We are missing one key element in a slug. Typically Santa Fe built their slugs, with transformers on board. The step-up transformers would convert the power coming in from the mother ship...ahh...I mean locomotive (to much Star Trek). This power is then converted to full power and the slug MU'd with the Yard Locomotive, producing enough power to move long strings of freight cars, within Yard Limits. Downside they weren't able to operate at main line speeds. The F7A #359 a B unit in Santa Fe passenger red and silver. The question is, is this a slug?. Not likely. This picture was discussed on another web site and it was determined that the unit was being moved to the deadline. If you look at the grime, grease and oil on the locomotive it appears to have blown out all the oil. Another prime mover bites the dust. The F7B's in ATSF blue pin stripe. These were actually used as remote control units to control train helper units. If you look at the bottom of these you will see the fuel tanks have been removed. Look at the top and you will see a good sized antenna. MR's and rail fans alike made the mistake of calling these "Slugs"...not so. The F7 car body makes it difficult to remove the prime mover and rather then try to pull it out through the roof Santa Fe elected to keep them as is. Many were later turned into CF7's and those units where the prime mover had died, were either traded back or torched. Knowing Santa Fe as well as I do, I wouldn't put it past them to try using one or two as "Slugs". However, the F units, had inherent problems with safety due to the lack of visibility. This safety issue was apparent right from the get go or manufacturers build date. Thus the GP's came into being with improved visibility, to handle the switching and yard duty. At the time Amtrak took over passenger service many of these F units were leased to Amtrak. Those remaining saw the boiler works removed and concrete and metal weights added in their place. This would provide better adhesion / traction... without using traction tires. Grin, you know good and well, I had to say that! There is an ATSF, F-7, what we MR's call B unit, that shows up here in this thread... in what appears to be slug service. I checked out the picture and the accompanying information. At first I was puzzled as the information refers to it as an "A" unit. So, was the cab removed? No not at all. Santa Fe used a LABC designation for what we model railroaders, MR's, call an ABBA set. It is this "A" designation that is referred to. To my best knowledge of the subject Santa Fe didn't use the F units LAB or C, as slugs. They retained their prime mover until their demise. If you look at the slugs Santa Fe operated they are longer then the F units and are cut down to allow for crew visibility. Some Eastern Railroads may have experimented with slugs, a concept for mainline service but it didn't last very long. They opted for the standard prime mover thus giving them the flexibility to operate at main line speeds. Here in the west, (the true west) SP and UP did something similar. SP did experiment with a cut down version to aide with breaking over Donner Pass and called them "Brake Sleds". Only two were converted and the suits decided it wasn't worth the effort so the program was dropped. During my short stay in Dayton, OH. I was able to talk to the crews at the CSX Yard, Dayton, OH and learned they used a GP 30 and operated it as a slug for a short period of time. Seems to me Conrail had a similar unit working their yard as well. Cheap conversion. Well, that should do it for now. I hope that helps.
Did find this pic in my search for one of my fav Santa Fe locos #2964. Evidently 2964 was involved in a firery crash in Ca. and wound up BNSF 3971...a yard slug. These chopped down locos are what I vision as 'slugs' when I hear the term...as applied to railroading...thnxs http://rrpicturearchives.net/showPicture.aspx?id=510045 .
George, That's an authentic ATSF approved "Slug". Picture capture, taken in the Barstow ATSF Yard. How about that. Good topic and interesting discussion.
