Bob, Sam, et al, I believe it is quite reasonable to assume much of the difference in the "sound of the FTs is due to the exhaust manifold differences with the FTs as opposed to later F units and other EMD 567x engined locomotives. Think "Cherry Bombers" as opposed to stock exhausts. I'd bet there were considerable manifold back pressure differences with four exhaust stacks rather than two. About the dynamic brakes, three things come to mind in order of increasing likelihood which would affect the sound: First the way the dynamic brake vents were located on the FTs could present a rather different frequency distribution heard from outside the units. Second, the FTs had mechanically driven cooling fans rather than electrically driven fans of the other F units. And probably the most important and likely factor is that the original FT dynamic brakes had a very narrow operational range. All through EMD production the dynamic brakes were improved with a wider usable range. The lowest usable, controllable speed improved with each model release. As the electrical characteristics of traction motors and other components improved, the lowest safe speed of the dynamic brakes improved. This certainly would impact what was heard, different harmonics, etc. Preston or Jimmy might be the people to ask for a more conclusive response. Regards, Will Dlw1el2_@_aol.com wrote: > > I can't comment on the sound. They all had 567A engines. Maybe the four > exhausts slightly altered the sound? Same with the Dynamic Brake sound being > different, unexplainable! > > Bob Bahrs > The Erie Lackawanna Mailing List Sponsored by the ELH&TS http://www.elhts.org ------------------------------
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