From: Anthony New <>
Subject: Re: "00" Gauge wheel/track standards (longishpost)
Date: 25 Nov 1999 00:00:00 GMT
Newsgroups: uk.rec.models.rail

Here as promised are the results of my tests of rolling stock for flange
depth and back-to-back measurements. I haven't measured the flange width
for various reasons, including the belief that the two basic
measurements are the key to most of the problems I have encountered, but
I accept that these should ideally be considered as well to ensure
satisfactory frog hopping, so to speak. The table was formatted without
tabs for a constant-width font in 77 cols.

I have also repeated the Peco specifications and recommendations for
their 00/H0 track.
Measurements are all in mm, and were measured by a (Draper) vernier
caliper, cross-checked against a a good engineering micrometer, which
agree within 0.02mm at 14mm. Although the calipers have a resolution of
0.02mm, I don't consider the measurements to be reliable/meaningful to
better than around 0.1mm in this application. I have measured several
wheels/axles of each type and any with severe warp were discounted,
however a small amount of warp is inevitable on plastic axles.

The results are interesting in several ways:

Firstly, as far as flange depth is concerned this isn't really an issue.
Only the very early Triang (pre-1960?) stock such as the early knurled
wheels fails to run properly on code-100 rail, and all except some of
the other Triang/Hornby (ie pre-1970?) has flanges within 1.2mm and
should run on code-75 rail (as indeed it seems to in my experience).
Even Hornby-Dublo and Wren are ok on this by measurements, though I have
heard reports that some Lima items may have problem flanges (can anyone
provide measurements for these?).

In back-to-back measurements (BB) the situation is more complicated;
Peco recommend a nominal BB of 14.5mm and a minimum BB of 14.3mm, which
on my tests only the GRAFAR, Mainline, Bachmann, and some Dapol would
just about meet (ie a few probably wouldn't). The NMRA spec of 14.4mm
min BB and 0.71mm flange depth would exclude *all* current uk-outline
rtr locomotive manufacturers (Bachmann for flange depth, the rest for
BB); Of the stock I've tested only the Mainline and Dapol would pass and
they aren't made any longer! For the EM-based finescale standard of
14.8mm suggested, none of the items tested would pass except (amusingly
enough) the early Triang split-axle type which can be easily set to
14.8mm and if necessary held there with a spot of glue!

Let me restate here that I consider for "00" gauge any standards *must*
be suitable for the majority of rolling stock in existance without
large-scale modification (this is the only purpose of rtr "00" gauge
after all), and therefore any finescale standards which require complete
re-wheeling have no_value_whatever in "00" gauge - anyone prepared to go
to this length would be better off changing to EM, P4, etc.

It is all very well to re-wheel old coaches and wagons to finer scale
wheels (I've been doing this myself for 25 years), but large changes in
BB are IMHO simply neither practicable or desirable for a locomotive
fleet, though the odd gentle tweak may be possible.
So what can we say about BB for rtr stock?

A minimum BB setting of 14mm dead (14.0mm if you prefer) would appear to
be suitable for all except Hornby but would leave little margin for
error - 13.9 would be preferable IMHO. I note that most of Hornby
products will meet a 13.9mm BB, the exceptions being mainly the square
axle wheels used in wagons for a while. A minimum BB of 14.3mm would
just about suit Bachmann, but no-one else. I could add that the
finer-scale wheels that Bachmann produce look nice but might suffer from
problems at point frogs if the large BB prevents the check-rail from
operating correctly when the point is constructed to accept other rtr

Whatever finescale modellers may think, I don't think a spec for rtr
products which excludes all of the products of one of the leading
manufacturers can be acceptable. ISTM therefore that the manufacturer
that is out of step is not Hornby but Peco - if trying to produce track
to a standard that simply does not suit a large proportion of all the
rtr "00" stock in existance.

As for the NMRA - get real!

OK, I've had my say - what do you think?

Table follows:
Make               Wheel/Axle Type         Flange Depth     Min BB     Max BB
Hornby Dublo       2-rail, loco                  1.2          14.2       14.4
Hornby Dublo       plastic 1-piece               1.0          13.9       14.2
Triang-Wren        metal, loco                   1.2          14.3       14.3
Wren               plastic                       1.1          14.1       14.2
Triang, 1950's     solid wheel, loco             1.5          13.7       14.0
Triang, 1960?      early knurled, loco           1.5          13.7       13.9
Triang, 1970       late knurled, loco            1.1          13.9       13.9
Triang, 1960's     early split axle              1.1          13.9       14.8
Hornby, 1970's     late split axle               1.0          14.0       14.3
Triang-Hornby      plain tyre loco, spoked       1.3          13.7       13.9
Triang-Hornby      early coarse                  1.2          13.4       13.8
Triang-Hornby      early white rim               1.1          14.1       14.5
Triang-Hornby      late white rim                1.0          13.8       14.1
Hornby, 1980's     square axle, metal tyre       1.0          13.4       13.4
Hornby, 1990's     plastic 1-piece               1.0          13.9       13.9
Hornby, 1990's     loco (tender drive)           1.0          13.9       14.1
Grafar             metal, loco                   1.0          14.3       14.4
Grafar             plastic                       1.0          14.3       14.4
Ratio              plastic                       0.95         13.9       14.4
Lima               metal, loco                   0.9          14.2       14.3
Airfix             plastic                       0.9          14.0       14.1
Mainline           metal, loco                   0.7          14.5       14.5
Dapol              plastic                       0.7          14.4       14.5
Bachmann           plastic wheel                 0.8          14.3       14.4
Bachman            all-metal spoked              0.85         14.3       14.4

Peco Track    Track nom. depth     Flange rec depth        min BB        max FF
Code-75            1.346                 1.143              14.3           15.2
Code-100           1.6                   1.397              14.3           15.2
Recommended nominal back-back setting:  14.5

Track nominal depth is the height between the top of the rail and the
top of the chairs. The BB and FF for code-100 rail is not stated
separately in the leaflet and is assumed to be the same as for code-75


The biggest problem today is that people don't recognise
a reductio ad absurdam when they see one.

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