As I said, I couldn't find the details online. However, I would guess that something like that or a little more is a reasonable "as installed" tolerance with the rest of the range reserved for wear over time.
--- On Sun, 3/8/09, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> wrote: > From: Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> > Subject: Re: [USMA:43511] Re: Metric discussion on the railroad list (1) > To: jmsteele9...@sbcglobal.net, "U.S. Metric Association" <usma@colostate.edu> > Date: Sunday, March 8, 2009, 6:03 PM > So what this all means is that all of the sub-millimeter > lengths that those opposed to metric would insist on being > there is all nonsense. A 1440 mm gauge would work just as > well as a 1430 mm. > > Jerry > > > > > ________________________________ > From: John M. Steele <jmsteele9...@sbcglobal.net> > To: U.S. Metric Association <usma@colostate.edu> > Sent: Sunday, March 8, 2009 1:50:04 PM > Subject: [USMA:43511] Re: Metric discussion on the railroad > list (1) > > > > My calculator says 37 mm. However, other articles say the > forces tend to widen the gauge, and ultimately that sets the > need for maintenance. So I would guess a fraction of that > is initial tolerance, and part is allowance for widening > over time. I couldn't find details online though. > > Also the shape of the railhead, wheel and flange are all > somewhat complex shapes and controlled. > > > --- On Sun, 3/8/09, Jeremiah MacGregor > <jeremiahmacgre...@rocketmail.com> wrote: > > > From: Jeremiah MacGregor > <jeremiahmacgre...@rocketmail.com> > > Subject: Re: [USMA:43495] Re: Metric discussion on the > railroad list (1) > > To: jmsteele9...@sbcglobal.net, "U.S. Metric > Association" <usma@colostate.edu> > > Date: Sunday, March 8, 2009, 1:28 PM > > Interesting. That is a 27 mm tolerance. The > average of > > the two extremes is 1441.5 mm. This means that the > > railroads track widths can easily be stated as 1440 mm > as it > > will fall within the tolerance. This also means that > > vehicles built for the railroads may also experience > such a > > large tolerance (maybe not as large as 27 mm) and thus > when > > being built can be expressed in round numbers. > > > > Carleton should express this information to his > Railroad > > Engineer forum friend. > > > > > > Jerry > > > > > > > > ________________________________ > > From: John M. Steele > <jmsteele9...@sbcglobal.net> > > To: U.S. Metric Association <usma@colostate.edu> > > Sent: Sunday, March 8, 2009 12:33:57 PM > > 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.
