Bogie chatter

[Anonymous]

Over a period of 15 months I have travelled between Melbourne and Sydney, (Australia) a journey which takes 11 hours overnight on the train known as the XPT. During or after every trip I have complained to a crew member or Countrylink about a noise which starts when the train begins to move and gradually increases until it becomes a high speed chatter, it causes vibration if you try to lean against the side of the carriage and prevents sleep, One enquiry brought an explanation that a certain bogie was due for change, however the last trip three weeks ago again produced the same annoying noise and I am still trying to find out what is the cause of it. Once you recognize that it exists it is impossible to shut it out, and it has annoyed me so much that it has made me determined that if I need to make the trip again that that train will be the last choice. I hope some of our Train lovers will be able to give me some clues.

[Hugh Jampton]

Coulld be wheel flats, corrugations, simply running on jointed track or any number of other things with the suspension.

[stmtrolleyguy]

Could be a number of things. Flat spots, as preveously mentioned, would do it. The faster the train goes, the more frequently the wheel bangs as it hits the corners of the flat spots on the wheel. Also, as mentioned before, it could be the rail joints. Rail joints are usually staggered, for example, one on the left, then on on the right another 50 or 75 feet later. If the joints are even, it is a much greater impact every time you go over one (like a small pothole in a car compared to a speedbump.)

Is it the same trainset/car that provides this service? If it is, they probably haven't managed to pull it from service to fix the problem yet.

[oubliette]

Probably wheel flats, as the train accelerates the noise gets louder. Not sure what the maximum allowed in Austrailia or the US is but in the UK anything over 60mm (15mm for cavities) has to be stopped for tyre turning. The problem with wheel flats is that they can then become rolling contact fatigue (RCF) and cavities start to form and the tread starts to disintigrate. A flat is usually caused by the wheel locking up and sliding. As the flat is produced it can also cause the metal to migrate to the extremes of the flat. Eventually this starts to decay and cavities can form. Sometimes a flat will run out but should be monitored.

Another possiblity though less likely is the bogie may be hunting. Basically instead of running in a straight line it veers from rail to rail as the train accelerates causing the knocking sound.

Take a look at the following link to see a cavity

http://www.rrpicturearchives.net/showPicture.aspx?id=145912

[waltersrails]

yep