"Trimming" Both Engines of a Mallet

NW Mailing List nw-mailing-list at nwhs.org
Sat Jul 23 11:55:13 EDT 2022

In the US there was always a single lever, the reverser, to adjust cutoff
on compound locos. In France it was discovered that having individual
cutoff control of the hp and lp cylinders increased efficiency but required
more engineer training.
John Rhodes

On Sat, Jul 23, 2022, 10:48 AM NW Mailing List <nw-mailing-list at nwhs.org>

> I woke up this morning thinking about this question.  Never thought about
> it before.  It must be the hot weather...
> By what mechanism or linkage is the steam cut-off of both the front and
> the rear engines of a Mallet properly adjusted, simultaneously, from the
> single power reverse cylinder (as in the case of reversing the engine or
> "trimming" the cut-off for speed and efficiency) ?
> A little thought leads me to believe that two reach rods must have been
> connected to the business end of the power reverse cylinder... but I never
> remember seeing two rods.  If so, I bet the rod reaching to the valve gear
> of the front engine had a turnbuckle it, for adjustment.
> Bonus Question:  How was this function accomplished on the first N&W
> Mallets, the Class X engines?  Or was the power reverse already invented
> and in place at that time?
> Sorry to be a pest, but such things trouble me.  Perhaps I need
> counseling, huh...?
> He who gives guidance and slakes my conscience on this matter shall
> receive a gift box of our finest T-things... you know.
> -- abram burnett
> July is World Turnip Month -- Eat Mo' Turnips
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