Ringo58
EMD 567 Non-Transition Switcher
EMD 567 Non-Transition 12 Cylinder
What does non transition mean?
To add to what's been said above: I read somewhere (but have not verified) that old EMD switchers do not make transition. They don't reach high speeds, plus, as I understand it, it's not a problem to be in too low a transition position (i.e. 1 when you should be in 4) but it is a problm to be too high (4 when you should be in 1), so it would make sense that switchers, which need to pull heavy loads, could do without transition. I think we have some switcher operator manuals at the club and I'll look -- I used to have one floating around here (SW1/NW2) and I don't believe it referred to transition.
That said, if that's right, I can't guess what EMD locos other than switchers would have 12-cyl engines and not make transition.
If it hasn't been covered (I'm tired and forgot what I read), on manual-transition locos, transition was made by looking at the ammeter, which had sections labeled 1, 2, 3, 4 corresponding to postions of the transition lever. When you were pulling hard at low speeds, power draw (amps) would be high, and you'd require a lower transition setting. As speed rose, amperage draw lowered and you would "shift" into higher transition position.
I believe EMD introduced automatic transition with the F3 (or perhaps during its run) where the lever stayed in one position, but locos retained their four-position transition levers because you still needed to "shift" if you had manual-transition locos in the consist.
Also IIRC you only had to reduce throttle (down to run 6) for certain transition steps. Reducing power was a problem because lower speed meant higher power draw and you could slip below the locomotive's minimum continuous speed rating.
Actually there are more positions because the transition lever (technically called the selector, I believe) also controlled the dynamic brake.
HTH
Aaron