Santa Fe Other Rolling Stock & Misc. Cabooses: Keel Middleton wrote about the gull wing cabooses, and incidentally about ore and coal on the Santa Fe: Allen is correct that the Gull Wing cabs on the 500s and 800s were designed to clear the loader at York Canyon. As a footnote, Kaiser Steel shut down its Fontana, CA mill in 1984. I don't know when the last coal train ran, but it would have been before that, and well before the widenose GE's showed up. Coal continued to come out of York Canyon through the 80's and into the 90's, just not heading for Fontana. Allen Clum responded: True, when Kaiser closed the Fontana mill the York Canyon mine was forced to find another customer for the coal and the entire personality of the train changed at that time. Enter the big GEs and exit the Transco coal gons. The coal no longer went west but east instead. I believe the new customer was Wisconsin Electric in Milwaukee WI. The Transco gons were replaced by I believe, the 5 pocket rapid discharge hopppers. The trains I saw had three or four GEs on the point and no mid trains and Fred instead of a caboose. The trains were too heavy for Raton Pass in one bite so the train ran from theYork Canyon mine to the town of Raton NM where the train was broken in three pieces and each piece was taken over the pass to Trinidad CO. When the triple was completed the train was put back together and headed east. This lasted till the York Canyon mine closed. About slugs Kevin Wood wrote: Road Slugs (and the yard slugs as well) get their power from the main generator of the mother unit.The EMD locomotives chosen for road mother duty is usually GP40-2 units with a few being GP38-2 units. The slugs are in the CSX 2200-2300 number series.The slugs are made from former GP30, GP35, GP38, GP39 and GP40 units.The slugs have complete cabs with all controls for lead operation.The Dash-2 Mother units are equipped with AR10 Main Generators (actually an alternator with integral rectifiers) that has the capability to pump out 4200 amps @ 1200 volts.This power is then fed to 4 traction motors in parallel on the mother. The power is also fed to the slug through 4 heavy cables between the units.AC from the companion alternator on the mother feeds the traction motor blowers on the slug through a 3 phase cable.The MU cable and an additional 23 pin MU cable carry control voltages to and from the slug, including lighting.The slugs are equipped with dynamic braking.At slow speeds, the horsepower output is much more than the single unit can reasonably use at the rail, account of wheel slip, etc.By connecting the slug to the mother unit, 4 more traction motors are available for tractive effort at slow speed without incurring the use of more fuel for another locomotive.The road slugs have their traction motors wired in series-parallel similar to old GP7/9/18 so as to not to draw too much from the main generator.Once the units are up to speed, the slug makes transition to parallel and becomes nearly useless. But at that point, who cares. Its the starting tractive effort that counts in this situation.As for tractive effort ratings, the slug is nearly rated as a 4 axle locomotive.Thus you get more tractive effort for the fuel cost.The other great advantage is that pairing the mother-slug sets in a back to back configuration allows the control of the mother unit to be handled from a control stand in the slug.In fact, the cabs are setup identical, except the slug is real quiet and therefore loved by the crews.Mother-slug sets are perfect for road switcher assignments and MofW trains where the ability to swap ends easily and operate short hood forward for safety sake is important.Yard slugs (since we are on the subject) are much simpler machines.Most of our (CSX) slugs are built on retired GP7/9/18 frames. We also have a small handful of 6 axle yard slugs built from old RS27 ALCO units. These units do not have cabs.The yard slug has all of its traction motors hard wired in series and once the speed reaches the point of first transition (about 20MPH) the slug drops completely out.These slugs are great in the yard environment, such as a hump yard like Tilford.At Tilford Yard we have 3 mother-slug yard sets that work the receiving yard/hump.In this case, they are SD40-2 units in the 2400 number series mated with 4 axle slugs (1000 number series).In the case for both types of slug, the engine, equipment rack and compressor have all been removed and replaced with a large block of concrete to get the weight.The fuel tanks are now sealed but when the road slugs were first built, the tanks carried fuel and had a transfer pump to supply fuel to the fuel tank on the mother unit.It did not take long for the transfer hoses to get ruptured between units and they finally did away with that practice.