Standard guage all over the world is 1435 mm. However Russia (and the old
USSR, as well as some satellite states such as Finland) used - quite why for
totally metric countries - a gauge of 5' 0" (1520 mm). Ostensibly that was
to preserve Russian sovereignty by preventing through running of trains from
Western Europe. I do not know however quite why an imperial dimension was
used in a totally metric country. Does anyone know the answer to this?
----- Original Message -----
From: "Martin Vlietstra" <vliets...@btinternet.com>
To: "U.S. Metric Association" <usma@colostate.edu>
Sent: Sunday, March 08, 2009 8:10 PM
Subject: [USMA:43526] Re: Metric discussion on the railroad list (1)
The US standard rail gage was derived from the British standard gauge of
4ft
8½in (1435.1 mm). However the Irish works out in round numbers in both
metric and imperial units - 1600 mm differs from 5ft 3in by 0.2 mm - well
within tolerance limits.
-----Original Message-----
From: owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf
Of John M. Steele
Sent: 08 March 2009 16:34
To: U.S. Metric Association
Subject: [USMA:43495] Re: Metric discussion on the railroad list (1)
Assuming Wikipedia is correct, the tolerance of 1435 mm gauge track is
1423
mm to 1460 mm for track rated for 60 MPH travel. I assume lower grade
(lower speed) track is allowed a wider tolerance. Thus, that 0.1 mm
confusion in nominal is entirely negligible.
I assume the tolerance is asymmetric because the width can not be narrower
than maximum wheel flange spacing (the flanges are on the inside, and
ideally do not touch)
http://en.wikipedia.org/wiki/Rail_gauge
--- On Sun, 3/8/09, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com>
wrote:
From: Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com>
Subject: [USMA:43489] Re: Metric discussion on the railroad list (1)
To: "U.S. Metric Association" <usma@colostate.edu>
Date: Sunday, March 8, 2009, 11:53 AM
Carleton,
> Also in the design of railroad equipment, can you tell us
what the usual tolerance ranges usually are? You are
correct that in the world they don't get precise to
sub-millimeter precision unless they have to. They would
round everything to whole numbers if it wouldn't effect
the outcome or if it falls within acceptable tolerances.
The standard rail gage in the US is 56.5 inches, which
equals 1435.1 mm. Everywhere else it is equal to exactly
1435 mm. I don't know anything about railroads but I
bet that nowhere will one find the tracks consistently 1435
mm due to many factors that distance will vary to some
degree. There is constant exposure to heat and cold.
There are movements in the earth which can shift tracks,
etc. Thus to worry about sub-millimeter lengths is
ridiculous.
