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Ultrasonic examinations of T-joints

Equipment for hollow axle examination - version 03/2012


Hollow railway axels have a hole the entire length of the axis, most commonly the diameter of 60 or 90 mm. It does not, however, weaken the durability of the axel. Hollow axles are becoming more and more popular, being used in a lot of new equipment. The hole allows for ultrasonic examinations without taking apart the entire set. Tests on the hollow axel are performed on the entire volume of the material, placing the head into this hole. Because this is a place not easily accessible it is necessary to perform studies specifically designed for this system.


Model of a locomotive hollow axle for ultrasonic testing.


A railway hollow axel test is conducted using two 2 MHz heads, with an input beam angle of 45° facing in opposite directions. Some problems during testing of hollow railway axles are:

  • The correct identification of indications regarding the temporary place of testing is possible by external measurements of the distance and angle of rotation, but much more conveniently and accurately is to use structural solutions of system identifying the UIP position. For example, the equipment ULTRA in which probes are positioned at the end of the drawbar. In addition, it uses the third probe inside the axle. The entire volume of the axis hole between the stopper at the end of the axis, and the probe is filled with oil. The stopper contains a third normal head at the frequency of 1 MHz, which working with the method of echo determines the position of research probes along the axis. The inclinometer used determines the angular position of probes measured, for example at position 3 or 11, etc. The operator manually positions the probes at the selected distance and makes a half turn rotation right and left from the starting point. If the probe moves from the selected position, 5 mm for example, the after the rotation the next section of the axel is analyzed. The operator on the screen which is divided into parts can simultaneously observe:
      • identify possible echoes from the two measuring probes,
      • longitudinal axis of the cross-section diagram which has marked both the temporary points currently being tested and by differentiation of gray length of the subject and to test, over set a jump longitudinal,
      • current cross-section diagram of axis and the position of the two temporary points research in the angular position.

    Screen shot of the monitor during the hollow axel test. The screen shot shows a two-channel defectoscope, and longitudinal and transverse axis of selected sites currently tested..


  • need contact between the axis and the probe, filling the axis with oil is effective, best of all is contact between the axis and probe
  • indication of where changes in diameter of the axis may result in mistakes. Indications of change in diameter of the axis are different from the indications of defects that are distributed around the circumference of the axis, if we make a turn of 360°

Example model test report


Other ways to improve the system are: Longitudinal hydraulic sliding system powered by a hand pump where one cycle slides the measuring probes on both sides. Another convenience is the use of solenoid valves and motor supply. After pressing the button, the hydraulic system slides or ejects the drawbar. Upon request, the system auto-rotates the drawbar with probe.


The system captures a digital device and archives all axis test results. This allows you at any time to replay all results of research.


Applications: The device is used in Depas in Vilnius, and serves as a teaching aid in the training center in the company Lucchini Poland in Minsk Mazowiecki.


Training station for testing hollow railway axles.
Axis test
Example test of the locomotive.
Przełącznik głowic