I was recently sitting in the cab of an EMD SW9 with a B engine that had a complete overhaul. The timing etc. was freshly adjusted. The cab shakes rather intense when the engine is sitting at idle. What would cause something like this and is there a way to fix it? It's a good thing I don't have fillings, or they probably would have fallen out!

Could be a problem with the generator, we have an old one sitting on the floor that supposedly vibrated the whole loco pretty bad.

I seem to recall when one of the DL&W F units at Steamtown had a coupling go bad between the prime mover and the air compressor, one of the symptoms was that at certain throttle positions the locomotive shook in rhythm with the prime mover. Being that it's an end cab switcher, the fans are driven directly from the prime mover and spin constantly. That could be another source of vibration.

Agreeing with Baldwin and the problem perhaps being with the generator... Had a MARC GP-39-2 which shook so bad you could stand in the cab without holding on. Turns out some lead-putty which had been used to balance the generator had come loose and been lost. Re-balanced the generator and the problem went away.

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It could also me caused by mis-alignment when the main generator was applied or shifted as a result of impact. Check for loose base bolts and sheared or missing dowel pins.

With the engine running observe the movement of the brushes in the brush holders. If the com is really out of whack it will be apparent. With a properly dialed in generator the brushes will be motionless. As strange as it may be an out of alignment generator will also sound differently than one running true.

EBL

It's like my Norwegian friend always said, "If it's not one thing it's two things".