[N&W] eccentric crank

nw-mailing-list at nwhs.org nw-mailing-list at nwhs.org
Thu May 6 22:04:04 EDT 2004

[Oops! Should have put this with Ed's reply.]

To answer the question posed by Ben Blevins on the eccentric crank, on a
steam locomotive it is connected to the pin of the driver where the main
rod(the one from the cylinders) and is used to operate the valve gear.
The crank is offset either forward or backward between 15 and 25
degrees, as near as I have been able to determine from photos, so that
the drivers will move when steam is applied to the cylinders.  When
moving the crank end traces an elliptical path, look closely at steam
videos to see what it looks like.  With the exception of some S and O
scale models, I have not seen a brass locomotive come in with the crank
set right(which I immediately correct).


Kurt S. Kramke

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