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Bill Anderson

Well-Known Member
Some railroads converted old/obsolete/unwanted diesel units to "slugs." The "donor" unit's diesel power plant was removed and its traction motors received electricity from a "mother" unit to which it was mated. Slugs were used during high tonnage, low speed operations where a high revving prime mover might generate too much electricity and burn out its traction motors.

The Milwaukee Road employed slugs converted from old F7B units on the Tacoma Hill in the 70's.

My question for the membership: Is there any reason why a slug made from an old B unit could not also house an auxiliary fuel tank to give the "mother" unit extra range? I thought of this for a model railroad project, but I don't want to model something that would be technically impossible.
Slugs are typically used in yards, so range isn't a problem. Also if there was a fuel tank on the slug, there would need to be a method to get the fuel from the slug to the locomotive, which isn't something you want connected via a hose between the trains. What if the train brakes a knuckle? Diesel spill?
Auxiliary fuel tenders are nothing new, so I assume the matter of safely running fuel between the tender and the engine has been resolved. The UP used fuel tenders on their gas turbines in the 50's and 60's. Some of these same fuel tenders are used today with the UP's oil burning steam engines.

In the 1980's, Burlington Northern modified tank cars for use as fuel tenders for use on both mainline freights and helpers on Crawford Hill in Nebraska. The fuel tenders enabled road diesels to run between the Midwest and Pacific Coast on hotshot trains without refueling stops. The tenders also enabled helpers on Crawford Hill to remain in service longer before they had to be run to a refueling facility.

Plans for my HO model railroad empire include Athearn FM Trainmasters heading up cross country ore trains. The Trainmasters had rather small fuel tanks, so I thought of using old AHM dummy FM C-Liner B units as fuel tenders. I think one B unit coupled between two Trainmasters would look better than a tank car and be easier to model. As long as the B unit is being used as a fuel tender, why not keep its traction motors to help the Trainmasters start up the heavy ore trains and climb slow, steep grades? The traction motors of slugs are usually cut out at speeds over 10-15 mph.

The B unit's original outside fuel tank could be used. I wondered if there would be problems with an auxiliary fuel tank housed inside the B unit body, such as total weight on the frame or flammable fumes circulating near the traction motors.
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