November 16, 2019, 11:01:55 am

Tram Discussion

Started by Barry Drive, April 21, 2019, 03:44:09 pm

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Barry Drive

This topic relates to the Trams/Vehicles, not the system.

To begin with: Canberra Metro claim their trams have WiFi on board. The one I was on today (006) certainly didn't. The air conditioning also wasn't working, but a technician got on board outside the depot and managed to get it working by about Nullarbor Ave.

triumph

The LRVs now have module identification underlined, with fleet number below, inside each module.

Module identifications are C1 - S1 - R - S2 - C2. This is slightly different from identification used by CAF (Mc-S-T-S-Mc).

Riding recently on several, orientation varied vehicle to vehicle, with LRV004 noted being reversed between 24th and 26th. This is very likely due to the Depot junction layout (eg an LRV commencing the day at Gungahlin and finishing the day at Alinga St would end up reversed when back in the Depot). Frequent random reversals would be a good thing as wear would be evened out (especially considering the dominant effect on wear by the one really sharp curve, Flemington/Federal Highway).

Busnerd

Quote from: triumph on April 28, 2019, 05:09:33 pmThe LRVs now have module identification underlined, with fleet number below, inside each module.

Module identifications are C1 - S1 - R - S2 - C2. This is slightly different from identification used by CAF (Mc-S-T-S-Mc).
Those were all installed prior to revenue service commencement, so not sure it's really a matter of them 'now' having it, as far as the public is concerned they always did.

triumph

Quote from: Busnerd on April 28, 2019, 11:12:39 pmThose were all installed prior to revenue service commencement, so not sure it's really a matter of them 'now' having it, as far as the public is concerned they always did.

Ok Ok I wasn't wearing my pedantry hat.

A while ago I attended a technical interest group's inspection. At that time someone in the group asked about module identification and (though the fleet already had numbers) this appeared to be an entirely new thought to our host. Thus the word 'now' popped into my mind without deep consideration.

The point of course, is that modules are identified and the identification system used is now on the Forum record.

triumph

Some time ago I remarked on the variable 'thrumming' noise coming from underneath various light rail vehicles as they travel along the track. Was this rail roughness or problems with wheels?

Have now come to conclusion that the wheels are the source and that the principle cause is various imperfections ('flat' spots) distributed both circumferentially and transversely on wheels. The random transverse distribution would tend to explain why the 'thrum' is partially inconsistent.

If, in fact, the wheels have developed minor imperfections, then the cause is most likely minor skids/slips during severe braking related to acceptance testing and/or performance validation, and to extensive driver training. The only solution, if imperfections as described are
present, is the wheel lathe.

Busnerd

Also perhaps running over the bark and rocks etc. in the track grooves could cause temporary 'flat spot' style noises.

triumph

Quote from: Busnerd on July 18, 2019, 04:25:38 pmAlso perhaps running over the bark and rocks etc. in the track grooves could cause temporary 'flat spot' style noises.

Agree any debris solid enough would result in audible noise and, if substantial, would be firmly felt too (note the clunks at pointwork).

The 'thrum' is particularly noticeable in the centre (R) module of some of the LRVs. Whilst of variable presence, when it is present, the frequency is quite uniform and varying with the speed variation of the LRV. It is mostly more obvious under acceleration/braking too. I am now convinced this points to wheel 'flats'. It remains possible that rail surface imperfections after grinding, and/or suspension/bearing vibrations might also contribute or aggravate the 'thrum', but I think wheel 'flats' is the priniciple source.

What did puzzle me for awhile, was the inconsistency of occurrence. It then occurred to me that track geometry and dynamic effects could move  the wheel - rail contact point transversely across the wheel. Thus if the 'flat' spot(s), as might be expected, did not extend across the full width of the wheel, then it is quite plausible that the 'flat' spot(s) would not always be contacting the rail.

Whilst the maintenance base might have a wheel lathe. With only 14 LRV I rather think not, with wheel sets being sent away for reprofiling.

Barry Drive

Tram 008 resumed service this week after its collision at Swinden St last month

Which is convenient timing.

triumph

Quote from: triumph on July 19, 2019, 01:06:11 amWhilst the maintenance base might have a wheel lathe. With only 14 LRV I rather think not, with wheel sets being sent away for reprofiling.

I thought wrong. The maintenance base has a wheel lathe built into one of the 4 tracks within the maintenance building.