WO1992000214A1

WO1992000214A1 - Device for detecting defective wheels on rail cars

Info

Publication number: WO1992000214A1
Application number: PCT/CA1991/000081
Authority: WO
Inventors: Darren P. L. Maine; Harold Medd
Original assignee: Railbase Technologies, Incorporated
Priority date: 1990-06-25
Filing date: 1991-03-15
Publication date: 1992-01-09
Also published as: AU5779890A

Abstract

Flanged steel wheels remain in service on rail cars, locomotives, and other heavy rail guided machinery until they no longer maintain minimum specified rim or flange profile dimensions. If the rim or flange profile of the wheel cannot be returned to minimum specifications by surface machining operations, the wheel is condemned as being defective and is removed from service and scrapped. It is desirable to use an automated inspection device to determine if a wheel is approaching this condemning limit of profile wear. The invention automatically detects profile defects upon passing the wheel (26) by a rail mounted antennae (21a, 21b, 21c) which forms a resonator cavity and transmits microwave radiation for producing a signal indicative of a wear condition of the rim or wheel. A rim ranging transmitting/receiving antenna (50) is directed to a non-wear reference area (F) on the wheel for producing an output signal useable as a constant reference in relation to the microwave antenna position in determining the magnitude of the wear condition. The circuit of the device may include a source for continuously energizing the antennae during a passage period of the wheel being tested, and the circuit of the device continuously receives data in the form of a curve for each antenna. The continuously received data is compared with stored data for establishing optimal data points for selecting produced signals.

Description

DEVICE FOR DETECTING DEFECTIVE WHEELS ON RAIL _CAR_S

The invention pertains to a device for automatically detecting defective characteristics, such as high flange, thin rim, and flange surface profile defects, on steel wheels of rail cars by utilizing microwave frequency resonator cavity networks.

It has been customary to use a manual gauging operation in order to detect surface profile defects such as thin rim, high flange and thin flange profiles on the steel wheels of rail cars. This manual gauging was done using hand instruments and templates in accor iance with standards and procedures, such as set forth in the Association of American Railroad Wheels and Axle Manual (Section G, part 2) as well as the field interchange manual. However, manual wheel gauging is extremely slow, labor intensive, and highly subjective. Furthermore, it could not be performed while the wheel was in motion.

Attempts at automating wheel inspection in the railroad industry include a high flange detection device disclosed in U.S. Patent No. 4,076,192, and a wheel flange inspection device marketed by Wheel Checkers Ltd. of Denver, Colorado, USA, under the trade name WHEEL CHECKER. These devices mechanically detect a flange profile defect by relying on a defective flange to contact a gauging surface which actuates an alarm when contact is made. However, these devices have proven unsatisfactory due to their mechanical nature, their inability to detect profile defects other than on the flange of the wheel, and their difficulty in upgrading associated signal methods.

A further attempt at automating wheel inspec¬ tion includes a wheel profiling system recently intro¬ duced by Hegenscheidt Corporation. This system utilizes laser optics to effect non-surface contact profiling in-motion wheels. However, this system has been evaluated and determined not to be an entirely satisfactory approach for automated detection of wheel profile defects because it uses light sensitive optics which are unreliable in the dirty and rough service environments typical of heavy freight railroad operations. All-weather protection as well as ambient light exclusion would be essential for effective operation of this system. Accordingly, the construction of pull-through sheds of approximately two to three car lengths in size would be necessary to accommodate the system. Further disadvantages include difficulty in using the system at locations isolated from terminal points, inability to group individual profiler installations into multi-unit networks controlled by a centralized computer, and extremely high purchase costs associated with the system.

In applicant's U.S. Patent No. 4,936,529, granted June 26, 1990, there is disclosed a device for detecting surface profile defects on a metal wheel having a rim and a flange adapted to run along a railway. The device includes a resonator cavity, mounted proximate the railway, for causing reflection of microwave energy from the surface of the wheel, and a microwave detector, connected to the resonator cavity, for measuring the reflection and determining surface profile defects in the wheel. The device includes one pair of antennae for each measurement being determined, such as the thin rim, the thin flange and the high flange measurements. Also provided in this circuit is a limit switch which acts as a triggering arrangement for energizing the microwave network as a wheel enters the environment of the device.

The present invention resides in a device for detecting surface profile defects on a metal wheel having a rim and a flange adapted to run along a railway, the device including a resonator cavity means, mounted proximate the railway, for causing reflection of microwave energy from the surface of the wheel and a microwave detector, connected to the resonator cavity for measuring the reflection and determining surface profile defects in the wheel. The resonator cavity means includes at least one microwave transmit¬ ting/receiving antennae mounted normal to a gauging point on the wheel for producing a signal indicative of the wear condition of the wheel.

According to one aspect of the present invention there is provided a rim ranging transmit¬ ting/receiving antennae directed to a nonwear reference area on the wheel for producing an output signal usable as a constant reference in relation to the microw--*.^-** antennae positioned in determining the magnitude ς. _he wear condition.

According to another aspect of the invention there is provide?? circuit means for monitoring output of the antennae and providing signals indicative of profile characteristics of the rim and flange. A source is provided for continuously energizing the antennae during a passage period of a wheel being tested, the circuit having means continuously receiving data substantially in the form of a curve from each antennae. Storage means is provided with includes stored data and the circuit has means for comparing the continuously received data with the stored data for establishing optimal data points for selecting the produced signals. The invention inspects the wheel for profile defects without utilizing mechanical contacts. Further- more, by utilizing microwave radiation rather than laser light, the invention eliminates the problems associated with optical methods of inspection.

The invention can form an inspection system which simultaneously detects rim thickness, flange height, and flange thickness defects by using several microwave resonator cavities. The invention can also be incorporated into an inspection system which includes modern hot box (wheel journal bearing temperature) detectors, and can be integrated into multiple unit networks monitored from a single centralized computer.

FIG. 1 is a block diagram of a microwave frequency resonator cavity and comparison bridge assembly in accordance with an earlier version of a wheel defect detection device. FIG. 2 is a diagram showing the outline of a simplified steel wheel profile and demonstrating critical areas of measurment.

FIG. 3 is a simplified block diagram il¬ lustrating an embodiment of the invention. FIG. 4 is a section along line 4—4 of FIG. 5 view.

FIG. 5 is an elevational view illustration the relative positioning of the detectors.

FIG. 6 is an elevational view of the rail indicating the positioning of the flange thickness detector in the embodiment of the invention shown in FIG. 3.

FIG. 7 is a sectional view through a pair of running rails forming a track and illustrating the positioning of the structures of the present invention.

FIG. 8 is a block diagram illustrating an RF source and distribution - front end.

FIG. 9 is a block diagram illustrating a typical bridge configuration.

FIG. 1 shows a comparison bridge portion and a resonator cavity portion of a microwave network that can detect high flange thin rim, and thin flange surface profile defects on a steel wheel in accordance with the device disclosed in above-identified U.S. Patent No. 4,936,529. The comparison bridge portion of the microwave network comprises a radio frequency microwave source 1, and attenuator 2, and a single pole, single throw (SPST) microwave switch 3 which is closed by introducing a first voltage to a first input 4 and is opened by applying a second voltage to a second input 5. The microwave signal feeds forward from the switch 3 to a summing port 6 of a four-port 0 degree/180 degree hybrid coupler 7. The other three ports of the hybrid coupler 7 include a difference port 8 coupled to a microwave detector 9, a 0 degree port 10 coupled to a directional coupler 11, and a 180 degree port 12 coupled to a tuner 13 which terminates at a microwave termina¬ tion 14. The directional coupler 11 is, in turn, coupled to a second microwave detector 15 having an output 16 accessible for monitoring during network tuning.

The resonator cavity portion of the microwave network comprises a three-port circulator 17 having a phase shifter 20 and an antenna 21 connected to a port 18, and an antenna 22 connected to a port 19. A controller 23 monitors the output of the microwave detector 9 for development of a direct current (D.C.) voltage. The output of the controller 23 is connected to an alarm device 24 and an annunciator/printer 25. All the components of the network are interconnected using either microwave quality waveguide, coaxial cable, or stripline transmission lines equipped for intercon¬ nection with the network components.

The network is tuned by adjusting the tuner 13 and the phase shifter 20 until the voltage output, which represents the network standing wave ratio from the microwave detectors 9 and 15, is at a minimum value when the resonator cavity is influenced by a wheel having normal rim or flange profile dimensions. Sensitivity of the resonator cavity, i.e. the ability of the resonator cavity to detect dimensional variations of a small order on the flange or rim profiles, is adjustable by increas ing or decreasing the frequency of the incidental microwave radiation generated by the microwave source l.

The network of the invention is based on a network suggested by Dr. K.C. Gupta in "Microwaves", Wiley International, 1979. As disclosed by Dr. Gupta, microwaves are useful for measuring the thickness of metal sheets in rolling mills. At microwave frequen¬ cies, metals exhibit very small skin depths, and thus, microwaves are essentially totally reflected at the surface of a metal. Because wave lengths of microwaves are small and phase variations are rapid, a small discrepancy in thickness of the metal gives rise to a significant phase change that can be detected and measured. Variations of Dr. Gupta's basic network can also be found in foreign patents SU 1193462, SU 1183874 and FR 1594032, which relate to microwave frequency, resonator cavity-type gauging devices for metallic phase materials.

Referring now to FIG. 2, the reference characters A, B and C designate the rim thickness measurement, the flange thickness measurement and the flange height measurement, respectively which are relevant to the test conducted by the system of the present invention. A typical rim thickness A will vary dependent upon whether or not the wheel is multiple or single wear but the new rim thickness will generally be within 2.000 inches to 2.750 inches while the condem- nable wear limit is reached when rim thickness A equals 0.750 to 1.000 inches. It can be seen that the readings a' and a" which would be-obtained by an upper pair of antennae 21 and 22 located on opposite sides of the wheel in accordance with the invention of above iden¬ tified U.S. Patent No. 4,076,192 are processed using an addition/subtraction method to effectively establish the distance between the transversely disposed side surfaces of the wheel. The two microwaves which are reflected back to each of the two respective antennae are compared to one another, and w_*. n the distance across the rim decreases to a predetermined amount, i.e. the upper edge of the rim section has effectively moved down due to the reduction of the rim thickness A so as to indicate a longer distance between the points reflecting the microwave beam, a wheel wear is indicated. Similarly, the microwaves reflected back by the middle antennae 21 and 22 establish the distances b' and b" and on com- parison of these readings there is established the flange thickness B which will eventually reduce to a condemnable wear limit. The typical flange thickness of a new wheel profile is from 1.375 to 1.156 inches, and the condemnable wear limit is reached when the thickness B equals 0.875 inches. In a typical new wheel profile the flange height C is 1.00 inches. When the wear of the wheel reaches a point where this flange height increases to 1.500 inches, a condemnable wear limit is reached. The bottom antennae 21 and 22 by way of the two microwaves reflected back to each of the two detectors at the bottom of FIG. 2 provide an indication of distances c' and c" which, when compared by an ad¬ dition/subtraction method, establish a distance across the bottom of the flange which indicates that the flange height C has reached an unacceptable height.

In the above described arrangement, the system uses three independent scanners to section the wheel profile into discrete components of rim thickness, flange thickness and flange height, the profile depen- dent analog signals transmitted from each reflectometer network being processed by analog blocks which serve to condition the data prior to final processing by a digital remote terminal. The above arrangement shows six microwave antennae 21 and 22 used in pairs to detect the three critical rail wheel measurements of rim thickness, flange thickness and flange height. That is - 8 - two antennae are used for each measurement, one on either side of the rim so that the data from each can be used in combination to determine and account for the position of any minor lateral movement of the rim relative to the antennae. The two microwaves reflected back to each of the two antennae are compared to one another. It has been determined that in certain applications, the placing of the antennae 21 and 22 on both sides of the rim is not feasible, and in the embodiment of the present invention illustrated in FIG. 3, the number of detectors required has been reduced. Comparing the location of the detectors in the embodi¬ ment of FIGS. 4 and 5, for example, with the above described arrangement, it can be seen that in effect all of the three antennae 22 have been removed. Previous antennae pair 21 and 22 utilized to determine the flange thickness has been replaced by an antenna 21b located on the inside of the running rail. Antenna 21a is shown as being utilized in place of the two antennae 21 and 22 located at the top of the guard rails 27 and 33.

Antenna 21c replaces previous antennae 21 and 22 located on opposite sides of the flange for determining the flange height. There is provided, however, an addition¬ al rim ranging antenna 50 mounted in the antenna mounting plate 52 as can be seen in FIG. 5.

It has been found possible that by generating a very narrow wave pattern aimed at an area which may represent a maximum one inch spot on the rim, a reference point can be established for use with the readings from antennae 21a, 21b and 21c. The area F (FIG. 2) on the inside of the rim does not wear and therefore its location does not vary with respect to the relative positions of the antennae 21a, 21b and 21c. It is, therefore, possible to monitor from all three antennae 21a, 21b and 21c, and in conjunction with the output from the rim ranging antenna, the three critical measurements can be calculated without using the ad¬ dition/subtraction method used when two microwave antennae are utilized for each measurement. Looking at FIG. 2, it will be appreciated that when the outer surface of the rim engages the guard rail 27, the horizontal distance between the outer surface of the rim, as represented by the line K in FIG. 2 and the surface on which the spot F is located remains constant. It will be further appreciated that as wear occurs on the rim, the distance A, as shown in FIG. 2, decreases, and accordingly, the particular area F, against which the microwave had been beamed moves downwardly relative to the antenna 50. It has been discovered, however, that although the area F on the side of the rim in effect moves vertical in the plane of the inner surface of the wheel rim as wear occurs on the rim, this area on the side of the rim is of sufficient size to still provide the required area F thus, this point is a constant reference for the rim ranging antennae. Moreover, even when the condemnable wear limit has been reached for the rim thickness, at least the effective position of the maximum one inch spot or area remains available. Thus, it can be seen that because the spot does not wear, it can be used as a constant reference point to determine the relative position or distance of the rim in relation to all three of the antennae 21a, 21b and 21c.

The rim ranging antennae may be in the form of the microwave antenna 21 described above. There are, however, different antennae configurations which may be used in focusing the output RF from the antennae, such as dielectric or metallic lenses, arrayed elements, or reflectors. It has been found, however, that the radar detector or antenna must generate a very narrow wave pattern suitable for directing at the one inch area. - ID ¬ AS is readily apparent from FIGS. 4 and 5, the microwave transmitter/detector means in the form of antennae 21a and 21c are mounted in mounting plate 51. The antennae 50 is also carried by the mounting plate 52 and is located to one side of the euitennae 21a, 21c, but it is positioned to be beamed at the area F on the side of the rim. The microwave transmitter/detector means in the form of antenna 21b, however, must still be mounted to be beamed at the inside of the flange, and therefore, this antenna is located in a cavity 53 as illustrated in FIGS. 3 and 6.

In a manner similar to that discussed in connection with the invention of applicant's U.S. Patent No. 4,936,529, the guard rail 27 which provides a surface for location of the outer surface of the wheel rim is bolted by way of a bolt assembly 28 to the running rail 29. The same bolt assembly 28 passes through an opening in a lower flange of the mounting plate 52 so as to clamp the guard rail 27 and the mounting means 52 to opposite sides of the running rail 29.

While it has been described above that a single guard rail 27 may be utilized on one of the running rails 29, in order to stabilize the rim during the measurement process and minimize any lateral movement of the rim relative to the detectors, it may be found that the tolerance for lateral movement is relatively small. Therefore, accuracy of the measure¬ ments may be enhanced by introducing a second opposing guard rail 27 on the opposite side of the railroad i.e. on the other of the pair of running rails 29 shown in FIG. 6 mounted on railroad tie 54. The guard rail is positioned for simultaneous engagement with the outside of both of the wheels on a single axle for more ac- curately locating of the rim during the measurement process. In the structure of above-identified U.S. Patent No. 4,936,529, the switch contacts of a switch open when the wheel becomes proximate the switch so as to feed a voltage from a power supply line to the port 4 of a SPST microwave switch. This action causes the contacts of the SPST microwave switch to close so as to energize the microwave network. Also, once the wheel 15 no longer proximate the switch, the SPST microwave switch 3 is caused to open which in turn allows the microwave network to become de-energized. Under certain conditions, it is possible that some time would be required to warm up the system before the measurement is taken and the lead time may not be necessarily entirely constant. Also, it may be found that the intermittent discharge of the detectors also affects their longevity and long term reliability. In the conventional manual method of taking the three critical rim measurements, there is utilized a hand held calibration tool that takes all three measurements from the same point on the rim. With the embodiment described in the U.S. patent, the three measurements are taken from a slightly different point on the rim, thus, and if one is to accept the data generated by the system described above, one must make the assumption that the rim is truly round. It may be preferable, therefore, to have the measurements taken at the same point on the rim to avoid having to make this assumption.

Instead of providing a triggering device in the form of the switch, the system of the present invention may be powered on a continuous basis through¬ out the entire time the rim rolls by the antennae. Thus, the system may be activated in advance of a set of wheels rolling past the test area or even before a series of cars moves past the area. With this approach, instead of an instantaneous measurement being made, continuous data is collected which essentially produces a curve having known statistical attributes. In this arrangement the system includes stored data which is used in comparing values representative of the curve to thereby allow for analysis of the received data and thereby establishing a location on the curve which represents the optimum value for the required measure¬ ment thickness test. The exact data points which relate to a single point on the rim for all three measurements at the optimum location can be determined more ac- curately using statistical analysis in this matter.

Moreover, any data points can be sampled at any area on the rim from the entire data set. A further result of sampling the data in a continuous manner as indicated by using the curve is that the location of the detectors become less critical. This makes it possible to cluster, as a single physical unit, the three antennae 21a, 21b and 21c, as well as the rim ranging antenna 50, as illustrated in FIGS. 4 and 5.

In some installations, it may be found that the system as described in U.S. Patent No. 4,936,529 is more sensitive than required in a railroad environment. Moreover, because of its sensitivity, the network disclosed therein requires more frequent calibration. It has been discovered that when the microwave antenna generates a wave and transmits it to the rim, the reflected wave does not perfectly match the wave sent. The imperfection in the reflected wave is mainly caused by the environment in which the wave is being trans¬ mitted as well as the distance between the antenna and the reflecting wheel surface. The majority of the schematic shown the U.S. Patent constitutes the com¬ parison bridge network which accommodates and adjusts for this effect while allowing a usable dimensional reading to be obtained from the transmitted versus reflected microwave signal. The comparison bridge network essentially performs a phase shift measurement or compares the transmitted wave with the reflected wave and makes adjustments to the data to account for this difference and translates the difference between the transmitted wave and the reflected wave into a dimension which if the network is properly calibrated will render the dimension of the wheel element desired. Because phase shifts may be on a very small order of dimension precise positional control of the wheel and a very controlled environment and calibration technique is essential for ensuring the absolute accuracy of the measurements. In the system shown in FIG. 2, there has been a substantial change in the method of detecting the reflected microwave and adjusting for the above described imperfection. Rather than using wave com- parison or phase shift as illustrated in the schematic of the U.S. patent, a less sensitive, more simplified method is used which involves an amplitude technique which uses the net change of the amplitude of the first wave and the reflected wave rather than the more complicated phase shifting method. While the earlier disclosed embodiment emphasizes a phase shift technique, which measures only the phase shift component of a returned, but reduced amplitude signal, the embodiment illustrated by FIG. 3 measures the net change of the signal due to many effects of which phase shift is only a component. In other words, the amplitude of the return signal is based in very simple terms on two primary components, namely phase shift and signal attenuation. In the embodiment now being described, there is used an amplitude bridge 60 for sensing the overall amplitude change rather than ι "ply the phase shift. It has been found that the ampl. je is adequate, i.e. it allows the circuitry to sense position changes on an order of ± 0.2 mm as compared to phase shift applications which are very sensitive with tolerances of at least approaching + 0.01 mm for the guaging process to be performed satisfactorily. In summary, whereas the described embodiment of applicant's U.S. Patent sensed a phase shift, in the presently described invention, an overall amplitude change is being sensed. The amplitude bridge 60 is illustrated in more detail in FIG. 9 wherein the reference character 61 denotes a directional coupler having an RF input from an RF source and distribution means 66 via lead 62. The directional coupler has an RF output terminal connected via lead 63 to the terminal 49 of the range scanning antenna 50 (FIG. 3) . An output 64 of the amplitude bridge, which provides a voltage to the alarm device input, includes a broad band detector 66 and an analog conditioner 65. The RF source and distribution means 61 as shown in FIG. 3 is illustrated in more detail in FIG. 8. In this embodiment, a single source of microwave generation is provided for all three microwave antennae as well as for the rim range antenna, rather than one source for each antenna. While the complexity of the schematic in the arrangement shown in applicant's U.S. Patent was such that the signal strength was diminished substantially after passing through the network, a sig¬ nificant simplification of the schematic as shown in FIG. 3, permits a single source of microwave generation for all three microwave detectors without significant loss of signal strength. Moreover, it has been deter mined that there are optimal frequencies of microwave generation for use with the schematic shown in FIG. 3. Microwave frequencies of less than 5 gigahertz are preferably used. In FIG. 8, 70 is an RF source of 2.0 to 4.0 GHz. This RF source is connected to a 1:4 balanced power splitter 71 connected via leads 66, 72, 73 and 74 to the rim ranging bridge assembly 60, the flange thickness bridge assembly 77, the rim thickness bridge assembly 76 and the flange height bridge assembly 75. The bridge assemblies 75, 76 and 77 may be of the same configuration as the bridge assembly shown in FIG. 9. Flange height bridge assembly 75 is connected via lead 80 to the terminal 40a of the flange height antenna 21c (not shown in FIG. 3) . The rim thickness bridge assembly 76 is connected by a lead 81 to the terminal 37a of the rim thickness antenna 21a and the flange thickness bridge assembly 77 is connected via lead 82 to the terminal 38a of the flange thickness antenna 21b. The system of the present invention is less sensitive to the environment, such as temperature, so that the reliability of the results are increased without affecting the accuracy. Moreover, the simpler network requires less recalibration, and the entire circuitry, with the exception of the microwave generator, may be passive. Also, as indicated above, the simplification of the network permits a single source of microwave generation for all three microwave detectors without significant loss of signal strength. While the invention has been described as means for detecting wheels of rolling stock which ai of unacceptable profile, it should be appreciated that the invention may be utilized in the maintenance shop for several purposes. An apparatus similar to that described above may be used to measure the three critical dimensions to determine the amount to be ground, giving increased accuracy and consistency over the method of measurements taken by field personnel. Also, the apparatus could be used to check the rim and flange after grinding to ensure that they have been altered to acceptable standards. Contrary to the conventional methods of ( inding a predetermined amount from the entire rim surf -e and flange, the data, which is specific to the three different critical measure- ments, can be used separately to instruct the operator or milling machine to only remove certain differing - 16 - amounts from differing places on the rim surface or flange where needed without taking off more than what is required in any one place. The greater accuracy would result, of course, in a prolonged life for the rim. Although the invention has been described with reference to various preferred embodiments, numerous modifications and rearrangements can be made with the result still coming within the scope of the invention.

Claims

1. A device for detecting surface profile defects on a metal wheel having a rim and a flange adapted to run along a railway, comprising: a resonator cavity means, mounted proximate said railway, for causing reflection of microwave energy from the surface of said wheel; a microwave detector, connected to said resonator cavity, for measuring said reflection and determining surface profile defects in said wheel; said resonator cavity means including at least one microwave transmitting/receiving antenna mounted normal to a gauging point on said wheel for producing a signal indicative of a wear condition of said wheel, and a rim ranging transmitting/receiving antenna directed to a non-wear reference area on the wheel for producing an output signal usable as a constant reference in relation to the microwave antenna position in determining the magnitude of the wear condition.

2. A device according to claim 1, wherein a plurality of microwave antennae are located to provide a plurality of signals indicative of the position of a plurality of different gauging points; and including circuit means for comparing said plurality of signals with the constant reference of said output signal for determining a profile of the rim and flange of said wheel.

3. A device according to claim 2, wherein there are three microwave antennae signals providing data for gauging a rim thickness, a flange thickness and a flange height.

4. A device according to claim 1, 2 or 3, wherein said rim ranging antenna is a microwave antenna.

- 18 -

5. A device according to claim 1, 2 or 3, wherein said rim ranging antenna is a radar antenna.

6. A device according to claim 1, wherein said railroad includes a pair of parallel rails, and includ¬ ing a guard rail assembly mounted adjacent at least one of said running rails for providing a positioning surface for engagement with a side surface of said rim.

7. A device according to claim 6, wherein two guard rail assemblies are provided transversely opposed on said pair of running rails, the pair of guard rail assemblies providing positioning surfaces for simul- taneous engagement with side surfaces of wheels on a common axle for accurately positioning of said wheels on the running rails.

8. A device according to claim 6 or 7, wherein said guard rail assembly includes a mounting plate positioned on the opposite side of the running rail as said positioning surface, said microwave antennae providing data for the gauging of the rim thickness and the flange thickness being carried on said mounting plate normal to gauging points on the flange side of the wheel.

9. A device according to claim 8, wherein said rim ranging antenna is mounted on said mounting plate normal to the reference area on an inner side surface of said rim.

10. A device according to claim 8 or 9, wherein the microwave antenna providing the data signal for gauging said flange thickness is located in a cavity formed in an inner side surface of said running rail.

11. A device according to claim 4, wherein said circuit means is provided with an RF source for provid¬ ing a microwave of less than 5 GHz.

12. A device according to claim 11, wherein said source provides an RF in the range of 2.0 to 4.0 GHz, said source being connected to said antennae through a 1:4 balanced power splitter.

13. A device according to claim 1, and including circuit means for monitoring output of said antennae and providing signals indicative of profile characteristics of said rim and flange.

14. A device according to claim 13, wherein said circuit means is provided with a source for continuously energizing said antennae during a passage period of a wheel being tested, said circuit including means con- tinuously receiving data substantially in the form of a curve from each antennae, said circuit means having storage means including stored data, and means for comparing said continuously received data with said stored data for establishing optimal data points for selecting said produced signals.

15. A device according to claim 13, wherein said circuit means includes an RF power source connected to each microwave antenna through an amplitude bridge for sensing overall amplitude change between the source microwave and the reflected microwave of each antenna, said bridge supplying an output voltage signal indica¬ tive of the sensed change and therefore representing a measurement between each antenna and the associated engaging point on the wheel.

16. A device according to claim 13, wherein a plurality of resonators are provided to form a profiling station for detecting surface profile defects in said rim and said flange of said wheel.

17. A device according to claim 16, wherein said resonators comprises microwave frequency antennae positioned to gauge said rim and said flange of said wheel.

18. A device for detecting surface profile defects on a metal wheel having a rim and a flange adapted to run along a railway, comprising: a resonator cavity means, mounted proximate said railway, for causing reflection of microwave energy from the surface of said wheel; a microwave detector, connected to said resonator cavity, for measuring said reflection and determining surface profile defects in said wheel; said resonator cavity means including at least one microwave transmitting/receiving antenna mounted normal to a gauging point on said wheel for producing a signal indicative of a wear condition of said wheel, said microwave detector including circuit means for monitoring output of said antennae and providing signals indicative of profile characteristics of said rim and flange, and a source for continuously energizing said antennae during a passage period of a wheel being tested, said circuit means having means continuously receiving data substantially in the form of a curve from each antennae, storage means including stored data, and means for comparing said continuously received data with said stored data for establishing optimal data points for selecting said produced signals.

19. A device according to claim 18, wherein said circuit means includes an RF power source connected to each microwave antenna through an amplitude bridge for sensing overall amplitude change between the source microwave and the reflected microwave of each antenna, said bridge supplying an output voltage signal indica¬ tive of the sensed change and therefore representing a measurement between each antenna and the associated engaging point on the wheel.

20. A device according to claim 18 or 19, wherein a plurality of resonators are provided to form a profiling station for detecting surface profile defects in said rim and said flange of said wheel.

21. A device according to claim 20, wherein said resonators comprises microwave frequency antennae positioned to gauge said rim and said flange of said wheel.

22. A system for detecting surface profile defects on a metal wheel substantially as described with reference to figures 3 to 9.