--- In STMFC@..., Denny Anspach <danspach@...> wrote:
Aha, Denny I see you are adding a new requirement to the sets of
quality issues of trucks and wheelsets. ;-)
Since I have no layout to make my stuff roll only endplay is what I am
looking for. OTOH every layout here would never reach those gigantic
dimensions an attic in California presents to run long trains. So the
issue of rollability is a somewhat secondary thought.
I found that the internal form of the trucksides' bearings are a major
factor of how endplay and maximum rollability are interacting. It the
very end (tip) of the bearing hole has seen some wear it becomes wider
than the nominal cone is was produced with in the first place. That
means the tip of the axle is not riding on the cone but a point
somewhat closer to the wheel. Which makes the diameter of the axle
larger than the (not) ideal point at the end of the axles. Therefore
more resistance if endplay is reduced to the minimum and more
rollability if the axle becomes shorter. In the latter case the tip
comes out of the widenend area at the end of the bearing and gets back
onto the regular cone. This in turn makes the axle touch with its tip
again reducing roll resistance.
I wonder how much the rollability factors in in the pulling ability of
the loco. Would a "standard" Athearn Genesis F9 be able to pull
considerably more cars as one will put behind it anyway? I think US-
practice is to use multiple unit engines in this case. With other
words: will the rollability improvement have a real effect on trains'
length that are run on model layouts?
What is the experience here?