METHOD OF INDICATING A CHANGED ANGULAR POSITION BETWEEN WEAR RINGS IN WHEEL PAIRS OF RAIL VEHICLES

Abstract: A changed angular position between the two steel wear rings of a rotationally fixedly connected pair of wheels of a rail vehicle are indicated by applying a magnetic pattern to the wear ring (3) and sensing the magnetic pattern by means of sensors (6, 7) connected to a comparator (9) interpreting the magnetic picture by comparing the magnetic patterns of both wear rings (3), enabling in this way to determine the mutual angular position of the wear rings (3). The magnetic pattern is constituted by one or more permanent magnetic fields of the wear rings, preferably arranged so that every second field is of a direction opposite to the preceding field.

Description: between wear rings, preferably in wheel pairs of rail vehicles TECHNICAL FIELD In general the invention relates to a method of indicating a changed angular position of wear rings, particularly in rail vehicle wheel pairs. TECHNICAL PROBLEM In the operation of rail-ways and in particular in passenger wagons which usually perform a long annual milage the wheels are normally provided with shrunk-on wheel rings consisting of steel. This technique permits renovation of worn-out wheels whereby important savings can be made. However, in this connection the problem is encountered that due to faulty shrink-on connections , over-heating and other factors the wheel ring may start to creep in relation to the hub portion of the wheel which in the long run may cause the wheel ring to get loose with ensueing risk for injuries to passengers and serious break-downs. STATE OF THE ART At present there is no method to check the quality of the connection upon manufacture. During operation the connec¬ tions are checked by a person passing along the train and manually knocking with a hammer against the wheels to compare acoustically and only with the aid of the ear the sound from respectively the hub portion and the wheel ring. Due to in particular the ever-increasing wages and the uncertainty of the testing method described, this technique to an increasing extent has been abandoned leaving the wheel ring loosening problem still unsolved. SOLUTION In connection with the method according to the invention a changed angular position between the two steel wheel & rings in a pair of rotationally fixed coupled wheels of a rail vehicle is indicated in such a way that a magnetic pattern initially is applied to the wear ring and that the magnetic pattern is sensed by sensors connected to an ana- lysator or comparator to compare the magnetic patterns of both wear rings, this analysator in this way determining the mutual angular positions of the rings. By the present invention the above-indicated problem is eliminated, this result being obtained by the method as defined in the attached claims. An alternative way to solve the problem according to the invention would be to mark the wheel rings by other means for the identification of the angular position. A marking by means of radio-activity might be considered, but psychological factors, security problems etc. form severe drawbacks for such a system in addition to the fact that said technique probably will be expensive. ADVANTAGES It is further to be considered that only a minimum of mechanical action means such as holes or the like can be permitted because of the high stresses during operation. The difficulty to attach some element on the outside of the wheel ring can scarcely be overrated. As for the rest, environmental conditions in respect to soil, wear, tempe¬ rature etc. are severe. However, in the method according to the invention any such difficulties as may appear at all are eliminated. DESCRIPTION OF THE DRAWINGS In the attached drawing FIGURE 1 is a schematic view of a wheel pair in connection v/ith the magnetizing process, FIGURE 2 schematically shows the same wheel pair at a control station, and FIGURE 3 shows a rail vehicle wheel in elevation magnetize in accordance with the invention. BEST EMBODIMENT The invention is thus concerned with a method to indicate a changed angular position between the two steel wear rings of a rail vehicle pair of rotationally fixed coupled wheels. Fig. 1 shows how a hub portion 1 is rigidly con¬ nected to a wheel shaft 2. On the outer circumference of the hub portion 1 a wear ring 3 is shrunk-on. Due to the fact that the wheel shaft 2 and the wheel hubs 1 are rigidly connected as far as rotation is concerned,the wheel shaft 2 will participate in the rotational movement of the wheels. According to the method of the invention a magnetic pat¬ tern is applied to the wear ring, this being performed in a magnetizing station 4 schematically shown in Figure 1. When the wheel pairs of the rail vehicle pass through the magnetizing station 4 the wheel rings 3 will be magnetized in such a way that a given magnetic "pattern" is obtained. In Fig. 3 there is illustrated a magnetic pattern having poles at eight points evenly distributed around the peri¬ phery and with alternating field direction. Even if such a pattern at present has been chosen for illustration pur¬ poses, the expert will appreciate that different number of poles and different magnetic pattern may be present within the frame of the invention. Fig. 2 illustrates a control station provided somewhere along the rail-way line. During passage past the control station, generally designated as 5, sensors 6 sense the magnetic patterns of the individual wheel rings 3. A sig¬ nal is generated and transferred to a reinforcing and sig- nal forming unit 8. The output signal from these reinforc¬ ing and signal forming units are transferred to a compara¬ tor 9 and a signal is emitted from this comparator 9 to an output unit 10. For handling and comparing the signals modern integrated micro-processor technique is used and units of the Hall- element type, coils and the like can be used as sensors. During comparison in the control station 5 the sensors 6 read the remanent magnetic field of the wheel rings and in the comparator 9 the pattern position of both wheel rings are mutually compared to indicate any angular fault. INDUSTRIAL EXPLOITATION As all parts of the shaft unit are rigidly connected with each other the magnetic pattern on both wheel rings nor¬ mally has a certain given position in relation to each other. According to the invention the magnetic patterns of the " wheel rings in a wheel pair are compared, but the in¬ vention comprises providing the hub or the wheel shaft with a magnetic pattern and comparing the pattern of the wheel ring with the magnetic pattern of the hub or shaft. The magnetic pattern applied to the wheel rings in the magnetizing station will be preserved in the wheel rings during several years, whereafter the magnetizing proce¬ dure may be repeated if necessary. One of the advantages obtained by the method " according to the invention is that no mechanical intervention is required in the running material. Moreover, the system is not sensitive to the operational environment. These fac¬ tors as well as the fact that the magnetic marking can be applied at a low cost and can be restored if necessary means that the invention offers an economically attractive way of indicating a changed angular position between the two steel wear rings in a rotationally fixedly connected wheel pair of rail vehicles. Another alternative of the above described method of O i A W applying a pattern is to apply pieces of permanently mag¬ netic material in one or more depressions in the lateral surfaces of the wheel rings.

Claims: CLAIMS 1. Method of indicating a changed angular position bet ween the two steel wear rings of a rotationally fixedly coupled wheel pair in rail vehicles, c h a r a c- t e r i z e d in that a magnetic pattern is applied to th wear ring (3) and that the magnetic pattern is sensed by sensors (6, 7) coupled to a comparator (9) interpreting the magnetic picture by comparing the magnetic patterns of both wear rings (3) enabling in this way the mutual angular positions of the wear rings (3) to be determined. 2. The method as claimed in claim 1, c h a r a c- t e r i z e d in that the magnetic pattern is constituted by one or more permanent magnetic fields on the wear rings preferably arranged in such a way that every second field is of opposite direction in comparison with the preceding field. - 3. The method as claimed in claim 2, c h a r a c- t e r i z e d in that the number of permanent magnetic fields amounts to eight. 4. The method as claimed in claim 1, c h a r a c- t e r i z e d in that sensors of the inductive type are used. 5. The method as claimed in claim 4, c h a r a c- t e r i z e d in that so-called Hall-elements are used as sensors.

Inventors: KAEHR G, WALLANDER O
Applicants: CONORT ENG AB, KAEHR G, WALLANDER O
Application year: 1981
Main classification: G01B7
IPC codes: B61K9, G01B7, G01D5