RE: Re: Tram-train: where did we go wrong?
  Dudley

Railway style wheels have much wider tyres than street tramway tyres. This enables them
to bridge the wide gaps at frogs. See
https://en.wikipedia.org/wiki/Comparison_of_train_and_tram_tracks for a diagram showing
the relative widths of tyres - unfortunately without dimensions.

Yarra trams specification for the width of the groove on normal straight or curved track
is 30 mm, but this is reduced to 26 mm opposite frogs at sets of points. The 30 mm on the
straight allows for lateral play, but this is reduced to the minimum where this lateral
play cannot be allowed. The nominal gauge of 1435 mm is widened at points to 1438 mm -
see diagrams YTS 1103 and 1208.

In the UK, apart from Crich, flange thicknesses vary from 22.0 to 29.0mm, with 6 systems
using widths between 22.0 and 23.2mm, with Docklands at 27.5 and Tyne and Wear at 29.0mm.
See:
http://webarchive.nationalarchives.gov.uk/20170206160525/http://orr.gov.uk/__data/assets/p
df_file/0004/4387/sres-RTU-rep_90_3A_iss1.pdf - an invaluable document for comparison of
wheel profiles and rail profiles in the UK.

https://books.google.com.au/books?id=04z0Lw1qKiIC&pg=SA2-PA44&lpg=SA2-PA44&dq=AAR++wheel+d
esign&source=bl&ots=rP8lYTZpBX&sig=GwEb8e5zH6h47e2t9dKYhoTpVj8&hl=en&sa=X&ved=0ahUKEwi-wJu
mhqzWAhULvbwKHTPICMIQ6AEISzAL#v=onepage&q=AAR%20%20wheel%20design&f=false

According to the above book, at 2.6.6, the AAR standard wheel thickness for Light rail
vehicles is, if I read it correctly, 145mm. This is 10 to 20mm wider than most of the UK
wheel profiles, which are down to 115mm for some trams (excluding the Crich trams which
have even narrower wheels). Para 2.6.6 gives the reasons for having a wider tread when
not using flange running.

I have no idea what dimensions the IWLR and the CSELR use for their flangeways, flange
widths and wheel treads, but I cannot help thinking that given the use of the railway
standard points on the IWLR - which are no longer needed as the connexion with the Goods
Lines has been severed, never likely to be reopened - it would be desirable to convert all
the railway style points to flange running, so there is no problem with the wheels falling
into the gap at frogs. At the same time, it would be desirable to reduce flangeway widths
at frogs to 26mm as peer YT standard (fat chance I hear you say, copy Melbourne? No
way!).

-----Original Message-----
From:TramsDownUnder@... [mailto:TramsDownUnder@yahoogroups.com]
Sent: Sunday, 17 September 2017 4:06 PM
To:TramsDownUnder@...
Subject: Re: [TramsDownUnder] Re: Tram-train: where did we go wrong?

On 17/09/17 00:37, Mal Rowemal.rowe@... [TramsDownUnder] wrote:

>> The attached is part of a drawing with an original date of 1995 and it makes reference

to an even older ABB drawing. And presumably Karlsruhe had to solve this issue 'way back'.
>>

>> The key item is the stepped wheel back.

>>

>

> Is this only a major issue when you keep railway style points?

>


Yes.
I believe back when the Sydney Light Rail wass being planned, the mills along the line
were still operating. So the system was designed to allow wheat trains to access the mill
at Jones Street near the fish market at what is now the Wentworth Park tram stop. The mill
closed before the light rail project even started and was an abandoned factory by the time
the trams started running.

Despite the mill ceasing to operate (and others along the goods line following over the
next few years) the railway points were kept in the design, even on the Dulwich Hill
'extension' where they quite definitely cut the connection to the heavy rail network.


Shortly after the line opened, the residents next to Wentworth Park made many complaints
about the noise from the trams, and thus 'fillers' were put in the frogs so the wheels
would flange run through the points instead of banging through them. Thus the points can
no longer take a rail vehicle anyway.
At the same time one of the Variotrams (I think 2102, but would have to look it up) was
fitted with a flange lubrication system. Just one tram fitted with this cut down the
flange squeal for the entire fleet.


It's not clear what modifications will be needed to allow the street wheel profile Citadis
to access the Lilyfield maintenance centre - there are several sets of railway geometry
points between Haymarket and Lilyfield.

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Posted by: Matthew Geier matthew@...>
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