Re: "Out-of-Square" valves on #484

#484 has been "out-of-square" since at least last September - see [ngdiscussion.net].

"Out-of-square" means that one (or both) of the valves that control the admission of steam to
the cylinder(s) is (are) out of adjustment. Assuming the usual inside-admission piston valves
as on all the ex-D&RGW mikes these days, if the spool is a bit too far forward then too much
steam is allowed to enter in front of the piston on the "push" stroke, and too little steam behind
the piston on the "pull" stroke. The result is an uneven thrust on each stroke and thus an uneven
Chug-CHUG-Chug-chug sound.  If the valve is WAY out of adjustment and the engine is moving
very slowly with a heavy load, there may not be enough inertia to carry it through the weak stroke
and it will stall.

Aggravated by a problem with her sanders, this is what appears to have happened to #484 after
crossing Lobato Trestle last September 29th ...   See [ngdiscussion.net]

- Russo



Edited 2 time(s). Last edit at 06/04/2010 09:07PM by Russo Loco.