Wheel standards

[Richard R]

Hi there All,

Have been talking to a supplier about buying ready turned wheels. They say that their wheel profiles are to the dimensions in Martin Evans book.

My society apparently stipulates that wheels need to be turned to SMEE standards. Are the dimensions in Martin Evans books and the SMEE wheel standards one in the same thing?

Any thoughts anyone.


Yours,


Rich

[alanstepney]

The two are very similar and, from memory, only on minor dimensions.
I doubt that the differences would be noticed.

[puffernutter]

What gauge is this?

I assume 5" as the 7.25" society has its own set of standards for "standard" and "narrow gauge" profile.

Cheers

Peter

[Richard R]

Cheers Alan, that's useful to know.

Peter - the standards I'm considering are those for 5" gauge. What you say about the 7.25" gauge standards sounds familiar, although I'm curous about how you could get the two different wheel standards to work on club track, or is it all heavily compromised to give the same back to back distances and the same width of flange on the wheels?


Yours,


Rich.

[alanstepney]

(Also posted on the modeleng email list.)

I checked on the differences between the Martin Evans and SMEE standards and, the latest figures are that they are identical.
Was not always so as originally there were some slight differences, but nothing that was significant or noticeable.

However, Martin has published some designs in which the engines have wheels with parallel treads, and strictly speaking these would not be to the standards.
(His S & D 2-8-0 is one.)

The only other common (?) standard is the one by Dennis Monk used at Derby, in which there are two differences from SMEE, which are, the back-to-back is 31 thou less and flange way on the track is 28 thou more than SMEE.
Not enough to make much, if any, difference to anyone, although it is possible that clearances might be tight if you used SMEE and ran on Derby's track.

There have been a few proposed modifications to the SMEE standards which some people might gave used.
These include such things as a double-coned tread, and increasing the tread coning angle from 2 to, assorted figures between 2.25 and 2.75 degrees.I believe Martin Evans proposed using 2.25.

Whilst there might be some, perhaps excellent, technical reasons why figures other than 2 degrees might be better, in practice I doubt that it would make much difference.
That, of course, assumes that you CAN actually make them to an accuracy within fractions of a degree.

These figures are all for 5" gauge.

Alan

[russell]

I wonder why we are still discussing wheel standards when there are agreed European Standards.

In July 1988 a meeting took place in Guildford at the instigation of the French club, the CAV, to adress the problem of model railway standards with more engines traveling between various European countries for meetings or being sold. After two years of work standards where agreed and these were published as Normes Européeannes (European Standards) in January 1991.

There are two standards;
NEDG 310: European Standards for steam garden railways; Axles and wheels, rails and points.
NEDG 311: European Standards for steam garden railways; Wheel profiles.

The differences between these and Martin Evans standards are slight but they are a bit more comprehensive, for example defining the flange profile and giving tolerances where necessary.

If we work with these we know there will be no problems when visiting tracks in other European countries.

Russell.