by either pair of coils separately by reason of the fact that the impulses generated by the pairs of coils in this arrangement reinforce each other.

The accuracy of the detector mechanism dep nds upon maintaining the axis of the coils at all times at a fixed distance above the rail surface. For this reason itis highly desirable that some provision be made whereby the coils may follow the contour of the top surface of thelrail since a burn or similar defect on the surface will 'tend to increase the distance of the axis from the rail surface and thus cause the coils to cut a different number of lines of force than normally to induce an E. M. F. and give a false indication of flaw. To permit the coils to follow the contour of the rail surface without complicating the mechanism whereby the housings 2| .and 2| are supported on the detector carriage 22, I have provided for a mounting of each housing 2| and 2| on a pivotal axis formed by bearings 30, 30' on the upper surface of the housings 2| and 2|. Bell-cranks 32, 32' are pivotally -J'ournaled at 34, 34' on the detector carriage 22,

maintain the housings 2 2| in depressed position' in engagement with the rail, but permitting said housings to adjust themselves to surface irregularities. The housings 2|, 2| may ride upon the rail 'either on sleds 39, or upon rollers as shown in applicants Patent No. 1,960,968, granted May 29, 1934.

By the construction described above it will be seen that each housing 2|, 2| is free to pivot about its axis 30, 30' and about the axes 34, 34', so that each end of the housing may follow the contour of the rail into each hollow or elevated portion, as case may be, and thus maintain the axis of the coila constant distance above the Portion of the rail which it is testin irrespective of the movements of detector carriage 22. At the same time, it is impossible for one 'coil of a pair to move laterally relative to the other coil, which movement would generate an impulse like that of a flaw, by reason of the mounting of each balanced pair in a housing which is so mounted that both ends thereof are constrained to move laterally tothe same degree. Stops 4| and 4| may be fixed to the carriage 22 in the path of movement of the bell-crank to limit the downarrangement of coils is made possible, whereby stronger impulses are obtained at the flaws; and, second, each pair of balanced coils is contained in its own housing and the housing so mounted that it is impossible for one coil of a pair to move laterally with respect to the other coil.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the 20 apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it 25 is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use. 30

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said hous- 35 ings having means, engaging the rail, a support for said housings, and means whereby each of said housings is pivotally mounted on said support for movement about an axis transverse to the rail; said axis being positioned intermediate the inductive means in each housing.

2. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, a support for said housings, and means whereby each of said housings is pivotally mounted on said support for vertical movement relative to said rail and said support, and means whereby each of said housings is pivotally mounted for rocking movement about an axis transverse to the rail.

3. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, 9. support for said housings, and means whereby each of said housings is pivotally mounted on said support about an axis transverse to the rail for vertical movement relative to said rail and said sup port;and means whereby each of said housings'oo is pivotally mounted for rocking movement about an axis transverse to the rail.

4. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, a support for said housings, and means whereby each of said housings is pivotally mounted on said support about an axis transverse to the rail for vertical movement relative to said rail and said support, and means whereby each of said housings is pivotally mounted for-rocking movement about an axis transverse to the rail, said last-named axis being positioned between the inductive means in each housing.

anaemia 5. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, a support for said housings, and means whereby each of said housings is pivotally mounted on said support, said last-named means comprising a plurality of links, each link pivotally connected at one end to said support and pivotally connected at the other end to one of said housings.

6. In a rail flawdetector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, a support for said housings, and means whereby each of said housings is pivotally mounted on said support, said last-pained means comprising a plurality of links, each link pivotally connected at one end to said support and pivotally connected at the other end to one of said housings, each of said pivotal connections being about an axis transverse to the rail.

7. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, a housing for each set, each of said housings having means engaging the rail, a support for said housings, means whereby eachof said housings is pivotally mounted on said support for vertical movement relative to said rail andsaidsupport, means whereby each of said housings is pivotally mounted for rocking movement about an axis transverse to the rail, .and means for limiting the movement of said housings relative to said support 8. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, each set comprising a pair of balanced coils, said coils being arranged so that the-coils of one pair alternate with the corresponding coils of another pair, a housing for each pair of coils,

, pair alternate with a support for said housings, and means whereby each of said housings is pivotally mounted on said support. 7

9. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive 5.

rail head, said coils being arranged so that the 10 coils of one pair alternate with the corresponding coils of another pair, a housing for each pair of coils, a support for said ,housings, and means whereby each of said housings is pivotally mounted on said support. 15 10. Ina rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, each set comprising a pair of balanced coils, one pair cooperating principally with the gauge side of the rail head and the other pair 20 cooperating principally with the outside of the rail head, the portions of the ,rail head with which said pairs of coils cooperate overlapping, said coils being arranged so that the coils of one the corresponding coils of 25 another pair, a housing for each pair of coils, the portions of the rail head withwhich said housings cooperate overlapping, a support for said housings, and means whereby each of said housings is pivotally mounted on said support. 30 11. In a rail flaw detector car, flaw responsive means comprising a plurality of sets of inductive means, eachset comprising a pair of balanced coils, said coils being arranged so. that the coils of one pair alternate with the corresponding coils of another pair, a housing for each pair of coils, and a support for each of saidhousings including meansfor constraining said housings to vertical movement.

r HARCOURT C. DRAKE. 4

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