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REF: Uncompensated Wagon Weight vs. NMRA

Posted: Fri Jun 21, 2019 2:17 pm
by Proto87Stores
For reference, and having spent several years as a member of the then NMRA standards Dept:

The NMRA recommended practice for wagon weighting has no theoretical basis as far as I am aware. But was produced on the basis of experience with the US style of model wagons, trains and and track curves. Applying those suggestions to UK P4 is rather risky, as the conditions of US modelling are quite different.

1. There are almost no US style 4 wheel wagons. At the time of testing, typical wagons were bogie units, a scale 40 ft long.
2. US wagons do not have buffers. All pushing is done via (recommended) body mounted couplers.
3. The wheels used were/are 0.110" wide with 0.038-0.030 flange depth. Scale 33" wheel diameter. (note this effects Nadal's formula)
4. The NMRA standards apply to radii as small as 18", with a typical min. radius for large/club layouts of 24", including full 360 turns and more for helixes, etc..
5. Train lengths on large layouts are commonly in the 25-100 wagon range.

P4 needs its own well thought out and dependable weighting values. As per my earlier missing post, I would strongly recommend that subject should be incorporated in an updated Suspension Digest.

Andy

Typo in: REF: Uncompensated Wagon Weight vs. NMRA

Posted: Fri Jun 21, 2019 3:36 pm
by proto87stores
Typo: previous wheel flange depth range should be 0.028" -0.030"

Andy